Alkali activated winter melon peel as absorbent: Characterization and its adsorption performance for heavy metal ions in aqueous solutions

Agricultural waste winter melon peel was used as raw material as adsorbent material. In order to improve adsorption characteristic, this material modified with NaOH (AWMP). The AWMP was characterized by IR, XRD and XPS. The adsorption performance of AWMP on Cu (II) and Pb (II) in aqueous solution were investigated.The effects of the initial concentration of Cu(II) and Pb(II), contact time, solution pH, and temperature are studied in batch adsorption. The kinetics shows that the equilibrium reached in 60 min and the adsorption is favored above pH 5.0. The highest adsorption capacity for Langmuir isotherm for Cu(II) and Pb(II) onto AWMP was observed to be 197.8 mg/g and 188.8 mg/g respectively. Based on predicted and experimental values of equilibrium capacity, kinetic modeling demonstrated the suitability of the pseudo-second-order kinetic model. Finally, the regeneration of AWMP was also studied up to 10 cycles. Thus, AWMP showed excellent adsorption characteristics during the uptake of Cu(II) and Pb(II) from wastewater effluent and can be used as low-cost agricultural waste biomass as an adsorbent.