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
