Laboratory of Water-Energy-Environment (LR3E), Code: AD-10-02, National School of Engineers of Sfax, University of Sfax, BP W, 3038, Sfax, Tunisia.
Tunisian Chemical Group, 6000, Gabes, Tunisia.
Environ Sci Pollut Res Int. 2016 Aug;23(16):15820-31. doi: 10.1007/s11356-015-5557-5. Epub 2015 Oct 30.
The current problem of excess impurities in industrial phosphoric acid (IPA) 54 % P2O5 makes phosphates industries look toward low-cost but efficient adsorbents. In the present study, iron-oxide-modified bentonite (Fe-PILB) was prepared and investigated as a possible adsorbent for the removal of organic matter (OM) like humic acid (HA), chromium (Cr(III)), and zinc (Zn(II)) from IPA aqueous solutions. These adsorbents were characterized using XRD, TEM, and BET. The adsorption of impurities is well described by the pseudo-second-order model. The results indicate that Fe-PILB has a good ability to resist co-existing anions and the low-pH condition of IPA and owns a relatively high-removal capacity of 80.42 and 25 % for OM, Cr(III), and Zn(II). The mechanism of adsorption may be described by the ligand and ion exchange that happened on the active sites. The selected order of adsorption OM > Cr(3+) > Zn(2+) showed the importance of the competitive phenomenon onto bentonite materials' pore adsorption. For the adsorption of OM at the low pH of IPA, H-bond complexation was the dominant mechanism. From the adsorption of heavy metals and OM complex compounds contained in IPA 54 % on Fe-PILB, the bridging of humic acid between bentonite and heavy metals (Zn(II) or Cr(III)) is proposed as the dominant adsorption mechanism (bentonite-HA-Me). Overall, the results obtained in this study indicate Fe-pillared bentonite possesses a potential for the practical application of impurity (OM, Zn(II), and Cr(III)) removal from IPA aqueous solutions.
目前，工业磷酸（IPA）54% P2O5 中杂质过多的问题，促使磷酸盐工业寻求低成本但高效的吸附剂。本研究制备了氧化铁改性膨润土（Fe-PILB），并将其作为一种可能的吸附剂，用于去除 IPA 水溶液中的有机物（如腐殖酸（HA）、铬（Cr(III)）和锌（Zn(II)）。这些吸附剂采用 XRD、TEM 和 BET 进行了表征。吸附杂质的行为很好地符合伪二级模型。结果表明，Fe-PILB 具有良好的抵抗共存阴离子和 IPA 低 pH 条件的能力，对有机物、Cr(III) 和 Zn(II)的去除率分别高达 80.42%和 25%。吸附的机理可能是通过配体和离子交换在活性位点上发生的。吸附有机物的顺序为 OM > Cr(3+) > Zn(2+)，表明竞争现象对膨润土材料孔吸附的重要性。对于 IPA 低 pH 下有机物的吸附，氢键络合是主要的机理。从 IPA 54%中有机物和重金属（Zn(II)或 Cr(III)）等复杂化合物在 Fe-PILB 上的吸附情况来看，提出了腐殖酸在膨润土和重金属（Zn(II)或 Cr(III)）之间的桥接作为主要的吸附机理（膨润土-HA-Me）。总的来说，本研究结果表明，Fe 柱撑膨润土具有从 IPA 水溶液中去除杂质（有机物、Zn(II)和 Cr(III)）的实际应用潜力。
