Preparation,Performance Regulation Of Absorption Materials And Their Application In The Detection Of Volatile Organic Compounds

Volatile organic compounds?VOCs?have become one of the main pollutants for atmospheric pollution,they are harmful to human health and ecological environment due to their toxicity,carcinogenicity and mutagenicity.With the continued growth of VOCs and the emission standards become stricter,the detection of low concentration VOCs is more and more important.The key point to the low concentration VOCs detection process is the sample collection,in which the selection of suitable solid adsorbents for detection of VOCs is crucial.The adsorbents generally should have the characteristics of large adsorption capacity,strong hydrophobicity,good stability,easy desorption and so on.Here,the different adsorbents were prepared by simple treatments of activated carbon,biomass materials and silica gel by different modifications.Then,the morphological structure and chemical composition of these materials were analyzed through different characterization methods,and exploring its practical application in the detection of different sorts of VOCs.The commercial activated carbon?AC?was steamed via HNO₃ vapour at high temperature for controllable polarity of materials.The HNO₃ modified AC-3?AC-NA-3?was obtained by steaming when at 160 ^oC for 5 h,and V_HNO3:m_AC=0.5 mL/g.Compared with AC,the as-prepared AC-NA-3 could test twenty-two compoments of twenty-four kinds of VOCs in fixed pollution sources,which exhibited a better effect on adsorption/thermal desorption,it is better than that of AC,and similar to Tenax.In addition,the prepared AC-NA-3 improves the difference in the adsorption of eight benzene series in ambient air by AC,and can detect thirty-five sorts of VOCs components in ambient air.AC-NA-3 was used as an adsorbent for detection of different sorts of VOCs,which exhibited high desorption rate and recyclability,so it has the good prospect of practical application.AC was treated by sodium lauryl sulfate?SDS?,and the best alumina modified activated carbon-0.5?2Al₂O₃/AC?was prepared in aluminum nitrate solution with the concentration of 0.5 mol/L.The specific surface area and pore diameter of 2Al₂O₃/AC decrease slightly,but the prepared 2Al₂O₃/AC exhibited better adsorption/heat desorption performance on twenty-four VOCs in fixed pollution sources and 8 benzene series in ambient air,and can detect thirty-five sorts of VOCs components of ambient air.In addition,the 2Al₂O₃/AC exhibited excellent test standard working curve?R²>0.99?,high desorption efficiency and recycl.Biomass carbon?PAC?was obtained by using the pine tower as the raw material and calcination at 700°C in a nitrogen atmosphere.And hierarchical porous biomass carbon@Al₂O₃?PPAC@Al₂O₃?was obtained through simple activation and reaming treatment of PAC,followed by hydrothermal method.Compared with PAC,the successful recombination of Al₂O₃ resulted in the decrease of the specific surface area and pore volume of PPAC@Al₂O₃,but the excellent adsorption performance of Al₂O₃was brought into play.which could improve the adsorption/thermal desorption performance for benzene series.Also,there are seven sorts of components with a standard curve correlation coefficient greater than 0.99,and the thermal desorption rate of PPAC@Al₂O₃ is more than 99%,which exhibites the excellent recycling performance.Above all,the prepared PPAC@Al₂O₃ has certain feasibility for the detection of eight benzenes.And the excellent for detection of twenty-four kinds of VOCs from fixed pollution sources and thirty-five kinds of VOCs from ambient were better than PAC.The silicon-carbon composite?SG@C?was obtained by using cheap silica gel?SG?as raw material and resorcinol-formaldehyde resin?RF?as carbon source,followed by calcined at 700°C in N₂ atmosphere.With the introduction of carbon materials,the hydrophilic group on the surface of SG@C is less than that of SG,the prepared SG@C tends to balance the adsorption capacity of each of the eight sorts of benzene components.Also,the thermal desorption efficiency of SG@C can reach 99%,and the standard curve R² is more than 0.9,which exhibit the excellent recycling performance.The SG could be re-obtained by calcination of SG@C at 500°C in air atmosphere.The material was recycled and exhibited excellent reusability.Above all,the SG@C has a potential value in the detection of twenty four sorts of VOCs in fixed pollution sources,thirty five sorts of VOCs and eight benzenes in ambient air.