Underutilized Luffa cylindrica sponge: A local bio-adsorbent for the removal of Pb(II) pollutant from water system

Biosorption of Pb2+ ions from aqueous solution onto Luffa cylindrica sponge as adsorbent (LCSA) was investigated in batch adsorption system. LCSA was characterized by X-ray diffraction analysis technique (XRD), Scanning Electron Microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), Fourier Transform Infrared spectrometer (FTIR), particle size dispersion, zeta potential, thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) surface area analyzer. The sorption of Pb2+ ions by LCSA was subjected to equilibrium, thermodynamics and kinetic studies and was carried out by considering the effects of pH, initial metal ions concentration, contact time and temperature. BET surface area of LCSA was 6.00 m2/g with mean distribution size of 0.02 µm while the zeta potential was found to increase as the value of pH increased from 4 to 14. The findings revealed the maximum equilibrium adsorption capacity to be 75.853 mg/g. The process is chemisorptive and controlled by intra-particle diffusion. The values of thermodynamic parameters such as ΔG°, ΔH° and ΔS° showed a stable adsorbent-adsorbate (LCSA-Pb) configuration which is exothermic. The adsorption capacity of LCSA compared better than some natural bio-sorbent found in literature.