酸改性生物炭对柴油等温吸附的研究

Isothermal adsorption of diesel on biochar modified using pickling

以小麦秸秆和稻壳为原材料,分别在300,500,600℃下采用限氧裂解法制备生物炭。利用HCl和HCL-HF混合溶液对稻壳炭(RHB)和麦秆炭(WSB)进行酸洗。采用BET,SEM,FTIR等方法对生物炭酸洗前后形态结构变化及生物炭对柴油的等温吸附行为进行表征。表征结果显示,酸洗和热解温度升高均能增大生物炭比表面积和总孔体积,使孔隙结构更加丰富。实验结果表明,热解温度升高可增加生物炭的芳香程度,生物炭吸附柴油能力也随热解温度升高而增强,且WSB高于RHB;酸洗可去除生物炭中的灰分,SiO振动吸收峰强度明显减弱,并可提高生物炭对柴油的吸附量;Freundlich模型能够更好地描述生物炭对柴油的等温吸附过程,表明生物炭对柴油的吸附除了孔隙填充、π-π作用外,还有多分子层吸附作用。

Biochar was prepared from wheat straw and rice husk under the limited oxygen pyrolysis condition and at different temperature 300,500,600℃.Rice husk biochar(RHB)and wheat straw biochar(WSB)were acidified by HCl and HCl-HF mixed solution.BET,SEM and FTIR were used to study the change of the morphological structure of biochar and the isothermal adsorption behavior of diesel.Characterization results indicated that the surface area and total pore volume of biochar increased by pickling and pyrolysis temperature increase,which made the pore structure more abundant.Experimental results showed that the increase of the pyrolysis temperature could increase the aroma of biochar and the ability of biochar to adsorb diesel where WSB was higher than RHB.Pickling could remove the ash from the biochar.The vibration absorption peak intensity of Si-O was obviously weakened,and the adsorption capacity of diesel on biochar was increased.The Freundlich model could better describe the isothermal adsorption process of diesel on biochar,indicating that,in addition to the pore-filling andπ-πinteractions,the adsorption of diesel also included multiple molecular layer adsorption.