The Preparation And Application Of A Novel Heavy Metal Enrichment Agent

Kaolin shows a certain adsorption ability to heavy metals, but is limited by the influenceof its surface characteristics, and its adsorption amount is not high. In order to improve thekaolin’s adsorption towards heavy metal ions in aqueous solution, the hydrotalcite is used tochange its surface characteristics in this study. One side the problem of kaolin’s pooradsorption ability is solved, on the other side the hydrotalcite’s disadvantages of insoluble inwater, poor dispersibility for adsorbing heavy metal ions in aqueous solution are overcome.This experience firstly discussed hydrotalcite’s preparation process and adsorptioninfluencing factors. The results showed that hydrotalcite’s preparation temperature is70℃,stirring speed is250r/min, response time is10min.The study of hydrotalcite adsorbingCr(Ⅵ)in aqueous solution found that adding0.08g hydrotalcite to100mL solution, containing10mg/L Cr(Ⅵ), the adsorption effect is the best when temperature is20℃, adsorption time is25min. Then the preparation process of kaolin loading hydrotalcite and adsorption influencingfactors of modified kaolin were studied. In the process, according to the preparation methodof hydrotalcite, combined with the characteristics of hydrotalcite and kaolin, a stable processwas gotten to preparate modified kaolin. The influence factors of modified kaolin forremoving Cr(Ⅵ)in aqueous solution are showed as following: Cr (Ⅵ) solution’s initial pHplay an important element in using modified kaolin to remove Cr (Ⅵ) in aqueous solution, theadsorption effect in the acid condition is obviously better than in the alkaline condition. Theenrichment amount is9.551mg/g when pH value is3, just5.816mg/g when pH value is11.The effect of temperature is little.Langmuir equation and Freundlich equation is used todescribe the adsorption mechanism in the preliminary analysis the mechanism of modifiedkaolin remove Cr (Ⅵ) in aqueous solution. The results showed that its removal mechanism isbetter suited for Freundlich equation. The adsorption enthalpy of modified kaolin adsorb Cr(Ⅵ) in aqueous solution is positive number, explained that the adsorption of modified kaolinadsorb Cr (Ⅵ) in aqueous solution is an endothermic process. Modified kaolin adsorbing Cr(Ⅵ) accords with simulative2level dynamic model.