Research advances on adsorption of heavy metals by biochar

In the past decades, biochar has received considerable attention due to potential environmental applications and advantages of low cost, environmental friendliness and renewability. In this paper, the concept, applications and properties of biochar were summarized, as well as research advances on adsorption of heavy metals. Biochar is the porous carbonaceous materials produced by thermochemical conversion of biomass in zero or limited oxygen atmosphere and it is suitable for soil amendment. Biochar can improve crop yields, realize carbon sequestration and mitigate climate change, and also has potential applications in catalysis, energy production and wastewater treatment. Biochar can be prepared by pyrolysis, gasification and hydrothermal carbonization, and its properties depend on biomass feeds, thermochemical process and technical parameters. Adsorption of heavy metals onto biochar was surveyed, including affecting parameters, adsorption mechanism and modifications of biochar. Adsorption mechanism can be revealed by adsorption kinetics, isotherms, thermodynamics and advanced characterizations. Recent advances focus on improving adsorption performance of biochar by surface modifications, which are achieved via physicochemical activations or impregnating metal oxides, functional organics or nano particles. There exist some challenges and wide gap for treatment of real wastewater by biochar. © 2019, Chemical Industry Press. All right reserved.