Removal of cadmium from water using by-product Crambe abyssinica Hochst seeds as biosorbent material

Abstract

The effectiveness of Crambe abyssinica Hochst seeds by-product as a biosorbent for the removal of cadmium ions from wastewater was analyzed. The biomass of crambe was characterized by scanning electron microscopy, infrared spectroscopy and determining the point of zero charge. The optimum adsorption conditions obtained were 400 mg of biomass in a solution of pH 6.0 and contact time of 60 min to remove 19.342 mg g−1 cadmium ions. The isotherms of adsorption were constructed and, according to the mathematical linearization, the best fitting followed the Freundlich and Dubinin–Radushkevich models, describing a multilayer adsorption and chemical interaction, also confirmed by the pseudo-second order model and enthalpy value. In the desorption process, about 79% of cadmium ions that had been adsorbed were recovered. The same conditions applied for studying the isotherms of adsorption and desorption were used for comparative study with activated carbon. It was concluded that the use of crambe by-product as biosorbent for cadmium removal in wastewaters was not only a viable alternative to activated carbon, but also required no previous treatment, so it represents a sustainable material with high applicability and low environmental impact.