Key Laboratory of Mine Water Resource Utilization of Anhui Higher Education Institute, School of Resources and Civil Engineering, Suzhou University, Suzhou, 234000, Anhui, PR China; College of the Environment and Ecology, Xiamen University, Xiamen, 361102, Fujian province, PR China.
College of the Environment and Ecology, Xiamen University, Xiamen, 361102, Fujian province, PR China; China-ASEAN College of Marine Sciences, Xiamen University Malaysia, Selangor Darul Ehsan, 43900, Malaysia.
Chemosphere. 2021 May;271:129861. doi: 10.1016/j.chemosphere.2021.129861. Epub 2021 Feb 6.
This work incorporated technological values into ZnCr-layered double hydroxide (LDH), synthesized from unused resources, for removal of pyrophosphate (PP) in electroplating wastewater. To adopt a resource recovery for the remediation of the aquatic environment, the ZnCr-LDH was fabricated by co-precipitation from concentrated metals of plating waste that remained as industrial by-products from metal finishing processes. To examine its applicability for water treatment, batch experiments were conducted at optimum M/M, pH, reaction time, and temperature. To understand the adsorption mechanisms of the PP by the adsorbent, the ZnCr-LDH was characterized using Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses before and after adsorption treatment. An almost complete PP removal was attained by the ZnCr-LDH at optimized conditions: 50 mg/L of PP, 1 g/L of adsorbent, pH 6, and 6 h of reaction. Ion exchange controlled the PP removal by the adsorbent at acidic conditions. The PP removal well fitted a pseudo-second-order kinetics and/or the Langmuir isotherm model with 79 mg/g of PP adsorption capacity. The spent ZnCr-LDH was regenerated with NaOH with 86% of efficiency for the first cycle. The treated effluents could comply with the discharge limit of <1 mg/L. Overall, the use of the ZnCr-LDH as a low-cost adsorbent for wastewater treatment has contributed to national policy that promotes a zero-waste approach for a circular economy (CE) through a resource recovery paradigm.
这项工作将技术价值融入到由未使用资源合成的锌铬层状双氢氧化物 (LDH) 中，用于去除电镀废水中的焦磷酸盐 (PP)。为了采用资源回收的方法来修复水生态环境，通过共沉淀法从金属精整过程中产生的工业副产品——电镀废水中浓缩的金属来制备 ZnCr-LDH。为了检验其在水处理方面的适用性，在最佳的 M/M、pH、反应时间和温度下进行了批量实验。为了了解吸附剂对 PP 的吸附机制，在吸附处理前后，使用比表面积仪（BET）、X 射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、扫描电子显微镜/能谱（SEM/EDS）、透射电子显微镜（TEM）和 X 射线光电子能谱（XPS）对 ZnCr-LDH 进行了表征。在优化条件下：PP 浓度为 50mg/L，吸附剂用量为 1g/L，pH 值为 6，反应时间为 6h，ZnCr-LDH 几乎能完全去除 PP。在酸性条件下，离子交换控制着吸附剂对 PP 的去除。PP 的去除很好地符合准二级动力学和/或 Langmuir 等温模型，其对 PP 的吸附容量为 79mg/g。用 NaOH 对 ZnCr-LDH 进行再生，在第一个循环中效率为 86%。处理后的废水可以达到 <1mg/L 的排放标准。总的来说，将 ZnCr-LDH 用作废水处理的低成本吸附剂，符合国家政策，该政策通过资源回收范式促进了循环经济（CE）的零废物方法。
