Composite material with high adsorption-catalytic activity based on biochar from sawdust of birch (Betula Pendula)

Currently, a pressing issue is the search for new methods of wastewater treatment based on cheap environmentally friendly materials. Composite materials based on a biocoal matrix with nanosized modifiers make it possible to solve problems of increasing the efficiency of pollutant adsorption and photocatalytic purification of aquatic environments. Nanosized cobalt ferrite with a CoFe2O4 spinel structure and a biocoal-based composite with cobalt ferrite nanoparticles CoFe2O4@C were synthesized by the citrate combustion method. Carbon for the composite was obtained by carbonization of birch sawdust at a temperature of 600 ⁰C. The formation of nanosized CoFe2O4 spinel crystallites in all samples was confirmed by X-ray diffractometry. The average size of nanoparticles decreases from 31 ± 4 nm for pure cobalt ferrite to 17 ± 2 nm for a biocoal-based composite. The formation of the cobalt spinel phase and the presence of a large number of surface functional groups (–OH, –C=O, –C=C, –CH3) in the composite were confirmed by IR spectroscopy. The adsorption and catalytic activity of CoFe2O4 and CoFe2O4@C in relation to the purification of aqueous solutions from 2,4-dinitrophenol (DNP) was analyzed. High efficiency of DNP purification by nanosized cobalt ferrite (99.95%) and biochar-based composite (96.84%) was established due to sorption on porous materials and photocatalytic degradation of the toxicant under UV irradiation. The results of the study confirm that biochar-based composites from wood processing waste are promising sorbents/catalysts for the purification of wastewater from paper, pharmaceutical and textile industries from organic pollutants. Due to the magnetic sensitivity of the composite due to CoFe2O4 nanoparticles, the extraction of the sorbent/catalyst by an external magnetic field is significantly simplified for subsequent regeneration and reuse.