Removal of furfural using zero gap electrocoagulation by a scrap iron anode from aqueous solution

Abstract

In the present study, furfural removal by a new electrochemical reactor with a zero-gap distance between the scrap iron anode and the cathode from aqueous solutions was investigated. The effects of the operational parameters, including initial furfural concentration (100–600 mg/L), current density (0.68–3.44 mA/cm2), solution pH (4–11), and hydraulic retention time (5–180 min), were evaluated.The experimental results indicated that a current density of 2.75 mA/cm2, an initial furfural concentration of 100 mg/L, and a pH of 7.0 were the most favorable conditions for the complete removal of furfural (>88 %) within 120 min of hydraulic time. Based on the LC-MS analysis, furan-2-carboxylic acid, furan-2-yl hydrogen carbonate, furan-2-ol, furan-2(5H)-one, maleic acid, acetic acid, oxalic acid, and formic acid were the main intermediates identified in furfural degradation. The TOC and COD removal rates were 64.75 and 75.62 % in the zero-gap electrocoagulation (ZG-EC) system under the optimized conditions, respectively. According to the kinetic results, the rate of furfural removal by the ZG-EC process followed the pseudo-first-order kinetics (R2 > 0.9). Finally, the degradation pathway of furfural using the ZG-EC process is proposed.