Y-type Molecular Sieve Loaded Ce/Iron Oxide Adsorbent For Sb Adsorption In Aqueous Solution:Performance And Mechanisms

Antimony(Sb)is a toxic heavy metal,and Sb(Ⅲ)is 10 times more toxic than Sb(V).In recent years,China’s limits on antimony emissions from water are becoming stricter,and the control of antimony pollution in water needs to be addressed urgently.In this paper,a novel adsorbent was prepared by using Y-type molecular sieve(NaY)loaded with Ce/iron oxide,and its removal behavior and mechanism of Sb(Ⅲ)and Sb(Ⅴ)in water were investigated,and the following conclusions were drawn:(1)The surface morphology analysis showed that NaY was a porous material with huge specific surface area,which was an excellent carrier for the synthesis of composite adsorbent materials,but the adsorption capacities of the original NaY for Sb(Ⅲ)and Sb(Ⅴ)were only 0.13 mg/g and 0.62 mg/g,respectively.The new adsorbent NaY@Ce/Fe2O3,whose surface morphology was rougher than that of NaY,and the adsorption capacities of Sb(Ⅲ)and Sb(V)were significantly enhanced.The maximum adsorption capacities of NaY@Ce/Fe2O3 for Sb(Ⅲ)and Sb(Ⅴ)reached 74.65 mg/g and 11.59 mg/g at pH=7.0,respectively.(2)Kinetic experiments showed that the adsorption of Sb(Ⅲ)and Sb(Ⅴ)on NaY@Ce/Fe2O3 were both consistent with the pseudo-secondary kinetic model,indicating a chemisorption behavior.The presence of coexisting anions,except for H2PO4-,had relatively little effect on the adsorption of Sb(Ⅲ)and Sb(Ⅴ)on NaY@Ce/Fe2O3,which had strong stability and good prospects for antimony removal applications over a wide pH range(pH=4～9).XRD,FTIR and XPS studies indicated that the possible adsorption mechanisms of Sb(Ⅲ)and Sb(Ⅴ)on NaY@Ce/Fe2O3,including electrostatic attraction,surface complexation and redox reactions.The results of the adsorption experiments simulating the actual wastewater showed that the total antimony concentration of the effluent was 85 μg/L when NaY@Ce/Fe2O3 was dosed at 1 g/L,which could meet the Emission Standard for Water Pollutants in Textile Dyeing and Finishing Industry(<100 μg/L).It shows that NaY@Ce/Fe2O3 is an ideal adsorbent for antimony removal from actual wastewater.(3)In order to solve the problem that adsorbent particles are too small to separate from water,a new magnetic composite adsorbent NaY@Ce/Fe3O4 was prepared.The experimental results showed that NaY@Ce/Fe3O4 had good stability,and the maximum adsorption capacities of Sb(Ⅲ)and Sb(Ⅴ)under neutral conditions were 11,56 mg/g and 5.36 mg/g,respectively.In the presence of common coexisting ions,only H2PO4-had a significant effect.NaY@Ce/Fe3O4 had a saturation magnetization of 71.1 emu/g and can be separated from the solution in 3-5 seconds under the action of an external magnetic field.FTIR,XRD and XPS characterization revealed the adsorption removal mechanisms of Sb(Ⅲ)and Sb(Ⅴ)on NaY@Ce/Fe3O4,including electrostatic attraction,hydrogen bonding,ligand exchange and surface complexation.Compared with NaY@Ce/Fe2O3,the adsorption capacity of NaY@Ce/Fe3O4 on Sb(Ⅴ)only decreased a little,but the excellent magnetic separation performance of NaY@Ce/Fe3O4 indicated that the novel NaY@Ce/Fe3O4 adsorbent has a great practical value in the removal of antimony(Ⅴ)from printing and dyeing wastewater.