Monometallic nano-catalysts for the reduction of perchlorate in water

摘要

Perchlorate removal in a clean, cost-effective and publicly acceptable approach is one of the important issues in current drinking water treatment practice. Catalytic membrane (CM) was prepared by coating monometallic catalysts of the nano-size onto supports by chemical or electrochemical method. The support materials were stainless steel and graphite. Nano-catalysts were made of transitional metals from the first, the second and the third row of the periodic table. The CM was characterized by surface analysis techniques including SEM, XPS and BET. The CM was used as cathode where the reduction of perchlorate occurred through hydrogen atoms that were generated on the CM surface. All experiments were performed at ambient conditions. It was found that for the first time perchlorate could be reduced readily by hydrogen atoms in the presence of catalyst. At a maximum perchlorate concentration of 100 mg/L, it is possible to achieve a > 90% removal in 8 h using nano-catalysts such as Sn, Ti, and Co. The rate constants were between 5.1 and 9.6 μM-L~(-1)-hr~(-1) among the 18 different monometallic nano-catalysts tested. Chloride was the major end product, whereas a small quantity of chlorite was observed in the presence of Co catalyst. Membrane coated with metallic nano-catalysts at different mass showed different reduction rate, e.g., the optimum surface coverage for Sn was 0.6 to 0.7 mg per gram stainless steel membrane.