纳米零价铁-聚乳酸-生物炭复合材料协同微生物去除水中1,1,1-三氯乙烷

1,1,1-trichloroethane removal from water by nano-zero valent iron-polylactic acid-biochar composite coupled with microorganism

针对地下水1, 1, 1-三氯乙烷污染问题,通过溶液插层和液相还原法制备了纳米零价铁-聚乳酸-生物炭复合材料;采用扫描电镜观察、热重分析、傅里叶变换红外光谱分析和X射线衍射分析等手段对复合材料进行了表征;研究了复合材料在厌氧条件下协同胞外呼吸菌(Shewanella oneidensis MR-1)去除水中1, 1, 1-三氯乙烷的效果;确定了材料的最佳使用条件;探讨了协同体系中污染物的去除机理。结果表明:复合材料中纳米零价铁和聚乳酸颗粒较为均匀地分散于生物炭表面;材料中生物炭、聚乳酸和纳米零价铁的最佳质量比为7∶1∶2,材料最佳投加量为1.0%,且其对不同浓度污染物均有明显去除效果;在最佳条件下,培养360 h后协同体系中1, 1, 1-三氯乙烷的最大去除率为94.61%;复合材料促进胞外呼吸菌的异化铁还原脱氯是协同体系去除污染物的主要机理。该铁基生物炭复合材料能够有效协同胞外呼吸菌提高水中1, 1, 1-三氯乙烷的去除率,且具有良好的缓释长效性。

Aiming at the problem of 1,1,1-trichloroethane pollution in groundwater,a nano-zero valent ironpolylactic acid-biochar composite was prepared by the solution intercalation and the liquid-phase reduction methods,and it was characterized by the following analysis methods:SEM,TGA,FT-IR and XRD.The performance of this composite coupled with extracellular respiratory bacteria(Shewanella oneidensis MR-1)on1,1,1-trichloroethane removal under anaerobic conditions was studied,and the optimal conditions for this composite application was determined.Furthermore,the possible mechanisms of 1,1,1-trichloroethane removal in the synergistic system were discussed.The results showed that in this composite,both nano-zero valent iron and polylactic acid particles dispersed homogeneously on the biochar surface.The optimum mass ratio of biochar,polylactic acid and nano-zero valent iron in the composite was 7∶1∶2,and the optimal dosage of this composite was 1.0%,at which the contaminants with various concentrations could be removed effectively.After360 h-incubation,the maximum removal rate of 1,1,1-trichloroethane was 94.61%under the optimal application conditions.In the synergistic system,the main mechanism of contaminant removal was the dissimilatory iron reduction dechlorination of extracellular respiratory bacteria promoted by this composite.An synergistic process between this iron-based biochar composite could effective couple with extracellular respiratory bacteria to improve the removal rate of 1,1,1-trichloroethane in aqueous solution,and had good slow-release and longacting properties.