Sequential Design of Experiments for Removal of Methylene Blue Dye by Electrocoagulation Associated with Dissolved-Air System

Abstract

The present work presents a strategic sequential experimental planning to evaluate the removal of methylene blue dye from aqueous medium by electrocoagulation combined with dissolved air flotation. Effect of electrode pairs, electrode spacing, contact time, initial pH, voltage, and pressure were optimized according to the following response variables: color, final pH, turbidity, and dye removal. The best-achieved optimized conditions were: 4 pairs of electrodes, 2.5 cm spacing, electrolysis time of 203 min, initial pH 4, voltage of 32 V, and no pressure by dissolved air injection. Among the experimental results, it was possible to obtain a maximum removal of 95.1% of the dye. The analysis of the response surfaces showed that the initial pH has a great influence on the final characteristic of the treated effluent. Through the study of optimization, synthetic effluents have been obtained that meet the discharge standards according to the current Brazilian environmental legislation.

Simplified electrocoagulation for efficient biodiesel washing water treatment

“…The use of this technique, depending on the pH, impacts electrode consumption. Additionally, metal ions released as result of pH-dependent hydrolysis of aluminum interact with suspended particles, facilitating their removal (Goés et al, 2021b).…”

“…To address this issue, researchers have explored various technologies for biodiesel wastewater treatment, including biological, physicochemical, electrochemical, and combined processes (An et al, 2017;Jaruwat, Pitakpoolsil and Hunsom, 2016;Gomes, Arroyo and Pereira, 2015;Sari-erkan, 2019;Goés et al, 2021a;Desai et al, 2017;Savci, 2017;Alves et al, 2016;Daud, Nasir and Awang, 2013;Ngamlerdpokin et al, 2011, Nidheesh, Zhou andOturan, 2018). Among these methodologies, electrocoagulation has gained significant interest in the past decade due to its simplicity, ease of operation, shorter treatment time, rapid sedimentation of electrostatic flakes, lower sludge production, and high efficiency (Chen et al, 2021;Goés et al, 2021b;Shahedi et al, 2020). Another advantage of this technique is the absence of chemical addition, since the electrolytic cell provides the necessary coagulating (Goés et al, 2021b).…”

“…Among these methodologies, electrocoagulation has gained significant interest in the past decade due to its simplicity, ease of operation, shorter treatment time, rapid sedimentation of electrostatic flakes, lower sludge production, and high efficiency (Chen et al, 2021;Goés et al, 2021b;Shahedi et al, 2020). Another advantage of this technique is the absence of chemical addition, since the electrolytic cell provides the necessary coagulating (Goés et al, 2021b). Essentially, electrocoagulation involves passing an electrical current through sacrificial electrodes (usually aluminum), leading to the generation of a coagulating agent and H2(g) bubbles (Shahedi et al, 2020).…”

“…Numerous studies have demonstrated the high efficiency of electrocoagulation in removing various critical contaminants, including dyes, heavy metals, emulsions, and especially O&G (Goés et al, 2021b;Nidheesh et al, 2021;Bazrafshan et al, 2015;Razali, Hamid and Azoddein, 2016;Daud et al 2015;De Meneses et al, 2012;Rincón and La Motta, 2014;Cordeiro et al, 2015;Vieira et al, 2017;).…”