摘要
以丙烯酰胺(Acrylamide,AM)为基底,在引发聚合过程中接入羟基氧化铁(FeOOH),合成新型复合絮凝剂羟基氧化铁/聚丙烯酰胺(FeOOH@PAM).采用BET(Brunauer-Emmett-Teller)、SEM(Scanning Electron Microscope)、XRD(X-ray diffraction)方法对絮凝剂的孔结构、表面性质、晶体结构进行表征,采用 FT-IR(Fourier Transforms Infrared Spectroscopy)和 XPS(X-ray Photoelectron Spectroscopy)方法探究FeOOH@PAM去除Sb(V)的机制.系统考察不同FeOOH掺杂质量分数、pH值、絮凝剂及污染物投加质量浓度、共存离子种类、反应时间对絮凝剂除Sb(V)效果的影响以及絮凝过程中的粒径变化情况.结果显示:与羟基氧化铁相比,复合絮凝剂为多孔无定型结构且具有更大的比表面积.在最优条件下,絮凝剂对低质量浓度Sb(V)(20 fig/L)水源水的去除率在13 min时达98.03％,去除率受HPO34-和腐殖酸质量浓度的影响较大.絮体主要在慢速搅拌时形成,锑酸盐离子通过静电吸附迅速迁移至絮凝剂表面,与表面位点络合形成絮凝微团聚结沉降而被去除.
Abstract
In this work,a new inorganic-organic composite flocculant-hydroxy iron oxide/polyacrylamide(FeOOH@PAM)was synthesized to remove Sb(V)from water.Acrylamide was used as a substrate,and hydroxy iron oxide(FeOOH)was added during the initiation of polymerization.The surface properties and crystal structure of the flocculant were characterized by a fully automated specific surface and porosity analyzer(BET),scanning electron microscopy(SEM)and X-ray diffraction(XRD).The flocculant was found to be a porous amorphous structure with an increased specific surface area after compounding.The effects of FeOOH doping,initial pH,flocculant dosage and pollutant dosing,coexisting ions,and reaction time on the removal of Sb(V)by FeOOH@PAM were systematically investigated to determine the optimal doping of FeOOH and the best operational parameters.Results show that the removal of Sb(V)by FeOOH@PAM at low Sb(V)concentration(20 μg/L)is up to 98.03％at a FeOOH doping amount of 0.3,pH of 6 and dosage of 60 mg/L.The removal of Sb(V)occurs mainly in the first 13 min,and the flocculation process is strongly influenced by HCO3,SO24-,HPO4-and humic acid.The removal mechanism of Sb(V)was investigated by Zeta potentiometry,Malvern laser particle size measurement,Fourier transforms infrared spectroscopy(FT-IR),and X-ray photoelectron spectroscopy(XPS).The floc surface zero charge point(pHZPC)is determined to be 5.28.The floc grew rapidly in the slow-stirring phase and the final floc size formed under acidic conditions is smaller than the final floc size formed under alkaline conditions.Under acidic conditions,the flocculant rapidly adsorbed antimonate ions onto its surface by adsorption bridging and adsorption electro-neutralization.Under neutral and alkaline conditions,complexation,adsorption bridging,and netting sweeping acted together.Electro-neutralization and complexation were mainly achieved by the various coordination groups,namely,—CONH2,—OH,—COOH and—NH2 on FeOOH@PAM,while adsorption bridging and netting sweeping were obtained by PAM.The flocculant,FeOOH@PAM,prepared in this work to remove Sb(V)from antimony-contaminated water via the existing flocculation process provides guidelines for the development of an efficient flocculant.
维普
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