炭铁材料修复三氯乙烯污染地下水的性能

The performance of biochar/nZVI composite in remediating trichloroethylene contaminated groundwater

采用生物炭(BC)为载体的纳米零价铁复合材料作为可渗透反应墙系统(PRB)中的反应介质,通过柱实验和渗透实验,研究了生物炭负载纳米零价铁(BC-nZVI)对三氯乙烯(TCE)的去除效果和炭铁复合材料在长期水流作用下的渗透性能.结果表明:炭铁复合材料对TCE的去除率在2h内可达到90%以上,10h时接近100%,随着炭铁复合材料的消耗,去除率逐渐降低,但在24h内仍能保持显著的修复效果,去除率保持在90%以上,72h后降为73.96%.PRB系统中反应介质材料在长期水流作用下出现明显的迁移,炭铁复合材料的稳定性随着炭铁比的减小而降低.5BC-1nZVI材料在持续3d的渗流作用下,其迁移流失率最低,相比纯BC材料的迁移流失情况具有明显的改善效果.微观结果表明球磨法可成功合成炭铁复合材料,合成后的nZVI颗粒存在一定程度的氧化,与TCE接触反应后的炭铁复合材料由于降解产物的附着,炭铁复合材料的表面会形成一层白色薄膜,孔径变小,进而炭铁复合材料对TCE的去除性能降低.

The column test and permeability test were carried out to explore the biochar/nZVI composite removal effect on trichloroethylene and the permeability of the BC-nZVI composite.The results show biochar/nZVI composite for TCE removal rate can reach more than 90%in 2h,close to 100%at 10h.The removal rate gradually declined with the consumption of Biochar/nZVI composite;however,it maintained a noticeable remediation effect within 24hours,and the removal rate remained at over 90%but decreased to 73.96%after 72h.In the PRB system,the reaction medium material migrates under the long-term water flow,and the stability of the BC-nZVI composite decreases with the decrease in the iron ratio.Compared with pure BC material,the migration and loss of 5BC-1nZVI material were relatively low under continuous 3-day seepage.The microscopic results show that the BC-nZVI composite can be successfully synthesized by the ball milling method,and it was found that after ball milling,nZVI particles have a certain degree of oxidation.Due to the adhesion of degradation products by the reaction of BC-nZVI composites with TCE,a white film will be formed on the surface of the carbon-iron material,and the pore size decreases;hence,the removal efficiency of BC-nZVI composites for TCE decreases.