| Due to the toxic and non-biodegradable of heavy metals,it will cause great harm to the natural environment and human health by excessive enrichment in the food chain.The water pollution was an urgent environmental and health problem to be solved in the world,which was caused by heavy metals.It is necessary and meaningful to control heavy metal pollution.Starch microspheres are an artificial derivative with abundant raw material sources.They have the advantages of space network structure,good adsorption performance and nontoxicity.They are widely used in wastewater treatment.Humic acid(HA)has a wide range of sources and high reactivity,and the polymer composite adsorbent prepared from it has excellent adsorption performance,simple preparation process and stable product structure.Therefore,this subject draws on the synthesis of starch microspheres,and uses starch(St)and ?-cyclodextrin(?-CD)to cross-link with HA to form two kinds of polymer composite adsorption materials and investigated the sorption of them.The main research contents were as follows:(1)Synthesis and characterization of humic acid/starch composite microspheres(HS-CM)HS-CM were prepared by reverse phase emulsion polymeriza-tion method using HA and St as raw materials,N.N'-methylenebisacrylamide(MBAA)as cross-linking agent,K2S2O8/NaHSO3 as initiator.Optimized the synthesis process of HS-CM through single-factor experiments and response surface design.HS-CM was characterized by FTIR,SEM,laser particle size distribution analyzer,XRD and TGA.It was found that HS-CM was regular in shape and rough in surface with a uniform particle size distribution.In addition,the HS-CM had good thermal stability.It was found that hs-cm was spherical with rough surface,(2)Study on adsorption of metal ions by HS-CMThe sorption of HS-CM was investigated by taking Cr3+,Pb2+ and Cu2+as the target.The effects of pH,initial concentration,adsorption time,and temperature on the sorption of HS-CM were investigated,and the adsorption mechanism was studied by fitted with kinetic and isothermal adsorption models.The sorption of HS-CM for metal ions were favorable,spontaneous and endothermic in nature.The sorption of HS-CM could be better described by the kinetic model of pseudo-second-order and the isotherm model of Sips,showing that the sorption of HS-CM was most probable limited by chemisorption and the adsorption processes on HS-CM maybe contains multilayer layer adsorption and heterogeneous adsorption.Under the conditions of pH=6 and adsorped 3 h,with the temperature increased from 298.15 K to 308.15 K,the maximum adsorption quantity(qm)of HS-CM for Cr3+,Pb2+ and Cu2+ increased from 230.35,165.30 and 176.29 mg/g to 277.58,176.29 and 229.42 mg/g,respectively.(3)Synthesis and characterization of Humic acid/?-cyclodextrin composite microspheres(H?-CM)H?-CM were prepared by reverse phase emulsion polymerization method using HA and(3-CD as raw materials,MBAA as cross-linking agent,K2S2O8/NaHSO3 as initiator.Optimized the synthesis process of H?-CM through single-factor experiments and response surface design.H?-CM was characterized by FTIR,SEM,laser particle size distribution analyzer,XRD and TGA.It was found that H?-CM was regular in shape and rough in surface with a uniform particle size distribution.In addition,the H?-CM had good thermal stability.(4)Study on adsorption of metal ions by H(3-CMThe sorption of H(3-CM was investigated by taking Cr3+,Pb2+and Cu2+ as the target.The effects of pH,initial concentration,adsorption time,and temperature on the sorption of H?-CM were investigated,and the adsorption mechanism was studied by fitted with kinetic and isothermal adsorption models.The sorption of H?-CM for metal ions were favorable,spontaneous and endothermic in nature.The sorption of H?-CM could be better described by the kinetic model of pseudo-second-order and the isotherm model of Sips,showing that the sorption of H?-CM was most probable limited by chemisorption and the adsorption processes on H?-CM maybe contains multilayer layer adsorption and heterogeneous adsorption.Under the conditions of pH=6 and adsorped 3 h,with the temperature increased from 298.15 K to 308.15 K,the qm of H?-CM for Cr3+,Pb2+ and Cu2+increased from 329.44,327.51 and 322.19 mg/g to 364.41,418.27 and 354.26 mg/g,respectively.Compared with HS-CM,the adsorption performance of H?-CM has great improved. |
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