Construction of a spinel/biochar/attapulgite composite for efficient catalytic oxidation of volatile organic compounds

Abstract Volatile organic compounds (VOCs) pose risks to human health and the environment, making the development of efficient technologies to reduce their emissions a priority. Catalytic oxidation represents a simple, efficient and environmentally friendly method for eliminating VOCs. Herein, a spinel CuCo 2 O 4 /biochar/attapulgite (ATP) composite was successfully synthesized via a sol–gel method using waste walnut shell powder as both a complexing agent and a combustion promoter. The effect of the mass ratio on toluene degradation performance was systematically investigated. The results indicated that when the mass ratio of CuCo 2 O 4 /ATP to the biomass precursor was optimized to 1:4, the catalyst exhibited excellent catalytic oxidation performance for toluene degradation, achieving 99% conversion at 300°C along with high stability. The introduction of biochar induced the formation of abundant oxygen vacancies on the spinel surface and effectively suppressed the agglomeration of CuCo 2 O 4 particles. Moreover, the rich functional groups on biochar improved toluene adsorption, favouring the subsequent catalytic oxidation. The current study offers a cost-effective strategy for VOC abatement by taking advantage of minerals and biomass.