缓释型活性炭负载纳米铁(nZVI-C)对废水中Cr(Ⅵ)的去除性能及机制

Performance and mechanism of Cr(Ⅵ)removal from wastewater by sustained-release nZVI-loaded activated carbon(nZVI-C)

纳米零价铁(nanoscale zero-valent iron,nZVI)具有污染物去除效率高、易制备、成本低、环境友好等优点,在环境修复领域得到广泛应用。目前针对nZVI的研究热点是通过改性,改善其易团聚、易被氧化等缺点并提升修复性能。本研究将负载法和聚合物包覆改性法相结合,使用活性炭和绿色无毒聚天冬氨酸(polyaspartic acid,PASP)对nZVI起到了良好的稳定和缓释效果,减少了nZVI的团聚并增大了比表面积、延长了反应平衡时间,显著提升了对水中Cr(Ⅵ)的去除效果。铁碳比为2∶1时,复合材料的修复性能是nZVI与活性炭单独处理加和的1.75倍,最高可去除99.91%的Cr(Ⅵ)。本研究还通过正交实验筛选了复合材料的最佳制备条件,分析了C-PASP-nZVI投加量、污染物浓度和pH对含Cr(Ⅵ)废水修复效果的影响。C-PASP-nZVI对Cr(Ⅵ)的吸附动力学过程符合Lagergren准二级模型,说明复合材料对Cr(Ⅵ)的去除过程由化学吸附主导。以上研究结果表明,C-PASP-nZVI是一种可用于重金属污染水体修复的潜在理想材料。

Nanoscale zero-valent iron(nZVI)have advantages such as high pollutant removal efficiency,easy preparation,low cost,and environmental friendliness,and are widely used in the field of environmental remediation.Currently,the research focus on nZVI is to improve its drawbacks of easy aggregation and oxidation by modification,and enhance its remediation performance.This study combined the loading method and polymer coating modification method,and used activated carbon and non-toxic green polyaspartic acid(PASP)to achieve good stability and sustained-release effects for nZVI,which reduced nZVI aggregation,increasing specific surface area,prolonging reaction equilibrium time,and significantly increasing the removal of Cr(Ⅵ)in water.When the ratio of iron to carbon was 2:1,the remediation performance of the composite material was 1.75 times that of the sum of nZVI alone and activated carbon alone,and the highest Cr(Ⅵ)remove rate could reach 99.91%.In the study,the optimal preparation conditions of the composite were screened by the orthogonal experiments,and the effects of C-PASP-nZVI dosage,pollutant concentration and pH on the remediation effect of Cr(Ⅵ)containing wastewater were analyzed.The adsorption kinetics of Cr(Ⅵ)on C-PASP-nZVI conformed to the Lagergren pseudo-second-order model,indicating that the removal process of Cr(Ⅵ)on the composite was dominated by chemical adsorption.The results of above study indicate that CPASP-nZVI is a potential ideal material for the remediation of heavy metal-contaminated water bodies.