Studies On Preparation And Adsorption Properties Of Novel Chelating Adsorption Material For Heavy-Metal Ions

The let of heavy metal ion wastewater is a primary source of water pollution, and havebeen engendering great endangerment for the human society. At the same time, many heavymetal ions in industry wastewater are very useful, and need to recycle. Therefore, via themolecule design, preparing the high-powered chelating adsorption material that could notonly effectively treat heavy metal ions in wastewater, but also effectively separate and recycleheavy metal ions, have important environment protecting and resource recycling value.Cooperate processes of polyethyleneimine (PEI) with Cu²⁺,Cd²⁺ and Zn²⁺ ions werestudied by using spectrophotometric method and conductometric titration, and the structure ofthe chelate were determined. A novel measurement method for Cu²⁺ content has been found,that is conductometric titration method by using PEI. The effects of various factors on theanalysis method were examined, and the analysis conditions were optimized. Theexperimental result show that the chelate with four coordinations forms between PEI andCu²⁺,Cd²⁺ and Zn²⁺ ions, the rate of coordination is fast, and the chelate is stable. Via theexperiment of recoveries with standard addition and comparing with national standard method,the feasibility and veracity of this method has been proved.PEI was triumphantly grafted onto the surface of silica gel particles via the couplingeffect of γ-chloropropyl trimethoxy silane(CP), the novel composite adsorption materialPEI/SiO₂ was prepared, and the adsorption mechanism was analyzed by infrared spectrum.The experiment results show that the composite material PEI/SiO₂ possesses very strongchelating adsorption ability for heavy-metal ions;the saturated adsorption capacity is highestfor Cu²⁺ ion. The isothermal adsorption data fit to Langmuir equation, and the adsorption istypical chemical adsorption with monomolecular layer. The adsorbing capacity increases withtemperature rising, and the fact indicates the adsorbing process of PEI/SiO2 for metal ions isendothermic. The pH has great influence on the sorption, and as pH=6～7, the adsorptioncapacity is the greatest.Cu2+ qua template ion, the PEI on the surface of silica gel particles were polymerizedwith cross-linking epichlorohydrin (ECH), ion imprint was actualized on the surface of silicagel, the Cu2+ ion imprint adsorption material IMP-PEI/SiO2 was prepared, and thepreparation conditions were optimized. The chemical structure and component were analyzedby infrared spectrum, and the adsorption properties of IMP-PEI/SiO2 for Cu2+,Cd2+ andZn2+ ions were researched. The experiment results show that, compared with PEI/SiO2, theIMP-PEI/SiO2 possesses very strong identify and memory ability for Cu2+ ions, theselectivity was obviously improved, and the saturated adsorption capacity is two times thanPEI/SiO2 for Cu2+ ion. The isothermal adsorption data fit to Langmuir equation, and theadsorption is typical chemical adsorption with monomolecular layer. The adsorbing capacityincreases with temperature rising, and the fact indicates the adsorbing process of IMP-PEI/SiO2 for metal ions is endothermic. The pH has great influence on the sorption, and aspH=6, the adsorption capacity is the greatest. IMP-PEI/SiO2 possesses well elute and reusecapacity. As used 0.1mol·L-1 hydrochloric acid as eluent, the adsorbed heavy-metal ions areeluted easily from IMP-PEI/SiO2, and the adsorption capacity of IMP-PEI/SiO2 issteadiness after 10 times of use.