Arsenic adsorption from aqueous solution and groundwater using monometallic (Fe) and bimetallic (Fe/Mn) Tectona biochar synthesized from plant refuse: mechanism, isotherm, and kinetic study

Abstract

The present study deals with the utilization of waste biomass of Tectona plant refuse to synthesize the monometallic and bimetallic biochar and to examine their performance for As(III) removal from aqueous solution as well as from groundwater. The biochar materials were characterized using Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Particle Size Analysis (PSA), zeta potential and pHZPC. The enhanced removal of As(III) was observed with Fe/Mn-TB (bimetallic) which was greater than Fe-TB (monometallic) biochar. The highest adsorption was 90.35 % and 84.85 % achieved with Fe/Mn-TB and Fe-TB, respectively, at 0.5 mg/L As initial concentration 0.5 mg/L. The adsorption capacity was found to be 0.91 mg/g and 1.89 mg/g, respectively, by Fe-TB and Fe/Mn-TB. The adsorption process of As(III) has good compliance with pseudo-second order kinetics as well as Freundlich isotherm model. As(III) was adsorbed by the Fe-TB and Fe/Mn-TB possibly by electrostatic attraction, H-bond formation and complexation mechanism. Both these materials successfully removed As(III) from aqueous solution as well as from groundwater thus it can be used for the eradication of As(III) from the affected areas by utilizing them as an adsorbent in continuous flow system.