Characterization and pollutant removal efficiency of biochar derived from baggase, bamboo and tyre

Conversion of broad-spectrum organic waste into carbonaceous biochar has gained enormous interest in past few years. The present study aims to characterize feedstock (FS), i.e. bagasse (Bg), bamboo (Bm) and biochar (BC), i.e. baggase biochar (BBg), bamboo biochar (BBm) and tyre biochar (Ty). Significant changes in elemental composition, atomic ratio, proximate analyses, mineral content and heavy metal content were observed which was well supported by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. Impregnation with ferric hydroxide was done, and resultant modified biochars (MBC), i.e. iron-impregnated baggase biochar (FeBBg), iron-impregnated bamboo biochar (FeBBm) and iron-impregnated tyre biochar (FeTy), along feedstock and biochar were used for PO43−, Pb, Hg and Cu adsorption. In general, BBg, FeBBg, BBm, FeBBm, Ty and FeTy were found to adsorb PO43−, Pb, Hg and Cu better than Bg and Bm, except in few cases. Results from adsorption experiments were fitted into Langmuir, Freundlich and Temkin models of isotherms and pseudo-first-order, pseudo-second-order and Elovich models of kinetics. Result of batch study adsorption revealed that maximum adsorption of PO43−, Pb, Hg and Cu was done by FeBBg (adsorption mechanism explained by Freundlich model), FeTy (Temkin model), Ty (Langmuir model) and BBm (Langmuir model) respectively. According to R2 values, pseudo-first-order reaction was well suited to PO43−, Pb, Hg and Cu adsorption. The optimum pH for maximum adsorption was observed to be 7.4 for PO43−, 5 for Cu and 6 for Pb and Hg respectively