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

• Published in: Journal of the Serbian Chemical Society Vol. 82; no. 12; pp. 1417 - 1431
• Main Authors: Vukčević, Marija M, Pejić, Biljana M, Pajić-Lijaković, Ivana S, Kalijadis, Ana M, Kostić, Mirjana M, Laušević, Zoran V, Laušević, Mila D
• Format: Journal Article
• Language: English
• Published: Belgrade Journal of the Serbian Chemical Society 01-01-2017; Serbian Chemical Society
• Subjects: Adsorption; adsorption mechanism; biocarbon; Cannabis; Chemical composition; Chemisorption; Endothermic reactions; Fibers; heavy metal ions; Heavy metals; Hemp; hemp fibers; Lead; Lignocellulose; Nonlinear analysis; Organic chemistry; Precursors; Raw materials; Scanning electron microscopy; Surface area; Surface chemistry; Titration
• ISSN: 0352-5139; 1820-7421
• DOI: 10.2298/JSC170310080V

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.