Treatment Of Simulated Hydroquinone Wastewater By Modified Microeiectrolysis Method

Hydroquinone is an important chemical raw material. It is widely used as animportant intermediate of pesticide, medicine and dye. It is also widely used in themanufacture of anthraquinone, azo dyes, photosensitive materials and antioxidants ofrubber and food. Therefore, large quantities of hydroquinone often exists in all kindsof industrial wastewater, such as dye wastewater, rubber industry wastewater andpharmaceutical wastewater. Due to its high potential toxic effect to aquatic organismsand persistence in the waters, the discharge of hydroquinone to natural waters causesdifferent threats to human health and ecological environment. Therefore, there is anurgent need to treat hydroquinone in wastewater.In this study, we used microelectrolysis method to treat hydroquinone wastewater.On the basis of traditional Fe-C microelectrolysis packing, manganese, zinc, copperpowder was added respectively to modify Fe-C packings and prepare modifiedFe-Mn-C packings, Fe-Zn-C packings, and Fe-Cu-C packings. Removal effects ofhydroquinone by three kinds of modified packings were explored in the study. Thefactors affecting the removal performance of hydroquinone, such as packing type,packing dosage, reaction time, mass fraction of metal additive, and initial pH, wereexamined. In order to conclude the degradation process of hydroquinone, we detectedthe changes of solution pH and analyzed the intermediates of hydroquinonedegradation by GC-MS. In addition, the characterizations of the packings wereanalyzed by SEM and XRD before and after modification.The results showed that Fe-Mn-C packing exhibited the best removalperformance of hydroquinone during three kinds of modified packings (Fe-Mn-Cpackings, Fe-Zn-C packings, and Fe-Cu-C packings). When the initial concentrationof hydroquinone was1000.00mg·L-1, the optimal treatment conditions ofhydroquinone by Fe-Mn-C packing were as followed: the dosage of packing was29.17g·L-1, and the reaction time was4.0hours, and the mass fraction of Mn was9%, and the initial pH was3.00. The removal rate of hydroquinone in wastwater couldreach95.55%under the optimal conditions. Compared with Fe-C packing, Fe-Mn-Cmodified packing could greatly improve the removal effect of hydroquinone. Thatwas to say, the removal rate of hydroquinone increased by42.89%. The solution pHcould rise to8.50within30minutes and then returned to neutral. The adaptationrange of wastewater pH was wider by Fe-Mn-C packing than that by Fe-C packing.According to the results of GC-MS, SEM, and XRD, hydroquinone was firstoxidized to benzoquinone and then was gradually degraded into maleic acid, malonicacid, and acetic acid. With a low electrode potential, manganese was moreadvantageous in electrode reaction than iron. So the removal effect of hydroquinonewas improved after adding manganese powders into Fe-C packing. In addition,manganese in Fe-Mn-C packing could be oxidized to MnO2and Mn3O4. Thesemanganese oxides had high reactivity to oxidize hydroquinone.