生物质炭对三种不同极性有机污染物的吸附机理研究

发布时间：2018-09-17 14:36

【摘要】：本项目选择不同来源的高有机碳固体废弃物,采用程序升温法来制备多种生物质炭,利用电镜扫描、元素分析、比表面积分析、光谱分析等手段揭示了不同生物质炭的结构特性,并通过酸洗、温度梯度等措施优化生物质炭的表面特性;然后将生物质炭与不同类型的有机污染物进行批量吸附实验,并对吸附前后的生物质炭与污染物的复合物进行红外光谱分析,剖析了生物质炭对不同有机污染物的表面吸附过程,揭示了生物质炭对不同类型有机污染物的吸附机制。结果表明:(1)生物质炭的特性明显受原材料来源和裂解温度的影响。秸秆生物质炭含C量最高,杨树叶生物质炭含H和N量最高,污泥生物质炭的灰分含量最高。随着温度的升高,生物质炭的芳香性增强,比表面积和吸附容量增加,酸洗处理显著改变生物质炭表面官能团振动峰,并能够增加其表面孔容及中孔数量,提高了生物质炭的吸附性能。(2)2,4-D、阿特拉津和萘这三种有机污染物在生物质炭上的吸附过程都是一个先快后慢的过程,生物质炭对萘的吸附一般在15 h后达到吸附平衡,而对2,4-D和阿特拉津的吸附需要24 h以上才能达到平衡状态。批量吸附实验表明不同生物质炭对2,4-D、阿特拉津和萘的吸附等温曲线均符合Frendlich模型;对萘的吸附同时也符合Langmuir模型。生物质炭对三种有机污染物的吸附能力不同,秸秆生物质炭对萘的吸附能力最强,对2,4-D和阿特拉津的吸附能力较弱。(3)生物质炭的裂解温度和颗粒细度会影响其对有机物的吸附特性。随着生物质炭裂解温度的增加,秸秆炭和杨树叶炭对三种有机物的吸附能力增加;随着炭颗粒粒径的减小,生物质炭对有机污染物的平衡吸附量增加。(4)溶液环境会显著影响生物质炭吸附有机物分子的吸附特性及平衡吸附量。秸秆生物质炭对2,4-D和阿特拉津在离子强度为0.01 mol/L吸附量最强,而杨树叶生物质炭对2,4-D和阿特拉津的吸附能力随溶液中电解质强度的增加而增加。溶液环境为酸性时,生物质炭对2,4-D的吸附量最大,溶液环境为碱性时,炭对阿特拉津的吸附量最大;改变溶液的pH值不会影响秸秆炭对萘的吸附能力。(5)生物质炭对3种有机污染物的吸附机制不同。萘在水溶液中为非极性分子,秸秆生物质炭对其的吸附机制主要包括范德华力、疏水作用和π-πEDA相互作用。2,4-D分子在水溶液中表现为负极性,秸秆生物质炭对2,4-D的吸附过程还会受到范德华力、π-πEDA作用、静电作用以及氢键作用的影响;杨树叶生物质炭对2,4-D的吸附机制除了静电作用外,还包括范德华力、π-πEDA作用和疏水作用。阿特拉津在水溶液为正极性,秸秆生物质炭对阿特拉津的吸附机制包括疏水作用和静电作用,杨树叶生物质炭对阿特拉津的吸附机制包括范德华力、静电作用和疏水作用。
[Abstract]:In this project, high organic carbon solid waste from different sources was selected, and a variety of biomass carbon was prepared by temperature programmed method. Scanning electron microscopy, elemental analysis and specific surface area analysis were used. The structural characteristics of different biomass carbon were revealed by spectroscopic analysis, and the surface characteristics of biomass carbon were optimized by acid pickling and temperature gradient, and then the batch adsorption experiments were carried out between biomass carbon and different organic pollutants. The complex of biomass carbon and pollutants before and after adsorption was analyzed by infrared spectroscopy. The surface adsorption process of biomass carbon to different organic pollutants was analyzed, and the adsorption mechanism of biomass carbon to different organic pollutants was revealed. The results showed that: (1) the characteristics of biomass carbon were obviously affected by the source of raw materials and pyrolysis temperature. Straw biomass carbon had the highest content of C, poplar leaf biomass carbon had the highest H and N content, and sludge biomass carbon had the highest ash content. With the increase of temperature, the aromaticity, specific surface area and adsorption capacity of biomass carbon increased. The surface functional group vibration peak of biomass carbon was significantly changed by pickling treatment, and the surface pore volume and the number of mesoporous carbon were increased. The adsorption performance of biomass carbon was improved. (2) the adsorption process of three organic pollutants, atrazine and naphthalene, on biomass carbon was a fast process and then a slow process, and the adsorption equilibrium of naphthalene adsorbed by biomass carbon was generally reached after 15 h. However, it takes more than 24 hours to reach the equilibrium state for the adsorption of 2,4-D and atrazine. Batch adsorption experiments showed that the adsorption isotherm curves of 2h4 D, atrazine and naphthalene for different biomass carbon were in accordance with the Frendlich model, and the adsorption of naphthalene for naphthalene was also consistent with Langmuir model. The adsorption ability of biomass carbon to naphthalene was the highest, and the adsorption ability of biomass carbon to naphthalene was different. (3) the pyrolysis temperature and particle fineness of biomass carbon will affect the adsorption characteristics of organic matter. With the increase of pyrolysis temperature of biomass carbon, the adsorption ability of straw charcoal and poplar leaf charcoal to three organic compounds increased, and the diameter of carbon particles decreased with the increase of biomass carbon pyrolysis temperature. (4) the adsorption characteristics and equilibrium adsorption capacity of organic molecules adsorbed by biomass carbon were significantly affected by the solution environment. The adsorption capacity of straw biomass carbon for 2na-4-D and atrazine was the strongest at ionic strength of 0. 01 mol/L, but the adsorption capacity of poplar leaf biomass charcoal for 2n4-D and atrazine increased with the increase of electrolyte strength in the solution. When the solution environment is acidic, the adsorption capacity of biochar to 2n4-D is the largest, and when the solution environment is alkaline, the adsorption capacity of carbon to atrazine is the largest. The adsorption ability of naphthalene by straw carbon was not affected by changing the pH value of the solution. (5) the adsorption mechanism of three organic pollutants by biomass carbon was different. Naphthalene is a nonpolar molecule in aqueous solution. The adsorption mechanism of naphthalene on straw biomass carbon mainly includes van der Waals force, hydrophobic interaction and 蟺-蟺 EDA interaction. The adsorption process of 2H 4-D by straw biomass carbon was also affected by van der Waals force, 蟺-蟺 EDA, electrostatic action and hydrogen bond interaction, and the adsorption mechanism of poplar leaf biomass charcoal to 2H4 D included van der Waals force, 蟺-蟺 EDA interaction and hydrophobicity. Atrazine has a positive polarity in aqueous solution. The adsorption mechanism of atrazine on straw biomass carbon includes hydrophobic and electrostatic interaction, while the adsorption mechanism of atrazine from poplar leaves includes van der Waals force, electrostatic action and hydrophobic effect.
【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X505

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