State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin, 150090, PR China.
Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Floyd Ave, Richmond, VA 23219, USA.
Chemosphere. 2018 Sep;207:50-59. doi: 10.1016/j.chemosphere.2018.05.046. Epub 2018 May 9.
The superiority of the nanoscale zero valent iron (nZVI) assisted biochar (BC) composites compared to traditional nZVI and its application feasibility are still unclear. This study aimed to provide valuable information for practical application. Firstly, the Fe/BC mass ratio of 2:1 during the preparation of nZVI-BC was proved obtaining the complete Cr removal. Then, results revealed that the initial pH value tuned Cr removal performance via varying existing Cr species, surface charge, and chemical states of iron nanoparticles (NPs). Improvement of colloidal stabilization and positive surface charge attributed to enhancement of Cr removal of nZVI-BC. The Cr removal process was well described using pseudo-second-order kinetic. By Langmuir isotherm model, the maximum removal capacity (58.82 mg g) was determined. Moreover, the multiple evidences (XRD, XPS, FTIR, and TEM results) explained the mechanisms of Cr removal (i.e. electrostatic force, complexes, metal reduction, and precipitates on the edges). Little inhibitory effect of coexisting anions (SO, PO, and NO) and well regeneration ability (82.2% removal efficiency after five cycles using acid washing), along with well Cr removal efficiencies of real contaminated water (electroplating wastewater, tannery wastewater and groundwater) treatment, suggested nZVI-BC was considered as a superior and cost-effective choice for Cr included polluted water treatment.
纳米零价铁（nZVI）辅助生物炭（BC）复合材料相对于传统 nZVI 的优越性及其应用可行性尚不清楚。本研究旨在提供有价值的信息以促进实际应用。首先，在制备 nZVI-BC 过程中，Fe/BC 质量比为 2:1 被证明可以完全去除 Cr。然后，结果表明初始 pH 值通过改变存在的 Cr 物种、表面电荷和铁纳米颗粒（NPs）的化学状态来调节 Cr 的去除性能。胶体稳定性的提高和表面正电荷归因于 nZVI-BC 的 Cr 去除性能的增强。Cr 的去除过程很好地符合准二级动力学。通过 Langmuir 等温模型，确定了最大去除容量（58.82mg/g）。此外，多种证据（XRD、XPS、FTIR 和 TEM 结果）解释了 Cr 去除的机制（即静电引力、络合、金属还原和在边缘形成沉淀物）。共存阴离子（SO、PO 和 NO）的抑制作用较小，良好的再生能力（酸洗脱后五次循环的去除效率为 82.2%），以及电镀废水、制革废水和地下水等实际污染水的良好 Cr 去除效率，表明 nZVI-BC 是一种处理含 Cr 污染水的优越且具有成本效益的选择。
