Study On The Preparation And Oil Adsorption Effect Of Biomass Based Cellulose Carbon Aerogel

With the development of industry and technology,the demand for non-renewable energy is increasing and the extraction and transportation of oil resources are becoming more frequent,but with this comes numerous oil spills and water pollution problems.Carbon aerogel（CA）is a type of lightweight,high specific surface area and porosity,chemically stable porous three-dimensional carbon material,which has been used as an efficient adsorbent material for oil spill pollution.Cellulose,as a biomass resource that exists in large quantities in nature,is a low-cost and renewable raw material for the preparation of carbon aerogels,but still needs to overcome the problems of cumbersome preparation process and low adsorption performance.In this study,cellulose was extracted from two agricultural wastes,corn straw（C）and rice straw（R）,and straw-based cellulose carbon aerogels CBCA and RBCA were produced by a facile ultrasonic dispersion-freeze-drying-one-step carbonization method,and ultra-light,hydrophobic and high oil absorption efficiency cellulose carbon aerogels N-CBCA and N-RBCA were produced by urea co-pyrolysis activation method,and the effects of cellulose mass fraction,carbonization temperature and activation on the morphological structure and adsorption properties of the carbon aerogels were investigated.The main findings are as follows.（1）Corn straw cellulose and rice straw cellulose were extracted and purified by alkali thermal-bleaching method,and cellulose carbon aerogels with mass fractions of 1/50,1/100and 1/200 were prepared and characterized to explore the effect of cellulose mass fraction on carbon aerogels.At the carbonization temperature of 600℃,the carbon aerogels with different mass fractions formed three-dimensional skeletons and showed good hydrophobic properties（water contact angle≥120°）.Both CBCA and RBCA showed the best adsorption effect at1:200,and the adsorption performance of CBCA-200 and RBCA-200 for different organic and oil substances were 87-128 g/g and 104-124 g/g,respectively.（2）Two kinds of cellulose aerogel samples were prepared with a cellulose/deionized water ratio of 1/200.Carbon aerogels with carbonization temperatures of 500°C,600°C and 700°C were prepared and characterized to explore the effect of carbonization temperature on carbon aerogels.With the increase of temperature to 700℃,the hydrophobicity of both CBCA and RBCA was enhanced（water contact angle≥130°）and the adsorption performance was effectively improved.The adsorption performance of CBCA₂₀₀-700 and RBCA₂₀₀-700 for different organic and oil substances were 95-173 g/g and 97-169 g/g,respectively.（3）Urea-activated carbon aerogels N-CBCA and N-RBCA were prepared and characterized by urea co-pyrolysis at a cellulose/deionized water ratio of 1/200 and a carbonization temperature of 700°C to explore the effect of activation on the properties of carbon aerogels.Urea activation further enhanced the hydrophobicity（water contact angle≥140°）,expanded the specific surface area and pore volume,and enhanced the adsorption performance.The specific surface areas of N-CBCA₂₀₀-700 and N-RBCA₂₀₀-700 after activation were 123.6335 m²/g and 143.3033 m²/g,respectively,which were 5-9 times higher than those before activation;the adsorption performances for different organic and oil substances were 99-197 g/g and 97-186 g/g,respectively.And the adsorption process is consistent with quasi-secondary adsorption kinetics.（4）Comparing（N-）CBCA with（N-）RBCA,the specific surface area,pore capacity and adsorption performance of CBCA are better than those of RBCA,indicating that the nature of the biomass material itself will have a greater impact on the performance of carbon aerogel.In this study,a simple way of preparing straw-based cellulose carbon aerogel is proposed,and the universality of carbon aerogel preparation from different straw biomass materials is discussed to some extent,which provides an experimental basis for the application of agricultural waste in the field of oil spill remediation.