Study On Selective Removal Of Antimony(?) In Water Using Ion-imprinted Polymers

With the widespread use of antimony in chemical production and healthcare filed,more and more antimony and its compounds have entered into the water body,causing serious antimony pollution in water.Antimony is an element with high toxicity,carcinogenicity,usually exists in the water with the form of Sb???and Sb?V?,the toxicity of Sb???is 10 times as much as Sb?V?,so it's urgent to develop an technology to effective remove Sb???in water.The Sb???ion-imprinted polymers adsorbents was prepared by ion imprinting technique to selective removal of Sb???in water.The main research results and conclusions are as follows:1,1-vinyl imidazole as functional monomer,antimony potassium tartrate as a template,using the method of bulk polymerization was successfully prepared Sb???-ion imprinted polymer?NCFM-IIP?and the corresponding non ion-imprinted polymer?NCFM-NIP?.The maximum adsorption capacity of NCFM-IIP for Sb???was 28 mg/g,while NCFM-NIP was only 14.36 mg/g,which indicates the imprinting effect and better adsorption capacity of imprinted polymer.The experimental data of isothermal adsorption were more fit with the Langmuir model,indicating that the adsorbent has the adsorption site with single layer uniform distribution.The adsorption reaches to equilibrium at 120 min,adsorption process meet the pseudo-second-order kinetics model.2,For the preparation of a higher adsorption capacity,higher selectivity of Sb???ion-imprinted polymer,we designed and synthesized a nitrogen heterocyclic compound,tetra-bromine-bi-4,5-2?methylene bi-imidazole?acridine.It has a positively charged imidazole moiety and specific cyclic size matching with Sb???.Tetra-bromine-bi-4,5-2?methylene bi-imidazole?acridine as functional monomer,antimony potassium tartrate as a template,using the method of bulk polymerization was successfully prepared novel Sb???-ion imprinted polymer?CFM-IIP?.From the scanning electron micrograph and N₂ adsorption-desorption curve,CFM-IIP is a mesoporous material with platelike porous structure.The specific surface area of CFM-IIP is 43.34 m²/g,average pore size is 14.57 nm.FT-IR analysis showed that functional monomer was successfully polymerized with template and crosslinking agent.The results of TGA show that CFM-IIP has good thermal stability.The experimental results show that CFM-IIP has a good stability in acid medium.3.CFM-IIP has a maximum Sb???adsorption capacity of 79.1 mg/g,while that of a non-cyclic functional monomer imprinted polymer?NCFM-IIP?is only 30.9 mg Sb???/g.The adsorption of CFM-IIP to Sb???was balanced in 80 min.Kinetic data fitted well with pseudo-second-order model.The relative selectivity coefficients of CFM-IIP compared to NCFM-IIP for Sb???/Cl^-,Sb???/NO₃^-,Sb???/PO₄^3-,Sb???/SO₄^2-,and Sb???/Cr₂O₇^2-were 6.6,78.4,5.9,3.0 and 3.2,respectively.The adsorption between Sb???and CFM-IIP was identified to be feasible,spontaneous and endothermic.Zeta-potential,X-ray photoelectron spectroscopic?XPS?analysis and density functional theory?DFT?calculations revealed the mechanism of Sb???adsorption on CFM-IIP is as follows:the microdomain confinement effect,derived from the nano-scale imprinted cavities of CFM-IIP,facilitates the hydrolysis of Sb?OH?₃ to SbO₄^5-,which is subsequently sequestered within the imprinted cavities of CFM-IIP due to the strong electrostatic attraction and size matching of CFM-IIP to SbO₄^5-.Therefore,CFM-IIP is very promising adsorbent for the efficient and selective removal of Sb???from aqueous solutions.