Modificação superficial de carvão ativado utilizando tratamento corona

Abstract

Activated carbons are used as adsorbent material of many processes. Studies which aimed increasing adsorption capacity of these materials are requested. Corona treatment can be a method to cause surface modification. This study aimed to promote surface modification of activated carbons using, for this, Corona treatment (electrical discharge). Moreover, study the impact of this treatment on adsorption capacity from treated and no treated activated carbons. In this study was used powdered commercial activated carbon from AlphaCarbo. Activated carbons were subjected to Corona treatment, provided by the Corona equipment on different exposure times (2, 5, 8 and 10 min) at 4.5 cm height from the source. To observe differences promoted by treating, activated carbons were analyzed by acidity, surface functional groups, spectroscopy (FTIR), thermogravimetry (TG), scanning electron microscopy (SEM), estimated surface area and adsorption process. Corona treatment impacts surface chemistry of activated carbons submitted to the treatment. There was a trend of increasing surface acidity due to carboxylic acid increase. FTIR analysis showed peaks in the bands 3500, 1650 due increasing of time expose, showing the presence of OH, C=O e –COO groups. There were differences in thermal degradation profiles and final residual masses between the treatments; however these differences are not directly related to exposure time. By SEM analyses, surface became more irregular and heterogeneous and there was destruction of porous structures due the treatment. In adsorption, there was a reduction of the adsorption isotherm for Methylene Blue (MB) and Congo Red (CR). The reduction was higher for methylene blue. In the adsorption kinetics adsorption rate were different, with methylene blue kinetics adsorption higher than Congo Red.