Adsorption and desorption of copper(II) ions onto garden grass

Abstract

The garden grass (GG) was firstly used to remove copper(II) from water as bioadsorbent. From the results of characterisation, the GG had the merits of high specific surface area, significant adsorption sites and functional groups. Copper-adsorption significantly depends on the initial copper concentrations, contact time, pH, adsorbent doses, particle sizes and temperature. The positive values of ΔG° indicates that the adsorption of copper onto garden grass is non-spontaneous and values lies within the ranges of 4.452–13.660kJ/mol for supporting physical adsorption. 0.1N H2SO4 was found as suitable eluent, which could be used 5 cycles of adsorption–desorption. The data from adsorption and desorption equilibrium were well fitted by the Langmuir, SIPS and Redlich–Peterson isotherm models. The maximum adsorption and desorption capacities were 58.34 and 319.03mg/g, respectively, for 1g dose. Adsorption and desorption kinetics could be described by the Pseudo-first-order model.