Graphene, which has unique physical and electrical properties, is the most promising nanomaterial with infinite applications through combination with various materials. As the demand for graphene in various industries, the production market of graphene flakes is increasing, which could result in an increase in wastewater from graphene manufacturing.<br/><br/>Potassium permanganate, a strong oxidant, is the most commonly used in the process of graphene oxide. The residual potassium permanganate used in graphite oxidation is later discarded as an amount of wastewater in the washing stage which is the last step for high-quality graphene, and the large amount of manganese ions are detected in the wastewater including permanganate. While large amounts of wastewater are harmful to the environment, manganese itself in wastewater is can be used important resource such as catalyst, cathode material, so if recovered, it can bring economic and environmental benefits as a resource recovery.<br/><br/>In present study, recovery of manganese in wastewater from graphene manufacturing as manganese dioxide that can be sufficiently utilized as a resource in water treatment was investigated. First of all, manganese sulfate is recovered by a pretreatment process using a solubility difference from wastewater and finally manganese dioxide is recovered by oxidative precipitation using hydrothermal method. Manganese dioxide is synthesized by Hydrothermal reaction of sodium persulfate with Manganese sulfate obtained during pretreatment. In this time, the optimum conditions for preparation of MnO2 are evaluated by recovery rate and nanostructure. We will determine an applicability of recovered MnO2 in water treatment as a catalyst by evaluating the degradation of brominated flame retardants (BFR), one of the persistent organic pollutants (POPs). Also, MnO2 can be applied to battery materials using electrochemical characteristics in the future. This study suggests that the possibility of recovery of MnO2 from graphene oxide manufacturing wastewater and the application to water treatment.

Recovery of manganese dioxide from wastewater on graphene oxide manufacturing and its application for brominated flame retardants removal

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.