Detoxification of toxic metal ions by sorption onto activated carbon from hevea brasiliensis bark – a comparative study

Sorption of toxic metal ions (Ni2+, Cu2+ and Cd2+) from Hevea brasiliensis bark carbon (HBBC) was
carried out at 30±1 °C under various experimental conditions. Effect of various process parameters
has been investigated by following the batch adsorption technique at 30 +1°C. The percentage
removal increased with decrease in initial concentration and particle size and increase in contact
time and dose of adsorbent. As initial pH of the slurry increased, the percentage removal increased,
reached a maximum. The adsorption is highly pH sensitive. Adsorption data were modelled with
various isotherms and first order kinetic equations proposed by Natarajan-Khalaf, Lagergren and
Bhattacharya-Venkobachar and intraparticle diffusion models found to be applicable. Kinetics of
adsorption is observed to be first order with Intra- particle diffusion as one of the rate determining
steps. The monolayer adsorption capacities of HBBC also studied by Langmuir isotherms. HBBC
could be used as low-cost adsorbents in effluent treatment, especially for the removal of metal ions,
particular in Ni2+, Cu2+ and Cd2+ ions. It is confirmed by FT-IR studies before and after adsorption.