doiSerbia

Influence of the precursor chemical composition on heavy metal adsorption properties of hemp (Cannabis Sativa) fibers based biocarbon

Vukčević Marija M. (Faculty of Technology and Metallurgy, Belgrade)
Pejić Biljana M. (Faculty of Technology and Metallurgy, Belgrade)
Pajić-Lijaković Ivana S. (Faculty of Technology and Metallurgy, Belgrade)
Kalijadis Ana M. (Vinča Institute of Nuclear Science, Belgrade)
Kostić Mirjana M. (Faculty of Technology and Metallurgy, Belgrade)
Laušević Zoran V. (Vinča Institute of Nuclear Science, Belgrade)
Laušević Mila D. (Faculty of Technology and Metallurgy, Belgrade)

Waste hemp (Cannabis sativa) fibers were used as sustainable and renewable raw materials for production of low-cost biocarbon sorbent for heavy metals removal. Carbon precursors of different chemical composition were obtained by oxidative and alkaline treatments of hemp fibers. Influence of lignocellulosic precursor chemical composition on hemp fibers-based biocarbon (HFB) characteristics was examined by BET surface area measurement, scanning electron microscopy and mass titration. It was found that lignin content and polymorphic transformation of cellulose increase the SBET of microporous HFBs, while hemicelluloses induce more homogeneous distribution of adsorption active sites. Heavy metal ions adsorption onto HFBs is primarily influenced by the amount of surface oxygen groups, while specific surface area plays a secondary role. Equilibrium data obtained for lead ions adsorption were analyzed by different nonlinear adsorption isotherms, and the best fitting model was chosen using standard deviation and Akaike information criterion (AICC). The maximum adsorption capacities of HFBs ranged from 103.1 to 116.3 mg Pb/g. Thermodynamic parameters showed that Pb2+ adsorption onto HFBs is a spontaneous and complex endothermic process, suggesting the coexistence of physisorption and chemisorption mechanisms.

Keywords: hemp fibers, chemical composition, biocarbon, heavy metal ions, adsorption mechanism

Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172007 and Grant no. 172029