负载纳米零价铁／钯（ZVI／Pd）双金属活性炭去除水中三氯乙烯（TCE）的研究

使用“初湿含浸法”将纳米级零价铁，钯（ZVI／Pd）颗粒负载于颗粒活性炭（GAC）上，考察制得的反应性活性炭（RAC）去除地下水中三氯乙烯（TCE）的有效性。研究发现，在制得的RAC中零价铁以纳米颗粒的形式负载其上，粒径范围在50～100nm之间，其负载量具有上限，一般低于30％。相比于GAC，RAC的BET比表面积有一定程度的下降。RAC上的铁成分主要以非晶态的形式存在，具有较高的分散度。通过批式试验发现，RAC能够快速有效降低水中TCE浓度，其去除动力学符合伪一级动力学模型。萃取试验和氯离子检测结果表明，RAC在吸附TCE的同时可以对其进行还原脱氯，在48h内不同RAC对于吸附其上的TCE的脱氯比例可达14．5％-30．4％。RAC对于水中TCE的去除能力短期内以吸附为主，铁含量的增加不利于其对于TCE的吸附但会有助于增加长期TCE的还原降解量。RAC在不同溶解氧环境下对TCE的去除性能优良，在短期内并没有太大区别；但若经过大量好氧（DO=6．9mg/L）的纯水浸泡，表面零价铁颗粒可能逐渐腐蚀。

Removal of Trichlorethylene (TCE) in Water by GAC/ZVI/Pd Processes

Through a synthesis procedure that includes consecutive steps of an incipient wetness impregnation method, heat-treat- ment, boro-hydride reduction, and Pd doping, granular activated carbon （GAC） was impregnated with nanoscale ZVI with palladium （GAC/ZVI-Pd） to function as reactive activated carbon （RAC） for removing TCE from water. SEM photomicrographs and XRD results confirm the presence of nanoscale amorphous ZVI particles （50-100 nm） are well-distributed in the base GAC. The maximum content of ZVI in RAC is up to about 30 %. The BET surface area of the RAC is lower than the source GAC due to the Fe impregnation. The batch experimental data show that RAC is capable of reducing the TCE concentration quickly and effectively and that the concentra- tion profile is consistent with the pseudo first order reaction model. The RAC adsorbs and dechlorinates TCE simultaneously and that 14.5-30.4 % of the adsorbed TCE is deehlorinated in 48 h. During the initial period, RAC removes the TCE primarily by adsorption. Increasing the ZVI loading, although may result in more TCE reduction; is detrimental to the RAC＇s adsorptive capacity. The TCE re- moval capacities of RAC at different DO levels are almost the same; however, exposure to high DO （6.9 mg/L） for a long period, ZVI may be oxidized and thus reduces its reductive capability.