Comparative Study of Removal of Cadmium Ions from Aqueous Solution Using Dialium indum and Santalum album Fruitshells as Adsorbents

Sandal and velvet tamarind fruit shells were screened for their metal uptake capacities for Cd(II)ions, at various initial concentrations of 10, 20, 30 40 and 50 mg/ L at variable contact period of between 30 and 180 minutes and different adsorbent dosages of 0.2 – 1 g/l, pH(1 to 6) using batch adsorption mode. The adsorbents were characterized using standard methods. The amount of adsorbate adsorbed by the developed adsorbents for Cd2+ increased with increase in initial metal concentration, contact time, adsorbent dosage and pH until equilibrium point was reached. At equilibrium; the optimum contact time for this operation was 90 minutes for velvet tamarind and 120 minutes for sandal fruit, effective pH for both adsorbents is 5.5, the equilibrium initial metal concentrations are 42 and 41 mg/l for sandal fruit and velvet tamarind shell respectively. The data conformed to Freundlich isotherm with r2˃ 0.95 for both adsorbents and were also fit for second-order kinetics. The surface areas of the sandal fruit and velvet tamarind shell as determined were 615 and 570 m2/g. The results obtained from this study indicated a high adsorption ability of the adsorbents for Cd(II) with sandal fruit having better performance.