Adsorption Of Sb （Ⅲ） In Water Environment By Nano Zirconium Iron Oxide Loaded Sludge Activated Carbon

Antimony（Sb）is a V group metal element naturally occurring in the Earth’s crust.Due to the influence of human activities and the wide application of antimony,the problem of antimony pollution in water is becoming more and more serious.Antimony pollution has been concerned by some countries and international organizations.The nano metal particle adsorption method has a remarkable effect on the removal of heavy metal pollutants in water.zirconium iron oxide nanocomposites with sludge activated carbon（Zr/Fe@SAC）as carrier were prepared in this experiment.The material was characterized and applied to the removal of Sb（Ⅲ）in aqueous environment.The effects of the optimum preparation conditions,dosage,p H value of solution,initial Sb（Ⅲ）concentration and contact time on the adsorption effect of Sb（Ⅲ）and the adsorption mechanism were studied.The main results are as follows:（1）The optimum conditions for preparing Zr/Fe@SAC were analyzed by orthogonal test and load proportion experiment:the mass fraction of Zn Cl₂solution was 50%,the volume ratio of sludge to Zn Cl₂solution was 1:3,the calcination temperature of tube furnace was500℃,the calcination time was 1 h,the molar ratio of zirconium to iron was 7:3,and the mass ratio of activated carbon to zirconium iron oxide from sludge was 2:1.（2）The synthesized nanocomposites were characterized by SEM,BET,VSM and other instruments.The results showed that the distribution of nano-zirconium iron oxide particles on the surface of Zr/Fe@SAC was uniform and dense,the specific surface area and pore size were higher than SAC,with a large number of adsorption sites,and the small coercivity indicated that the materials were not easy to aggregate but easy to separate from water under the action of magnetic field.The reaction mechanism of Zr/Fe@SAC to Sb（Ⅲ）was analyzed by XRD,FTIR and XPS.The reaction mechanism is that,-OH,Zr-O,-COOH and other functional groups on the surface of Zr/Fe@SAC adsorb Sb（Ⅲ）through electrostatic adsorption and ligand exchange.Part of Sb（Ⅲ）adsorbed on the surface will react with Fe₃O₄to form Sb（Ⅴ）and adsorb on the surface of Zr/Fe@SAC.（3）Single factor experiment was used to investigate the effects of adsorbent dosage,initial concentration of Sb（Ⅲ）,solution p H,ionic strength and coexisting ions on adsorption.The results showed that the optimum dosage of Zr/Fe@SAC nanocomposites was 0.4 g/L,and the removal rate reached 96.60%.When the p H value was 3,the removal rate of Sb（Ⅲ）was the highest,the removal rate reached 96.60%,and the removal rate of other p H values was about 95%.From the ionic strength experiment,it was known that the adsorption of Sb（Ⅲ）by Zr/Fe@SAC formed an inner spherical complex.According to the experiments of coexisting ions,in the complex water environment,the materials were not easily affected by CO₃^2-and SO₄^2-,but easily disturbed by PO₄^3-and Cl^-.The results of reuse study showed that the material still maintained a removal rate of about 90%for Sb（Ⅲ）after adsorption and desorption for five times.（4）Adsorption isotherm experiments and adsorption kinetics experiments showed that the adsorption process of Sb（Ⅲ）by Zr/Fe@SAC accords with Freundlich adsorption isotherm model and quasi-quadratic kinetic model,indicated that the adsorption reaction is multi-molecular layer adsorption,the adsorption type is chemical adsorption,and the adsorption equilibrium can be reached in 120 min.The theoretical maximum adsorption capacity is 28.17 mg/g,and the adsorption process can be carried out spontaneously in the range of 288-308 K.