Sustainable removal of organic pollutants using biochar based ZnO composites: Experimental and theoretical studies of remediation process

Abstract

The tailoring of biochar to enhance its remediation efficiency for removal of pollutants from water has been a hot topic these days. Fabricating two different biochar materials using metal oxide nano particles in four ratios has been done in this work. The synthesized materials have been characterized by XRD, surface functional groups were analyzed using FTIR and XPS, band gap calculation were carried out using Tauc's method, recombination of charges was studied using photoluminescence spectroscopy, morphological, textural properties and elemental analysis was done using SEM, BET, TGA, EIS and EDX analysis. The removal of organic pollutants including phenol, dibutyl phthalate and gallic acid up to 91.6%, 84% and 95% was observed employing these composites. The band gap reduction from 3.1 eV to 2.5 eV and 2.8 eV was observed in case of ZW(1-10) and ZP(1-10) respectively. The formation of Zn-O-C bond in the composite could be possible reasons for the band gap reduction and excellent performance exhibited by the composite. The results highlight the influence of functional groups on the efficiency of synthesized material. Furthermore, density functional theory (DFT) calculations were performed using Gaussian16 software to propose the adsorption mechanism for the observed results. The energy calculation for different binding modes were carried out. Theoretical findings agreed with the empirically demonstrated remediation mechanism.