Effect of inorganic anions and oxidizing agents on electrochemical oxidation of methyl orange, malachite green and 2,4-dinitrophenol

Abstract

Abstract Electrochemical oxidation of methyl orange, malachite green and 2,4-dinitrophenol were performed in the presence of varying concentrations of inorganic anions and oxidizing agents. Methyl orange oxidation was positively affected by carbonate ( −1 ), H 2 PO 4 − (100–500 mg L −1 ), H 2 O 2 ( −1 ) and S 2 O 8 2− (> 400 mg L −1 ). Carbonate (> 400 mg L − 1 ), bicarbonate (100–500 mg L −1 ), nitrate (> 300 mg L −1 ) and H 2 O 2 (> 400 mg L −1 ) inhibited the COD removal efficiency of methyl orange. Electrochemical oxidation of malachite green was inhibited by carbonate (100–500 mg L −1 ), bicarbonate (100–500 mg L −1 ), nitrate (> 400 mg L −1 ) and H 2 PO 4 − (> 400 mg L −1 ), whereas nitrate ( −1 ), H 2 PO 4 − ( −1 ), H 2 O 2 ( −1 ) and S 2 O 8 2 − (100–500 mg L − 1 ) increased the COD removal efficiency. The COD removal efficiency of 2,4-dinitrophenol was inhibited by bicarbonate (100–500 mg L −1 ), nitrate ( −1 ) and H 2 O 2 (500 mg L − 1 ). A positive effect on the COD removal efficiency of 2,4-dinitrophenol was obtained in the presence of H 2 PO 4 − (100–500 mg L −1 ), H 2 O 2 ( −1 ) and S 2 O 8 2 − (100–500 mg L −1 ). The degradation of 2,4-dinitrophenol was unaffected by the presence of carbonate. Addition of sulphate had no effect on the COD removal efficiency of all the three contaminants.