Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Environ Pollut. 2019 Apr;247:410-420. doi: 10.1016/j.envpol.2019.01.047. Epub 2019 Jan 14.
This study introduced a new approach for simultaneously enhancing Cr(VI) removal performance and mitigating release of dissolved Fe during nanoscale zero-valent iron (nZVI)-mediated reactions. After entrapping nZVI-impregnated biochar (BC) in the matrix of calcium-alginate (CA) bead, the physicochemical characterization of nZVI/BC/CA composites revealed that nZVI/BC particles were embedded inside CA having a spherical shape and several cracks on its outer layer. The multi-functionality of nZVI/BC/CA composites consisting of reductant (nZVI), porous adsorbent (BC), and external screening layer (CA) enhanced the removal of Cr(VI) with the maximum adsorption capacity of 86.4 mg/g (based on the Langmuir isotherm) and little release of dissolved Fe. With the XPS analysis and fitting results of kinetics (pseudo second order) and isotherms (Redlich-Peterson model), plausible removal mechanisms of Cr(VI) were simultaneous adsorption and micro-electrolysis reactions by nZVI/BC/CA composites. The practical applicability of nZVI/BC/CA composites was further demonstrated through the fixed-bed column experiments. These results provide new insights into the design of high-performance engineered biochar for wastewater treatment.
本研究提出了一种新的方法，可同时提高纳米零价铁（nZVI）介导反应中 Cr(VI) 的去除性能和减少溶解态 Fe 的释放。将负载 nZVI 的生物炭（BC）包埋在海藻酸钠（CA）珠的基质中后，nZVI/BC/CA 复合材料的物理化学特性表明，nZVI/BC 颗粒嵌入 CA 中，呈球形且外层有几个裂缝。nZVI/BC/CA 复合材料由还原剂（nZVI）、多孔吸附剂（BC）和外部屏蔽层（CA）组成，具有多功能性，可增强 Cr(VI) 的去除，最大吸附容量为 86.4mg/g（基于 Langmuir 等温线），且溶解态 Fe 的释放量较少。通过 XPS 分析和动力学（拟二级）和等温线（Redlich-Peterson 模型）拟合结果，nZVI/BC/CA 复合材料对 Cr(VI) 的可能去除机制是同时进行吸附和微电解反应。通过固定床柱实验进一步证明了 nZVI/BC/CA 复合材料的实际适用性。这些结果为用于废水处理的高性能工程生物炭的设计提供了新的见解。
