Furfural removal by heat-activated PS/PMS and heat-supported PC oxidation: Optimization, kinetic modelling, and anion effect

Abstract

In this study, removal of furfural that is an organic contaminant having low biodegradability by heat-activated persulfate (HA/PS), heat-activated peroxymonosulfate (HA/PMS), and heat-supported percarbonate (HS/PC) processes was investigated. To determine the performance of single and combined processes, preliminary control experiments were conducted. The variables of the processes were optimized using the classical optimization method and effect of process parameters (temperature, oxidant dose, initial furfural concentration, and solution input pH) on HA/PS, HA/PMS, and HS/PC oxidation were determined. The control experiments demonstrated that heat significantly effected all three processes. The activation energy values were found to be 61,526, 86,640, and 56,992 Joules/mol for the HA/PS, HA/PMS, and HS/PC processes respectively. Under optimal operating conditions (10 mg/L initial furfural concentration, 80 degrees C temperature, 2 mM PS, 4 mM PMS, 2 mM PC dose, pH of 8.72 for HA/PS, HA/PMS, pH of 3 for HS/PC, reaction time 60 min.) removal efficiencies of 95.7 %, 96.0 %, and 95.5 % were achieved for the HA/PS, HA/PMS, and HS/PC processes, respectively. The first-order reaction rate constants for the HA/PS, HA/PMS, and HS/PC processes were calculated as 0.0487, 0.0522, and 0.0526 min-1 , respectively. The effect of inorganic anions (bicarbonate, chloride, nitrate, sulfate, and phosphate) on furfural removal by the HA/PS, HA/PMS, and HS/PC processes was also investigated, revealing that all inorganic anions had a negative impact on all three processes, reducing removal efficiencies. Chloride and bicarbonate anions showed the greatest effect leading to the highest reduction in removal efficiencies.