【作者】 刘澜；

【导师】 郑怀礼；

【作者基本信息】 重庆大学 ， 市政工程， 2011， 博士

【摘要】 论文利用农业废弃物稻秆为原料,对其进行化学改性以及利用复合菌系进行生物改性,制备染料吸附剂。通过实验室的静态实验,采用多种分析方法研究改性前后稻秆的比表面积、结构形貌、纤维素、半纤维素和木质素成分等物理结构及化学性质,以及pH值、吸附剂投加量、初始浓度和温度对稻秆吸附剂处理亚甲基蓝染料溶液的吸附性能影响,建立吸附热力学及吸附动力学模型。主要研究内容及结果如下:1.稻秆化学及生物改性后物理结构及化学性质的变化。采用多种仪器及分析方法对改性前后稻秆的物理结构和化学性质进行表征,结果表明,稻秆经化学及生物改性后,失重率都不同程度的增加,其中,碱化稻秆生物改性后的失重率最高,达47.3%。稻杆改性后的纤维素、半纤维素和木质素含量也都发生明显变化,碱化稻秆生物改性后的半纤维素降解率也最高,从21.3%降至0.9%。改性后,稻杆的色泽变浅,纤维明显变细,质地变得柔软。而且,经生物改性后,稻秆孔隙增多,微孔结构得到改善,比表面积增大,稻杆经超声生物改性后,比表面积由3.9 m2/g增加到6.9m2/g。稻杆改性后,化学结构发生了改变,纤维素、半纤维素与木质素之间连接的氢键被打断,-OH、-COOH、-OCH等基团游离,含量增加。2.化学及生物改性稻杆的吸附性能。用改性稻杆吸附亚甲基蓝溶液,结果表明,碱化、氨化、超声波改性和复合菌系生物改性稻杆吸附剂处理亚甲基蓝溶液的吸附性能优于原始稻杆吸附剂。碱化改性稻杆吸附量最高,为52.91mg/g,远高于原始稻杆15.625 mg/g的吸附量。碱化改性稻杆再经生物改性后,吸附量进一步得到提高,最大吸附量达56.083 mg/g。3. pH、投加量、初始浓度、温度对改性稻秆吸附剂处理甲基蓝溶液性能的影响.研究表明,pH值增加吸附率增加。pH为12时,改性稻秆对亚甲基蓝染料的吸附率最高;吸附剂投加量为2～10 g/L范围内,吸附剂投加量增加,吸附率增加,原始稻秆吸附剂最佳投加量为6 g/L,碱化、氨化和超声改性稻秆吸附剂最佳投加量为4 g/L;随着亚甲基蓝溶液初始浓度增加,吸附率增加;温度升高,吸附量增加,升高温度可以提高吸附效果。4.吸附热力学研究。碱化、氨化、超声波改性和复合菌系生物改性稻秆吸附剂处理亚甲基蓝溶液的吸附等温线能很好的符合Freundlich吸附等温式,稻秆吸附剂处理亚甲基蓝溶液的吸附介于单分子层和多分子层之间,稻秆吸附剂吸附表面的不均匀性对吸附过程有一定影响。碱化、氨化、超声波改性和复合菌系生物改性稻秆吸附剂处理亚甲基蓝溶液的吸附过程的焓变△H均为正值,稻秆吸附剂处理亚甲基蓝溶液的吸附是一个吸热过程,升高温度有利于吸附进行。在不同吸附温度及吸附浓度下,稻秆吸附剂吸附亚甲基蓝的吉布斯自由能△G均为负值,表明稻秆吸附剂处理亚甲基蓝溶液的吸附过程是自发进行的。在不同吸附温度及吸附浓度下,稻秆吸附剂吸附亚甲基蓝熵变△S均为正值,表明反应体系处于比较无序的状态。5.吸附动力学的研究。碱化、氨化、超声波改性和复合菌系生物改性稻秆吸附剂处理亚甲基蓝溶液的吸附是一个快速吸附过程。伪二级动力学方程能很好的描述碱化、氨化、超声波改性稻杆吸附剂吸附亚甲基蓝溶液的吸附过程,吸附速率主要受液膜扩散控制。颗粒内扩散方程和伪二级动力学方程能很好的描述复合菌系生物改性稻秆吸附剂处理亚甲基蓝溶液的吸附过程,吸附速率主要受颗粒内扩散和液膜扩散控制。学位论文为染料废水的处理提供了一种新的高效、低成本处理思路;拓宽了利用农业废弃物制备水处理吸附剂的研究方法;利用复合菌系生物法改性稻杆,为木质纤维素的经济、合理、高值化的利用提供一条新的途径。更多还原

【Abstract】 In this paper, agricultural waste paper straw as raw materials , was modified with chemical modification and composite strains biological modification, for preparation of the dye adsorbent. All kinds of analysis methods were used to study the physical structure and chemical properties , such as specific surface area, the structural configuration, cellulose and hemicellulose and lignin components. Through the laboratory experiment, the adsorption capacity of modified adsorbent of straw to deal with the methylene blue dye solutions was studied under different PH value , adsorbent dosing quantity, initial concentration and the temperature condition, and the model of adsorption thermodynamics and adsorption dynamics were established. The main conclusions are as follows:1.The change of straw’s chemical and biological modified physical structure and chemical properties.Using a variety of instruments and the analysis method and modified straw to the physical and chemical structure characterizing the nature, and the results show that, by chemical and biological straw after modification, weightlessness rate have varying degrees of increase, among them, alkalize straw biological modified weightlessness highest rate of 47.3%. Rice stem modified cellulose, half cellulose and lignin and all content change greatly, alkalize straw biological modified half cellulose degradation rate is the highest, from 21.3% to 0.9%. After modification, the colour and lustre of rice stem becomes shallow, fiber obvious thinner, texture is soft. And the biological modification, straw pore increased, microporous structure is improved, specific surface area increases, rice stem by ultrasound biological modification, specific surface area of 3.9 m 2 / g increases to 6.9 m 2 / g. Rice stem after modification, chemical structure changed, cellulose and hemicellulose and lignin, the connection between the hydrogen bonding is interrupted, the content of free groups such as -OH,-COOH,-OCH, increased.2.Chemical and biological adsorption performance of modified straw. Using modified straw to deal with the methylene blue dye solutions, the results show that the alkalify, amination, ultrasonic modification and composite strains of straw adsorbent biological modification processing methylene blue adsorption performance are better than the original solution straw adsorbent. Alkaline modified straw adsorption quantity is the highest, about 52.91 mg/g, far higher than the primitive straw 15.625 mg/g adsorption capacity. After biological modified, the adsorption quantity of alkaline modified straw has further improvement, the biggest adsorption can get 56.083 mg/g.3.The effect of reaction conditions (pH, dosing quantity, initial concentration, temperature) to absorption , when modification straw deals with methylene blue dye. Different reaction conditions on the adsorption effect are studied, and the research shows that, pH value increases as adsorption rate increase. When PH is12, modification of straw methylene blue dye adsorption rate are the highest; when adsorbent dosing quantity is 2 ~ 10 g/L range, absorbent dosing quantity increased, adsorption rate increase. The optimal dosing quantity of primitive straw is 6g/L, and for alkalify, ammoniation and ultrasonic modified straw the best dosing quantity is 4g/L. With methylene blue solution initial concentration increases, adsorption rate increase. With temperature increasing, adsorption increased. Raising temperature can increase the absorption effect.4.Adsorption thermodynamics research. Adsorption thermodynamics research shows that the adsorption isotherm of alkalify, amination, ultrasonic modification and composite strains biological modification straw adsorbent to seal with methylene blue solution are in line with two adsorption isotherm mode which are Langmuir and Freundlich, but the latter’s degree of correspondence is better. The straw adsorbent processing of methylene blue adsorption is between single molecule layer and polymolecular layer. The uniformity of adsorption surface of straw adsorbent has certain influence.with adsorption process .The value of enthalpy change△H of adsorbent processing of modification straw such as alkalify, amination, ultrasonic modification and composite strains biological modification to deal with methylene blue solution are all positive. The adsorbent processing of straw adsorbent to handle methylene blue solution is a process of heat absorption, so raising temperature is good to adsorption.In different adsorption temperature and concentration of adsorption, gibbs free energy△G of adsorbent processing of modification straw adsorption of methylene blue is negative, indicating that adsorbent processing of methylene blue adsorption process of solution is spontaneous.In different adsorption temperature and concentration of adsorption, entropy change△S of adsorbent processing of modification straw adsorption of methylene blue is negative, indicating that adsorbent processing of methylene blue adsorption process of solution is under a disorder of the state. 5.Research into the dynamics of adsorption.Adsorption dynamics research shows that, adsorbent processing of alkalify, amination, ultrasonic modification and composite strains biological modification straw to deal with methylene blue solution is a fast adsorption process. The sorption processes of alkalify, amination, ultrasonic modified absorbent follow the pseudo-second-order kinetics equation ,and the absorption rate is controlled mainly by liquid membrane diffusionThe sorption processes of composite strains biological modification straw follow the pseudo-second-order kinetics equation and diffusion equation,and the absorption rate is controlled mainly by liquid membrane diffusion and spread within particles.This study provides a new idea with high efficiency and low cost for the dye wastewater treatment; research methods of preparation are broaden ,when use of agricultural waste to make water treatment adsorbent; composite strains biological modification straw are utilized to pervide a new road for the lignocellulose to have a economic, reasonable, high threshold way to use更多还原