共查询到20条相似文献,搜索用时 843 毫秒
1.
为提高植物染料儿茶的纯度及其染色效果,采用PVDF中空纤维微滤膜对儿茶染液进行精制,比较儿茶染液在膜分离前后的浑浊度及其所染毛织物、棉织物的颜色特征值,并测试在该分离体系中儿茶染液透过液流量与运行时间、色素浓度与运行时间的关系。结果表明:PVDF微滤膜分离技术降低了儿茶染液的浑浊度,提高了其对棉织物、毛织物上的染色性能;该分离体系运行1h后,儿茶染液膜通量降低、色素浓度下降,需对膜进行清洗;清洗剂选用强碱性NaOH为好,当膜污染情况比较严重时,采用超声波清洗可提高膜通量。 相似文献
2.
3.
被生酱油污染后的陶瓷膜再生方法的研究 总被引:1,自引:0,他引:1
从可逆及不可逆污染的角度,研究了被生酱油污染后陶瓷膜的清洗再生方法,考察了水冲洗时间、化学清洗条件以及单步和多步骤化学清洗对清洗效果的影响。结果表明,在低压,高流速条件下,经过4个步骤清洗,即先在(20±3)℃下水冲30min;再在(40±3)℃下以质量分数为1.5%的NaOH溶液循环清洗40min;进而在(40+3)℃下以0.15mol/L HNO_3循环清洗40min;最后用水冲洗装置至中性,可以达到比较理想的清洗效果,膜通量恢复到新膜通量的85%以上。 相似文献
4.
研究了指孔状结构和网状结构的亲水性聚偏氟乙烯(PVDF)微滤膜的滤菌性能与膜结构、膜孔径的关系,探讨了生啤酒过滤过程中膜结构、清洗方式对除菌效果和膜过滤通量的影响规律,通过SEM和接触角测定仪表征了微滤膜的结构和亲水性。结果表明:膜的结构对滤菌效果影响不大;0.22μm数量级的PVDF微滤膜的滤菌效果达到啤酒生产要求;清水清洗和碱、清水、酸、清水连续清洗两种清洗方式对网状结构的PVDF膜影响不大,其平衡过滤通量保持在22.2~22.4L/(m2·h),但碱、清水、酸、清水连续清洗方式更有利于指孔状结构PVDF膜性能的恢复,平衡通量约为40.8L/(m2·h),而同样条件下清水清洗的平衡通量为35.0L/(m2·h)。实验数据表明用亲水性的PVDF微滤膜过滤生啤除菌,仅采用清水清洗膜在操作上是可行的。 相似文献
5.
研究了膜法制备食品级浓缩磷脂过程中膜污染的清洗问题。实验研究了生产过程中正己烷溶剂溶清洗及重度污染后NaOH溶液清洗对无机膜的膜通量、产品丙酮不溶物含量的影响。实验结果表明,过滤过程中适时地用含水率低的正己烷清洗系统可较理想的延缓膜污染。对于重度膜污染,采用2g/dLNaOH溶液80℃清洗2h后用清水冲洗可使膜通量达到最优水平,产品丙酮不溶物含量超过质量分数60%。 相似文献
6.
超滤膜的污染原因及清洗方法 总被引:18,自引:3,他引:15
研究了超滤膜的污染原因及其影响因素,针对中空纤维超滤大豆分离蛋白所引起的膜污染问题提出了预防措施,对不同清洗方法和清洗剂的清洗效果进行了研究,试验表明,物理清洗和合适的化学清洗相结合,可使超滤膜的透水通量恢复至原来的90%以上。 相似文献
7.
8.
选择聚芳醚砜酮(PPESK)中空纤维微滤膜对酱油原液进行除菌实验,代替其传统工艺中高温灭菌-静置沉降-多次过滤等工艺,考察了滤膜的除菌效果及操作参数(压力、温度、时间等)对渗透通量的影响,选择了冷、热水反洗和碱液清洗的方法对污染膜进行再生处理,并对反洗效果进行了考察比较,确定了最佳操作参数。结果表明,任何情况下滤膜的除菌率均达到100%,最佳操作压力为0.07MPa,可选择的操作温度范围较宽,在近30h内膜渗透通量变化较小,表现出较强的耐污染性,热水及碱液反洗均有很好的再生效果,渗透通量恢复率高至100%,而碱洗更佳。滤膜具有耐污染性、可长期操作性、耐高温性及耐碱腐蚀性等优良特性。 相似文献
9.
10.
11.
An ultrafiltration system fouled by pectin solutions was used as a model system. The fouled membrane flux was fully restored by circulating 0.5% NaOH solution for 1 hr. By adding 0.003% polyethylene oxide) in 0.5% NaOH solution, the cleaning time required to fully recover flux of the fouled membrane was reduced to 2 min. The mechanism of improving cleaning efficiency may not be wholly attributed to the scouring effect of the polymer on the membrane surface. The cleaning and rinsing results suggest that polymers in cleaning solutions convert the pectin foulant into a foulant-polymer complex which could be readily rinsed from the membrane surface by water. 相似文献
12.
Alireza MirzaieToraj Mohammadi 《Journal of food engineering》2012,108(1):77-86
In this work, effect of ultrasonic waves on permeation flux of a microfiltration membrane fouled with fresh cow milk as feed was studied. Also, effects of various parameters such as feed pressure, ultrasonic irradiation power, ultrasonic source diameter, distance between the irradiation source and the fouled membrane surface and pulse irradiation were studied and permeation flux variations were recorded. In all experiments, it was found that ultrasonic irradiation increases the microfiltration flux. The highest flux enhancement factor (%FE = 490%) was obtained at a pressure of 0.5 bar, power of 40 W and distance of 2.6 cm. Continuous irradiation of ultrasonic waves uplifted the flux enhancement factor in a degree of 33% more than pulse irradiation. Also, both SEM analysis and permeation flux of pure water confirmed that ultrasonic irradiation has no destructive effects on the membrane surface. 相似文献
13.
14.
15.
Svetlana Popovi? Mirjana Djuri? Spasenija Milanovi? Miodrag N. Teki? Nataša Luki? 《Journal of food engineering》2010,101(3):296-302
Chemical cleaning of a severe in-pore-fouling may be improved by applying an ultrasound (US) field in a cleaning-in-place (CIP) system, under both the batch and flow conditions. This study is concerned with the cleaning of a 200-nm ceramic membrane, fouled with whey proteins, in an US field of relatively low frequency of 35 kHz, without applying a transmembrane pressure (TMP) and cross-flow velocity. Two types of cleaning agent solutions of different concentrations were applied: alkali (NaOH) and a mixture of commercial detergents (P3-Ultrasil 67 and 69) at a sonication time of 30 min. It was found that the application of US was less effective in the combination with sodium hydroxide than with the mixture of commercial detergents. Using US in a mixture of 0.25% w/w P3-Ultrasil 67 and 0.4% w/w P3-Ultrasil 69 resulted in the highest flux recovery of 86.5 ± 2.9%, after 30 min of sonication, and produced an overall efficiency of 96.3 ± 0.4%, after the second sonication. It was concluded that the application of the US field in a batch mode, combined with the mentioned chemical agents, can significantly improve the cleaning efficiency. 相似文献
16.
17.
Proteins and polyphenols are the principal fouling constituents in the ultrafiltration (UF) of black tea liquor. The aim of this study was to determine the relative importance of individual components in the fouling process, to investigate any synergetic interactions that were occurring and to compare the cleaning characteristics of different fouled membranes. A 30‐kD molecular weight cutoff polysulfone UF membrane in dead‐end mode was challenged with model solutions of tea components. Model solutions consisted of tea proteins, theaflavins (TFs), thearubigins and caffeine. Sodium hydroxide was used as a cleaning reagent. Permeate flux decline curves were presented for single components and mixtures. Individual component transfer fluxes and rejections were also presented. An unexpected finding was that protein in a mixture with TFs could permeate the membrane to a degree, while a protein solution in the absence of the polyphenol was completely rejected. The inspection of membranes fouled by different solutions revealed different foulant morphologies. Membrane cleaning with 0.2 wt % sodium hydroxide was generally found to be effective. 相似文献
18.
THIERRY GALLOT-LAVALLEE MARC LALANDE GEORGES CORRIEU 《Journal of food process engineering》1984,7(2):123-142
In the present study, 25 cm tubes fouled during pilot plant scale pasteurization of raw whole milk were cleaned with sodium hydroxide. The pasteurization conditions resembled those of the dairy industry. An optical sensor sensitive to the turbidity of suspended deposits removed by the cleaning solution was placed successively at the outlet of each fouled tube. Use of this sensor combined with a nonrecycled cleaning solution process enabled us to measure the cleaning rate on line. In these conditions it was observed that, at zero time, the cleaning rate was null. Based on the above observations a kinetic model of cleaning was established. It consists of two steps in series. The adhesive deposit passes through an intermediate state before being washed away by the cleaning solution. Each step is a first order reaction related to the mass of the adhesive deposit and the mass of the intermediate compound, respectively. Among the many physico-chemical parameters affecting the cleaning process, three major ones were studied; temperature, concentration and circulation rate of the soda solution. An empirical model of the rate constant was set up which takes into account those three parameters and the initial weight of deposit to be cleaned. A 1% increase in the amount of NaOH caused the same increase in the constant rate as 8°C or 0.5 m/s. 相似文献
19.
20.
应用F3 流变发酵仪和动态流变仪研究冰结构蛋白(ISP)对冻藏0、1、2、3、4 周鲜酵母发酵特性和冷冻面团动态流变学特性的影响。结果表明:随着冻藏时间延长,所有酵母样品发酵过程中气体释放曲线最大高度H′m、产生CO2 气体总体积V总及面团最大膨胀高度Hm 均逐渐降低,冷冻面团的弹性模量(G′)和黏性模量(G 〞)逐渐下降,冷冻面团包子比容显著减小。引入冰结构蛋白(ISP)后,冻藏时间相同时,酵母发酵过程中的H′m、V 总及Hm 均有所增大,G′和G 〞下降趋势减缓,冷冻面团包子比容明显大于空白组,说明ISP 能够抑制冻藏过程中冰晶的形成和重结晶,减弱冰晶对酵母及面筋蛋白质网络结构的破坏,同时也说明ISP 能够增强面筋蛋白质网络结构的强度,提高面筋蛋白质对冰晶破坏的抵抗力。 相似文献