绿色Fe0@PAN冻凝胶复合材料去除水中Cr(VI)的性能研究

Performance study of green Fe0@PAN cryogel composites for Cr(VI)removal from water

纳米零价铁(NZVI)颗粒易于团聚和氧化,导致其活性降低.以绿色多相冰晶致孔的冷冻凝胶法构建聚丙烯腈(PAN)冻凝胶膜稳定负载NZVI,制备了高效Fe0@PAN复合材料.通过在酸性含Cr废水中的去除实验,考察了复合材料的最佳合成条件及反应活性.同时,利用SEM、XRD和XPS分析了复合材料的表面形貌、化学组成及晶体结构以及Cr(VI)在反应介质中的分布情况.此外,还进行了反应动力学分析和Cr(VI)去除机理研究.结果表明,PAN冻凝胶膜具有3D大孔网状结构,NZVI负载量为24.0 mg·g^(-1).综合考虑时间和经济成本,当FeSO4浓度为0.3 mol·L^(-1),负载时间为3 h,Fe0@PAN投加剂量为0.132 g时,Fe0@PAN复合材料活性最佳且NZVI利用率较高.与未改性的NZVI相比,复合材料对Cr(VI)的去除效率提高了68.2%,吸附量达到15.35 mg·g^(-1).准一级动力学、XPS和Visual MINTEQ拟合结果揭示,Fe0@PAN去除Cr(VI)的机理主要包括酸性反应介质促进静电吸引,随后活性组分NZVI和Fe2+与HCrO4-发生氧化还原反应,最终产物吸附在Fe0@PAN复合材料表面形成共沉淀.综上所述,冷冻凝胶法有望为NZVI构建绿色新型载体,促进纳米材料在酸性废水处理领域的应用.

Nano zero-valent iron(NZVI)particles are prone to agglomerate and be oxidized,resulting in the decrease in their activity.Polyacrylonitrile(PAN)cryogel film with immobilized NZVI were constructed by green and multiphasic ice crystal porosity-inducing cryogel method to prepare highly activite Fe0@PAN composites.The optimal synthesis conditions and reactivity of Fe0@PAN were investigated by Cr(VI)removal in acidic Cr(VI)-containing wastewater.The surface morphology,chemical composition,crystal structure of the composites and distribution of Cr(VI)ions in the reaction medium were also analyzed by SEM,XRD and XPS.The reaction kinetic,and Cr(VI)removal mechanism were also studied.The results show that the PAN cryogel film had a 3D macroporous mesh structure with NZVI loading amount of 24.0 mg‧g^(-1).Concerning the time and economic cost,the highest composite activity and optimal NZVI dosage was achieved under conditions with 0.3 mol‧L^(-1) FeSO4 of addition,3 h of reaction time,0.132 g of dosage.Compared with that of unmodified NZVI,the removal efficiency was increased by 68.2%.The adsorption amount of Cr(VI)reached 15.35 mg‧g^(-1).The pseudo-first-order kinetics,XPS and Visual MINTEQ fitting results revealed that the Cr(VI)removal mechanism by Fe0@PAN mainly includes the promotion of electrostatic attraction by the acidic reaction medium,followed by the redox reaction of the active components,NZVI and Fe2+,with HCrO4-,and ultimately,the adsorption of final products on Fe0@PAN surface to form a co-precipitation.In summary,the green and multiphasic ice crystal porosity-inducing cryogel method is expected to construct novel carriers for NZVI and promote the application of nanomaterial in the acidic wastewater treatment.