Biochar is a stabilized carbon-rich product, and has drawn scientists’ interest because of its specific properties and potential use in many environmental areas. It is emphasized that innovative technologies comprised of engineered nanoparticles in conventional biochar systems could ameliorate the functions of biochar to some extent, such as carbon sequestration, soil fertility and wastewater treatment. As a result, it enables an enhanced sorption of both inorganic and organic pollutants to their surfaces, reducing environmental fate and mobility. In this study, biochar and graphene-coated biochars were prepared by dip-coating of biomass by slow pyrolysis. Batch sorption experiments were performed on the resultant biochars to evaluate sorption ability. The graphene covering on biochar surface changes to increase the surface properties of the biochars, exhibiting the greatest surface area, pore volume and carbon content. Graphene-coated biochars had the ultimate sorption ability compared to their corresponding chars. The sorption data indicated that electrostatic attraction, π-π interaction between graphene sheets on the char surface and aromatic domain, was the controlling mechanism for the sorption of organic chemicals onto the chars. Graphene-coated biochars can thus be used as a stable, cheap sorbent, biomaterial for the removal of organic pollutants from aqueous media.

Highly active and stable La-modified Cu/SiO₂ catalysts were fabricated for the vapor-phase hydrogenation of methyl acetate to ethanol.

Multi-walled carbon nanotubes (MWCNTs) and their oxidized derivatives were used as adsorbents for the removal of methylene blue dye from aqueous solution. CNTs have consistent surface and distinct structure, thus they were selected as the novel adsorbents in this study. The site-energy distribution analysis could provide significant information for adsorption mechanisms. Therefore, this study concentrated on the site-sorption energy distribution analysis in combination with thermodynamic behavior of methylene blue adsorption on CNTs. The single point adsorption coefficient K _d was in order of MWCNTs-Ox>MWCNTs following the temperature 308 K>298 K. Surface area could not be the only single factor for methylene blue adsorption on CNTs, which suggested that morphology of CNTs, π-π electron donor-acceptor, electrostatic interaction and functional groups were also contributing factors. Thus, these all of interactions may drive the methylene blue adsorption. The thermodynamic parameters showed that the adsorption mechanism is spontaneous and exothermic. The site-energy distribution suggested that higher energy active sites would be engaged first, and consequently, the methylene blue molecules adsorb on the comparatively lower energy active sites of CNTs.