DAYA ADSORPSI BIRNESSITE SINTESIS TERHADAP LARUTAN ION LOGAM Cd2+

Abstract

Birnessite can be used as an adsorbent of heavy metals found on the aquatic environment and solid waste. This could occur because birnessite is a porous material with a large surface area and are able to exchange cations from the solution. This research focuses on the removal of Cd ion from synthetic solution using the batch method. The removal Cd ions have been studed intensively for decade due to the toxic effect on environment and living organisms. To date, a number of methods have been developed to minimize the concentration of Cd ions in the environment, one of which is through adsorption method. The experimental results indicated that the synthetic birnessite has high affinity toward Cd2+ ion solution. To optimize the adsorption capacity of the birnessite, a wide range of experimental procedures are studied such as the differences of contact time, concentration, adsorbent weight, temperature, and pH. The uptakes of the ions by the adsorbent were monitored using atomic absorption spectroscopy (AAS) and were modelled using two types of isotherm adsorption. The thermodynamic parameters were calculated using the equation found in literature. The results showed that the optimum conditions for birnessite adsorption for Cd2+ ions are as follows: contact time of 5 minutes, pH of 6, optimum concentration of 8.4675 mg/L, temperature of 600C, adsorbent weigh of 0,5 gram with adsorption capacity of 95,63%. The adsorption Cd ions onto birnessite follows the Freundlich isotherm models. The adsorption is physical adsorption (physichsorps) with the value of ΔH and ΔS of 8,7713 kJ / mol and 1,9621 J / mol K, respectively. The positive value of ΔH indicates that the reaction is endothermic whereas positive ΔG (0,282 kJ / mol), shows the reaction is not spontaneous