Energy & Environment Laboratory, Department of Applied Chemistry, Defence Institute of Advanced Technology (DU), Ministry of Defence, Girinagar, Pune, 411 025 India.
Chemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Pune, India.
Chemosphere. 2020 Jul;250:126298. doi: 10.1016/j.chemosphere.2020.126298. Epub 2020 Feb 22.
Chlorophenol (CP) is considered as environmentally hazardous material due to its acute toxicity, persistent nature and strong bioaccumulation. The dechlorination of 4-CP was investigated by using various catalysts such as bimetallic (Fe/Cu, Al/Fe), Pd/C, Raney Ni and Fe at room temperature. Among the catalysts studied, Raney Ni proved to be very economical and efficient catalyst that worked without the use of an external reducing agent. The dechlorination of 4-CP by Raney Ni was therefore further explored. Complete dechlorination of 4-CP (30 mg L) was achieved in 6 h at an optimum Raney Ni catalyst loading of 3 g L. The effect of triethylamine (TEA) and tripropylamine (TPA) was also investigated and it was observed that 100% dechlorination is possible in presence of 45 mg L of TEA. The kinetics of dechlorination of 4-CP was investigated and found to be first order with a rate constant of 0.017 min at 50 C, and it enhances to 0.109 min with addition of TEA. In the absence of a reducing agent, acidic to neutral pH favors dechlorination of 4-CP. The final product of dechlorination was estimated to be phenol by performing HPLC, LCMS and NMR analysis. Based on the results, a probable dechlorination mechanism of 4-CP is also proposed. It can be concluded that the catalytic hydrodechlorination is an effective and economical technique for dechlorination of 4-CP and it has a potential for the dechlorination of other toxic derivatives of chlorinated aromatics.
氯酚（CP）因其急性毒性、持久性和强生物累积性而被认为是对环境有害的物质。使用各种催化剂，如双金属（Fe/Cu、Al/Fe）、Pd/C、雷尼镍和 Fe，在室温下研究了 4-CP 的脱氯反应。在所研究的催化剂中，雷尼镍被证明是一种非常经济高效的催化剂，无需使用外部还原剂即可工作。因此，进一步探索了雷尼镍对 4-CP 的脱氯作用。在最佳雷尼镍催化剂用量为 3 g/L 的条件下，30 mg/L 的 4-CP 在 6 h 内即可完全脱氯。还研究了三乙胺（TEA）和三丙胺（TPA）的影响，结果表明在存在 45 mg/L 的 TEA 时可以实现 100%脱氯。研究了 4-CP 的脱氯动力学，发现其动力学为一级反应，在 50°C 时的速率常数为 0.017 min，加入 TEA 后可提高至 0.109 min。在没有还原剂的情况下，酸性到中性 pH 值有利于 4-CP 的脱氯。通过进行 HPLC、LCMS 和 NMR 分析，估计脱氯的最终产物为苯酚。根据结果，还提出了 4-CP 脱氯的可能机制。可以得出结论，催化加氢脱氯是脱除 4-CP 的有效且经济的技术，并且具有脱除其他氯化芳烃有毒衍生物的潜力。
