A characteristic study on generation and interactive effect of electrocoagulated floc with Direct Green 1 and Reactive Red 2

Abstract

Abstract The present investigation involves an optimization of the electrocoagulation on aqueous organic dye solutions with two different group of operational conditions namely reactor design such as applied voltage, effective surface area, inter electrode distance, stirring speed and nature of the organic dye solutions such as pH, conductivity, dye concentration, temperature. The experiments are focused on the maximum colour and COD removal with minimum energy and electrode consumption. The kinetic study reveals the colour removal efficiency of two organic dye solutions is decreases from 0.142 to 0.026 min− 1 for DG1 and from 0.119 to 0.023 min− 1 for RR2 with increase in pH. Thermodynamic parameter of ΔH and ΔS shows the endothermic nature of adsorption of dyes. Freundlich constant evidenced the adsorption of both dyes over floc surface is spontaneous. The maximum dye removed per unit area of electrode is 26.8 ppm/cm2 for DG1 and 21.2 ppm/cm2 for RR2 observed at the 10 cm2 effective surface area. The FTIR analysis of floc residue, peak values at 3452.56 and 1496.93 cm− 1 of RR2 alone shifted to 3418.31 and 1425.78 cm− 1 in electrocoagulated floc residue suggests the adsorption of RR2 over iron flocs. The peak at 1493.32 cm− 1 supports the presence of azo group in the parent dye structure of DG1 and disappearance of the peak in electrocoagulated flocs residue evidenced the adsorption of partially degraded dyes on electrocoagulated flocs.