Kinetic Modelling of Liquid-Phase Adsorption of Sulfate onto Raw Date Palm Seeds

Adsorption kinetics in multi-component systems has been a subject of intensive research because it is of both theoretical and practical importance. In this paper, raw date palm seeds (RDPS) were investigated to assess the possible use of this raw material as an effective adsorbent for the removal of sulfate from aqueous solution. The influence of various parameters such as sulfate initial concentration, pH, adsorbent dose and stirring time has been studied for the adsorption of sulfate in batch mode. Effects of foreign anions on the adsorption of sulfate onto RDPS have been also investigated. The pseudo-second-order, Elovich and intraparticle diffusion kinetic models have been developed to predict the rate constants of adsorption and equilibrium capacities. The maximum adsorption capacity of sulfate (q(subscript e) ≈ 3.2 mg/g) onto RDPS was reached for the initial sulfate concentration = 100 mg/L, pH = 3.5, adsorbent dose = 10 g/L and for a stirring intensity = 200 rpm at 25 ± 2 °C. The results showed that the adsorption of sulfate onto this raw materials followed pseudo-second-order rate kinetic predicting a chemisorption process.