Remediation of wastewaters containing tetrahydrofuran. Study of the electrochemical mineralization on BDD electrodes

Abstract

This work contributes to the development of electro-oxidation on commercial boron doped diamond (BDD) anodes as an efficient and versatile environmental technology to deal with remediation of tetrahydrofuran (THF) polluted industrial wastewaters. Working with an undivided flow-by electrochemical cell, a systematic experimental study has been carried out to analyze the influence of the following operation variables: (i) initial THF concentrations in the range 500–1100 mg/L, (ii) supporting electrolyte, Na2SO4 and NaCl and (iii) current density in the range 300–1200 A/m2. The performance of the oxidation process was assessed through the change in the concentration of THF, Chemical Oxygen Demand (COD), and Total Organic Carbon (TOC) being the current density the variable that exerted the most positive kinetic influence; more precisely the reduction of COD after 60 min changed from 40% at japp = 300 A/m2 to 95.5% at japp = 1200 A/m2, whereas the reductions of TOC were typically higher than 95% for a value of the specific charge of Q = 10 A/h L. Besides, THF oxidation products have been analyzed, and the reactions’ pathway are proposed. Finally, the formation of chloride by-products, such as perchlorate was assessed observing that it was hindered at low current densities. In the view of these findings, it is concluded that THF oxidation on BDD anodes should be better performed at low current densities, i.e. 300 A/m2 for the type of wastewaters analyzed in the present work, to reach a compromise between effective degradation and the formation of undesirable chlorinated by-products.