Abstract:
Natural clays have potential as adsorbents of heavy metals in wastewater treatment processes. This is due to the high adsorption capacity and selectivity of the clay. This research was done by contacting the clay directly with Pb (II). This study aims to determine the adsorption equilibrium models corresponding to the adsorption of Pb(II) with natural clay from Palas village. The study was conducted with reference to the adsorption equilibrium models which are Langmuir and Freundlich adsorption equilibrium models. Adsorption equilibrium is the model with R2 values approaching 1 and smallest χ2 value which a suitable model equation for Pb adsorption on natural clay from Palas village. Some variables studied in this research were the contact time, adsorbate concentration, temperature, weight of adsorbent and pH. Analyzes Pb was performed using atomic absorption spectrophotometer (AAS). The results showed that Langmuir equilibrium model was the most suitable equilibrium model, with a correlation coefficient of 0.9979. It was found that the optimum conditions of several variables were 30 minutes for contact time, 20 ppm for adsorbate concentration, 30oC for the temperature, 1 g for adsorbent weight and pH 7. Thermodynamic parameter data obtained from the adsorption equilibrium experiment are 3.150 kJ mol-1, 6.5343 kJ mol-1 and 11.169 J molK-1 for ΔH, ΔS, and ΔG respectively. It can be concluded that the type of adsorption which dominates the natural clay from Palas village is physical adsorption which is characterized by low ΔH (<20 kJ mol-1), and positive value of ΔG (3.150 kJ mol-1).
