【作者】 戚建华；

【导师】 梁宗锁；

【作者基本信息】 西北农林科技大学 ， 植物学， 2010， 博士

【摘要】 中国是板栗（Castanea mollissima）的生产大国,占全球栗子总产量的3/4左右。板栗壳是板栗食品生产过程中产生的加工剩余物,目前尚未产业化开发利用。色素广泛用于工业、农业和日常生活的各个方面,出于对健康和环境安全的考虑,近年来天然色素越来越受到人们的推崇,成为研究的热点。重金属污染是目前重要的环境问题之一,生物吸附因其高效、低成本、无二次污染而成为污水处理领域研究的热点之一。本研究以板栗壳为原料提取天然色素,并对天然色素进行了分级精制、性质结构表征,同时还研究了板栗壳生物吸附水中的Cu（Ⅱ）的性能和机理,主要研究内容和结论如下:（1）以NH4OH水溶液为溶剂,采用响应面法对超声波辅助提取板栗壳色素的工艺条件进行了优化。采用中心复合设计（CCD）研究了NH₄OH浓度、液料比和提取时间对色素粗提物得率和色阶的影响。以色素粗提物得率为考察指标优化后的提取条件为:NH4OH浓度为1.1 mol/L,液料比为16.5 mL/g,提取时间为121 min;以粗提物色价为考察指标优化后的提取条件为:NH4OH浓度为0.74 mol/L,液料比为14.7 mL/g,提取时间为111 min。在此优化条件下进行验证试验,得到提取得率的观测值为238.6±4.9 mg/g,色阶为11.96±0.58,与模型预测值235.1 mg/g和12.39接近。（2）根据溶解性将板栗壳色素进行分级,得到类腐植酸（HULS）、类西玛多美朗酸（HYLS）和类富里酸（FLS）3个组分,HULS只溶于碱性水溶液,HYLS溶于碱性水溶液和甲醇、乙醇和丙酮等极性有机溶剂,FLS溶于任何pH的水中和极性有机溶剂。通过化学定性分析、元素分析、官能团分析、紫外——可见光光谱、红外光谱、13C核磁共振、1H核磁共振和电子顺磁共振技术对色素各分级组分进行了表征。板栗壳色素为植物黑色素。比较而言,HULS芳环取代程度最高,含有较多的脂肪链,其中的烷基链多且短,结合了较多的碳水化合物和蛋白质,羧基含量最高,半醌自由基含量最低;HYLS芳环取代程度最低,酚羟基含量最高,半醌自由基含量最高;FLS中含有较多的烷基链,且长而少分支。Na⁺、Mg²⁺、蔗糖、还原剂对板栗壳色素各组分没有显著影响,但各组分对Al³⁺、Ca²⁺、Fe²⁺、Fe3+、Cu²⁺、光照、加热和pH不稳定。（3）采用体外试验模型对板栗壳色素各分级组分的抗氧化能力进行了研究。抗脂质过氧化能力HULS > HYLS >FLS;清除H₂O₂能力和对Fe²⁺的螯合能力HYLS > FLS > HULS;总多酚含量FLS > HYLS > HULS,且清除羟自由基（·OH）、1,1-二苯基-2-苦基肼自由基（DPPH·）活性以及还原力都和总多酚含量存在着正的线性相关关系,而清除超氧阴离子（O₂·^-）活性与总多酚含量存在着负的线性相关关系。（4）采用静态吸附池吸附和柱吸附对板栗壳吸附水中Cu（Ⅱ）的工艺条件和吸附机理进行了研究。合适的起始pH值为5,静态吸附平衡实验数据符合Langmuir模型和Redlich–Peterson模型,分离因子RL值间于0与1之间,为有利吸附;动力学实验数据符合准二级动力学方程;粒内扩散是吸附的限速步骤之一,但非唯一限速步骤;焓变（ΔH^o）和熵变（ΔS^o）分别为-17.423 kJ·mol^-1和-54.667 J·mol^-1·K^-1,自由能变（ΔGo）为负值,表明板栗壳吸附Cu²⁺为放热过程,可以自发进行,吸附过程受热焓驱动;基于Redlich–Peterson等温吸附模型推导出的板栗壳用量计算公式可用于预测将一定体积一定起始浓度Cu²⁺溶液经过吸附降至所需浓度的板栗壳用量。本研究选用NH₄OH作为溶剂提取色素,克服了以往文献中乙醇作溶剂提取不全面、NaOH作溶剂提取杂质多等不足;首次将板栗壳色素进行了分级,得到3种组分,并其进行了系统的性质分析、结构表征和抗氧化活性研究;首次将板栗壳作为Cu（Ⅱ）的生物剂,研究了吸附性能和机理。研究结果对我国板栗资源的高效利用、加工企业的清洁生产等方面具有重要的现实价值。更多还原

【Abstract】 China is the biggest producer of chestnut, who counts for about 3/4 of total world production. Chestnut shell is generated as a residue of the food processing industry, and has no significant industrial and commercial uses, but becomes an issue and contributes to serious environmental problems. Pigments are widely used in industry, agriculture, and daily life. For health and environmental safety considerations, the natural pigments more and more recommended and have become a hot field for scientists. Heavy metal pollution is one of the important environmental issues, and biosorption is being paid more attention to recently for its high efficiency, low cost, and no secondary pollution concern. In present work, nature pigments were extracted from the chestnut shell, and fractionated into 3 parts according to their solubility. The fractions were characterized and their antioxidant properties were evaluated by in vitro models. These researches are helpful for industrial utilization of this processing residue. The research contents were list and the main conclusions drawn as following:（1） The ultrasound-assisted extraction of nature pigment from chestnut shell using NH₄OH solution was optimized by response surface methodology. A central composite design （CCD） was used to investigate the effects of the three variables （NH₄OH concentration, liquid–solid ratio, and reaction time） on crude pigment yield and its color value. The quadratic model obtained produced a satisfactory fitting of the experimental data and predicted that the optimum conditions for crude pigment yield consisted of a NH₄OH concentration of 1.1 mol/L, a liquid–solid ratio of 16.5 mL/g, and a reaction time of 121 min, and for color value a NH₄OH concentration of 0.74 mol/L, a liquid–solid ratio of 14.7 mL/g, and a reaction time of 111 min. Verification tests performed under these optimum conditions gave 238.6±4.9 mg/g of crude yield and 11.96±0.58 of color value, which was close to predicted values of 235.1 mg/g and 12.39 respectively.（2） The chestnut shell pigment was fractionated into humic-acid-like substance （HULS）, hymatomelanic-acid-like substance （HYLS）, and fulvic-acid-like substance （FLS） according to their solubility. HULS is soluble in alkaline water only, and HYLS soluble both in alkaline water and in polar organic solvent （methanol, ethanol, and acetone） but insoluble in acidic water, and FLS soluble in water at any pH value and in polar organic solvent. The pigment fractions were characterized using chemical, elemental and functional group analysis, and spectroscopies of UV-vis, FT-IR, ³C-NMR, ¹H-NMR and EPR. The chestnut shell pigment is a phyto-melanin. Contrastingly, HULS has the highest level of aromatic substituted, contains the most aliphatic structures with short and rich-branched alkyl chains, binds more carbohydrate and protein, possesses the richest carboxyl groups and the poorest semi-quinone free radicals; HYLS is riches in aromatic ring with less substitute, and in phenolic hydroxyl groups and semi-quinone free radicals; FLS contains more alkyl structures with long and poor-branched chains. Na⁺, Mg²⁺, sugar and reducer insignificantly affected the pigment fractions, and the samples are instable to Al³⁺, Ca²⁺, Fe²⁺, Fe3+, Cu²⁺, heat, light and pH.（3） The antioxidant properties of the pigment fractions were investigated in vitro. The order of antioxidant activity of the samples showed variations in different tests. The decreasing orders were HULS > HYLS >FLS for inhibition of lipid peroxidation, HYLS > FLS > HULS for H₂O₂-scavenging and Fe²⁺-chelating, and FLS > HYLS > HULS for total polyphenol content. The positively linear correlation of the total polyphenol content with the reducing power and radical scavenging activity of hydroxyl radical （·OH） and 2, 2-diphenyl^-1-picrylhydrazyl （DPPH·）, and the negatively linear correlation between the total polyphenol content and superoxide anion （O₂·^-） scavenging activity have been found.（4）The biosorption of Cu（Ⅱ） onto chestnut shell in a batch adsorber and a fixed-bed column have been studied. Optimum adsorption condition occurs at pH 5. The batch adsorber equilibrium data agreed well with Langmuir isotherm and Redlich–Peterson isotherm models. Separation factors （RL） are in the range of 0– 1, showing favorable adsorption of Cu²⁺ on the chestnut shells. The kinetic data were found to follow the pseudo-second-order model. Intra-particle diffusion is not the sole rate-controlling factor. Enthalpy change （ΔHo） and entropy change （ΔS^o） were found to be ^-17.423 kJ·mol^-1 and ?54.667 J·mol^-1·K^-1, respectively. The values of Gibbs free energy change （ΔG^o） were negative. Those demonstrate the adsorption is exothermic, spontaneous and enthalpy driven. A single stage batch adsorber was designed using the Redlich–Peterson to predict the optimized amount of chestnut shells at various volumes of effluent treated for different final desired concentrations of copper ions.In present work, NH₄OH solutions were used as solvents for the pigment extraction to overcome the shortcoming of ethanol or NaOH solvents in literatures. The pigment was fractionated into three parts for the first time, and their physicochemical properties and antioxidant activities were studied systematically. A pioneer research was conduct on the capacity and the mechanisms of Cu（II） biosorption by chestnut shell. The research findings have some important practical values in efficient use of chestnut resources and clean production of processing enterprises in China.更多还原