Preparation of CeO2@C nanomaterials by adsorption of metal ions on microbial waste

The use of microbial adsorption for metal ions to prepare novel carbon-supported metal nanomaterials has attracted growing research attention. However, the relationship between the adsorbed metal content and catalytic performance of the resulting nanomaterials is unclear. In this work, Pichia pastoris residues was utilized to adsorb Ce(III) at different metal ion concentrations, and then CeO2@C nanomaterials were prepared by pyrolysis. The effects of solution pH and adsorption behavior were investigated. The prepared nanostructures were characterized using electron microscopy and different spectroscopy methods, and their catalytic performances in the removal of salicylic acid from solution by catalytic ozonation were invested. The microbial residue had a metal uptake of 172.00 +/- 2.82 mg center dot g(-1) at pH 6. In addition, the efficiency of total organic carbon (TOC) removal increased from 21.54% to 34.10% with an increase in metal content in the catalysts from 0 mg center dot g(-1) to 170.05 mg center dot g(-1). After pyrolysis, the absorbed Ce(III) metal transformed to CeO2 metal nanoparticles embedded in a carbon matrix and had a core-shell CeO2@C structure. Therefore, this work not only reveals a relationship between metal content and catalytic performance, but also provides an approach for studying performance of materials with different metal contents loaded on various carriers.