Polyethylene glycol-modified mesoporous zerovalent iron nanoparticle as potential catalyst for improved reductive degradation of Congo red from wastewater.

In this study, bare zero-valent iron nanoparticles (nZVI) have been modified using polyethylene glycol (PEG) of various molecular weight in a facile technique. The synthesized nZVI modified with PEG, M.W. of 600 and 6000 was denoted by nZVI-PEG600 and nZVI-PEG6000, respectively, and compared their catalytic activity towards the reductive degradation of Congo red (CR) using NaBH4.The existence of PEG layer surrounds the nZVI core was confirmed by several characterization tools, such as XRD, FTIR, FESEM and TEM. Herein, both nZVI-PEG600 and nZVI-PEG6000 exhibited remarkable removal efficiencies of 89.6% and 99.2% within 14 min of reaction time. The optimum reaction parameters were found to be as follows: 0.2 g L-1 catalyst dose and initial dye concentration of 2 × 10-5 molL-1 etc. Kinetic studies of dye degradation were investigated which follow pseudo-1st-order kinetics. The TOC analysis confirmed the complete mineralization of CR dye by nZVI-PEG6000 nanocatalyst. GCMS analysis of plausible degraded products was performed to elucidate a probable mechanistic pathway of CR degradation. Further, we have investigated the degradation of two anionic dyes mixture, i.e., CR and methyl orange (MO) using best catalyst, i.e., nZVI-PEG6000.