Activated carbon adsorbents with micro-mesoporous structure derived from waste biomass by stepwise activation for toluene removal from air

Abstract

The waste biomass was used as raw materials to prepare activated carbon adsorbents with micro-mesoporous structure. And the prepared activated carbon adsorbents were used to adsorption remove toluene from air, which can achieve the goal of “treat waste with waste”. In this paper, biomass activated carbon adsorbents with micro‒mesoporous structure were prepared by two-stage process of “low temperature carbonization‒high temperature activation” using waste biomass as raw materials and H3PO4 as activator. The obtained results show that the activation temperature can significantly affect the structural characteristics, graphitization degree and surface chemical properties of the prepared adsorbents, and the toluene adsorption and regeneration performances of the adsorbent are significantly affected by its physicochemical properties. High thermal desorption temperature (100 °C) can destroy the strong interaction between the oxygen atoms of the oxygen-containing functional groups on the surface of the adsorbent and the p-electrons of toluene aromatic ring, thus realizing the desorption of corresponding adsorbed toluene molecules. The low heat treatment temperature of 60 °C can destroy the strong adsorption from narrow micropores for toluene and π‒π conjugation effect between the adsorbent and toluene molecules, which can realize the corresponding adsorbed toluene molecules to be desorbed. When the activation temperature is 650 °C, the activated carbon adsorbent with surface area of 1006.2 m2/g, micro-mesoporous structure and mesoporous proportion of 65.5% can be prepared. The adsorption capacity of toluene can reach 417.0 mg/g, and the toluene thermal desorption regeneration can be realized at 60 °C. The results indicate that it is a promising adsorbent material for toluene removal from air