Magnetic Biochar Fibers for Copper Removal

The present chapter gives an overview of the environmental chemistry of divalent copper ions (Cu(II)), including analysis, chemical behavior, and removal of Cu(II) using magnetic biochar fibers. After a short overview of preparation/modification procedures and characterization techniques associated with biochar adsorbents, a comprehensive compilation of data related to Cu(II) adsorption by magnetic biochar materials is presented and the data discussed. The discussion involves Cu(II) binding by the biochar surface, thermodynamic and kinetic modelling, and surface speciation. Generally, the removal of Cu(II) ions from (waste)waters by magnetic biochars is based on different sorption mechanisms such as ion exchange, surface complexation, cation π-interaction, and surface polynucleation and precipitation, depending on the solution pH, the surface modification, and the Cu(II) ion concentration. The adsorption capacity ranges from 2 to 141 mg/g and the adsorption data are best fitted by the Langmuir adsorption isotherm and the pseudo second-order kinetic model. Future work has to be focused on the characterization of surface species by sophisticated spectroscopic techniques (e.g., EXAFS, XPS, and RAMAN) and studies related to Cu(II) redox reactions occurring on the biochar surface.