蘑菇菌渣生物炭对高环PAHs的吸附特征研究

Study on the adsorption characteristics of high-ring PAHs on mushroom residue biochar

本研究以蘑菇菌渣为原料,通过控制不同温度(200、300、500、700℃)制备4种生物炭(M200、M300、M500、M700),以芘(Pyr)、苯并芘(BaP)和苯并苝(BghiP)为高环PAHs典型代表,采用吸附动力学和吸附等温线模型研究不同蘑菇菌渣生物炭对3种高环PAHs的吸附特征。结果表明:随着热解温度升高,不同生物炭的产率、羧基含量和酸性官能团含量降低,而灰分含量和pH升高。4种生物炭对高环PAHs的吸附遵循Lagergren准一级动力学模型,且以M700吸附能力表现最高,对3种PAHs的吸附呈现出Pyr(382.14 mg/kg)>BaP(340.08 mg/kg)>BghiP(319.76 mg/kg)的显著差异特征。Langmuir吸附模型(R^(2)=0.8769-0.9901)能更好地描述M500和M700对高环PAHs的等温吸附过程,且吸附能力表现为M700>M500。进一步通过分析生物炭吸附量与其表面官能团含量的相关性发现,酚羟基作为酸性官能团使生物炭具有阳离子交换特性,其含量与BghiP的生物炭吸附呈显著正相关,更有利于吸附BghiP。综上,700℃制备的蘑菇菌渣生物炭吸附量表现最优,推荐用于开展高环PAHs污染土壤修复的生物炭材料。

In this study,four kinds of biochar(M200,M300,M500,M700)were prepared from mushroom dregs at different temperatures(200,300,500,700℃).Pyrene(Pyr),Benzo[a]pyrene(BaP)and Benzo[g,h,i]perylene(BghiP)were taken as the typical representatives of high-ring PAHs.The adsorption characteristics of three kinds of high-ring PAHs on different mushroom residue biochar were studied by adsorption kinetics and adsorption isotherm model.The results showed that the yield,carboxyl content and acid functional group content of different biochar decreased with the increase of pyrolysis temperature,while the ash content and pH increased.The adsorption of high ring PAHs on four kinds of biochar followed Lagergren quasi-first-order kinetic model,and the adsorption capacity of M700 was the highest.The adsorption of three kinds of PAHs displayed significant difference in the order as Pyr(382.14 mg/kg)>BaP(340.08 mg/kg)>BghiP(319.76 mg/kg).The Langmuir adsorption model(R^(2):0.8769-0.9901)can better describe the isothermal adsorption process of high ring PAHs on M500 and M700 whose adsorption capacity is M700>M500.Further correlation analysis of the adsorption capacity of biochar with the content of surface functional groups found that the phenolic hydroxyl group as an acidic functional group gave the biochar the characteristics of cation exchange,and its content was significantly positively correlated with the adsorption of biochar of BghiP,which was more favorable for the adsorption of BghiP.In summary,the biochar adsorption capacity of mushroom residue prepared at 700℃was the best and it was recommended to be used for the remediation of high-ring PAHs-contaminated soil.