Volatile organic compounds analysis and characterization on activated biochar prepared from rice husk

Activated biochar has been used in various areas, i.e., wastewater treatment. However, biochar contains volatile organic compounds, some of which are toxic organic pollutants that pose health risks to human. In this study, activated biochar was prepared by pyrolysis method using rice husks as raw materials and H2O as the activator. The volatile organic compound concentration of biochar before and after activation, as well as the adsorption characteristics of activated biochar, was investigated. The structure of the biochar was characterized by FTIR, SEM, and specific surface area analyzer. The results showed that activated biochar surface was mainly composed of carboxyl groups, and no phenolic hydroxyl or lactone groups formed during the process. In total, 54 volatile organic compounds were analyzed by a gas chromatography–mass spectrometer. The detection frequency of 45 volatile organic compounds reached 100%. The concentration of sum of these compounds was 93.26 and 110.62 μg/g in the biochar before and after activation, respectively. Results of adsorption experiments showed that the adsorption and resolution of activated biochar to n-hexane were 29.33 and 5.4 mg/g, respectively. Compared to the biochar sample without activation, the activated biochar with the ratio of charcoal to water of 3:1 showed the best adsorption to n-hexane, whose surface area reached 351.23 m2/g.