Abstract:

In the present study, microwave-H₂O₂ (MW-H₂O₂) process was applied for the treatment of Cu-EDTA containing wastewater. The effects of reaction time, initial pH, H₂O₂ dosage, microwave power and coexistent substances were investigated in detail. The corresponding degradation mechanism of Cu-EDTA was also described. The results showed that for the elimination of 1.57 mmol·L^-1 Cu-EDTA, the highest removal efficiencies of Cu (97.0%) and TOC (60.7%) were achieved under the optimum conditions (i.e. initial pH 3, H₂O₂ dosage 41 mmol·L^-1, microwave power 210 W, and reaction time 10 min). In this situation, the effluent conductivity decreased to 1.8 mS·cm^-1, and only 0.15 g·L^-1 of the sludge yield was generated. The presence of coexistent substances such as NO₃^- had nearly no effects on the degradation processes, while Cl^-, H₂PO₄^- and tartaric acid were unfavorable to the oxidation degradation of Cu-EDTA. After treated for 4 min, Cu-EDTA was almost totally oxidized to various Cu-intermediates, which rapidly degraded within 4-6 min, leading to the final formation of low molecular organic acids, NH₃-N, and inorganic carbon. The solid sludge mainly presented in the forms of CuO. Compared with traditional Fenton process, MW-H₂O₂ process exhibited more excellent performance in terms of oxidation efficiency, effluent conductivity and sludge yield.

Key words: microwave-hydrogen peroxide, Cu-EDTA, oxidation, wastewater, Fenton, pollution

摘要：

采用微波-过氧化氢工艺处理含Cu-EDTA废水，考察反应时间、初始pH、H₂O₂投加量、微波功率以及共存物质等因素对该工艺处理效能的影响，并分析了氧化作用机制。结果表明，在初始pH为3，H₂O₂投加量为41 mmol·L^-1，微波功率为210 W时，1.57 mmol·L^-1Cu-EDTA反应10 min后，Cu和TOC去除率分别高达97.0%和60.7%，出水电导率低至1.8 mS·cm^-1，产泥量仅为0.15 g·L^-1。NO₃^-的存在对Cu-EDTA的氧化降解过程无明显影响，而Cl^-、H₂PO₄^-和酒石酸对反应过程有一定的抑制作用。该工艺下反应4 min后Cu-EDTA基本氧化为中间产物，并在4～6 min内急剧降解，最终形成小分子羧酸类物质、NH₃-N和无机碳。反应过程沉淀产物主要以CuO形式存在。相比Fenton工艺，该工艺在氧化效能、出水电导率及产泥量等方面有显著优势。

关键词: 微波-过氧化氢, Cu-EDTA, 氧化, 废水, 芬顿, 污染