Study on preparation of iron oxyhydroxide doped polyacrylamide flocculant for antimony removal
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.
environmental engineeringpollution by antimonyFeOOHpolyacrylamideflocculationadsorption charge neutralization
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