This study focussed on the utilisation of both unmodified and acid modified snail shells as low cost adsorbents for the removal of Congo Red (CR) from aqueous solution using batch adsorption process. Different parameters such as pH, Contact time, temperature and adsorbent dose were varied. The kinetic studies using pseudo first order and pseudo second order of the adsorption were carried out. The adsorption of Congo Red (CR) was found to be dependent on the varied parameters. The optimum time for the uptake was 60 min, adsorbent dosage of 2 g and pH was found to be 2.0. The amount of CR removed (qe) rose from 2.445 to 19.230 mg/g when the contact time progressed from 5 to 60 min for unmodified snail shell and from 5.540 to 26.170 mg/g when treated snail shell was used. Pseudo-first- order model better described the kinetic of the adsorption process. The value of ΔH obtained was 42.20 kJ/mol with ΔS value of 20.30 kJ/mol) and this is an indication that the process of adsorption to be endothermic reaction. FT-IR characterization of the adsorbent before and after adsorption process revealed the probable functional groups present on the surface of the adsorbent to be –OH, C=O and C-H. Thus, snail shells can be deployed as low cost adsorbent for Congo Red removal from effluents.
