RESUMO
The effects of acidic, basic and neutral reagents on the recovery of Pb2+ and Cd2+ from metal-loaded biomass of wild cocoyam (C. bicolor) were investigated by eluting the biomass in five successive cycles using 0.01 M HCl, 0.1 M HCl, 0.01 M NaOH, 0.1 M NaOH and distilled water at different contact times. The data showed that the ease of metal ion recovery from metal -loaded biomass by the eluent solutions is of the order 0.01 M HCl > 0.1 M HCl > 0.01 M NaOH > 0.1 M NaOH > distilled water. Over 94 percent Pb2+ and 74 percent Cd2+ of the initially adsorbed metals were recovered by 0.01 M HCl, while < 20 percent of both metals was recovered by basic reagent. Distilled water recovered less than 9 percent of both metal ions from the biomass. Macroscopic changes were also observed as the concentration of recovery reagent increased. This study has demonstrated that the selection of a recovery reagent for metal ions on a biomaterial should give consideration to the reusability of the biomass.
RESUMO
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.