Uptake capacity of ZN²⁺ by natural vietnamese basalt and their application for wastewater treatment

This study describes experiments on the uptake capacity of Phuoc Long basalt, Vietnam, for Zn²⁺ and their application to wastewater treatment. Results have been compared with powdered activated carbon (PAC). The adsorption of Zn²⁺ from aqueous solution onto basalt and PAC was investigated in aqueous solution at pre-determined conditions (pH: 4.51−4.67, temperature 31 ± 0.5°C). Experimental values indicated that the first plateau of adsorption isotherm is at 12.50mM concentration of Zn²⁺ and the second at 50.00mM. The linear Langmuir 2 and Freundlich models were applied to describe equilibrium isotherm and both models fitted well. At Zn²⁺ concentration 12.50mM, the experimental adsorption capacity (qe) of basalt and PAC was 8.00 and 3.79mg/g, respectively. The calculated Langmuir adsorption capacity of basalt and PAC was found to be 19.42 and 76.92mg/g; r² = 0.989 and 0.998; respectively. At 50.00mM Zn²⁺ concentration, the experimental adsorption capacity (qe) of basalt and PAC was 37.88 and 15.438mg/g, respectively. The calculated Langmuir adsorption capacity of basalt and PAC was found 17.73 and 71.43mg/g; r² = 0.971 and 0.997, respectively. The Lagergren pseudo-first order and pseudo-second order were used to describe the kinetics data of basalt. The experimental data fitted well to the pseudo-second order r² = 0.989 for the first 30min and to the first-order reaction (r² = 0.988) beyond 30min.