Avaliação da eficiência dos processos oxidativos avançados na regeneração de carvão ativado saturado com poluente orgânico

Abstract

The adsorption process is a viable alternative in effluent treatment due to its high efficiency and easy operation. Among the various existing adsorbent materials, Activated Carbon (CA) has been cited as the most prevalent separation tool, because it has a high specific surface area and functional groups on its surface that favor the adsorption process. The feasibility of using Activated Carbon (AC) as an adsorbent in wastewater treatments, comes up against the difficulty of regenerating and/or reusing such materials, since, when saturated, it can become a potential pollutant. Faced with this problem, the present study aims to evaluate the efficiency of Advanced Oxidative Processes (AOPs) in restoring saturated AC adsorption performance. For this, an AC commercially obtained was evaluated for its ability to remove methylene blue (MB) dye in adsorption tests. Subsequently, the saturated material was subjected to the processes of photolysis, peroxidation, Fenton and electrochemistry in regeneration tests. The efficiency of the processes was evaluated by the recovery of the adsorption capacity and the physical-chemical properties obtained through BET, FTIR, SEM-EDS, pH (pZC) analysis. The results obtained showed that after the treatment by photolysis, the AC recovered 30% of its adsorption capacity, the treatment with H2O2 reached a maximum of 40% regeneration, and the Fenton treatment with, reached 71% regeneration, maintained for 7 successive adsorption/regeneration cycles. The Electrochemical regeneration proved to be the most efficient process for CA recovery, reaching 79% and 84% when the AC was subjected to anodic and cathodic currents, respectively. Characterization analysis for electrochemical assays showed a reduction in the CA specific surface area for anodic regeneration. Whereas, the tests which the cathodic regeneration was used, little variation in CA properties was observed, even after 8 regeneration cycles, which can explain the good stability observed in the assays.