Preparation Of Carbon Black Based Porous Carbon Material And Its Adsorption Performance For Toluene

Carbon black based porous carbon materials were prepared by chemical pore forming method with waste carbon black as raw material and applied to toluene adsorption and elimination in the atmosphere.It helps to solve the environmental problems caused by improper treatment of waste carbon black,and can realize the resource utilization of carbon black;At the same time,it can also provide high-performance carbon based adsorption materials for atmospheric purification containing VOCs.In this paper,a series of carbon black based porous carbon adsorbents were prepared by using waste carbon black as raw material and optimizing the type,amount and temperature of pore forming agent.The surface chemical properties and structural characteristics of the carbon based adsorbent were studied by scanning electron microscopy（SEM）,N₂ adsorption desorption（BET）,X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FT-IR）and Raman spectroscopy.The toluene adsorption and desorption properties of the carbon based adsorbent were evaluated by toluene adsorption/removal experiments.At the same time,the adsorption behavior of toluene on carbon based adsorbents and the recycling performance of carbon based adsorbents were investigated by using kinetic models（quasi-first-order,quasi-second-order and Bangham kinetic models）and renewable performance tests.The main conclusions are as follows:1.The types of pore forming agents significantly affect the pore structure and surface chemical properties of the prepared carbon based adsorbents,such as micropore ratio,specific surface area and surface functional groups.Different pore forming agents have significantly different pore forming ability,and carbon based adsorbents with significantly different properties are prepared.The carbon based adsorbent（PCBA-HK）prepared from KOH pore forming agent has the largest specific surface area（1031.4 m~2/g）,while the adsorbent（PCBA-CN）prepared from（NH₄）₂CO₃pore forming agent has almost no difference in toluene adsorption performance due to its high graphitization degree and maximum micropore rate（81.7%）,and the toluene saturated adsorption capacity is 306.0 and 298.9 mg/g respectively.The surface of carbon based adsorbents is rich in oxygen-containing functional groups,which can form strong interaction with toluene molecules,which is not conducive to the desorption of adsorbed toluene molecules,and it is difficult to achieve the recycling and regeneration of the corresponding adsorbents at low temperature.The kinetic results showed that the adsorption behavior of toluene on each carbon based adsorbent was controlled by pore diffusion.2.The pore structure and surface chemical properties of carbon based adsorbents can be effectively adjusted by the amount of pore forming agent.The specific surface area of carbon based adsorbents shows a"volcanic"trend with the increase of the amount of pore forming agent.When the amount of（NH₄）₂CO₃pore forming agent is0.2 g,the carbon based adsorbent has the largest specific surface area（738.7 m~2/g）and the highest micropore rate（81.7%）,which can not only greatly enhance the pore wall effect andπ-πconjugation effect of the carbon based adsorbent,but also provide more adsorption active sites,thus showing the best toluene adsorption performance（298.9 mg/g）.At the same time,the prepared carbon based adsorbent has excellent recycling performance,and the toluene adsorption performance of carbon based adsorbent can be regenerated by thermal desorption at 120°C.3.The pore forming temperature can significantly affect the pore structure of carbon based adsorbent.High pore forming temperature is conducive to improving the surface roughness and porosity of the prepared porous carbon material.The microporous rate of the carbon based adsorbent activated at 850°C can reach 81.7%and has a high degree of graphitization.High porosity and graphitization degree can form strong pore wall effect andπ-πconjugation effect,so as to improve its toluene adsorption performance.High mesoporous ratio is more conducive to the desorption of adsorbed toluene molecules on the corresponding carbon based adsorbents.The adsorption performance of toluene can be completely regenerated by low temperature thermal desorption,thus showing excellent recycling performance.