Performance evaluation of photolytic and electrochemical oxidation processes for enhanced degradation of food dyes laden wastewater

• Published in: Water science and technology Vol. 81; no. 5; pp. 971 - 984
• Main Authors: Sartaj, Seema, Ali, Nisar, Khan, Adnan, Malik, Sumeet, Bilal, Muhammad, Khan, Menhad, Ali, Nauman, Hussain, Sajjad, Khan, Hammad, Khan, Sabir
• Format: Journal Article
• Language: English
• Published: England IWA Publishing 01-03-2020
• Subjects: Anodes; Chlorine; Color removal; Coloring Agents; Colour; Current density; Degradation; Design; Dyes; Electrochemical oxidation; Electrochemistry; Electrodes; Electrolysis; Electrolytes; Energy consumption; Food; Food dyes; Hypochlorous acid; Light; Oxidants; Oxidation; Oxidation-Reduction; Oxidizing agents; Performance evaluation; pH effects; Pollutants; Power supply; Ruthenium; Ruthenium oxide; Sodium; Sodium chloride; Titanium; Ultraviolet radiation; Variables; Waste Water; Wastewater; Water Pollutants, Chemical; United States > US; Germany
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2020.182

Wastewater containing dyes is considered as the top-priority pollutant when discharged into the environment. Herein, we report for the applicability of 254 nm ultraviolet light and electrochemical process using a titanium ruthenium oxide anode for the degradation of Allura red and erythrosine dyes. During the photolytic process, 95% of Allura red dye (50 ppm) was removed after 1 h at pH 12 and 35 °C, whereas 90% color removal of erythrosine dye (50 ppm) was achieved after 6 h of treatment at pH 6.0 and 30 °C. On the other hand, 99.60% of Allura red dye (200 ppm) was removed within 5 min by the electrochemical process applying a current density (5 mA cm
) at pH 5.0 and 0.1 mol L
sodium chloride (NaCl) electrolytic medium. Similarly, 99.61% of erythrosine dye (50 ppm) degradation was achieved after 10 min at a current density of 8 mA cm
, pH 6.0, and 0.1 mol L
of NaCl electrolyte. The minimum energy consumption value for Allura red and erythrosine dyes (0.196 and 0.941 kWh m
, respectively) was calculated at optimum current densities of 5 and 8 mA cm
. The results demonstrated that the electrochemical process is more efficient at removing dyes in a shorter time than the photolytic process since it generates powerful oxidants like the chlorine molecule, hypochlorous acid, and hypochlorite on the surface of the anode and initiates a chain reaction to oxidize the dyes molecules.