A novel biochar-based 3D composite for ultrafast and selective Cr(VI) removal in electroplating wastewater
Zongzheng Yang, Jinjin Wang, Nan Zhao, Runyi Pang, Chuanfang Zhao, Ying Deng, Di Yang, Haochen Jiang, Zhiguo Wu, Rongliang Qiu
Abstract
Abstract In this study, a newly developed composite of biochar-poly( m -phenylenediamine) (BC-P m PD) exhibiting a distinct skeletal structure was synthesized for the purpose of extracting Cr(VI) from aqueous solutions. BC was employed as a supportive carrier onto which P m PD nanoparticles were uniformly affixed through in - situ polymerization and oxidation synthesis, both within and outside the layered configuration of BC. The structural stability and morphologies of BC-P m PD were assessed utilizing Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, thermogravimetric analysis, analysis of specific surface area and pore size, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction. In comparison to other modified BCs reported, BC-P m PD exhibited the highest Cr(VI) removal rate. Specifically, at 303 K, BC-P m PD achieved a maximum Cr(VI) removal capacity of 775 mg g −1 , surpassing the capabilities of unmodified BC and P m PD by 10.4 and 2.13 times, respectively. Analyses involving XPS, FTIR, and density functional theory calculation confirmed that proton transfer happened between protonated amine (−NH 2 ) functional group within the structure of BC-P m PD and HCrO 4 − before the formation of hydrogen bond. Subsequently, environmentally persistent free radicals facilitated the reduction of the adsorbed Cr(VI). Quantification of the functional groups indicated that the amino group was responsible for 93.0% of the Cr(VI) adsorption in BC-P m PD. BC-P m PD displayed potent adsorption and reduction capabilities, alongside notable stability, repeatability, and promising potential for application in the remediation for high concentrations of Cr(VI) in electroplating wastewater scenarios. Graphical Abstract