Visible light assisted photooxidative facile degradation of azo dyes in water using a green method

Abstract

In this study, the methyl orange (MO) dye has been degraded after screening several azo dyes due to its effective results and being toxic and carcinogenic to aquatic life and humans. An environmentally friendly, economical, and green method for water purification was used in this study using the photooxidative method. Several organic acids were screened for oxidative applications against various azo dyes but due to better results, methyl orange was selected for the whole study. Ascorbic acid, also known as vitamin C, was found to be best for photodegradation due to its high oxidative activity among various organic acids utilized. A newly developed photoreactor box has been used to conduct the photooxidation process. To evaluate the degradation efficiency of AsA, photooxidative activity was monitored periodically. When the dose of AsA was used at a contact time of 180 minutes, degradation efficiency was 96%. The analysis of degraded products was performed using HPLC and GC-MS. The nucleophilicity of HOMO–LUMO and MEPs was confirmed using density functional theory. For the optimization of the process, central composite design (CCD) in Response Surface Methodology (RSM) was utilized.