Synthesis And Application Of Chelator On Heavy Metal Of Modified Cassava Starch

The ecological environment is becoming increasingly serious, heavy metal pollution has caused high attention. Heavy metals migration into the water and soil will eventually be absorbed in animal and human organisms, enrichment eventually lead to poisoning,eventually death. Research, therefore, effectively removal of heavy metal treatment technology has become an urgent demand of environment governance in heavy metal pollution in China.In this thesis,After cassava starch was grafted glycidyl methacrylate,getting pure grafting product by extraction. Pure grafting product, by amination, reacted with divinyl three amine to obtain aminated starch that is the target product—chelator on heavy metal of modified cassava starch. Study on the preparation and reaction conditions of grafted starch, and amination of starch.The dynamics of adsorption model for Cu (II) and Cr (VI) and the isothermal adsorption model for Cu (Ⅱ) on the chelator on heavy metal of modified cassava starch was investigated. Under the single and mixed state, the effect of different pH conditions in system on chelating agent adsorption of the heavy metals was discussed. Under the condition of acid and alkali, The ionic release character on chelating precipitation product and the adsorption mechanism of chelating heavy metals was researched.The main conclusions can be summarized as follows:In the synthesis of chelator on heavy metal of modified cassava starch, the G%,GE%,EV of grafted starch is63.2%,99.95%,4.03mmol/g and N%,adsorption capacity for heavy metal ions of the amination of starch is6.2%,38.4mg/g,under the optimum synthesis conditions. The chelator on heavy metal of modified cassava starch adsorption for Cu(II)and Cr(VI)are more fit to the second-order kinetics law;the adsorption processes of the chelator for Cu(II)is more fit to the Langmuir isotherm adsorp-tion monolayer adsorption theory and is an endothermic reaction.The effect of the adsorption for heavy metal ions Cu(Ⅱ)、Fe(Ⅲ)and Cr(VI) are well in the single state than mixed state, because of maybe the increasing ion reactivity in the coexistences, both competitive effects and synergistic effects. The precipitation pr-oducts of the chelator on heavy metal of modified cassava starch for adsorption Cu(II) is easy to desorbed by acid at less than2of pH, but under the condition of weak acid(pH≥4) and alkali, the chelated product is easily stable.That’s means under the condition of acid rain, the chelated product is stable under the envir-onmental conditions and is diffiuclt for desorption back into the environment, so it’s possble for recycling the activation of the chelating agent under the cond-itions of strong acid desorption phenomenon.It was found that the combination way of the chelator on heavy metal of modified cassava starch and heavy metal belongs to coordinate bond by element energy spectrum analysis instrument. The actual coordination ratio in line with the theoretical value, coordination ratio of Chelating agent to Cu (II) is4:1, and Cr (VI) is6:1.