Preparation Of Porous Carbon Materials And Toluene Removal In Air

Waste biomass was selected as raw material to prepare activated carbons,and applied to toluene removal in air,which can realize its resource recycling and high-value utilization;effectively alleviate the environmental problems caused by improper treatment of waste biomass;alleviate the dependence of raw materials for activated carbon preparation on nonrenewable resources such as coal and petroleum by-products.Meanwhile,it can support high-performance adsorbent for VOCs removal in air,and achieve the purpose of treating waste with waste.Generally,activated carbon materials owned limited adsorption capacity for VOCs.Fortunately,surface modification can increase its adsorption amount toward VOCs,improve the efficient use of activated carbons,and make it possesses superior practical application value.In this paper,waste zanthoxylum bungeanum branches were selected as raw materials and H₃PO₄ as activating agent to prepare biomass activated carbon adsorbents.They were characterized via scanning electron microscope?SEM?,N₂adsorption-desorption?BET?,fourier transform infrared spectroscopy?FT-IR?,X-ray diffraction?XRD?,and raman spectra.The effects of heating rate and activating temperature on the toluene adsorption and desorption of adsorbens were investigated.At the same time,CuO species were introduced to modify activated carbons,and the effect of CuO species on it toluene adsorption performance was studied.Some conclusions can be drawn as follows:1.The activating temperature can significantly affect the structure and surface chemical properties of the biomass activated carbons,and the toluene adsorption and regeneration performance were obviously affected by its structure and surface functional groups.The high temperature?150??could destroy the strong interaction between the oxygen atom of oxygen functional group on the adsorbent surface and the p-orbital electron of toluene aromatic ring,while the low temperature?60??could destroy the strong adsorption force on narrow micropores toward toluene molecules andp-pconjugate effect between the adsorbent and toluene molecules.When the heating rate,the activation time and temperature were 10?/min,180 min and 650?,BAC650 adsorbent exhibit typical micro-mesopore structure and the mesopore proportion was 65.5%.Interestingly,the toluene adsorption amount of BAC650adsorbents was 417.0 mg/g,which was superior to other activated carbon materials reported in the literature.Thus,it was a very promising adsorbent.2.Adjusting the heating rate during the preparation of biomass activated carbons can availably control its structure and surface chemical properties,which would directly determine the toluene adsorption and regeneration performance of the adsorbent.The prepared adsorbents possessed typical micro-mesopore structure,and it displayed unique spatial effect,which drived it exhibiting excellent toluene adsorption performance.Futhermore,the prepared adsorbents owned preferable renewability,which can be realized through thermal desorption at low temperature??150??or even air purging at room temperature?20??.When the activating temperature was600?,the activating time was 180 minutes,and the heating rate was 10?/min,the toluene adsorption amount on BAC10 adsorbent could reach 360.0 mg/g,which was significantly higher than other adsorbents reported in the literature,and own favorable regeneration performance.3.The introduction of CuO species evidently improved the adsorption performance of activated carbon toward toluene.The CuO species on the surface of CuO/AC adsorbent combined with toluene molecules to form P-complex bond,which increased the active adsorption site,thus strengthening the adsorption performance toward toluene molecules.Additionally,the CuO content remarkably affect the toluene adsorption performance on CuO/AC adsorbents.The CuO/AC adsorbent with CuO species content of 0.3%showed optimal adsorption performance toward toluene,the toluene adsorption capacity was as high as 701.8 mg/g?blank activated carbon was406.1 mg/g?,and the recycling efficiency was 92.8%after thermal desorption at200?.