School of Environment, Tsinghua University, Key Laboratory for Solid Waste Management and Environment Safety, Ministry of education of China, Beijing 100084, China.
J Environ Sci (China). 2013 Mar 1;25(3):473-8. doi: 10.1016/s1001-0742(12)60088-6.
The feasibility of the rapid degradation of hexachlorobenzene (HCB) by micron-size silver (Ag)/iron (Fe) particles was investigated. Ag/Fe particles with different ratios (0, 0.05%, 0.09%, 0.20%, and 0.45%) were prepared by electroless silver plating on 300 mesh Fe powder, and were used to degrade HCB at different pH values and temperatures. The dechlorination ability of Fe greatly increased with small Ag addition, whereas too much added Ag would cover the Fe surface and reduce the effective reaction surface, thereby decreasing the extent of dechlorination. The optimal Ag/Fe ratio was 0.09%. Tafel polarization curves showed that HCB was rapidly degraded at neutral or acidic pH, whereas low pH levels severely intensified H2 production, which consumed the reducing electrons needed for the HCB degradation. HCB degradation was more sensitive to temperature than pH. The rate constant of HCB dechlorination was 0.452 min- at 85 degrees C, 50 times higher than that at 31 degrees C. HCB was degraded in a successive dechlorination pathway, yielding the main products 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene within 2 hr.
研究了微米尺寸的银（Ag）/铁（Fe）颗粒快速降解六氯苯（HCB）的可行性。通过在 300 目的 Fe 粉上电沉积银，制备了不同比例（0、0.05%、0.09%、0.20%和 0.45%）的 Ag/Fe 颗粒，并在不同 pH 值和温度下用于降解 HCB。少量 Ag 的添加极大地提高了 Fe 的脱氯能力，而过多的添加 Ag 会覆盖 Fe 表面并减少有效反应表面，从而降低脱氯程度。最佳的 Ag/Fe 比例为 0.09%。塔菲尔极化曲线表明，HCB 在中性或酸性 pH 下迅速降解，而较低的 pH 值会严重加剧氢气的产生，从而消耗 HCB 降解所需的还原电子。HCB 降解对温度比 pH 值更敏感。在 85°C 时，HCB 脱氯的速率常数为 0.452 min-1，是在 31°C 时的 50 倍。HCB 按连续脱氯途径降解，在 2 小时内生成主要产物 1,2,4,5-四氯苯和 1,2,4-三氯苯。
