Adsorptive removal of acid violet 17 dye from wastewater using biosorbent obtained from NaOH and H2SO4 activation of fallen leaves of Ficus racemosa

Biosorbents obtained from NaOH and H2SO4 activation of fallen leaves of Ficus racemosa were used for the adsorptive removal of Acid Violet 17 dye from wastewater. BET, SEM and FTIR techniques were used for the characterization of biosorbent. Batch studies were conducted to study the effect of various operating parameters on the extent of adsorption of dye. Maximum dye removal was obtained under optimized conditions of pH as 2 and 3 g/L of biosorbent dose for NaOH activated biosorbent whereas lower extent of removal was obtained for H2SO4 activated biosorbent under similar conditions. The obtained kinetic data were best fitted to pseudo-second order model whereas the adsorption equilibrium data was observed to be in good agreement with Langmuir model. Maximum Langmuir biosorption capacities were estimated to be 45.25, 61.35 and 119.05 mg/g for raw biosorbent, H2SO4 activated biosorbent and NaOH activated biosorbent respectively. The obtained thermodynamic data confirmed that adsorption was endothermic whereas the obtained activation energy as 7.07 kJ/mol confirmed physical nature of the adsorption. Column studies were also performed to establish the practical applicability of the synthesized biosorbent with understanding into effect of biosorbent bed height, initial dye concentration and flow rate. The column data for the equilibrium adsorption was observed to best fit Thomas model. Maximum biosorption capacity obtained in continuous mode under the optimized conditions was 69.08 mg/g. Batch and column desorption studies performed for five cycles established effectiveness and the reusability of synthesized biosorbent to treat industrial dye effluent effectively.