Surface oxidized and un-oxidized activated carbon derived from Ziziphus jujube Stem, and its application in removal of Cd(II) and Pb(II) from aqueous media

Agricultural waste based low cost oxidized activated carbon (OSD) and un-oxidized activated carbon (USD) samples were prepared from saw dust of Ziziphus jujube by chemical activation with phosphoric acid (H3PO4). The activated carbon was used for the removal of toxic metal ions such as cadmium(II) and lead(II) from aqueous solutions. The effect of pH (2–9), initial concentration (70–100 mg/L), contact time (5–700 min), activated carbon dose (0.1–1.0 g) and temperature (298–328 K) was investigated. In addition, the kinetic study was performed at pH 6, while the carbon dose of 0.1 g was used for 40 mL solution of 70 mg/L at four different temperatures (298, 308, 318 and 328 K). The adsorption efficiency of USD was found higher than OSD. Comparatively higher uptake of Pb(II) ions was observed by each carbon sample. Pseudo-second order equation best fitted the experimental data. As such, both activated carbon samples (USD and OSD) exhibited higher adsorption capacities and faster kinetics which revealed their commercial usefulness.