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Cucumissativus peel (CSP), was investigated as a new adsorbent for Pb(II) removal from aqueous solution under several varying conditions such as pH, adsorbent dosage, and contact time. Maximum metal sorption was found to occur at initial pH 5.0. The adsorption capacity of CSP was found to be 28.25mg/g for initial Pb(II) concentration of 25 mg/l at 25°C. The equilibrium data best fitted to the Langmuir adsorption isotherm model. Batch adsorption models, based on the assumption of the pseudo first-order and pseudo second order mechanism were applied to examine the kinetics of the adsorption. The results showed that kinetic data were followed pseudo secondorder model than the pseudo first-order equation. With no loss in the Pb(II) ion removal efficiency, CSP could be regenerated using 1M HNO 3 during repeated sorption-desorption cycles and showed recovery of 93.5% for 25mg/l of Pb(II) ion concentration. Comprehensive characterization parameters using FTIR, and SEM were recorded before and after adsorption to explore the number and position of the functional groups available for Pb(II) binding onto adsorbent and changes in surface morphology of the adsorbent.

This paper describes the adsorption of Cd(II) ions from aqueous solutions by modified Cucumis sativus peel (CSP) by HCl treatment. The optimum pH, adsorbent mass, contact time, and initial ion concentration were determined. The maximum removal efficiency was 84.85% for 20 mg/L Cd(II) ion at pH 5. The adsorption isotherms were obtained using concentrations of the metal ions ranging from 5 to 150 mg/L. The adsorption process follows Langmuir isotherm and pseudo-second-order reaction kinetics. CSPs exhibit monolayer adsorption capacity of 58.14 mg/g at 298 K. The paper also discusses the thermodynamic parameters of the adsorption (the Gibbs free energy, entropy, and enthalpy). Our results establish that the adsorption process was spontaneous and endothermic under normal conditions.