Enhanced adsorption of cationic dyes using sulfonic acid modified activated carbon

Abstract

Activated carbon (MTLAC) and sulfonic acid modified activated carbon (MTLAC-SA) were prepared from a low cost agricultural waste material matured tea leaf (MTL). BET surface area of MTLAC and MTLAC-SA was found to be 1313.4m2/g and 1169.3m2/g respectively. Synthesized materials were applied for adsorption of both anionic and cationic dyes. Rhodamine B (RhB), methylene blue (MB), brilliant green (BG), crystal violet (CV) and orange G (OG) were taken as the model dye. After modification, the activated carbon showed enhanced adsorption capacity for adsorption of cationic dyes. The effect of various parameters such as pH, initial dye concentration, adsorbent dose, ionic strength on adsorption process was investigated. A slight increase in adsorption capacity was observed with increase in concentration of existing ion. The equilibrium adsorption data were best described by Langmuir model. The maximum adsorption capacity for RhB and OG using MTLAC-SA (MTLAC) was found to be 757.6 (398.4)mg/g and 105.7 (318.5)mg/g respectively. The adsorption kinetics was best fitted with pseudo second order kinetic model. The thermodynamic study illustrated that the adsorption process is endothermic and spontaneous in nature.