Zn-based metal organic frameworks encapsuated cauliflower leaves-derived biochar composite for photocatalytic removal of victoria blue and crystal violet

The rising concerns regarding the discharge of waste effluents and their side effects in our environment has ignited the minds of different researchers for finding feasible, economic and practical ways to mitigate the ongoing alarming issue. Several harmful organic dyes, pharmaceuticals and nitro-aromatic compounds etc. constitute the key harmful toxic contributors often found in the industrial wastes. This manuscript proposes the compositing of novel cauliflower leaves waste derived biochar (CF) with porous zinc-based metal organic framework (ZIF-8). The study of the crystalline planes, surface morphology, composition of different elements and optical features of the CF-ZIF-8 composite was examined through different analytical characterization methods including PXRD, TEM, FE-SEM, EDS, XPS, UV-DRS and PL analysis. The influence of the synergistic beneficial aspects of both the materials helped to boost the photocatalytic degradation performance of the CF-ZIF-8 catalyst with 92 ± 1.57% removal of victoria blue (VB) and 89 ± 1.21% removal of craystal violet (CV) and their degradation obeyed the first-order kinetics. The catalyst exerted a maximum degradation performance at an optimized catalyst dosage of 18 mg, starting dye concentration of 30 ppm and pH 10. Under optimized conditions, the degradation rate constant for decomposition of VB and CV were 0.0474 min^-1 and 0.0454 min^-1 respectively. Moreover, from the scavenger analysis and PL investigations it was confirmed that the ^·OH and ^·O₂^- radicals were the key contributors for the photocatalytic breakdown of both the organic pollutant molecules. The CF-ZIF-8 catalyst also showed good sustainability as there was very little decline of the degradation efficiency until the fourth catalytic run and the intact of the crystalline structure revealed by the PXRD analysis with no appreciable changes in the PXRD pattern of the recycled catalyst.