Electrochemical treatment of textile wastewater using electrodes from pyrolyzed rice husk

Abstract

Rice husk char (RHC) electrodes were used for the first time in electrochemical treatment of textile wastewater. SEM analysis revealed RHC's porous structure, while TGA showed it decomposes in four stages and is stable up to 189 °C. BET analysis indicated a high surface area of 734 m2/g and a microporous structure with 11.7 Å pore diameter and 0.213 mL/g pore volume. RHC electrodes pyrolyzed at 700 °C for 2 h and placed 15 cm apart worked best in a 2 L batch reactor with methylene blue (MB) as the model pollutant and 6 g/L NaCl as the electrolyte. The process followed first-order kinetics, with fastest reaction at 100 mg/L initial MB. Reduced TOC and changed FTIR spectra confirmed MB breakdown. The batch system removed 85.8 % of dye from real textile wastewater in 150 min. In continuous flow, lower rates achieved higher efficiencies, up to 90 % at 0.45 L/h after 210 min. Although RHC electrodes had lower conductivity and strength than metal, they represent a sustainable, cost-effective alternative for electrochemical wastewater treatment.