【作者】 雷超；

【导师】 孙小梅； 李步海；

【作者基本信息】 中南民族大学 ， 分析化学， 2009， 硕士

【摘要】 随着工业的发展,大量重金属废水的排放严重污染了环境,因此急切需要一种高效的水处理方法。微生物吸附法作为一种新型的水处理方法,具有原材料来源丰富、处理成本低、效率高、不会造成二次污染等优点,受到广泛的关注。在众多的生物吸附剂中,选用了啤酒废酵母作为吸附剂的原材料,其表面富含羟基、氨基、羧基等官能团,并且分布广、繁殖快,原材料廉价、易得,这可以大大的降低实际水处理的成本。另一方面,啤酒废酵母作为一种生物吸附剂也面临着机械强度差、吸附容量较低、吸附干扰大、吸附选择性差、再生较困难等多种问题。很多文献报道了用酸化、碱化、交联等简单的物理化学方法来改善酵母性能,结果均不理想。针对以上问题,本论文对失活的微生物表面修饰或改性制备成新的吸附剂对金属离子的吸附开展了以下研究:1、以胱氨酸和戊二醛制备了聚合物包裹的啤酒废酵母,用显微镜、红外、XPS对废酵母进行了表征,同时用滴定法测定了废酵母表面的氨基含量。研究了修饰废酵母和未修饰废酵母对Hg(Ⅱ)和Cd(Ⅱ)两种重金属离子的吸附行为,包括吸附溶液的不同酸度,吸附动力学,金属离子溶液浓度等。其中重点考察了它对这两种金属离子的吸附模式,结果表明,Langmuir最适合模拟修饰废酵母对两种金属离子的吸附模式。依据Langmuir等温式,修饰废酵母对Hg(Ⅱ)和Cd(Ⅱ)的吸附容量分别为42.34 mg·g-1和15.15 mg·g-1,明显的高于未修饰废酵母。而且滴定分析结果表明:啤酒废酵母表面氨基的量是0.54mmol·g-1,修饰啤酒废酵母表面氨基的量为0.89mmol·g-1,修饰后细胞表面的氨基提高了1.6倍。胱氨酸修饰的啤酒废酵母处理含Hg(Ⅱ)模拟水样,Hg(Ⅱ)去除率达86.60%。2、将胱氨酸修饰啤酒废酵母应用于氧化铝负载钴基催化剂样品中贵金属Pt(Ⅳ)的吸附。通过修饰废酵母对Pt(Ⅳ)吸附前后的XPS能谱N谱图分析表明,吸附主要依赖于氨基。研究了溶液pH、吸附时间、Pt(Ⅳ)的初始浓度以及溶液中存在Al(Ⅲ)和Co(Ⅱ)等主要因素对吸附剂选择性吸附Pt(Ⅳ)的影响。结果表明,在pH1.0的条件下,吸附平衡时间为60min,Pt(Ⅳ)的浓度为86.60mg·L-1,溶液中250倍的Al(Ⅲ)和75倍的Co(Ⅱ)不影响Pt(Ⅳ)的吸附与测定,可选择性的吸附Pt(Ⅳ)。最大吸附量为20.36 mg·g-1,是啤酒废酵母(5.08 mg·g-1)的4倍。3、啤酒废酵母等吸附剂因其表面细胞的电负性而对重铬酸根等金属阴离子吸附效果不好,采用酸化和Fe(Ⅲ)改性啤酒废酵母表面电负性的方法制得对Cr(Ⅵ)吸附容量大,机械强度高的改性废酵母表面的吸附剂。研究了用于改性废酵母的金属离子的选择,改性废酵母对Cr(Ⅵ)吸附的不同影响因素。从啤酒废酵母、酸化废酵母、改性废酵母的对比可以看出,pH2.0～6.0的溶液中,吸附剂的吸附能力没有很大的改变;吸附时间在50min基本达到吸附平衡,吸附过程符合准二级动力学方程;Langmuir适合模拟改性废酵母对Cr(Ⅵ)的吸附模式,吸附量达12.98 mg·g-1。Fe(Ⅲ)改性啤酒废酵母对电镀废水中Cr(Ⅵ)的去除率达97.90%。更多还原

【Abstract】 With the development of the industry, the environment was contaminated by heavy metal ions, so it is urgent to find an efficient method to deal with it. Biosorption, as a new method is a potential method for the removal of heavy metal ions due to the low cost, abundant source, high efficiency and no second pollution.Among the biosorbents, waste beer’s yeast was used to be researched. It has abundant functional groups such as: hydroxyl, amide, carboxyl etc. Additionally, waste beer’s yeast was wide-spread and easy availability. Due to the poor mechanical strengthen, low adsorption ability, bad selectivity and difficult regeneration, the practical use was limited.Many literatures had reported that treating the biomass with the simple physical chemistry method such as acid, alkali or crosslinker treatments could improve the performance of the biomass, but the results were not satisfied. According to these problems, the main work about the biosorbent for metal ions are summarized as follows:1、The surface of dried biomass of waste beer’s yeast was modified by crosslinking cystine with glutaraldehyde. X-ray photoelectron spectroscopy, FTIR and microscope were used to characterize the modified biomass. The factors, including pH, initial metal ions concentration and adsorption time, which can influence the adsorption capacity for Hg(Ⅱ) and Cd(Ⅱ) , were studied. The adsorption behavior especially, the adsorption isotherms of the modified and unmodified biomass were investigated, and Langmuir, Fruendlich, Temkin and Dubinin-Radushkevich models were used to fit the isotherm, and Langmuir model gave the best fitness. According to Langmuir model, the adsorption capacities of the modified biomass for Hg(Ⅱ) and Cd(Ⅱ) were 42.34 mg·g-1 and 15.15 mg·g-1, respectively, which is higher than the unmodified biomass. The result of amount of–NH3 indicated that the surface of modified biomass of–NH3(0.89mmol ? g-1) was about 1.6 times higher than that of the unmodified biomass(0.54mmol ? g-1). By reaching the request of simulated wastewater the adsorption rate of Hg(Ⅱ) was 86.60%.2、The modified cystine of waste beer’s yeast was used to adsorption the Pt(Ⅳ), which was from Co/Al2O3 catalyst. Through the adsorbent on the Pt(Ⅳ) before and after adsorption, spectroscopy XPS analysis showed that the adsorption mainly depended on the amino. The major affect factors of Pt(Ⅳ) selective absorded on sorbent were investigated, including pH, original concentration of Pt(Ⅳ) , adsorption time , Al(Ⅲ) and Co(Ⅱ) existed in solution and so on. The results show that the optimal adsorption conditions as follows: the solution pH was at 1.0, the adsorption time was for 60 min, and the concentration of Pt(Ⅳ) was 86.60 mg·L-1, and Al(Ⅲ) and Co(Ⅱ) could not influence on adsorption. The highest adsorbing capacity is 20.36 mg·g-1 under the conditions. It is about 4 times higher than that of the unmodified biomass (5.08 mg·g-1).3、Because of effect of anionic charge on the biomass surface, the adsorption of waste beer’s yeast for Cr(Ⅵ) is bad. In this study, the surface of waste beer’s yeast with higher mechanical strength and changing electronegative was prepared by using acid and Fe(Ⅲ) solution through a simple method. The factors, including choosing of metal ions,the amount of the modified biomass, which can influence the adsorption capacity for Cr(Ⅵ), were studied. Compared with the non-modified biomass, acid biomass, and modified biomass, the adsorption behaviour was affected little by pH. It applied use to waste water in the range from pH2.0 to pH6.0. The completion of the adsorption process needed for 50 min. The adsorption process followed the pseudo second-order kinetics. The adsorption for Cr(Ⅵ) fitted Langmuir monolayer model. The highest adsorbing capacity was 12.98 mg·g-1 under the conditions. The adsorption rate for Cr(Ⅵ) in electroplating wastewater of modified Fe(Ⅲ)–modified waste beer’s yeast was 97.90%.更多还原