Adsorptive removal of Co(II) in aqueous solutions using clearing nut seed powder

The present study assessed the potential use of clearing nut seed powder (Strychnos potatorum) as an adsorbent for the removal of Co(II) ions from aqueous solutions. Based on FTIR analysis, the adsorbent possesses hydroxyl, C-N, and C-O functional groups and SEM analysis indicated the presence of uneven porous surface structure, which is important for adsorption. Batch adsorption studies were performed to investigate the effect of contact time, initial pH, initial Co(II) concentration, adsorbent dosage, and temperature on adsorption. The Langmuir isotherm model provided the best explanation to experimental data with the highest correlation coefficient and the maximum monolayer adsorption capacity obtained was 4.245 mg/g. The pseudo-second-order kinetic model fitted well with the adsorption kinetic data. Sorption thermodynamic data showed that the adsorption process is spontaneous and exothermic in nature. The clearing nut seed powder obtained after surface modification by acid treatment showed a higher adsorption capacity.