基于Cr(Ⅵ)/Cr(Ⅲ)价态转化的铬废水治理技术研究

Study on chromium-containing wastewater treatment based on Cr(Ⅵ)/Cr(Ⅲ)valence conversion

将微纳米聚吡咯(PPy)分散在生物质凝胶体系中,构建光敏感的凝胶复合材料,利用PPy的光还原特性及Cr(Ⅵ)/Cr(Ⅲ)的价态转化,在凝胶材料内部实现Cr(Ⅵ)的吸附-光还原-固化-再吸附的循环富集过程,最终形成富集态的铬团簇。结果表明,相较于其他生物质,壳聚糖(CS)与PPy的复合能够有效吸附Cr(Ⅵ),壳聚糖的脱乙酰度越高吸附能力越强,最佳吸附条件为:50 mL浓度50 mg/L的Cr(Ⅵ)溶液,吸附剂用量1.0 g,温度36℃,pH 3.3。SEM、UV-Vis光谱、红外光谱和X射线光电子能谱表征证实,CS与PPy可有效复合,复合材料具有宽泛的光吸收能力,吸附的Cr(Ⅵ)可光催化还原为Cr(Ⅲ),并可利用Cr的价态转化,进一步吸附Cr(Ⅵ),实现Cr团簇体的形成。

Micro-nanOpolypyrrole(PPy)was dispersed in a biomass gel system to construct light-sensitive gel composites.The composites utilize the photoreduction property of PPy and the valence conversion of Cr(Ⅵ)/Cr(Ⅲ)to realize the cyclic enrichment process of Cr(Ⅵ)adsorption-photoreduction-immobilization-readsorption within the gel material,and finally the enriched chromium clusters were formed.Results shows that the composite of chitosan(CS)and PPy could effectively adsorb Cr(Ⅵ).Meanwhile,higher degree of deacetylation of chitosan lead to higher adsorption capacity.The optimal adsorption conditions were:50 mL concentration,50 mg/L Cr(Ⅵ)solution,the dosage of adsorbent 1.0 g,temperature 36℃,pH 3.3.SEM,UV-Vis spectroscopy,infrared spectroscopy,and X-ray photoelectron spectroscopy characterization,it was confirmed CS and PPy can be effectively compounded.The obtained composite had broad light absorption capacity and the adsorbed Cr(Ⅵ)can be photocatalytic reduced to Cr(Ⅲ).The formed Cr(Ⅲ)can be further used to adsorb Cr(Ⅵ)and achieve the formation of Cr clusters by using the valence conversion of Cr(Ⅵ)and Cr(Ⅲ).