Removing lead from aqueous solution by activated carbon nanoparticle impregnated on lightweight expanded clay aggregate

Abstract

In the present study, a novel pervaporation technique was used to impregnate nano-activated carbon (nAC) on the lightweight expanded clay aggregate (LECA). The nAC was prepared from powdered activated carbon. XRD, FESEM, EDX, TEM, and BET analyses were used to investigate the adsorbent structure and morphology. FESEM and TEM demonstrated that the provided nanoparticles have dimensions smaller than 30 nm. Also, the influence of various parameters on the performance of impregnated nano-activated carbon on LECA (nAC-LECA) was investigated. These parameters include pH, initial metal concentration, contact time, adsorbent dose, and temperature. The investigations showed that the maximum amount of lead removal can be achieved in pH = 6. The experimental equilibrium data were fitted with the Langmuir, Freundlich, and Temkin isotherms. The Langmuir isotherm showed more consistency for this system. Calculations showed a maximum adsorption capacity of 22.83 mg/g. Furthermore, pseudo-first-order, pseudo-second-order, Morris Weber, and Elovich kinetic models were utilized to determine the kinetics of the adsorption process. Kinetic data were consistent with the pseudo-second-order model. The thermodynamic studies confirmed that the adsorption process is exothermic and spontaneous. Study on the different aspects of experimental conditions resulted in 98.845 % lead removal efficiency for (nAC-LECA) adsorbent in optimum conditions including pH = 6, 10 g/L of adsorbent dose, 100 mg/L of initial concentration, and contact time equal to 180 min at 298.25 K. The investigations demonstrated that the (nAC-LECA) adsorbent has proper and significant performance in removing lead ions from aqueous solutions. It is also feasible to separate contaminated adsorbent from water at the end of the process.