Adsorption Kinetics of Lead and Zinc Ions by Coffee Residues

作者：Wu Chung Hsin^*; Kuo Chao Yin; Guan Shu Shian

来源：Polish Journal of Environmental Studies, 2015, 24(2): 761-767.

DOI：10.15244/pjoes/31222

• adsorption
• coffee residues
• kinetics

Untreated coffee residues (UCRs) were used to remove heavy metal ions from aqueous solutions. The effects of solution pH, heavy metal ions, and UCR concentrations on heavy metal ion removal by UCRs were determined. The removal percentage for heavy metal ions increased as pH and UCR doses increased; conversely, it decreased as the concentration of heavy metal ions increased. This study employed the pseudo first- and second-order kinetics models, the intraparticle diffusion model, and the Bangham model to simulate adsorption kinetics of Pb2+ and Zn2+ onto UCRs. Simulation results indicate that adsorption kinetics fit well with the pseudo second-order model. After reaction for 180 min at [adsorbate] = 20 mg/L, [UCRs] = 2 g/L, and pH 5, the adsorption percentage of Pb2+ and Zn2+ was 96% and 44%, respectively; moreover, the adsorption density of Pb2+ and Zn2+ onto UCRs was 9.7 and 4.4 mg/g (4.7x10(-2) and 6.8x10(-2) mmol/g), respectively. The adsorption of Pb2+ and Zn2+ onto UCRs is controlled mainly by surface diffusion.

• 出版日期2015