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>Dechlorination of chlorophenols using magnesium–palladium bimetallic system
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Dechlorination of chlorophenols using magnesium–palladium bimetallic system
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机译：镁-钯双金属系统对氯酚进行脱氯
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摘要
Ninety-four percent removal of 10 mg L−1 of pentachlorophenol (PCP) was achieved by treatment with 154.5 mM Mg0 and 0.063 mM K2PdCl6 in the presence of 175 mM acetic acid in 1 h reaction time. Dechlorination of PCP was found to be sequential and phenol was identified as the end product along with accumulation of trace concentrations of tetra- and trichlorophenols. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) revealed that palladium in its metallic form (Pd0) produced by reduction of Pd4+, was spatially separated from magnesium granules when acid was included in the reaction. These colloidal palladium particles generated active reductive species of hydrogen and dechlorinated chlorophenols. In the absence of acid, the efficiency of dechlorination of PCP by Pd/Mg0 system was very low and chief mechanism of removal of the compound was through sorption onto solid surfaces. Thus, it was important to include acid in the system to: (a) facilitate corrosion of Mg0 and reduction of Pd4+ to Pd0, (b) provision of protons to produce H2, (c) retard formation of insoluble oxides and hydroxides that may deposit on the magnesium granules and sorb PCP and its partially dechlorinated products and. Application of 154.5 mM Mg0/0.063 mM K2PdCl6 on PCP, 2,4,5-trichlorophenol (TCP) and 2-chlorophenol (MCP) with organic chloride equivalence showed that the rate and extent of removal increased with decrease in number of chlorine atoms on phenol.
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机译：在175 mM乙酸存在下，在1 h反应时间内，通过用154.5 mM Mg0和0.063 mM K2PdCl6处理，可去除10 mg L-1的五氯苯酚94％。发现五氯苯酚的脱氯是连续的，苯酚与痕量浓度的四氯苯酚和三氯苯酚一起被鉴定为最终产物。扫描电子显微镜（SEM）和能量色散X射线光谱（EDX）表明，当反应中包含酸时，通过还原Pd4 +生成的金属形式的钯（Pd0）在空间上与镁颗粒分离。这些胶体钯颗粒产生了氢和脱氯氯酚的活性还原物种。在不存在酸的情况下，Pd / Mg0体系对PCP的脱氯效率非常低，而去除化合物的主要机理是通过吸附在固体表面上。因此，在系统中加入酸非常重要：（a）促进Mg0的腐蚀并将Pd4 +还原为Pd0，（b）提供质子产生H2，（c）阻止可能沉积的不溶性氧化物和氢氧化物的形成在镁颗粒上吸附PCP及其部分脱氯产物。在有机氯当量条件下，在PCP，2,4,5-三氯苯酚（TCP）和2-氯苯酚（MCP）上施用154.5 mM Mg0 / 0.063 mM K2PdCl6时，去除率和程度随氯原子数的减少而增加。苯酚。
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