Biosorption of Cd (II) ions onto raw biomass of the Papaya (Carica papaya) seed has been studied using the batch equilibrium adsorption method. The sorption characteristics of the adsorbent were investigated under various experimental conditions, such as pH, contact time, concentration of Cd (II), sorbent mass and temperature. The FT-IR analysis showed that likely functional groups responsible for the adsorption are carboxyl, carbonyl, amides and hydroxyl groups. The pH for optimum adsorption is 5.0. Equilibrium data fit well to the Langmuir isotherm. The estimated maximum adsorption capacity was found to be 63.58 mg/g at 308 K and 90.95 mg/g at 328 K. The kinetic data obeyed the pseudo second-order model. Taking into account its good adsorption capacity, ease of sample treatment, as well as availability, the biomass of Carica papaya seed is a promising cost-effective biosorbent for Cd2+ removal from aqueous environment.
 

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