Bentonite Sodium-modification And Development Of Wine-fining

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.