Fabrication and characterization of mesoporous activated carbon from Lemna minor using one-step H3PO4 activation for Pb(II) removal

• Published in: Applied surface science 2014-10, Vol.317, p.422-431
• Main Authors: Huang, Yang, Li, Shunxing, Lin, Haibin, Chen, Jianhua
• Format: Article
• Language: English
• Subjects: Activated carbon; Activation; Adsorption; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fourier transforms; Infrared spectroscopy; Lead; Lemna minor; Mathematical models; Mesoporous; Physics; Surface chemistry
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.08.152

•Activated carbon was prepared from Lemna minor using H3PO4 activation.•Materials have higher mesoporosity (92.2%) and more oxygen and nitrogen-containing functional groups.•Materials can remove Pb(II) rapidly with monolayer adsorption capacity (170.9mg/g).•The adsorption process fitted to Langmuir isotherm and pseudo-first-order kinetic.•Materials could be used as an economical, efficient adsorbent to remove Pb(II) ions. A low cost and locally available material, Lemna minor, was used to fabricate activated carbon using H3PO4 activation. After H3PO4 activation, the L. minor activated carbons (LACs) possess high mesoporosity (92.2%) and a surface area of 531.9m2/g according to Brunauer–Emmett–Teller (BET) analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS) analyses reveal the presence of rich hydroxyl, carboxyl, amide and phosphate functional groups on the LACs surface, leading to facile Pb(II) binding to the surface through strong chemisorptive bonds or ion-exchange. The kinetic and equilibrium data were well described by pseudo-first-order model and Langmuir isotherm, with the maximum monolayer adsorption capacity (qm) 170.9mg/g at 25°C. The intra-particle diffusion mechanism was partially responsible for the adsorption. The adsorption process was spontaneous and endothermic with negative ΔG and positive ΔH. The Pb(II)-loaded LACs could be easily regenerated using 0.1-M HCl and reused for seven cycles without significant adsorption capacity reduction. The maximum percentage removal rate for Pb(II) (20mg/L) was found to be 91.8% within 30min, at optimum conditions of pH 6.0 and 25°C. These suggested that the low-cost LACs could be used as a potential adsorbent in the treatment of lead-contaminated water.