Degradation performance of high-concentration coking wastewater by manganese oxide ore acidic oxidation

Abstract

The degradation of coking wastewater using a manganese oxide ore acidic oxidation was investigated. This work was performed in three stages. Firstly, the advantageous degradation conditions were measured by the degradation tests, and under the optimal conditions percentage degradation was obtained of 91.6% chemical oxygen demand measured by potassium dichromate oxidation (CODcr), 94.7% total nitrogen (TN), 98.3% phenols, 98.2% fatty acid, 89.5% tar, and 98.9% sulphide for the oxidized effluent, simultaneously cogenerating a Mn2+concentration of 46.2 g/L for Mn-electrolytic stock solution. Secondly, the transformation analysis of the special chemical group of coking wastewater contaminants illustrated that the employment of manganese oxide ore generated the degradation of low and high molecular weight organics, especially causing polymers to break down into oligomers. Thirdly, the electrochemical characteristics of the interface between wastewater and ore revealed that the contaminant degradation of coking wastewater greatly depended on the oxidation capacity of the surface oxide species, involving a simple answer to the MnO2 oxidation for small-molecule organic materials and a strengthening response to the MnO·OH oxidation for high-weight molecule organic substances. The treatment of coking wastewater using the Mn-oxide ore acidic oxidation process is an effective and value-added method, which is particularly applicable to high-concentration coking wastewater. HIGHLIGHTS The degradation and utilization of coking wastewater using the manganese oxide ore sulphuric acid oxidation process were investigated.; A probable degradation pathway of the intractable contaminants of coking wastewater stimulated by the Mn-oxide ore acidic oxidation was presented.; The oxidizing capacity and potential of Mn-oxide ore based on the interface reaction for the coking wastewater degradation were revealed.;

Keywords

• chemical group transformation
• coking wastewater
• degradation efficiency
• electrochemical behaviour
• manganese oxide ore acidic oxidation