College of Environmental Science and Engineering, Tongji University, Siping Rd. 1239, Shanghai, 200092, China.
Shanghai Institute of Pollution Control and Ecological Security, 1515 North Zhongshan Rd. (No. 2), Shanghai, 200092, China.
Environ Sci Pollut Res Int. 2019 Apr;26(10):9480-9489. doi: 10.1007/s11356-019-04221-2. Epub 2019 Feb 6.
Chlorine-containing organic waste (COWs) is a big threat for the waste incineration because of the dioxin generation and equipment corrosion. Recently, dechlorination and detoxification of COWs is emergent in order to lower the environmental risk and treatment costs. In this study, base-catalyzed decomposition processes with different hydroxides, hydrogen donors, and catalysts were conducted for pre-treatment of COWs to reduce organic chlorine content, with the TCB as a model compound and industrial rectification residues for verification. Results showed that maximum chlorine retention efficiency (CRE) of four alkalis followed the order of KOH > NaOH-KOH > NaOH > Mg(OH), which were 98.3%, 93.4%, 97.2%, and 1.5%, respectively, and could be expressed as an apparent first-order reaction. The differences were resulted from the varying ionic potentials of the metal cations. Hydrogen donors (glycol, glycerol, paraffin oil, and PEG 200) acted as effective dechlorination regents follow the order of PEG > glycol > paraffin oil > glycerol. In addition, Fe, Ni, Cu, and activated carbon catalysts increased the CRE by 68.9% to 92.4%, 91.9%, 89.2%, and 73.3%, respectively. Residue analysis through X-ray diffraction and Fourier transform infrared spectroscopy revealed that KCl, sodium oxalate, and phenol were the main products and a plausible stepwise dechlorination pathway was proposed. The effectiveness of three optimized combinations including NaOH/PEG, KOH/PEG, and NaOH-KOH/PEG (with the Fe catalyst) was confirmed by using them for dechlorinating rectification residues, and they restrained 98.2%, 91.2%, and 94.6% of the chlorine, respectively. The organochlorine content decreased from 19.2 to 1.8% within 180 min, while inorganic chorine content increased from 1.5 to 18.9%, indicating the potential for COWs dechlorination.
含氯有机废物（COWs）是垃圾焚烧的一大威胁，因为它会生成二恶英并腐蚀设备。为了降低环境风险和处理成本，最近 COWs 的脱氯解毒成为当务之急。在这项研究中，使用不同的氢氧化物、供氢体和催化剂进行了碱催化分解过程，以降低模型化合物三氯苯（TCB）和工业精馏残渣的有机氯含量。结果表明，四种碱的最大氯保留效率（CRE）顺序为 KOH > NaOH-KOH > NaOH > Mg(OH)₂，分别为 98.3%、93.4%、97.2%和 1.5%，可表示为一级反应。差异是由于金属阳离子的离子势不同造成的。供氢体（乙二醇、丙三醇、石蜡油和 PEG200）的脱氯效果依次为 PEG > 乙二醇 > 石蜡油 > 丙三醇。此外，Fe、Ni、Cu 和活性炭催化剂使 CRE 分别提高了 68.9%至 92.4%、91.9%、89.2%和 73.3%。X 射线衍射和傅里叶变换红外光谱分析表明，KCl、草酸钠和苯酚是主要产物，并提出了一个可能的逐步脱氯途径。使用 NaOH/PEG、KOH/PEG 和 NaOH-KOH/PEG（添加 Fe 催化剂）三种优化组合处理精馏残渣，证实了它们的有效性，分别脱除了 98.2%、91.2%和 94.6%的氯，而残渣中的有机氯含量从 19.2%降至 1.8%，在 180 分钟内，无机氯含量从 1.5%增加到 18.9%，这表明 COWs 具有脱氯潜力。
