Adsorption of Pb(II) from aqueous media using mesoporous adsorbents obtained from Daniellia oliveri leaves

Worldwide, there have been longstanding issues of heavy metal pollution of both ground and surface waters from industrial effluents. In this research, Daniella oliveri leaves were investigated as a precursor for the development of low-cost adsorbent for removing Pb(II) from aqueous media. The adsorbents (biosorbent and ash) were characterised using Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and Branueur-Emmet-Teller analysis (BET). The biosorbent (DO-B) and ash (DO-A) from Daniella oliveri leaves had a specific surface area of 574.5 m2/g and 723.0 m2/g respectively. Both adsorbents were mesoporous with pore diameter >2 nm. The ash was a better adsorbent for Pb(II) than the biosorbent powder, however, both adsorbents have over 99% removal of Pb(II) at optimal conditions. Best-fit isotherm for DO-B was Freundlich isotherm while no best fit for DO-A was observed. The adsorption for both adsorbents was best fit pseudo-second order kinetic model. Adsorbents from Daniella oliveri leaves could be used as an adsorbent for the removal of Pb(II) from aqueous media and can play an important role in mitigating the potential impact of the release of industrial effluent into the environment.