<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article  PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" dtd-version="3.0" xml:lang="en" article-type="research article"><front><journal-meta><journal-id journal-id-type="publisher-id">JWARP</journal-id><journal-title-group><journal-title>Journal of Water Resource and Protection</journal-title></journal-title-group><issn pub-type="epub">1945-3094</issn><publisher><publisher-name>Scientific Research Publishing</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.4236/jwarp.2019.116048</article-id><article-id pub-id-type="publisher-id">JWARP-93420</article-id><article-categories><subj-group subj-group-type="heading"><subject>Articles</subject></subj-group><subj-group subj-group-type="Discipline-v2"><subject>Earth&amp;Environmental Sciences</subject></subj-group></article-categories><title-group><article-title>
 
 
  Removing Iron Ions Contaminants from Groundwater Using Modified Nano-Hydroxyapatite by Nano Manganese Oxide
 
</article-title></title-group><contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Mohammed</surname><given-names>Abd-El-Aal Ahmed Ayash</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref><xref ref-type="corresp" rid="cor1"><sup>*</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Tarek</surname><given-names>Ahmed Seaf Elnasr</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref><xref ref-type="corresp" rid="cor1"><sup>*</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Madiha</surname><given-names>Hassan Soliman</given-names></name><xref ref-type="aff" rid="aff3"><sup>3</sup></xref><xref ref-type="corresp" rid="cor1"><sup>*</sup></xref></contrib></contrib-group><aff id="aff1"><addr-line>Sohag Company for Water and Waste Water, Dar El Salam, Sohag, Egypt</addr-line></aff><aff id="aff3"><addr-line>Chemistry Department, Faculty of Science, Helwan University, Cairo, Egypt</addr-line></aff><aff id="aff2"><addr-line>Chemistry Department, Faculty of Science, Al-Azhar University, Assiut, Egypt</addr-line></aff><pub-date pub-type="epub"><day>06</day><month>06</month><year>2019</year></pub-date><volume>11</volume><issue>06</issue><fpage>789</fpage><lpage>809</lpage><history><date date-type="received"><day>26,</day>	<month>May</month>	<year>2019</year></date><date date-type="rev-recd"><day>27,</day>	<month>June</month>	<year>2019</year>	</date><date date-type="accepted"><day>30,</day>	<month>June</month>	<year>2019</year></date></history><permissions><copyright-statement>&#169; Copyright  2014 by authors and Scientific Research Publishing Inc. </copyright-statement><copyright-year>2014</copyright-year><license><license-p>This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/</license-p></license></permissions><abstract><p>
 
 
  In this article, we study modified nano-hydroxyapatite (HAp) by nano manganese oxide (Mn
  <sub>3</sub>O
  <sub>4</sub>) as adsorbent material to remove iron ions from groundwater. Different parameters were studied to option optimum conditions of removing such as contact time, pH, initial concentration, a dosage of adsorbent, agitation speed and temperature. Kinetics studies included first order (
  R
  <sup>2</sup> = 0.915), pseudo-first order (
  R
  <sup>2</sup> = 0.936), second order (
  R
  <sup>2</sup> = 0.948), pseudo-second order (
  R
  <sup>2</sup> = 0.995), Elovich equation model (
  R
  <sup>2</sup> = 0.977), intraparticle diffusion (
  R
  <sup>2</sup> = 0.946), Natarajan and Khalaf (
  R
  <sup>2</sup> = 0.915) were carried out, the obtained results revealed that the pseudo-second order is the best to describe the adsorption process because the correlation coefficient is approaching one (
  R
  <sup>2</sup> = 0.995). Adsorption isotherm was calculated by using Freundlich, Langmuir and Temkin constants, adsorption capacity from Langmuir model was 0.606 mg/g. Thermodynamic parameters (Δ
  G, Δ
  H = −51 KJ/mol, and Δ
  S = −142 (KJ/mol)) for the adsorption process were also calculated and discussed.
 
</p></abstract><kwd-group><kwd>Groundwater</kwd><kwd> Adsorption</kwd><kwd> Nano Materials</kwd><kwd> Hydroxyapatite</kwd><kwd> Manganese Oxide</kwd><kwd> Iron Ions</kwd><kwd> Kinetic</kwd><kwd> Thermodynamic</kwd></kwd-group></article-meta></front><body><sec id="s1"><title>1. Introduction</title><p>Groundwater is an important resource for the livelihoods and food security of billions of people. It is one of the most difficult problems that pollute the groundwater and the presence of iron. Therefore, in this article, we try to find a solution to the problems of iron in the groundwater [<xref ref-type="bibr" rid="scirp.93420-ref1">1</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref2">2</xref>] .</p><p>Among the appropriate solutions to remove or reduce the proportion of iron in the groundwater is Ion exchange [<xref ref-type="bibr" rid="scirp.93420-ref3">3</xref>] , Reverse osmosis [<xref ref-type="bibr" rid="scirp.93420-ref4">4</xref>] , Chemical precipitation [<xref ref-type="bibr" rid="scirp.93420-ref5">5</xref>] , Electrolysis [<xref ref-type="bibr" rid="scirp.93420-ref6">6</xref>] and Adsorption [<xref ref-type="bibr" rid="scirp.93420-ref7">7</xref>] , the choice of which depends upon the type and concentration of both sorptive material and sorbent employed, as well as their costs [<xref ref-type="bibr" rid="scirp.93420-ref8">8</xref>] .</p><p>Among these, the adsorption method is more commonly used, adsorption is an effective technology to remove different contaminated from aqueous solutions. In this process, a very high rate of adsorption and excretion occurs. The simple function has caused this method to be one of the best ways to remove iron ions from groundwater such as Polyvinyl alcohol was used for removal of bromothymol blue and methylene blue from [<xref ref-type="bibr" rid="scirp.93420-ref9">9</xref>] . Removal of natural organic matter and its constituents from water by metal oxides and hydroxides based adsorbents were investigated [<xref ref-type="bibr" rid="scirp.93420-ref10">10</xref>] . Fluoride removal capacity from drinking water by Adsorption using nano-sized Alumina and Zirconia modified Alumina was tested [<xref ref-type="bibr" rid="scirp.93420-ref11">11</xref>] . Removal of Cu(II) and Zn(II) by unmodified Lignocellulosic Fibrous Layer of Palm Tree Trunk-Single was studied [<xref ref-type="bibr" rid="scirp.93420-ref12">12</xref>] . Removal of Cu(II) ions from water by rice husk (S.E. Abd Elhafez et al. 2016) [<xref ref-type="bibr" rid="scirp.93420-ref13">13</xref>] , Pb (II), La (III), and Ag (I) ions was removed from aqueous solutions using mediated cellulose nanofibers [<xref ref-type="bibr" rid="scirp.93420-ref14">14</xref>] . Adsorptive of ibuprofen and diclofenac from water using metal-organic framework-derived porous carbon was investigated [<xref ref-type="bibr" rid="scirp.93420-ref15">15</xref>] . Removal of Cr(VI) by a free metal material containing only C, N and O, and having environmental friendliness, was studied [<xref ref-type="bibr" rid="scirp.93420-ref16">16</xref>] . Removal of benzotriazole and benzimidazole from water over a Co-based metal azolate framework MAF-5(Co) was investigated [<xref ref-type="bibr" rid="scirp.93420-ref17">17</xref>] .</p><p>In this work, we have used modified nano hydroxyapatite by (Mn<sub>3</sub>O<sub>4</sub>) nanoparticles to remove the iron ions from water by adsorption; parameters such as contact time, pH, adsorbent dosage, stirring speed and temperature were investigated. Kinetic, Isotherm Adsorption and Thermodynamic parameters (ΔG, ΔH, and ΔS) for adsorption process were also calculated and discussed.</p></sec><sec id="s2"><title>2. Materials and Methods</title><sec id="s2_1"><title>2.1. Apparatus</title><p>We had all the measurements of pH using Misura Line 1010 pH meter (Romania). All samples are stirred and heated by multiple Heating Magnetic Stirrer (VELP Scientifica) during experimental procedures as well, as micropipette (100 - 1000 μL) is also used. Spectrophotometer Instruments (CECIL3021), Brand (Cambridge, England). Determine the iron ions by Phenanthroline method. The samples were first mixed with KBr and then pressed into pellets. X-ray powder diffraction (XRD) data were collected at room temperature using a Philips 1710 Diffractometer. The patterns were run with Cu target and Ni filter (λ = 1.5418 A˚) at 40 KV and 30 mA in the range of 2θ, with a scanning speed of 06 deg/s. Fourier transform infrared spectroscopy (FTIR) data were collected using a Perkin-Elmer spectrometer model 1430 in the wave number range from 4000 to 400 cm<sup>−1</sup> Examination on the TEM: Samples were examined by carbon coated grids with a JEOL 1010 Transmission Electron Microscope, made in Japan, at the Regional Center for Mycology and Biotechnology (RCMB), Al-Azhar University.</p></sec><sec id="s2_2"><title>2.2. Procedures</title><sec id="s2_2_1"><title>2.2.1. Synthesis of Hydroxyapatite (HAp)</title><p>We have prepared HAp powder using the titration between both H<sub>3</sub>PO<sub>4</sub>, adwic 85% in burette and CaCl<sub>2</sub>∙2H<sub>2</sub>O, Sigma-Aldrich, 99% - 103% in a beaker until adjustment the pH at a value of 10. Through the addition of NH<sub>4</sub>OH solution (adwic 30%) during the mixing process using a hotplate for heating the reaction mixture and stirring according to the following equation:</p><p>10CaCl<sub>2</sub>∙2H<sub>2</sub>O+6H<sub>3</sub>PO<sub>4</sub> + 20NH<sub>4</sub>OH → Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>(OH)<sub>2</sub> + 20NH<sub>4</sub>Cl + 38H<sub>2</sub>O (I)</p><p>The mixture was heated in a microwave oven for 10 min until completely dryness and formation the precipitate, and then it was washed with distilled water and filtrated. The precipitate dried by microwave for 4 min [<xref ref-type="bibr" rid="scirp.93420-ref18">18</xref>] .</p></sec><sec id="s2_2_2"><title>2.2.2. Synthesis of Manganese Oxide</title><p>We can manufacture nano-manganese oxide (Mn<sub>3</sub>O<sub>4</sub>) by oxidation of MnCl<sub>2</sub> solution with a concentrated H<sub>2</sub>O<sub>2</sub> solution, followed by the addition of an NH<sub>3</sub> aq. solution. The suspension thus obtained was treated at 90˚C [<xref ref-type="bibr" rid="scirp.93420-ref19">19</xref>] . With microwave for 7 mint to dryness and formation the precipitate, then it was washed with distilled water and filtrated. The precipitate dried by microwave for 3 min.</p></sec><sec id="s2_2_3"><title>2.2.3. Synthesis of Modified Hydroxyapatite Manganese Hydroxide (HApMn)</title><p>We have been able to prepare three modifications to test the removal of iron ions first (0.04 HAp:0.06 Mn<sub>3</sub>O<sub>4</sub>) second (0.06 HAp:0.04 Mn<sub>3</sub>O<sub>4</sub>) and the third (0.08 HAp:0.02 Mn<sub>3</sub>O<sub>4</sub>). The percentage of removing iron ions were (R%) = 49%, 47%, and 30% respectively. We chose (0.06 HAp:0.04 Mn<sub>3</sub>O<sub>4</sub>) R% = 47% and have found that the best modification is. Three composed of Modification of HAp by Mn<sub>3</sub>O<sub>4</sub> were prepared and exam to remove iron ions, to complete this study.</p></sec></sec><sec id="s2_3"><title>2.3. Analytical Methods</title><p>Amount of adsorbent of iron on happening at any time (q<sub>t</sub>) was calculated as follows [<xref ref-type="bibr" rid="scirp.93420-ref8">8</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref9">9</xref>] :</p><p>q t = ( C o − C t ) V / m (1)</p><p>where, C<sub>o</sub> and C<sub>t</sub> are the concentrations of iron ions at initial and equilibrium time, respectively (mg/L), V is the solution volume (L) and m is the mass of dry adsorbent used (g). At equilibrium, q<sub>e</sub> = q<sub>t</sub> and C<sub>t</sub> = C<sub>e</sub>; therefore, the amount of sorbed metal ion (q<sub>e</sub>) was calculated according to Equation (2)</p><p>q e = ( C o − C e ) V / m (2)</p><p>The removal efficiency (RE%) is calculated according to the following equation [<xref ref-type="bibr" rid="scirp.93420-ref12">12</xref>] :</p><p>RE ( % ) = ( ( C o − C e ) / C o ) &#215; 100 (3)</p></sec></sec><sec id="s3"><title>3. Results and Discussion</title><sec id="s3_1"><title>3.1. Characterizations</title><p><xref ref-type="fig" rid="fig1">Figure 1</xref>(a) shows the FTIR (Fourier transform infrared spectroscopy) of HAp. The broad bands in the regions 1600 - 1700 cm<sup>−1</sup> and 3200 - 3600 cm<sup>−1</sup> correspond to H-O-H bands of lattice water. The bands characteristics of the phosphate and hydrogen phosphate groups in apatite environment are observed at 565, 632, 603, 962, and 1000 - 1100 cm<sup>−1</sup> for PO 4 3 − and at 875 cm<sup>−1</sup> for HPO 4 2 − [<xref ref-type="bibr" rid="scirp.93420-ref18">18</xref>] .</p><p>FTIR of the Manganese Oxide sample is shown in <xref ref-type="fig" rid="fig1">Figure 1</xref>(b). Several absorption bands can be observed at 500 - 1000 cm<sup>−1</sup> for (Mn-O), 3000 - 3500 cm<sup>−1</sup> stretching, the 1636. While the 606, 564, 510.2 and 417 cm<sup>−1</sup> bands should be ascribed to the Mn–O vibrations in MnO<sub>6</sub> octahedral [<xref ref-type="bibr" rid="scirp.93420-ref19">19</xref>] .</p><p>FTIR results indicate the presence of some bounded water to HApMn.</p><p><xref ref-type="fig" rid="fig2">Figure 2</xref>(a) and <xref ref-type="fig" rid="fig2">Figure 2</xref>(b) shows XRD (X-ray Diffraction) patterns of the</p><p>HAp and Mn<sub>3</sub>O<sub>4</sub> samples, respectively. The intensive diffraction peaks appeared at 25.9, 28.9, 31, 32.3, 33, 33.9, 36.9, 39.2, 44.3, 46.4, 47.8, 49.5, 51.22, 53.4, 58.4, 60.2, 64.5, 74.4, 76.7 and 55.9 are assigned to the characteristic peaks for Mn-O, and the peaks occurred at respectively, should be ascribed to the characteristic peaks for Mn-O [<xref ref-type="bibr" rid="scirp.93420-ref19">19</xref>] . Hence, the sample appears to be composed of a majority of HApMn. Scherer equation can be written as [<xref ref-type="bibr" rid="scirp.93420-ref7">7</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref20">20</xref>] :</p><p>D = K λ / β cos θ (4)</p><p>where D is the crystal size (nm), λ is the wavelength of X-ray light, β is the full width of the half maximum of the diffraction peak, and θ is the diffraction angle. Shape factor of K is usually taken as 0.9. It was found that the particle sizes were 4.2 nm and 3.6 nm for HAp and Mn<sub>3</sub>O<sub>4</sub>, respectively. The result is tabulated in <xref ref-type="table" rid="table1">Table 1</xref>.</p><p><xref ref-type="fig" rid="fig3">Figure 3</xref>(a) and <xref ref-type="fig" rid="fig3">Figure 3</xref>(b) show TEM (Transmission electron microscopy) of HAp profiles and Mn<sub>3</sub>O<sub>4</sub> profiles respectively.</p></sec><sec id="s3_2"><title>3.2. Study of Adsorption Factors</title><p>We have used a Patch method for all adsorption work, 100 ml of sample (2- 10) ppm, temperature (25 - 75)˚C, pH (3 - 8), contact time (5 - 90) min, the speed of agitation (100 - 8000) rpm, iron ions concentration was measured before placing</p><table-wrap id="table1" ><label><xref ref-type="table" rid="table1">Table 1</xref></label><caption><title> Size of HAp and Mn<sub>3</sub>O<sub>4</sub> calculate by XRD (Scherer equation) and measured by TEM</title></caption><table><tbody><thead><tr><th align="center" valign="middle"  colspan="2"  >Calculate by Scherer equation (XRD)</th><th align="center" valign="middle"  colspan="3"  >From TEM</th></tr></thead><tr><td align="center" valign="middle" >HAp</td><td align="center" valign="middle" >Mn<sub>3</sub>O<sub>4</sub></td><td align="center" valign="middle" ></td><td align="center" valign="middle" >HAp</td><td align="center" valign="middle" >Mn<sub>3</sub>O<sub>4</sub></td></tr><tr><td align="center" valign="middle" >Distance</td><td align="center" valign="middle" >Distance</td><td align="center" valign="middle" >Statistical Function</td><td align="center" valign="middle" >Distance</td><td align="center" valign="middle" >Distance</td></tr><tr><td align="center" valign="middle" >nm</td><td align="center" valign="middle" >Nm</td><td align="center" valign="middle" >Base Unit</td><td align="center" valign="middle" >nm</td><td align="center" valign="middle" >Nm</td></tr><tr><td align="center" valign="middle" >22.62</td><td align="center" valign="middle" >8.91</td><td align="center" valign="middle" >Count</td><td align="center" valign="middle" >5</td><td align="center" valign="middle" >5</td></tr><tr><td align="center" valign="middle" >26.38</td><td align="center" valign="middle" >9.09</td><td align="center" valign="middle" >Mean</td><td align="center" valign="middle" >23.58</td><td align="center" valign="middle" >9.20</td></tr><tr><td align="center" valign="middle" >18.66</td><td align="center" valign="middle" >11.52</td><td align="center" valign="middle" >Minimum</td><td align="center" valign="middle" >18.66</td><td align="center" valign="middle" >8.14</td></tr><tr><td align="center" valign="middle" >28.42</td><td align="center" valign="middle" >8.34</td><td align="center" valign="middle" >Maximum</td><td align="center" valign="middle" >28.42</td><td align="center" valign="middle" >11.52</td></tr><tr><td align="center" valign="middle" >21.79</td><td align="center" valign="middle" >8.14</td><td align="center" valign="middle" >Standard Deviation</td><td align="center" valign="middle" >3.86</td><td align="center" valign="middle" >1.35</td></tr><tr><td align="center" valign="middle" ></td><td align="center" valign="middle" ></td><td align="center" valign="middle" >Cal. by XRD</td><td align="center" valign="middle" >4.2</td><td align="center" valign="middle" >3.6</td></tr></tbody></table></table-wrap><p>the adsorbent and after putting them for different samples obtained from different wells as shown in <xref ref-type="table" rid="table2">Table 2</xref>. Various adsorption parameters for the effective removal of iron ions using modified hydroxyapatite as an adsorbent from aqueous solution were studied and optimized.</p><sec id="s3_2_1"><title>3.2.1. Effect of Contact Time</title><p>We have studied the effect of contact time in different time periods ranging from 5 to 90 min with the initial metal concentration of 2 ppm iron ions in presence 0.1 g of HApMn with continuous stirring at 400 rpm and at pH 6 [<xref ref-type="bibr" rid="scirp.93420-ref21">21</xref>] . Remove iron ions over time, where it was about 25% in 5 minutes and reached 60% in 90 minutes see <xref ref-type="fig" rid="fig4">Figure 4</xref>.</p></sec><sec id="s3_2_2"><title>3.2.2. Effect of pH</title><p>PH is an important factor in the adsorption process. The pH of 3 - 8 is determined</p><table-wrap id="table2" ><label><xref ref-type="table" rid="table2">Table 2</xref></label><caption><title> Iron ion concentrations of well samples before and after treatment</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >no</th><th align="center" valign="middle" >Place (well name)</th><th align="center" valign="middle" >well name</th><th align="center" valign="middle" >Before Ppm</th><th align="center" valign="middle" >After Ppm</th></tr></thead><tr><td align="center" valign="middle" >1</td><td align="center" valign="middle" >New Awolad Khalf</td><td align="center" valign="middle" >3</td><td align="center" valign="middle" >0.94</td><td align="center" valign="middle" >0.22</td></tr><tr><td align="center" valign="middle" >2</td><td align="center" valign="middle" >New Awolad Khalf</td><td align="center" valign="middle" >4</td><td align="center" valign="middle" >1.03</td><td align="center" valign="middle" >0.23</td></tr><tr><td align="center" valign="middle" >3</td><td align="center" valign="middle" >New Awolad Khalf</td><td align="center" valign="middle" >5</td><td align="center" valign="middle" >1.1</td><td align="center" valign="middle" >0.24</td></tr><tr><td align="center" valign="middle" >4</td><td align="center" valign="middle" >Arab Elataiat south</td><td align="center" valign="middle" >2</td><td align="center" valign="middle" >0.68</td><td align="center" valign="middle" >0.155</td></tr><tr><td align="center" valign="middle" >5</td><td align="center" valign="middle" >Old Elkhamima</td><td align="center" valign="middle" >3</td><td align="center" valign="middle" >0.58</td><td align="center" valign="middle" >0.12</td></tr></tbody></table></table-wrap><p>by using 30% ammonia solution or 37% hydrochloric acid solution and the same conditions as above. Note that the increase in pH increases the removal iron ions (see <xref ref-type="fig" rid="fig5">Figure 5</xref>). It may be due to precipitation of iron ions as Fe<sup>+3</sup> hydroxide brown precipitate [<xref ref-type="bibr" rid="scirp.93420-ref22">22</xref>] .</p></sec><sec id="s3_2_3"><title>3.2.3. Effect of Agitation Speed</title><p>The effect of the stirring speed on the removal of iron ions under the same experimental conditions is studied by agitation Speed (100 - 800) rpm. The efficiency of the removal was found to increase with increased agitation speed (see <xref ref-type="fig" rid="fig6">Figure 6</xref>). Iron ions increase the speed of stirring [<xref ref-type="bibr" rid="scirp.93420-ref23">23</xref>] .</p></sec><sec id="s3_2_4"><title>3.2.4. Effect of Initial Concentration of Iron Ions</title><p>By studying the effect of iron ion concentration per 100 ml, we found that the removal efficiency was reduced by increasing the concentration of iron per 100 ml see <xref ref-type="fig" rid="fig7">Figure 7</xref> [<xref ref-type="bibr" rid="scirp.93420-ref24">24</xref>] .</p></sec><sec id="s3_2_5"><title>3.2.5. Effect of Temperature</title><p>Under the same experimental conditions the effect of temperature on iron ions removal was studied by varying the temperature from 25˚C to 75˚C. As we see from <xref ref-type="fig" rid="fig8">Figure 8</xref>, as the temperature increases the removal percentage increase [<xref ref-type="bibr" rid="scirp.93420-ref25">25</xref>] .</p></sec><sec id="s3_2_6"><title>3.2.6. Applications of the Method</title><p>Around 100 ml of sample (well water) at pH about 7.4, the temperature at 30˚C, stirring at 400 rpm, stirring time 30 min was used to measure iron ions concentrations.</p></sec></sec><sec id="s3_3"><title>3.3. Kinetics Modeling</title><p>We have done a study the kinetic of adsorption and adsorption rate controls; we found a metal ion uptake rate with a residence time of adsorbate uptake at solid interface solution. We have studied seven equations models, the first-order rate equation, pseudo-first order rate equation, second-order rate equation, pseudo-second order rate equation, intra-particle diffusion, and Elovich equations. See <xref ref-type="table" rid="table3">Table 3</xref> for the parameter values.</p><sec id="s3_3_1"><title>3.3.1. First Order Kinetic Equation</title><p>The equation of a straight line is applicable [<xref ref-type="bibr" rid="scirp.93420-ref12">12</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref26">26</xref>] :</p><p>− ln ( C t / C o ) = K 1 t (5)</p><p>where, C<sub>t</sub> (mg/L) is the concentration at a given time t and C<sub>o</sub> (mg/L) is initial concentration of iron ions in solution. K<sub>1</sub> (min<sup>−1</sup>) is the first order rate constant. The regression R<sup>2</sup> obtained by the linear plot of –ln(C<sub>t</sub>/C<sub>o</sub>) against t (<xref ref-type="fig" rid="fig9">Figure 9</xref>), is shown in <xref ref-type="table" rid="table3">Table 3</xref>, R<sup>2</sup> was greater than 0.9, which indicates a good fit to the experimental data.</p></sec><sec id="s3_3_2"><title>3.3.2. Second Order Kinetic Equation</title><p>The linear version is given by this relationship [<xref ref-type="bibr" rid="scirp.93420-ref12">12</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref26">26</xref>] :</p><p>( 1 / C t ) − ( 1 / C o ) = K 2 t . (6)</p><p>where, k<sub>2</sub> [L/mg/min] is the second order rate constant for the adsorption process, determined from the linear plot of (1/C<sub>t</sub> – 1/C<sub>o</sub>) against t, shown in (<xref ref-type="fig" rid="fig1">Figure 1</xref>0) for iron ions. See <xref ref-type="table" rid="table3">Table 3</xref>, for the value of the constants. The</p><table-wrap id="table3" ><label><xref ref-type="table" rid="table3">Table 3</xref></label><caption><title> Summary of kinetic modeling parameters</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >No</th><th align="center" valign="middle" >Kinetics model</th><th align="center" valign="middle" >Parameters</th><th align="center" valign="middle" >Value</th></tr></thead><tr><td align="center" valign="middle"  rowspan="2"  >1</td><td align="center" valign="middle"  rowspan="2"  >First-order rate equation –ln(C<sub>t</sub>/C<sub>o</sub>) = K<sub>1</sub>t</td><td align="center" valign="middle" >K<sub>1</sub> (min<sup>−1</sup>)</td><td align="center" valign="middle" >0.0116</td></tr><tr><td align="center" valign="middle" >R<sup>2</sup></td><td align="center" valign="middle" >0.915</td></tr><tr><td align="center" valign="middle"  rowspan="2"  >2</td><td align="center" valign="middle"  rowspan="2"  >Second order rate equation [1/C<sub>t</sub>] – [1/C<sub>o</sub>] = K<sub>2</sub>t</td><td align="center" valign="middle" >K<sub>2</sub> (L/mg∙min)</td><td align="center" valign="middle" >0.013</td></tr><tr><td align="center" valign="middle" >R<sup>2</sup></td><td align="center" valign="middle" >0.948</td></tr><tr><td align="center" valign="middle"  rowspan="2"  >3</td><td align="center" valign="middle"  rowspan="2"  >Lagergren pseudo first-order equation. Ln (q<sub>e</sub> – q<sub>t</sub>) = lnq<sub>e</sub> – K<sub>1</sub>t</td><td align="center" valign="middle" >K<sub>1</sub> (min<sup>−1</sup>)</td><td align="center" valign="middle" >−0.018</td></tr><tr><td align="center" valign="middle" >R<sup>2</sup></td><td align="center" valign="middle" >0.936</td></tr><tr><td align="center" valign="middle"  rowspan="3"  >4</td><td align="center" valign="middle"  rowspan="3"  >Pseudo second-order rate equation t / q t = 1 / K 2 q e 2 + t / q e</td><td align="center" valign="middle" >K<sub>2</sub> (g/mg∙min)</td><td align="center" valign="middle" >0.036</td></tr><tr><td align="center" valign="middle" >q<sub>e</sub></td><td align="center" valign="middle" >1.677</td></tr><tr><td align="center" valign="middle" >R<sup>2</sup></td><td align="center" valign="middle" >0.995</td></tr><tr><td align="center" valign="middle"  rowspan="3"  >5</td><td align="center" valign="middle"  rowspan="3"  >Intraparticle diffusion q<sub>t</sub> = K<sub>p</sub>t<sup>1/2</sup> + c</td><td align="center" valign="middle" >c (mg/g)</td><td align="center" valign="middle" >0.196</td></tr><tr><td align="center" valign="middle" >R<sup>2</sup></td><td align="center" valign="middle" >0.946</td></tr><tr><td align="center" valign="middle" >K<sub>p</sub> (mg/g∙min<sup>1/2</sup>)</td><td align="center" valign="middle" >0.143</td></tr><tr><td align="center" valign="middle"  rowspan="3"  >6</td><td align="center" valign="middle"  rowspan="3"  >Elovich equation model q<sub>t</sub> = [1/β]ln[αβ] + [1/β]lnt</td><td align="center" valign="middle" >R<sup>2</sup></td><td align="center" valign="middle" >0.977</td></tr><tr><td align="center" valign="middle" >α</td><td align="center" valign="middle" >0.214</td></tr><tr><td align="center" valign="middle" >b (g/mg)</td><td align="center" valign="middle" >2.691</td></tr><tr><td align="center" valign="middle"  rowspan="2"  >7</td><td align="center" valign="middle"  rowspan="2"  >Natarajan and Khalaf Ln(C<sub>o</sub>/C<sub>t</sub>) = Kt</td><td align="center" valign="middle" >K (min<sup>−1</sup>)</td><td align="center" valign="middle" >0.0116</td></tr><tr><td align="center" valign="middle" >R<sup>2</sup></td><td align="center" valign="middle" >0.915</td></tr></tbody></table></table-wrap><p>regression value (R<sup>2</sup>) is greater than 0.9 for iron ions. Indicating that the equation can be applied to experimental data for iron ions.</p></sec><sec id="s3_3_3"><title>3.3.3. Pseudo First Order Kinetic Equation</title><p>The mathematical relationship to describe the pseudo-motif model proposed by Lagergren is shown in equation [<xref ref-type="bibr" rid="scirp.93420-ref12">12</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref27">27</xref>] :</p><p>ln ( q e − q t ) = ln q e − K 1 p t (7)</p><p>where K<sub>1</sub> is the rate constant of pseudo-first order adsorption (L/min). q<sub>e</sub> and q<sub>t</sub> are adsorption capacity (mg/g) at equilibrium and at any time t, respectively. The value of the constants q<sub>e</sub>, k<sub>1</sub> and R<sup>2</sup> obtained from the linear plot of ln(q<sub>e</sub> − q<sub>t</sub>) vs t (<xref ref-type="fig" rid="fig1">Figure 1</xref>1) are shown in <xref ref-type="table" rid="table3">Table 3</xref>. The regression rate R<sup>2</sup> &gt; 0.9 For iron ions.</p></sec><sec id="s3_3_4"><title>3.3.4. Pseudo-Second Order Kinetic Equation</title><p>The linear relationship of pseudo-second order kinetic model is given by [<xref ref-type="bibr" rid="scirp.93420-ref12">12</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref23">23</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref24">24</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref25">25</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref27">27</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref28">28</xref>] :</p><p>t / q t = 1 / K 2 q e 2 + t / q e (8)</p><p>where K<sub>2</sub> (g/mg/min) is the rate constant of pseudo-second order adsorption rate constant. The values of k<sub>2</sub>, R<sup>2</sup> and q<sub>e</sub> were calculated from the plots of t/q<sub>t</sub> on the vertical axis, and t (min) on the horizontal axis (<xref ref-type="fig" rid="fig1">Figure 1</xref>2) as shown in <xref ref-type="table" rid="table3">Table 3</xref>. The regression R<sup>2</sup> &gt; 0.9, for iron meaning that this model provided the best fit for the adsorption data.</p></sec><sec id="s3_3_5"><title>3.3.5. Elovich Equation</title><p>The Elovich equation used to describe the kinetics of chemisorption of gas on solids, The linear relationship is given by [<xref ref-type="bibr" rid="scirp.93420-ref12">12</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref23">23</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref24">24</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref25">25</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref27">27</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref28">28</xref>] :</p><p>q t = ( 1 / β ) ln ( α β ) + ( 1 / β ) ln t (9)</p><p>where, the constants α and β were obtained from the slope and intercept of the linear plot of q<sub>t</sub> (mg/g) against ln(t, min) as shown in (<xref ref-type="fig" rid="fig1">Figure 1</xref>3), for the adsorption of iron ions on HApMn.</p></sec><sec id="s3_3_6"><title>3.3.6. Intra-Particle Diffusion Rate Equation</title><p>The intra-particle diffusion equation [<xref ref-type="bibr" rid="scirp.93420-ref12">12</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref28">28</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref29">29</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref30">30</xref>] is given as Equation (10) shown in <xref ref-type="fig" rid="fig1">Figure 1</xref>4.</p><p>q t = k p t 1 / 2 + C (10)</p><p>where, K<sub>p</sub> (mg/g∙min<sup>1/2</sup>) is the intraparticle diffusion rate constant and C is the intercept. by drawing q<sub>t</sub> on the Y-axis against t (min) on X-axis we can find the slope, intercept and correlation coefficient as seen in <xref ref-type="table" rid="table3">Table 3</xref>, it was observed that the intraparticle diffusion rate constant increased with an increase in initial concentrations.</p></sec><sec id="s3_3_7"><title>3.3.7. Natarajan and Khalaf</title><p>Natarajan and Khalaf equation [<xref ref-type="bibr" rid="scirp.93420-ref31">31</xref>] developed a relationship between the initial concentration and concentration at any time. The linear form is expressed as:</p><p>ln ( C o / C t ) = K n ⋅ t (11)</p><p>where, C<sub>t</sub> is the concentration of iron (mg/L) at time t. The plot of ln(C<sub>o</sub>/C<sub>t</sub>) against t will give a straight line and the value of k<sub>n</sub> can be obtained from the slope of the graph (<xref ref-type="fig" rid="fig1">Figure 1</xref>5). The values of k<sub>n</sub> and R<sup>2</sup> are shown in <xref ref-type="table" rid="table3">Table 3</xref>. The correlation coefficient R2 for the pseudo second order kinetic model is greater than 0.99.</p></sec></sec><sec id="s3_4"><title>3.4. Adsorption Isotherms</title><p>Adsorption data are generally described by adsorption isotherms, such as Freundlich, Langmuir, and Temkin isotherm models.</p><sec id="s3_4_1"><title>3.4.1. Freundlich Isotherm</title><p>This model proposes monolayer sorption with a heterogeneous energy distribution of active sites, accompanied by interactions between adsorbed molecules. The general form of this model is presented in the following equation [<xref ref-type="bibr" rid="scirp.93420-ref12">12</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref32">32</xref>] :</p><p>q e = K F C e 1 / n (12)</p><p>The linear form of the Equation (12) is [<xref ref-type="bibr" rid="scirp.93420-ref12">12</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref33">33</xref>] :</p><p>ln q e = ln K F + 1 / n ln C e (12a)</p><p>This isotherm relates the amount of solute adsorbed at equilibrium per weight</p><p>of adsorbent where q<sub>e</sub> (mol/g) to the adsorbate concentration at equilibrium C<sub>e</sub> (mol/dm<sup>3</sup>), is the most widely non-linear sorption models used. K<sub>F</sub> (mg/g) stands for adsorption capacity and 1/n stands for adsorption intensity.</p><p>By plotting of lnq<sub>e</sub> on Y-axis versus lnC on X-axis we can determine K<sub>F</sub> and 1/n from a slope and intercept respectively (<xref ref-type="fig" rid="fig1">Figure 1</xref>6).</p></sec><sec id="s3_4_2"><title>3.4.2. Langmuir Isotherm</title><p>The Langmuir model [<xref ref-type="bibr" rid="scirp.93420-ref8">8</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref26">26</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref29">29</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref32">32</xref>] describes adsorption as a monolayer surface corresponding to solids with identical homogeneous sites. This is according to the following linear relationship:</p><p>C e / q e = 1 / ( q max b ) + ( 1 / q max ) C (13)</p><p>where q<sub>e</sub> is the amount adsorbed (mg/g), C<sub>e</sub> is the equilibrium concentration of the adsorbate ions (mg/L), q<sub>max</sub> and b are Langmuir constants. Where, q<sub>max</sub> (mg/g) is Langmuir constant related to maximum adsorption capacity (monolayer capacity) andb (L/mg) is the energy of adsorption.</p><p>By plotting of C<sub>e</sub>/q<sub>e</sub> versus C<sub>e</sub> should indicate a straight line of slope 1/q<sub>max</sub> and an intercept of 1/q<sub>max</sub> b.</p><p><xref ref-type="fig" rid="fig1">Figure 1</xref>7: shows Langmuir isotherm for iron ions adsorption at various initial iron ions concentrations using HApMn at adsorbent dosage of 0.1 g, agitation speed of 400 rpm, solution pH 6 and temperature of 30˚C. Based on the correlation coefficient (R<sup>2</sup>) shown in <xref ref-type="table" rid="table4">Table 4</xref> the adsorption isotherm can be better described by Langmuir equation. Also, the Langmuir equation yields a better fit of the experimental data than the Freundlich equation. Further, the essential characteristics of Langmuir isotherm can be described by a separation factor R<sub>L</sub>, which indicates the shape of the isotherm and nature of the adsorption process. this is expressed by the following equation [<xref ref-type="bibr" rid="scirp.93420-ref8">8</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref29">29</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref30">30</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref34">34</xref>] .</p><p>R L = [ 1 / ( 1 + b C o ) ] (14)</p><p>where C<sub>o</sub> is the initial concentration of iron ions (mg/L). The separation factor When R<sub>L</sub> is greater than 1, the process is unfavourable, R<sub>L</sub> = 1, Linear, 0 &lt; R<sub>L</sub> &lt; 1, favorable and R<sub>L</sub> = 0 irreversible. In this study, the Calculated values for R<sub>L</sub> are</p><table-wrap id="table4" ><label><xref ref-type="table" rid="table4">Table 4</xref></label><caption><title> Adsorption isotherms constants</title></caption><table><tbody><thead><tr><th align="center" valign="middle"  colspan="3"  >Freundlich</th><th align="center" valign="middle"  colspan="3"  >Langmuir</th><th align="center" valign="middle"  colspan="3"  >Temkin</th></tr></thead><tr><td align="center" valign="middle" >K<sub>f</sub> (mg/g)</td><td align="center" valign="middle" >1/n</td><td align="center" valign="middle" >R<sup>2</sup></td><td align="center" valign="middle" >q<sub>max</sub> (mg/g)</td><td align="center" valign="middle" >B (L/mg)</td><td align="center" valign="middle" >R<sup>2</sup></td><td align="center" valign="middle" >KT (L/mg)</td><td align="center" valign="middle" >β (g/mg)</td><td align="center" valign="middle" >R<sup>2</sup></td></tr><tr><td align="center" valign="middle" >1.255</td><td align="center" valign="middle" >−0.222</td><td align="center" valign="middle" >0.799</td><td align="center" valign="middle" >0.603</td><td align="center" valign="middle" >−0.837</td><td align="center" valign="middle" >0.958</td><td align="center" valign="middle" >0.002</td><td align="center" valign="middle" >−0.201</td><td align="center" valign="middle" >−0.853</td></tr></tbody></table></table-wrap><p>found to be a fraction in the range of 0 - 1 (0.442), an indication that the adsorption process is favorable [<xref ref-type="bibr" rid="scirp.93420-ref35">35</xref>] .</p></sec><sec id="s3_4_3"><title>3.4.3. Temkin Isotherm</title><p>The linear form of the Temkin equation is given by [<xref ref-type="bibr" rid="scirp.93420-ref8">8</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref29">29</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref30">30</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref36">36</xref>] :</p><p>q e = β ln K T + β ln C e (15)</p><p>where, β which is related to the heat of adsorption, and KT (L/mg) is the equilibrium binding constant corresponding to the maximum binding energy. By plotting q<sub>e</sub> on Y-axis versus on X-axis we can be calculated β and KT calculated from the slope and the intercept. <xref ref-type="fig" rid="fig1">Figure 1</xref>8: shows Temkin model isotherm for iron ions adsorption at various initial iron ions concentrations using HApMn at adsorbent dosage of 0.1 g, agitation speed of 400 rpm, solution pH 6 and temperature of 25˚C.</p></sec></sec><sec id="s3_5"><title>3.5. Thermodynamic Parameters</title><p>Thermodynamic parameters [<xref ref-type="bibr" rid="scirp.93420-ref37">37</xref>] such as and entropy (ΔS), enthalpy (ΔH) and free energy (ΔG) were determined using Equations (16)-(19):</p><p>K c = q e / C e (16)</p><p>Δ G = − R T ln K c (17)</p><p>Ln K c = ( − Δ H / R ) ( 1 / T ) + Δ S / R (18)</p><p>where q<sub>e</sub> is the amount of solute adsorbed on the adsorbent cubic decimeter of the solution at equilibrium, K<sub>c</sub> is the equilibrium constant, and C<sub>e</sub> (mol/dm<sup>3</sup>) is the equilibrium concentration of the solute in solution, T is temperature in Kelvin and R (8.314 J/K/mol) is the gas constant. By plotting of on Y-axis against 1/T on X-axis we found ΔH and ΔS were obtained from the slope and intercept of Vant Hoff isotherm (<xref ref-type="fig" rid="fig1">Figure 1</xref>9). <xref ref-type="table" rid="table5">Table 5</xref> shows the calculated values of the thermodynamic parameters.</p><p>In order to understand this process better, we must calculate the entropies and enthalpies of temperature periods using the previous equations [<xref ref-type="bibr" rid="scirp.93420-ref32">32</xref>] [<xref ref-type="bibr" rid="scirp.93420-ref38">38</xref>] :</p><p>Δ G ˚ = Δ H ˚ − T Δ S ˚ (19)</p><p>where, K<sub>c</sub><sub>1</sub> is the equilibrium constant at temperature T<sub>1</sub> and K<sub>c</sub><sub>2</sub> are the equilibrium constant at temperature T<sub>2</sub>.</p><p>Increasing the value of ΔG˚ with increasing temperature leads to the process of adsorption of iron ions on HApMn become preferred in low temperatures. The negative value of ΔH˚ proves that the adsorption process was exothermic reaction and a certain amount of heat developed during the iron ions that adsorbed on the surface of the adsorbents. The more negative value of ΔS˚, the more degree of randomization in the solid/liquid interface during the absorption process where entropy expresses the amount of randomness or disorder in the system.We used entropy (ΔS˚) to determine the degree of disorder or randomness in the system. We know that the higher the negative values of ΔS˚, the lower the degree of randomization in the solid/liquid interface during the adsorption process [<xref ref-type="bibr" rid="scirp.93420-ref39">39</xref>] . The values of ΔH˚ and ΔS˚ calculated from the plot of lnK versus 1/T.</p><p>The value of ΔH˚ was negative, indicating that the adsorption reaction was exothermic (high heat of adsorption). Another equation that has been used to determine the possible adsorption mechanism is the Dubinin-Radushkevick</p><table-wrap id="table5" ><label><xref ref-type="table" rid="table5">Table 5</xref></label><caption><title> Thermodynamic parameters for adsorption of iron ions on HApMn</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >T (K)</th><th align="center" valign="middle" >K<sub>c</sub></th><th align="center" valign="middle" >DG (kg/mol)</th><th align="center" valign="middle" >DH</th><th align="center" valign="middle" >DS</th><th align="center" valign="middle" >R<sup>2</sup></th></tr></thead><tr><td align="center" valign="middle" >298</td><td align="center" valign="middle" >1.5</td><td align="center" valign="middle" >0.405</td><td align="center" valign="middle"  rowspan="4"  >−51</td><td align="center" valign="middle"  rowspan="4"  >−142</td><td align="center" valign="middle"  rowspan="4"  >0.991</td></tr><tr><td align="center" valign="middle" >318</td><td align="center" valign="middle" >0.379</td><td align="center" valign="middle" >−0.969</td></tr><tr><td align="center" valign="middle" >333</td><td align="center" valign="middle" >0.200</td><td align="center" valign="middle" >−1.609</td></tr><tr><td align="center" valign="middle" >348</td><td align="center" valign="middle" >0.127</td><td align="center" valign="middle" >−2.605</td></tr></tbody></table></table-wrap><p>[<xref ref-type="bibr" rid="scirp.93420-ref40">40</xref>] equation, which assumes a constant sorption potential. The linear presentation of this equation is expressed by</p><p>ln q e = ln q m − K E ε 2 (20)</p><p>ε = R T ln ( 1 + 1 / C e ) (21)</p><p>where ε is the Polanyi potential, q<sub>t</sub> is the monolayer capacity (mol/g), C<sub>e</sub> is the equilibrium concentration (mol/dm<sup>3</sup>), and K<sub>E</sub> is the constant related to sorption energy (mol<sup>2</sup>/KJ<sup>2</sup>) The parameters q<sub>t</sub> and K<sub>E</sub> can be obtained from the intercept and slope of the plot as shown in <xref ref-type="fig" rid="fig2">Figure 2</xref>0. The free energy of sorption (E) is calculated by</p><p>E = 1 / ( − 2 K E ) 1 / 2 (22)</p><p>Adsorption type could be estimated by evaluating of E value. If this value is &lt; 8, 8 - 16 or &gt;16 kJ/mol, the adsorption type can be explained by physical adsorption, ion-exchange, or chemical adsorption, respectively [<xref ref-type="bibr" rid="scirp.93420-ref41">41</xref>] . In this case, the adsorption is chemical adsorption at all temperatures because E value was 50 kJ/mol.</p></sec></sec><sec id="s4"><title>4. Conclusion</title><p>In this article, we use Modified HApMn for removing iron ions from groundwater. Adsorption of iron on HApMn follows pseudo-second order kinetic model, Langmuir adsorption isotherm, Adsorption capacity from the Langmuir model is 0.604 mg/g, the adsorption process is chemical type because adsorption energy value is 50 kJ/mol, and adsorption is favorable at low temperatures, the negative value of ΔH˚ confirms that the sorption process is exothermic in nature and a given amount of heat is evolved during the binding iron ions on the surface of adsorbents.</p></sec><sec id="s5"><title>Acknowlegements</title><p>It is my pleasure to express my deepest thanks to Chemistry Department, Faculty of Science, Helwan University, my thanks to Chemistry Department, Faculty of Science, Al-Azhar University, Assiut Branch, for his support and I thank Sohag Company for Water and Waste Water, Dar El Salam, Sohag, Egypt.</p></sec><sec id="s6"><title>Conflicts of Interest</title><p>The authors declare no conflicts of interest regarding the publication of this paper.</p></sec><sec id="s7"><title>Cite this paper</title><p>Abd-El-Aal Ahmed Ayash, M., Elnasr, T.A.S. and Soliman, M.H. (2019) Removing Iron Ions Contaminants from Groundwater Using Modified Nano-Hydroxyapatite by Nano Manganese Oxide. Journal of Water Resource and Protection, 11, 789-809. https://doi.org/10.4236/jwarp.2019.116048</p></sec></body><back><ref-list><title>References</title><ref id="scirp.93420-ref1"><label>1</label><mixed-citation publication-type="other" xlink:type="simple">Hossain, D., Islam, M.S., Sultana, N. and Tusher, T.R. (2013) Assessment of Iron Contamination in Groundwater at Tangail Municipality, Bangladesh. Journal of Environmental Science and Natural Resources, 6, 117-121. https://doi.org/10.3329/jesnr.v6i1.22051</mixed-citation></ref><ref id="scirp.93420-ref2"><label>2</label><mixed-citation publication-type="other" xlink:type="simple">Prentice, A.M., et al. (2017) Dietary Strategies for Improving Iron Status: Balancing Safety and Efficacy. Nutrition Reviews, 75, 49-60. https://doi.org/10.1093/nutrit/nuw055</mixed-citation></ref><ref id="scirp.93420-ref3"><label>3</label><mixed-citation publication-type="other" xlink:type="simple">Abdennebi, N., Benhabib, K., Goutaudier, C. and Bagane, M. (2017) Removal of Aluminium and Iron Ions from Phosphoric Acid by Precipitation of Organo-Metallic Complex Using Organophosphorous Reagent. Journal of Materials and Environmental Science, 8, 557-565.</mixed-citation></ref><ref id="scirp.93420-ref4"><label>4</label><mixed-citation publication-type="other" xlink:type="simple">Dubey, S., Banerjee, S., Upadhyay, S.N. and Sharma, Y.C. (2017) Application of Common Nano-Materials for Removal of Selected Metallic Species from Water and Wastewaters: A Critical Review. Journal of Molecular Liquids, 240, 656-677. https://doi.org/10.1016/j.molliq.2017.05.107</mixed-citation></ref><ref id="scirp.93420-ref5"><label>5</label><mixed-citation publication-type="other" xlink:type="simple">Hosseini, H., Rezaei, H., Shahbazi, A. and Maghsudlu, A. (2016) Application of Nano-Lignocellulose for Removal of Nickel Ions from Aqueous Solutions. Environmental Resource Research, 4, 213-229.</mixed-citation></ref><ref id="scirp.93420-ref6"><label>6</label><mixed-citation publication-type="other" xlink:type="simple">Piuleac, C.G., S&amp;#225;ez, C., Ca&amp;#241;izares, P. and Curteanu, S. (2012) Hybrid Model of a Wastewater-Treatment Electrolytic Process. International Journal of Electrochemical Science, 7, 6289-6301.</mixed-citation></ref><ref id="scirp.93420-ref7"><label>7</label><mixed-citation publication-type="other" xlink:type="simple">Mondal, P., Majumder, C.B. and Mohanty, B. (2008) Effects of Adsorbent Dose, Its Particle Size and Initial Arsenic Concentration on the Removal of Arsenic, Iron and Manganese from Simulated Ground Water by Fe3+ Impregnated Activated Carbon. Journal of Hazardous Materials, 150, 695-702. https://doi.org/10.1016/j.jhazmat.2007.05.040</mixed-citation></ref><ref id="scirp.93420-ref8"><label>8</label><mixed-citation publication-type="other" xlink:type="simple">Javadian, H., Ghorbani, F., Tayebi, H. and Asl, S.H. (2015) Study of the Adsorption of Cd (II) from Aqueous Solution Using Zeolite-Based Geopolymer, Synthesized from Coal Fly Ash; Kinetic, Isotherm and Thermodynamic Studies. Arabian Journal of Chemistry, 8, 837-849. https://doi.org/10.1016/j.arabjc.2013.02.018</mixed-citation></ref><ref id="scirp.93420-ref9"><label>9</label><mixed-citation publication-type="other" xlink:type="simple">Agarwal, S., et al. (2016) Efficient Removal of Toxic Bromothymol Blue and Methylene Blue from Wastewater by Polyvinyl Alcohol. Journal of Molecular Liquids, 218, 191-197. https://doi.org/10.1016/j.molliq.2016.02.060</mixed-citation></ref><ref id="scirp.93420-ref10"><label>10</label><mixed-citation publication-type="other" xlink:type="simple">Bhatnagar, A. and Sillanp&amp;#228;&amp;#228;, M. (2017) Removal of Natural Organic Matter (NOM) and Its Constituents from Water by Adsorption—A Review. Chemosphere, 166, 497-510. https://doi.org/10.1016/j.chemosphere.2016.09.098</mixed-citation></ref><ref id="scirp.93420-ref11"><label>11</label><mixed-citation publication-type="other" xlink:type="simple">Mrinal, D.D., Adak, K., Mondal, B., Dhak, P. and Sen, S. (2017) A Comparative Study on Fluoride Removal Capacity from Drinking Water by Adsorption Using Nano-Sized Alumina and Zirconia Modified Alumina Prepared by Chemical Route. Advances in Water Science and Technology, 4, 1-10.</mixed-citation></ref><ref id="scirp.93420-ref12"><label>12</label><mixed-citation publication-type="other" xlink:type="simple">Abuh, M.A., Akpomie, G.K., Nwagbara, N.K., Abia-Bassey, N., Ape, D.I. and Ayabie, B.U. (2013) Kinetic Rate Equations Application on the Removal of Copper (II) and Zinc (II) by Unmodified Lignocellulosic Fibrous Layer of Palm Tree Trunk-Single Component System Studies. International Journal of Basic and Applied Sciences, 50, 800-809.</mixed-citation></ref><ref id="scirp.93420-ref13"><label>13</label><mixed-citation publication-type="other" xlink:type="simple">Elhafez, S.E.A., Hamad, H.A., Zaatout, A.A. and Malash, G.F. (2017) Management of Agricultural Waste for Removal of Heavy Metals from Aqueous Solution: Adsorption Behaviors, Adsorption Mechanisms, Environmental Protection, and Techno-Economic Analysis. Environmental Science and Pollution Research, 24, 1397-1415. https://doi.org/10.1007/s11356-016-7891-7</mixed-citation></ref><ref id="scirp.93420-ref14"><label>14</label><mixed-citation publication-type="other" xlink:type="simple">Voisin, H., Bergstr&amp;#246;m, L., Liu, P. and Mathew, A. (2017) Nanocellulose-Based Materials for Water Purification. Nanomaterials, 7, 57. https://doi.org/10.3390/nano7030057</mixed-citation></ref><ref id="scirp.93420-ref15"><label>15</label><mixed-citation publication-type="other" xlink:type="simple">Bhadra, B.N., Ahmed, I., Kim, S. and Jhung, S.H. (2017) Adsorptive Removal of Ibuprofen and Diclofenac from Water Using Metal-Organic Framework-Derived Porous Carbon. Chemical Engineering Journal, 314, 50-58. https://doi.org/10.1016/j.cej.2016.12.127</mixed-citation></ref><ref id="scirp.93420-ref16"><label>16</label><mixed-citation publication-type="other" xlink:type="simple">Wang, X., Liang, Y., An, W., Hu, J., Zhu, Y. and Cui, W. (2017) Removal of Chromium (VI) by a Self-Regenerating and Metal Free g-C3N4/Graphene Hydrogel System via the Synergy of Adsorption and Photo-Catalysis under Visible Light. Applied Catalysis B: Environmental, 219, 53-62. https://doi.org/10.1016/j.apcatb.2017.07.008</mixed-citation></ref><ref id="scirp.93420-ref17"><label>17</label><mixed-citation publication-type="other" xlink:type="simple">Sarker, M., Bhadra, B.N., Seo, P.W. and Jhung, S.H. (2017) Adsorption of Benzotriazole and Benzimidazole from Water over a Co-Based Metal Azolate Framework MAF-5(Co). Journal of Hazardous Materials, 324, 131-138. https://doi.org/10.1016/j.jhazmat.2016.10.042</mixed-citation></ref><ref id="scirp.93420-ref18"><label>18</label><mixed-citation publication-type="other" xlink:type="simple">Elkady, M.F., Mahmoud, M.M. and Abd-El-Rahman, H.M. (2011) Kinetic Approach for Cadmium Sorption Using Microwave Synthesized Nano-Hydroxyapatite. Journal of Non-Crystalline Solids, 357, 1118-1129. https://doi.org/10.1016/j.jnoncrysol.2010.10.021</mixed-citation></ref><ref id="scirp.93420-ref19"><label>19</label><mixed-citation publication-type="other" xlink:type="simple">Goti&amp;#263;, M., Jurkin, T., Musi&amp;#263;, S., Unfried, K., Sydlik, U. and Bauer-&amp;#352;egvi&amp;#263;, A. (2013) Microstructural Characterizations of Different Mn-Oxide Nanoparticles Used as Models in Toxicity Studies. Journal of Molecular Structure, 1044, 248-254. https://doi.org/10.1016/j.molstruc.2012.09.083</mixed-citation></ref><ref id="scirp.93420-ref20"><label>20</label><mixed-citation publication-type="other" xlink:type="simple">Abdel Ghafar, H.H., Ali, G.A.M., Fouad, O.A. and Makhlouf, S.A. (2015) Enhancement of Adsorption Efficiency of Methylene Blue on Co3O4/SiO2 Nanocomposite. Desalination and Water Treatment, 53, 2980-2989. https://doi.org/10.1080/19443994.2013.871343</mixed-citation></ref><ref id="scirp.93420-ref21"><label>21</label><mixed-citation publication-type="other" xlink:type="simple">Hamdaoui, O. (2017) Adsorption of Cu(II) from Aqueous Phase by Cedar Bark. Journal of Dispersion Science and Technology, 38, 1087-1091. https://doi.org/10.1080/01932691.2016.1225261</mixed-citation></ref><ref id="scirp.93420-ref22"><label>22</label><mixed-citation publication-type="other" xlink:type="simple">Gupta, V.K., Agarwal, S., Sadegh, H., Ali, G.A.M., Bharti, A.K. and Hamdy Makhlouf, A.S. (2017) Facile Route Synthesis of Novel Graphene Oxide-β-Cyclodextrin Nanocomposite and Its Application as Adsorbent for Removal of Toxic Bisphenol A from the Aqueous Phase. Journal of Molecular Liquids, 237, 466-472. https://doi.org/10.1016/j.molliq.2017.04.113</mixed-citation></ref><ref id="scirp.93420-ref23"><label>23</label><mixed-citation publication-type="other" xlink:type="simple">Gomaa, H., Gomaa, A., Farid, M., Cheira, M., Ahmed, T. and Seaf, S.E.T.A. (2016) Removal of Uranium from Acidic Solution Using Activated Carbon Impregnated with Tri Butyl Phosphate. Biological and Chemical Research, 313-340.</mixed-citation></ref><ref id="scirp.93420-ref24"><label>24</label><mixed-citation publication-type="other" xlink:type="simple">Gomaa, H., et al. (2018) Highly-Efficient Removal of AsV, Pb2+, Fe3+, and Al3+ Pollutants from Water Using Hierarchical, Microscopic TiO2 and TiOF2 Adsorbents through Batch and Fixed-Bed Columnar Techniques. Journal of Cleaner Production, 182, 910-925. https://doi.org/10.1016/j.jclepro.2018.02.063</mixed-citation></ref><ref id="scirp.93420-ref25"><label>25</label><mixed-citation publication-type="other" xlink:type="simple">Abd El-Latif, M.M. and Elkady, M.F. (2011) Kinetics Study and Thermodynamic Behavior for Removing Cesium, Cobalt and Nickel Ions from Aqueous Solution Using Nano-Zirconium Vanadate Ion Exchanger. Desalination, 271, 41-54. https://doi.org/10.1016/j.desal.2010.12.004</mixed-citation></ref><ref id="scirp.93420-ref26"><label>26</label><mixed-citation publication-type="other" xlink:type="simple">Elnasr, A.T.S., Soliman, M.H. and Ayash, M.A.-E.-A.A. (2017) Modified Hydroxyapatite Adsorbent for Removal of Iron Dissolved in Water Wells in Sohag, Egypt. Chemistry of Advanced Materials, 1, 1-13.</mixed-citation></ref><ref id="scirp.93420-ref27"><label>27</label><mixed-citation publication-type="other" xlink:type="simple">Habeeb, O.A., et al. (2016) Modeling and Optimization for H2S Adsorption from Wastewater Using Coconut Shell Based Activated Carbon. Australian Journal of Basic and Applied Sciences, 10, 136-147.</mixed-citation></ref><ref id="scirp.93420-ref28"><label>28</label><mixed-citation publication-type="other" xlink:type="simple">Shah, A.F.S., Ajit, M.S. and Usmani, G.A. (2016) Kinetics Modelling Study: Adsorption of Victoria Blue on Mahaneem Leaf Powder. International Journal of Advanced Scientific and technical Research, 1, 293-302.</mixed-citation></ref><ref id="scirp.93420-ref29"><label>29</label><mixed-citation publication-type="other" xlink:type="simple">Habeeb, O.A., et al. (2016) Modeling and Optimization for H2S Adsorption from Wastewater Using Coconut Shell Based Activated Carbon. Australian Journal of Basic and Applied Sciences, 10, 136-147.</mixed-citation></ref><ref id="scirp.93420-ref30"><label>30</label><mixed-citation publication-type="other" xlink:type="simple">Dehghani, M.H., Sanaei, D., Ali, I. and Bhatnagar, A. (2016) Removal of Chromium (VI) from Aqueous Solution Using Treated Waste Newspaper as a Low-Cost Adsorbent: Kinetic Modeling and Isotherm Studies. Journal of Molecular Liquids, 215, 671-679. https://doi.org/10.1016/j.molliq.2015.12.057</mixed-citation></ref><ref id="scirp.93420-ref31"><label>31</label><mixed-citation publication-type="other" xlink:type="simple">Ioannou, Z. and Simitzis, J. (2009) Adsorption Kinetics of Phenol and 3-Nitrophenol from Aqueous Solutions on Conventional and Novel Carbons. Journal of Hazardous Materials, 171, 954-964. https://doi.org/10.1016/j.jhazmat.2009.06.098</mixed-citation></ref><ref id="scirp.93420-ref32"><label>32</label><mixed-citation publication-type="other" xlink:type="simple">Romero-Gonz&amp;#225;lez, J., Peralta-Videa, J.R., Rodri&amp;#237;guez, E., Ramirez, S.L. and Gardea-Torresdey, J.L. (2005) Determination of Thermodynamic Parameters of Cr(VI) Adsorption from Aqueous Solution onto Agave lechuguilla Biomass. The Journal of Chemical Thermodynamics, 37, 343-347. https://doi.org/10.1016/j.jct.2004.09.013</mixed-citation></ref><ref id="scirp.93420-ref33"><label>33</label><mixed-citation publication-type="other" xlink:type="simple">Zamani, S., Salahi, E. and Mobasherpour, I. (2013) Removal of Nickel from Aqueous Solution by Nano Hydroxyapatite Originated from Persian Gulf Corals. Canadian Chemical Transactions, 1, 173-190. https://doi.org/10.13179/canchemtrans.2013.01.03.0033</mixed-citation></ref><ref id="scirp.93420-ref34"><label>34</label><mixed-citation publication-type="other" xlink:type="simple">Demirk&amp;#305;ran, N., &amp;#214;zdemir, G.D.T., Sara&amp;#231;, M. and Darda&amp;#287;an, M. (2017) Adsorption of Methylene Blue from Aqueous Solutions by Pyrolusite Ore. Mongolian Journal of Chemistry, 18, 5-11. https://doi.org/10.5564/mjc.v18i44.880</mixed-citation></ref><ref id="scirp.93420-ref35"><label>35</label><mixed-citation publication-type="other" xlink:type="simple">Kooh, M.R.R., Lim, L.B.L., Lim, L.H. and Dahri, M.K. (2016) Separation of Toxic Rhodamine B from Aqueous Solution Using an Efficient Low-Cost Material, Azolla pinnata, by Adsorption Method. Environmental Monitoring and Assessment, 188, 1-15. https://doi.org/10.1007/s10661-016-5108-7</mixed-citation></ref><ref id="scirp.93420-ref36"><label>36</label><mixed-citation publication-type="other" xlink:type="simple">Wang, W. and Wang, J. (2018) Comparative Evaluation of Sorption Kinetics and Isotherms of Pyrene onto Microplastics. Chemosphere, 193, 567-573. https://doi.org/10.1016/j.chemosphere.2017.11.078</mixed-citation></ref><ref id="scirp.93420-ref37"><label>37</label><mixed-citation publication-type="other" xlink:type="simple">Foroutan, R., Esmaeili, H., Abbasi, M., Rezakazemi, M. and Mesbah, M. (2018) Adsorption Behavior of Cu(II) and Co(II) Using Chemically Modified Marine Algae. Environmental Technology, 39, 2792-2800. https://doi.org/10.1080/09593330.2017.1365946</mixed-citation></ref><ref id="scirp.93420-ref38"><label>38</label><mixed-citation publication-type="other" xlink:type="simple">Lima, E.C., Hosseini-Bandegharaei, A., Moreno-Piraj&amp;#225;n, J.C. and Anastopoulos, I. (2019) A Critical Review of the Estimation of the Thermodynamic Parameters on Adsorption Equilibria. Wrong Use of Equilibrium Constant in the Van’t Hoof Equation for Calculation of Thermodynamic Parameters of Adsorption. Journal of Molecular Liquids, 273, 425-434. https://doi.org/10.1016/j.molliq.2018.10.048</mixed-citation></ref><ref id="scirp.93420-ref39"><label>39</label><mixed-citation publication-type="other" xlink:type="simple">Labib, S.A., Yousif, A.M., Ibrahim, I.A. and Atia, A.A. (2018) Adsorption of Rhodium by Modified Mesoporous Cellulose/Silica Sorbents: Equilibrium, Kinetic, and Thermodynamic Studies. Journal of Porous Materials, 25, 383-396. https://doi.org/10.1007/s10934-017-0449-3</mixed-citation></ref><ref id="scirp.93420-ref40"><label>40</label><mixed-citation publication-type="other" xlink:type="simple">Kamga, F.T. (2019) Modeling Adsorption Mechanism of Paraquat onto Ayous (Triplochiton scleroxylon) Wood Sawdust. Applied Water Science, 9, 1. https://doi.org/10.1007/s13201-018-0879-3</mixed-citation></ref><ref id="scirp.93420-ref41"><label>41</label><mixed-citation publication-type="other" xlink:type="simple">Khatibikamal, V., Panahi, H.A., Torabian, A. and Baghdadi, M. (2019) Optimized Poly(amidoamine) Coated Magnetic Nanoparticles as Adsorbent for the Removal of Nonylphenol from Water. Microchemical Journal, 145, 508-516. https://doi.org/10.1016/j.microc.2018.11.018</mixed-citation></ref></ref-list></back></article>