Biosorbent derived from coffee husk for efficient removal of toxic heavy metals from wastewater

In this study, we investigated the feasibility on the utilization of coffee husk as biosorbents for the removal of heavy metal ions such as Pb2+ and Cd2+ from wastewater. Biochar was produced from coffee wastes and modified with sodium hydroxide to create functional groups on the surface and increase the specificic surface area. The resultant products were characterized by using various analytical methods such as scanning electron microscopy, specific area, surface functional group and zeta potential analysis. The as-prepared materials were employed as adsorbent to remove Pb2+ and Cd2+ ions from wastewater. The maximum sorption capacities of biosorbents were measured to be 116.3 and 139.5 mg g(-1) for Cd2+ and Pb2+, respectively, which is comparable to the conventional adsorbents. Kinetic studies showed that the sorption of Pb2+ and Cd2+ on biosorbents can be described by the Freundlich isotherm and second-order kinetic model. The coffee husk-derived biosorbent was capable of removing 89.6% of Pb2+ and 81.5% Cd2+ ions from wastewater, and therefore can be considered as low-cost and efficient adsorbent to remove heavy metal ions from wastewater.