EVALUATION OF ADSORPTION PERFORMANCE of Senna occidentalis SEEDS ON Pb2+ AND Cu2+ IONS

Abstract

The use of adsorbents of biological origin has proved to be desirable in the last decades as alternatives to the expensive conventional heavy metal remediation techniques. In this study, Senna occidentalis seeds were used for the removal of Pb2+ and Cu2+ from aqueous solution using Batch adsorption method. The metal ions in solution were determined by Atomic absorption spectroscopy and characterization of plant biomass was done using IR and SEM analytical techniques. The results indicate that the adsorption process was dependent upon all the reaction conditions used. Optimum absorption was achieved at pH 4 for both Pb2+ and Cu2+ with the corresponding percentage metal adsorbed of 100 and 77.54 %. The equilibrium was attained after 90 min of contact with Pb2+ using 20 mg and with Cu2+ using 50 mg biomass dosage  Temperature dependency showed optimum metal uptake at 40 oC and shaking speed of 150 and 200 rpm. The correlation coefficients indicate fitness of the adsorption data to Freundlich, Temkin and Dubbinin-Radushkevich isotherms. In addition, Pb2+ show fitness to Langmuir adsorption isotherm. The findings showed that Senna occidentalis seeds can be used as a low-cost adsorbent for the remediation of Pb2+ and Cu2+ from aqueous solution. Key words: Senna occidentalis, seeds, heavy metals, adsorption, isotherms