Enhanced hexavalent chromium removal performance and stabilization by magnetic iron nanoparticles assisted biochar in aqueous solution: Mechanisms and application potential. (September 2018)

• Record Type: Journal Article
• Authors: Zhu, Shishu; Huang, Xiaochen; Wang, Dawei; Wang, Li; Ma, Fang
• Is Part Of: Chemosphere. Volume 207(2018)
• Page Start: 50
• Page End: 59
• Publication Date: 2018-09
• Subjects: Biochar -- Hexavalent chromium -- Nanoscale zero valent iron -- Real wastewater treatment; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.05.046
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: 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 6+ removal. Then, results revealed that the initial pH value tuned Cr 6+ removal performance via varying existing Cr 6+ species, surface charge, and chemical states of iron nanoparticles (NPs). Improvement of colloidal stabilization and positive surface charge attributed to enhancement of Cr 6+ removal of nZVI-BC. The Cr 6+ removal process was well described using pseudo-second-order kinetic. By Langmuir isotherm model, the maximum removal capacity (58.82 mg g −1 ) was determined. Moreover, the multiple evidences (XRD, XPS, FTIR, and TEM results) explained the mechanisms of Cr 6+ removal ( i.e. electrostatic force, complexes, metal reduction, and precipitates on the edges). Little inhibitory effect of coexisting anions (SO4 2−, PO4 3−, and NO3 − ) and well regeneration ability (82.2% removal efficiency after five cycles using acid washing), along with well Cr 6+ 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 6+ included polluted water treatment. Graphical abstract: Image 1 Highlights: pH raised variance of Cr 6+ species, surface charged, and iron NPs' chemical state. nZVI-BC owned better colloid stabilization and positive surface charge. Pseudo-second-order kinetics and Langmuir isotherm models were well fitted. Electrostatic force, complex, reduction, and precipitate were involved in Cr 6+ removal. The Cr 6+ existed in various real wastewaters was significantly reduced by nZVI-BC.