School of Environmental Studies, Cochin University of Science and Technology, Kochi, India.
Department of Chemistry, Deva Matha College, Kuravilangad, India.
Environ Technol. 2022 Jan;43(3):443-459. doi: 10.1080/09593330.2020.1791972. Epub 2020 Jul 18.
A two-step process involving coagulation-flocculation followed by solar photocatalysis - based Advanced Oxidation Process (AOP) using TiO-Reduced Graphene Oxide (TRGO) nanocomposite as catalyst has been employed for the treatment of pulp and paper mill effluent. As the effluent is loaded with a high amount of organics with initial chemical oxygen demand (COD) as high as 3516, a pre-treatment is required before applying photocatalytic treatment. Coagulation-flocculation was identified as an effective pre-treatment strategy. Among the various coagulants tested, CuSO.5HO showed the best % COD reduction of 84 at pH 6, at a loading of 5 g/L. The primary treatment of coagulation improved the biodegradability index from 0.23 to 0.37. TRGO photocatalyst, employed in the second stage of photocatalytic treatment was synthesised by an ultrasound assisted solvothermal method and well characterised by various spectroscopic/analytical tools. The composite was found to be an efficient solar photocatalyst and achieved 1.76 and 2.1 times more COD reduction than synthesised TiO and commercial P25 respectively. The final effluent after the combined treatment was neutral and the biochemical oxygen demand (BOD) and COD were 11.7 and 120 mg/L respectively which were below the given limit of National Environmental Quality Standards.
采用两步法，首先进行混凝-絮凝处理，然后使用 TiO2-还原氧化石墨烯（TRGO）纳米复合材料作为催化剂进行基于太阳能光催化的高级氧化处理（AOP），对制浆造纸厂废水进行处理。由于废水中含有大量有机物，初始化学需氧量（COD）高达 3516，因此在进行光催化处理之前需要进行预处理。混凝-絮凝被确定为一种有效的预处理策略。在测试的各种混凝剂中，CuSO4·5H2O 在 pH 值为 6、用量为 5g/L 时表现出最好的 84%COD 去除率。混凝的初步处理将可生物降解性指数从 0.23 提高到 0.37。在光催化处理的第二阶段中使用的 TRGO 光催化剂是通过超声辅助溶剂热法合成的，并通过各种光谱/分析工具进行了很好的表征。该复合材料是一种高效的太阳能光催化剂，与合成的 TiO2 和商业 P25 相比，COD 去除率分别提高了 1.76 倍和 2.1 倍。联合处理后的最终废水呈中性，生化需氧量（BOD）和 COD 分别为 11.7 和 120mg/L，低于国家环境质量标准的规定限值。
