【摘要】 膨润土是以蒙脱石为主的粘土质矿石,新疆夏子街地区远景储量达50亿吨,但大都是品位较低的钙基和钠钙基膨润土,不利于产品的深加工。在对夏子街地区膨润土原矿进行物化性能分析及结构表征的基础上,以日月雷矿为主要研究对象,对其进行提纯、钠化改型及其不同膨润土产品应用于红葡萄酒澄清方面的研究,得到以下主要结论:1.确定出了最佳提纯工艺条件,即:制浆时间80min、液固比14:1、离心转速3000rpm和离心时间10min。提纯后蒙脱石含量由原来的68.5%提高到95%以上。XRD衍射分析及N2等温吸附-脱附性能表征表明,提纯后产品的杂质成分被有效去除,其品位及比表面积有较大程度的提高,其吸附性能有所改善。以日月雷矿膨润土为原料,以硝酸钠为改型剂,利用正交实验确定最佳提纯改型联合工艺条件:固液比为1:16、硝酸钠添加量为2%、离心转速为3000r/min、离心时间为15min、打浆时间为20min。改型产品钠离子交换容量由42.81提高到67.68 mmol/100g。2.通过不同类型膨润土的澄清实验,得出日月雷原矿RYL-B、日月雷提纯矿PRYL-B及日月雷改型矿MR对葡萄酒的澄清效果较好。在葡萄酒的澄清过程中,膨润土添加量在0.4g/L时的澄清度较好、对色素的吸附较少;在8h时膨润土对色素的吸附达到最高,8h后色度值基本不变;pH值对酒中色素和蛋白质均有很大影响,低pH条件有利于色素物质的保护和蛋白质的去除。澄清之后,葡萄酒中的各主要成分基本上没有变化,不影响葡萄酒的风味和口感。3.建立了检测有机酸的HPLC方法,测定了不同膨润土处理后的葡萄酒中各有机酸含量。结果得出,日月雷提纯矿（PRYL-B）对葡萄酒中的有机酸组分的影响最小,柠檬酸的平均去除率只有0.57%,酒石酸、苹果酸、乳酸、琥珀酸和乙酸的平均去除率分别为12.39%、9.80%、7.27%、6.27%和15.42%。膨润土对有机酸的吸附能力与膨润土的结构及有机酸自身的结构密切相关,有机酸分子中的–OH基团能够与膨润土表面的–Si-O或–Al-O基团之间以氢键的形式结合,导致各有机酸含量有不同的去除率。4.利用吸附热力学及动力学研究了模拟酒溶液中蛋白质的吸附规律。吸附实验数据能够很好的用Langmuir热力学模型及假二次动力学模型拟合。表观吸附活化能为51.35 kJ·mol-1,说明吸附过程存在潜在的吸附能垒。正的吉普斯自由能值表明吸附是非自发的过程,负的焓变和熵变值表明蛋白质吸附是一个放热的混乱度降低的过程。较高的比表面积、平均孔径、CEC和蒙脱石含量有助于膨润土从模拟酒溶液中吸附蛋白质。
【Abstract】 Bentonite is mainly composed of montmorillonite. The predicted resource measured is about 5 billion ton in Xiazijie of Xinjiang province. But the bentonite is mostly Ca-bentonite and Na-Ca-bentonite with lower montmorillonite, which was not favorable for the exploitation of deep-processing products. So the physical and chemical performance analysis and characterization of bentonite in this district were investigated. Moreover, the purification and modification of Riyuelei bentonite as material and the clarification of wine with different bentonite products were studied. The mainly conclusion obtained was followed as:1. The optimal conditions of purification processing was determined as followed: stirring time of 80 min, liquid and solid ratio of 14:1, centrifugal speed of 3000 rpm and centrifugal time of 10 min. The montmorillonite content of purified product was enhanced from 68.5% to 95%. The analysis of XRD and N2 adsorption-desorption isotherm characterization showed that the impurity in bentonite was effectively removed, the montmorillonite content and specific surface was greatly improved and the adsorption performance was amended. Utilizing the bentonite of Riyuelei mineral as material and abundant NaNO3 as modifier, the optimal processing conditions by orthogonal experiments was followed: solid and liquid ratio 1:16, the amount of NaNO3 2%, speed of centrifugal separation 3000r/min, centrifugal time of 15 min and stirring time of 20 min. The Na+ content of sodium-modification product was enhanced from 42.81 to 67.68 mmol/100g.2. The wine clarified with different bentonite was evaluated. Results indicated that good clarification effect was obtained utilizing RYL-B, PRYL-B and MR. During clarification, the clarity of wine was better and the pigment in wine varied little when the addition of bentonite arrived at 0.4 g/L. The adsorption of pigment arrived saturation at 8 h and after that the intensity colorate value was hardly changed. The effect of pH on the pigment and protein in wine was greater and lower pH was favorable for the protection of pigment and removing of protein. The main components of wine was almost not changed after clarification, and bentonite didn’t affect the taste and sensory of wine.3. The organic acids content in wine treated with different bentonite was determined by the developed HPLC method. Results showed that the effcct of PRYL-B on the content of organic acids was little. These organic acids concentration varied in certain extent, where the concentration of CA changed hardly with average elimination ratio （AER） of 0.57 %, and tartaric acid （TA）, malic acid （MA）, lactic acid （LA）, succinic acid （SA） and acetic acid （AA） were varied with AER of 12.39%, 9.80%, 7.27%, 6.27% and 15.42%, respectively. The adsorption capability of organic acids was greatly correlated with the surface structure characteristic of bentonite as well as their own structure and conformation. However, the–OH in organic acids can combine with–Si-O or–Al-O groups in bentonites surface by hydrogen band, which led to the different AER.4.The protein adsorption law in model wine solution was studied by adsorption thermodynamics and kinetics. The isothermal data could be well described by the Langmuir equation and the dynamical data fitted well with the pseudo-second-order kinetic model. The activation energy obtained was 51.35 kJ·mol-1, which may be an indicative of weak chemical adsorption, and the positive values of change in the free energy, varying from 11.32 kJ·mol-1 to 12.06 kJ·mol-1, indicated the adsorption was unspontaneous. Whereas, the negative values of the entropy, changing from -45.38 to -44.15J·K-1·mol-1, suggest decreased randomness at the bentonite-solution interface. The higher specific surface area, average diameter, cation exchange capacity and montmorillonite content of bentonite were contributed to the adsorption of protein from model wine solution. 更多还原
【关键词】 膨润土； 钠化改型； 葡萄酒澄清剂； 吸附； 蛋白质； 葡萄酒；
【Key words】 bentonite； sodium-modification； wine fining； adsorption； protein； wine；
