Degradation of Azo Dyes with Different Functional Groups in Simulated Wastewater by Electrocoagulation

Abstract

Increasing attention has been paid to the widespread contamination of azo dyes in water bodies globally. These chemicals can present high toxicity, possibly causing severe irritation of the respiratory tract and even carcinogenic effects. The present study focuses on the periodically reverse electrocoagulation (PREC) treatment of two typical azo dyes with different functional groups, involving methyl orange (MO) and alizarin yellow (AY), using Fe-Fe electrodes. Based upon the comparative analysis of three main parameters, including current intensity, pH, and electrolyte, the optimal color removal rates for MO and AY could be achieved at a rate of up to 98.7% and 98.6%, respectively, when the current intensity is set to 0.6 A, the pH is set at 6.0, and the electrolyte is selected as NaCl. An accurate predicted method of response surface methodology (RSM) was established to optimize the PREC process involving the three parameters above. The reaction time was the main influence for both azo dyes, while the condition of PREC treatment for AY simulated wastewater was time-saving and energy conserving. According to the further UV–Vis spectrophotometry analysis throughout the procedure of the PREC process, the removal efficiency for AY was better than that of MO, potentially because hydroxyl groups might donate electrons to iron flocs or electrolyze out hydroxyl free radicals. The present study revealed that the functional groups might pose a vital influence on the removal efficiencies of the PREC treatment for those two azo dyes.

Recent Advances in Efficient Photocatalytic Degradation Approaches for Azo Dyes

“…Te electrocoagulation process investigated by Lach et al [84] revealed a high azo dye removal efciency (96.5%) with TOC and COD of 93.5% and 85.0%, respectively. Liu et al [85] presented a reverse electrocoagulation treatment of methyl orange and alizarin yellow dyes using Fe-Fe electrodes. Te efciency for methyl orange and alizarin yellow achieved was 98.7% and 98.6%, respectively, using NaCl as the electrolyte.…”

Review on Recent Developments in Bioinspired-Materials for Sustainable Energy and Environmental Applications

“…Dyes show negative impacts on both the surface water and groundwater quality by blocking light transmission, affecting the photosynthesis of aquatic flora and by reducing dissolved oxygen in water [131]. Dyes are toxic to aquatic ecosystem and human beings due to its mutagenic, carcinogenic and genotoxic nature [132,133]. Many technologies have been applied for the treatment of wastewater such as electrochemical methods, reverse osmosis, ozone oxidation, chemical precipitation, membrane separation, adsorption and photocatalysis etc.…”

Synthesis, Characterization, and Photocatalytic Activity of Cu-Doped MgO Nanoparticles on Degradation of Methyl Orange (MO)

“…Organic dyes inhibit light penetration through water, slow down photosynthesis reactions, hinder sunlight penetration, lower photosynthesis activity, and cause oxygen defcit, all of which have an impact on water quality. Furthermore, certain chemical dyes like azo dyes can cause mutagenic and carcinogenic efects [4]. Synthetic dyes, which are used in large quantities in the textile industry, are chemically stable and harmful to the environment.…”