【作者】 龚仁敏；

【导师】 刘志礼；

【作者基本信息】 南京大学 ， 植物学， 2004， 博士

【摘要】 染料是能使其他物质获得鲜明而坚实颜色的有机物,迄今,染料商品已超过10000多种。染料可以分为三大类:1.阴离子染料(anionic):包括直接染料、酸性染料和活性染料等;2.阳离子染料(cationic):即碱性染料;3.非离子染料(non-ionic):即分散染料。合成染料大都具有复杂的芳香结构,这些芳香结构主要来自煤焦油中的碳氢化合物,这些碳氢化合物包括:苯、萘、蒽、甲苯和二甲苯等,复杂的芳香结构使得染料更加稳定和更难生物降解。染料被广泛用于纺织、皮革、造纸、橡胶、塑料、化妆品、制药和食品等工业领域,染料的广泛使用必然产生大量的染料废水排放到环境水体中,导致自然水体的污染。某些染料在浓度低于1 ppm时就能使接受水体明显着色,所以即便是少量的染料也会污染大面积水体,这不仅影响了水环境的美观而且会减少水体透光量,进而影响水生植物的光合作用,况且,有些染料或其降解产物有毒,甚至能诱发基因突变或致癌。传统的处理染料废水的物理化学方法有凝结和絮凝、氧化或臭氧氧化、膜分离和活性炭吸附等,但这些技术并未表现出高效率﹑低成本的优点。活性炭是目前应用最广的染料吸附剂,但活性炭相对较高的价格、高的操作费用和再生所产生的问题阻碍了这项技术的大规模应用。活性炭价格高,且质量越好价格就越高,使用后用溶液再生会产生小体积的二次污染液,而高温再生将导致活性炭及其吸附能力的损失。所以,越来越需要寻找地产的、可更新的低成本材料作为吸附剂用于染料污染的治理。一些廉价的植物材料已被直接用做染料废水的吸附剂,这些材料包括:苹果渣、麦草、橘子皮、香蕉皮、玉米轴穗、玉米茎杆、稻壳、大麦壳、碎木片、棕榈果枝、锯屑、树皮、树叶、椰壳纤维、香蕉木髓、蔗渣木髓、水生植物等。但是在我国,尚没有任何用低值植物材料作为染料吸附剂的研究报道,中国是世界上合成染料的最大生产国,作为一个发展中的国家,研发经济高效的染料处理新技术尤为重要。本文调查了粉碎的花生壳作为吸附剂去除水溶液中离子型染料的可行性,目的是在中国寻找新的、低值的、具有高效染料去除能力的地产植物材料加强染料废水污染的治理工作。据我们所知,迄今为止,国内外尚没有用花生壳作为染料吸附剂的研究报道。花生壳是一种农产品废弃物,我国的花生壳资源非常丰富,这一生物资源的开发利用必然带给我们明显的经济和社会效益。研究所选的染料是三种阴离子染料:苋菜红(Am)、日落黄(SY)、固绿FCF(FG)和三种阳离子染料:亚甲蓝(MB)、亮甲酚蓝(BCB)、中性红(NR)。研究了各种实验参数对染料吸附的影响,这些因素包括:吸附剂浓度、吸附剂颗粒大小、吸附时间、离子强度、染料浓度和pH值,确定了最佳吸附实验条件。通过化学修饰确定了一些官能团在染料吸附中的作用,用电感耦合等离子发射光谱分析技术阐明了阳离子染料吸附的离子交换机理。染料溶液初始pH值等于2时,三种阴离子染料的去除率较高;而pH值高于4时,三种阳离子染料均能被有效去除;除BCB外,其他五种染料吸附率随染料浓度的增加而下降;六种染料的吸附率随吸附剂量的增加而增加;对所有染料而言,吸附剂颗粒越小染料吸附率越高;染料溶液的离子强度明显影响三种阴离子染料的吸附;六种染料的吸附等温线符合Langmuir或Freundlich方程,所有吸附过程都符合准一级反应动力学方程。吸附剂的化学修饰证明,羧基阻碍了阴离子染料的吸附,但羧基在阳离子染料的吸附过程中起着主要的作用。羟基是吸附离子型染料的重要官能团,而氨基的甲基化对离子型染料的吸附影响不大。本项研究结果表明,花生壳是良好的离子型染料吸附剂,是一种廉价的染料废水处理生物材料。更多还原

【Abstract】 Dyes are the organic compounds which can bring bright and firm color to other substances. Today there are more than 10,000 dyes available commercially. Dyes can be classified into three categories: 1. anionic: direct, acid, and reactive dyes, etc; 2. cationic: basic dyes; and 3. non-ionic: disperse dyes. Dyes usually have a synthetic origin and complex aromatic molecular structures which possibly come from coal-tar based hydrocarbons such as benzene, naphthalene, anthracene, toluene, xylene, etc. The complex aromatic molecular structures of dyes make them more stable and more difficult to biodegrade. Synthetic dyes have been increasingly used in the textile, leather, paper, rubber, plastics, cosmetics, pharmaceutical and food industries. The extensive use of dyes often poses pollution problems in the form of colored wastewater discharged into environmental water bodies. For some dyes, the dye concentration of less than 1 ppm in receiving water bodies is highly visible,so that even small quantities of dyes can color large water bodies. This not only affects aesthetic merit but also reduces light penetration and hydrophyte photosynthesis. In addition, some dyes or their metabolites are either toxic or mutagenic and carcinogenic.The conventional physical-chemical methods for treating dye wastewater are coagulation and flocculation, oxidation or ozonation, membrane separation and activated carbon adsorption. These technologies do not show significant effectiveness or economic advantage. Activated carbon is the most popular and widely used dye sorbent, but its relatively high price, high operating costs and problems with regeneration hamper its largescale application. Activated carbon is expensive and the higher the quality the greater the cost, furthermore, regeneration using solutions produces a small additional effluent, while regeneration by refractory technique results in loss of sorbent and its uptake capacity. Therefore, there is a growing need in finding low cost, renewable, locally available materials as sorbent for the removal of dye colors.Some low cost botanic materials had directly been used as sorbent for dye adsorption from wastewater, which included apple pomace, wheat straw, orange peel, banana peel, maize cob, maize stalk, rice husk, barley husk, wood chip, palm fruit bunch, sawdust, bark, leaf, coir pith, banana pith, bagasse pith and aquatic plants. But in China, yet no any research work about using low cost botanic material as sorbent for removal of dyes from aqueous solution was done. China was the largest producer of synthetic dyes in the world. For a developing nation as China, new, economical and highly effective treatment technologies of dye wastewater were urgently needed.In this paper, the feasibility of granular peanut hull as sorbent for removal of ionic dyes from aqueous solution was investigated. The aim of this study was to search for a locally available, low cost and untried botanic material in China with high dye removal capacity in order to enhance the treatment of dye wastewater. To the best of our knowledge, up to now, there was no any report about peanut hull had been used as dye sorbent. Peanut hull is an agricultural waste residue and is widely available in large quantity in China. The exploitation and utilization of this bioresource must bring obvious economic and social benefit to us. The dyes selected as sorbate were three anionic dyes: amaranth (Am), sunset yellow (SY), fast green FCF (FG) and three cationic dyes: methylene blue (MB), brilliant cresyl blue (BCB), neutral red (NR). The effects of various experimental parameters (e.g. sorbent dosage, particle size, contact time, ion strength, initial dye concentration and pH etc.) were examined and optimal experimental conditions were decided. By chemical modification, action of some fuctional groups in dye adsorption was certified. The ion exchange mechanism of cationic dye adsorption was elucidate by ICP-AES.At the value of initial pH 2.0, the removal efficiencies of three anionic dyes studied were high and above the value of initial pH 4, three cationic dyes studied could be removed effectively. Except BCB, the adsorption percentages of other five dyes decreased with the increase of initial dye concentrations. The percentages of dyes sorbed increased as the sorbent dose was increased for all dyes studied. The smaller the sorbent particle size the higher the ratios of dyes sorbed for six dyes studied. The ion strength of dye solutions obviously affected adsorption of three anionic dyes. To all six ionic dyes, the isothermal data of adsorption followed the Langmuir or Freundlich models. The adsorption processes conformed the pseudo-first-order rate kinetics. By chemical modification of biomass, some conclusions could been drawn. Carboxyl groups inhibited the adsorption of anionic dyes but they were important in the adsorption of cationic dyes. Hydroxyl groups were important functional groups in the adsorption of ionic dyes. The effect of methylation of amino groups on ionic dye adsorption wasn’t significant.The results in this study indicated that granular peanut hull was a good ionic dye sorbent and a low cost biomaterial for dye wastewater treatment.更多还原