Studies on the effect of pH on the sorption of Pb2+ and Cd2+ ions from aqueous solutions by Caladium bicolor (Wild Cocoyam) biomass

ABSTRACT

Environmental protection requires the use of natural products instead of chemicals to minimize pollution. This investigation studies the use of a non-useful plant material as naturally occurring biosorbents for the removal of cationic pollutants in wastewater. The effect of pH on the sorption of Pb2+ and Cd2+ ion onto Caladium bicolor corm biomass was investigated. The experimental results have been analysed in terms of Langmuir, Freundlich and Flory-Huggins isotherms. The data showed that the maximum pH (pHmax) for efficient sorption of Pb2+ was 7.0 and for Cd2+ 5.0. Evaluation using Langmuir equation gave the monolayer sorption capacity as 88.50 mg/g and 65.50 mg/g at the respective pHmax for Pb2+ and Cd2+. Surface characterization of acid and base treated C. bicolor biomass indicates a physiosorption as the predominant mechanism for the sorption process. The thermodynamic assessment of the metal ion - Caladium bicolor biomass system indicates the feasibility and spontaneous nature of the process.