Genawi Nahid M, Mahmud Nafis, Hassan Elfatih A, El-Naas Muftah H
Department of Chemistry and Earth Science, Qatar University, Doha, 2713, Qatar.
Department of Chemistry, College of Science, Sudan University of Science & Technology, Western Campus, Almugran, PO Box: 407, Sudan.
ChemistryOpen. 2025 Aug;14(8):e202400497. doi: 10.1002/open.202400497. Epub 2025 May 9.
Electrocoagulation is an efficient electrochemical technology used for the treatment of contaminants in wastewater with reportedly high efficiency in treating chromium-rich wastewater. In this study, the removal of chromium (III) ions from tannery wastewater by electrocoagulation is investigated at different pH, current density, and chromium concentrations. The complete removal of chromium ions is achieved at a pH of 6.5, current density of 10.0 mA cm, and chromium concentration of 500 mg L in batch experiments within an hour. The results showed that the formation of coagulant species during the first 30 min facilitated the chromium removal efficiency through both electrocoagulation and adsorption at low pH of 4. When taking into account varying adsorbent mass, the acquired adsorption kinetics data demonstrates an excellent fit to the pseudo-second-order model, predicting a chromium absorption of 5000 mg g compared to the experimental uptake of 5108 mg g. In contrast, the experimental and calculated uptakes for fixed adsorbent mass were 5108 and 83333 mg g, respectively. The observed discrepancy in the uptake when using fixed mass confirms the advantage of considering the variable adsorbent mass for predicting the adsorption during electrocoagulation. Moreover, 97% of chromium was recovered from the generated sludge using 4% H2SO4 which can ensure the minimization of the hazardus sludge disposal.
电凝是一种高效的电化学技术，用于处理废水中的污染物，据报道在处理含铬废水方面具有很高的效率。在本研究中，研究了在不同pH值、电流密度和铬浓度下，通过电凝去除制革废水中的铬（III）离子。在分批实验中，1小时内pH值为6.5、电流密度为10.0 mA/cm且铬浓度为500 mg/L时，可实现铬离子的完全去除。结果表明，在前30分钟内形成的混凝剂物种在低pH值为4时通过电凝和吸附促进了铬的去除效率。考虑到不同的吸附剂质量，获得的吸附动力学数据与准二级模型拟合良好，预测铬吸附量为5000 mg/g，而实验吸附量为5108 mg/g。相比之下，固定吸附剂质量时的实验和计算吸附量分别为5108和83333 mg/g。使用固定质量时观察到的吸附差异证实了考虑可变吸附剂质量在预测电凝过程中吸附的优势。此外，使用4%的硫酸从产生的污泥中回收了97%的铬，这可以确保危险污泥处置量最小化。
