The evaluation of rhodamine FRBT dye removal by adsorption using coffee grounds as an adsorbent material

Resumo

The application of activated carbon as an adsorbent material has been widely studied in several areas of the industry. Different carbonaceous materials with adsorbent potential, such as coffee grounds, have shown interesting adsorption properties regarding the removal of textile dyes from industrial effluents. High volumes of coffee grounds are generated daily, whether as domestic or industrial waste. In this sense, the present study aimed to produce an adsorbent material from coffee grounds and to evaluate its effectiveness as activated carbon in the removal of rhodamine FRBT dye in aqueous solution. To obtain the adsorbents, two types of treatment were carried out: (i) treatment 1 (T1): the adsorbent material was prepared with sulfuric acid; (ii) treatment 2 (T2): the adsorbent material was washed with water for chemical activation. The effectiveness of the adsorbents was evaluated by filtering the dye solution (60 mg·L-1 and 180 mg·L-1) as a function of the stirring time. The results obtained indicated that the T1 filter showed slight discoloration over time at the concentration of 180 mg·L-1 dye. However, a transfer of pigments from the coffee grounds to the coloring solution was observed, indicating that the filter was not effective when prepared with the selected methods and that possible treatment failures may have occurred in the preparation of the adsorbent material. Therefore, it is necessary to review the filter activation interference analysis, as well as possible different chemical and thermal treatments, for a better adsorption of substances by the adsorbent material.