THE USE OF BONE CHARCOAL AS ADSORBENT FOR REACTIVE DYES COMMONLY USED IN TEXTILE INDUSTRY

摘要

Brazilian bone char was evaluated as adsorbent for Reactive Yellow 145 and Reactive Red 195, monochlorotryazines dyes, commonly present in textile wastewaters. The adsorbent was characterized with respect to its real density, morphology, presence of crystalline phases, specific surface area, zeta potential and surface groups. Bone char without any pre-treatment was used in batch and semi-continuous adsorption experiments. Batch tests were carried out in erlenmeyers containing 0.08 g/L of dye, at 25°C, at times from 0 to 100 minutes (kinetic tests) and 24 h (equilibrium tests) for adsorbent concentrations of 4, 6 and 8% w/v and particle sizes between 0.84 to 0.42 mm. Breakthrough curves for both dyes were obtained at 25°C. The adsorption kinetic followed a first order model for both dyes. Removal levels higher than 80% for both dyes in period of time higher than 60 minutes were observed. Both Freundlich and Langmuir models fitted well to the results. Maximum adsorption capacity according to Langmuir model was 19.23 mg/g and 20.00 mg/g for Reactive Yellow 145 (RY 145) and Reactive Red 195 (RR 195) dyes, respectively. The results suggest good perspectives of removal residual color of wastewaters from textile industries.