Adsorption of copper(II) and zinc(II) ions from aqueous solution by activated carbon derived from halophytes (Suaeda maritime)

Sample of a halophytes activated carbon (ACHs), Suaeda maritime, has been carbonized after impregnating with H3PO4. Batch adsorption technique was employed for the metal ions biosorption onto ACH2 in a single component system. The activated carbon prepared was characterized by SEM, XRD, FTIR analysis and also ash content, bulk density, moisture content, BET surface area and porosity analysis, were carried out. The influence of pH, contact time, initial metal ions concentration and temperature on metal sorption capacity have been examined. The maximum sorption capacities calculated by applying the Langmuir isotherm were 29.41 mg/g for Cu, and 14.64 mg/g for Zn, respectively. Thermodynamics and kinetic adsorption of two metal ions were examined in batch experiments. It was verified that the Freundlich, Langmuir and Temkin isotherms describe the adsorption of Cu(II) and Zn(II) ions reasonably well. Adsorption of Cu(II) and Zn(II) ions onto ACH2 was better fitted to Freundlich isotherm model. According to the obtained thermodynamic data, the adsorption of Cu(II) and Zn(II) ions onto ACH2 were spontaneous and an endothermic processes with large adsorption enthalpy. The kinetic study showed that the whole adsorption process fit the pseudo-second-order kinetics model well. The kinetic data confirmed that particle diffusion is not the only rate-limiting step in the adsorption process.