A Crambe abyssinica seed by-product as biosorbent for lead(II) removal from water

Abstract

This study assessed the performance of a Crambe abyssinica Hochst seed by-product as biosorbent for removing lead [Pb(II)] ions from water. The material was characterized by scanning electron microscopy and infrared spectroscopy techniques as well as by point of zero charge (pHPCZ) measurement. The following parameters were determined after adsorption experiments: solution pH, biosorbent mass, contact time, and temperature. The optimal conditions were found to be mass –400 mg, solution pH 7.0, and equilibration time –20 min; they were used for performing isotherm tests. The isotherms were best fitted to the Freundlich and Dubinin–Radushkevich mathematical models. Based on the results of kinetic and thermodynamic studies (pseudo-second-order kinetics, negative change in Gibbs free energy, positive change in enthalpy and low ion desorption rate), it was established that the Pb(II) ions interacted forcefully with the biosorbent, thus confirming that a spontaneous endothermic chemisorption process took place. To check the effectiveness of the novel adsorbent for the Pb(II) removal and retention, comparative studies were carried out with activated carbon. On the basis of the obtained results, it has been possible to conclude that the C. abyssinica seed by-product can feasibly be used as an alternative material for the remediation of lead-contaminated water, since it is sustainable and does not require pretreatment.