共查询到19条相似文献，搜索用时 171 毫秒
1.
无机陶瓷微滤膜对梨汁的澄清和除菌效果研究 总被引：4，自引：3，他引：4
该文研究了无机陶瓷微滤膜对梨汁的澄清和除菌效果的影响。采用3种孔径(0.8 μm、0.2 μm、50 nm)的氧化铝无机陶瓷微滤膜和自制的加压微滤装置进行试验。试验结果表明：3种膜微滤对梨汁的可溶性固形物、维生素C、还原糖含量和pH值的影响不大；50 nm和0.2 μm膜的澄清效果好于0.8 μm膜；50 nm膜澄清汁得率较低；0.2 μm和0.8 μm膜微滤澄清汁很好地保持了梨汁的风味。3种孔径膜微滤过程中，循环梨汁的温度在20～30℃之间；0.2 μm膜微滤过程中，有较好的通透量。50 nm膜除菌效果最好，微生物指标均达到国家食品卫生标准要求；0.2 μm和0.8 μm膜除菌效果不好。综合澄清效果、梨风味物质损失、膜通透量和除菌效果等指标可以看出，通过0.2 μm膜澄清梨汁的综合指标最好。 相似文献
2.
针对沼液中悬浮物含量高、重金属残留等问题,该研究采用陶瓷膜进行预处理,开展膜过滤工艺参数优化和污染物去除效果的试验。首先证明7种不同孔径陶瓷膜中10～50 nm超滤陶瓷膜通量较高,再选择20 nm膜进行后续沼液温度、膜面流速和浓缩倍数等因素对陶瓷膜通量影响的研究。结果显示：20 nm陶瓷膜通量随温度升高呈指数型增长;较适宜的膜面流速为3.0 m/s,对应的膜通量可达175 L/(m2·h);经济性较高的变频器运行频率范围为40～45 Hz;20 nm陶瓷膜的极限浓缩倍数大于10倍,优于100 nm膜。20 nm陶瓷膜可完全去除沼液中浊度,同时较好的保留溶解性有机质和氮磷钾等无机营养,并对沼液中多种重金属具有良好的阻控效果,综合考虑其生产工艺和使用成本,20 nm陶瓷膜有广阔的实际应用前景。 相似文献
3.
该研究以鸡骨素为原料,中试条件下对比分析了真空浓缩与2种膜组合偶联真空浓缩工艺的优劣。通过测定真空浓缩工艺的浓缩速率和水分去除率,微滤-反渗透和超滤-反渗透组合膜的膜通量、物料损失率、干物质损失率和蛋白损失率,研发了梯度膜分离与真空浓缩偶联的新型骨素浓缩工艺并进行了中试研究。结果显示:真空浓缩前期60 min内可溶性固形物含量升高缓慢,浓缩速率低,耗能大;微滤、超滤、纳滤和反渗透膜分离的物料损失率为0.5%、6.25%、4%、7.1%,干物质损失率为1.6%、19.4%、22.4%、20%,蛋白质损失率分别为35.8%、25.7%、22%、16%,膜通量衰减速率与膜孔径呈现负相关;膜组合结果表明超滤-反渗透膜组合能够提高反渗透膜通量,显著减少物料损失和干物质损失(P0.01)。中试结果表明,超滤-反渗透-真空浓缩工艺耗时110 min,耗资27.85元,耗煤11.018 8 kg,污染气体SO2和NOx的排放量分别为0.010 1 kg和0.014 6 kg。超滤-反渗透-真空浓缩新型工艺缩短了浓缩时间,降低了生产成本,污染气体的排放显著(P0.01)减少,一定程度上实现了节能减排,可以作为一种新型工艺用于鸡骨素浓缩生产。 相似文献
4.
中空纤维膜分离燕麦蛋白工艺及膜清洗方案 总被引：2，自引：1，他引：1
以燕麦蛋白回收率、总糖清除率、膜的污染度、浓缩效率及膜通量恢复率为指标,优化了中空纤维膜分离燕麦蛋白的工艺参数及膜的清洗方案。在温度35℃、压力0.02 MPa、pH值=8、流量25 L/h条件下利用MOF503分离经滤纸预处理的燕麦蛋白提取液,燕麦蛋白回收率、总糖清除率、膜的污染度及浓缩效率分别为80.3%、79.5%、41%、 43.5 L/(m2·h),同时,若采用分批超滤方式并辅以定期在线负压反冲清洗更有利于MOF503超滤处理燕麦蛋白提取液;通过物理和化学清洗方法对MOF503清洗效果的研究,表明物理清洗中的负压反冲清洗效果要明显优于等压水力清洗,化学清洗中HCl(pH值=2)和NaOH+H2O2+HCl比其他的效果要好,若物理和化学清洗协同作用,可使MOF503膜通量恢复率达94.74%。该研究表明利用中空纤维膜分离燕麦蛋白是可行的,并且将为膜分离蛋白的研究提供一定的技术依据。 相似文献
5.
陶瓷膜微滤秸秆木聚糖酶解液的阻力及膜通量模型 总被引：3，自引：2，他引：1
膜技术应用的障碍在于膜污染和膜通量下降.为掌握无机陶瓷膜微滤处理爆破秸秆木聚糖酶酶解液过程中纤维、粗蛋白、木质素在膜材料上的吸附和沉积及其对膜透过液通量影响的规律,依据试验结果,应用线性拟合建立了滤饼层阻力随时间变化的数学模型,相关系数为0.9914:分别基于饱和模型,修正Pearl生长模型和Pearl生长模型,应用非线性拟合建立了吸附阻力随时间变化的数学模型,三种吸附阻力模型预测值与试验值相关系数分别为0.9931,0.9980,0.9982.在此基础上,建立了计算微滤膜通量的微分方程数学模型,模型预测值与试验值相关系数达到0.9963,重复试验数据与模型预测值相关系数0.9838.结果表明所建立的模型可以很好地对该料液体系微滤过程的膜通量衰减进行预测. 相似文献
6.
陶瓷膜净化猪场沼液的效果试验 总被引：4，自引：3，他引：1
针对沼液中悬浮物和胶体颗粒物含量高、造成膜浓缩预处理难的问题,该研究选择50和200 nm两种孔径陶瓷膜进行了运行条件、水质处理和污染清洗效果的试验。结果显示:在0.3 MPa的运行压力下,50,200 nm两种孔径陶瓷膜对浊度的去除率均能够达到99%以上,对COD的去除率分别为36.2%±0.6%和32.6%±1.5%,无明显差异。同在0.3 MPa运行压力下,200 nm孔径陶瓷膜膜通量可以达到100.6 L/(m~2×h),高于50 nm陶瓷膜膜通量的52.8%。200 nm陶瓷膜对总磷、TOC、氨氮、总氮和总钾的去除率分别为61.2%,35.0%,3.8%,6.2%和3.0%。采用1%氢氧化钠+1%柠檬酸组合清洗方式取得了较好的清洗效果,陶瓷膜的膜通量恢复率可达95.4%。 相似文献
7.
秸秆低聚木糖溶液纳滤分离特性和渗滤工艺 总被引：3，自引：2，他引：1
该文研究了截留相对分子质量为250的纳滤膜分离以秸秆为原料生产的低聚木糖溶液的分离特性,并优化了渗滤纯化工艺。通过检测透过液和截留液中各糖组分的浓度,计算并得到了该膜对阿拉伯糖、木糖和聚合度（Degree of Polymerization）DP2到DP4的低聚木糖的截留率随膜通量变化的关系曲线;应用不可逆热力学模型对阿拉伯糖、木糖和DP2到DP4的低聚木糖中性溶质体系的截留率试验数据进行回归计算,求得了反射系数、溶质透过系数和水透过系数等膜分离特性参数,并根据立体位阻模型估算出膜的细孔结构参数。当糖液浓度为8.4%（总糖/糖浆）,膜系统温度控制在(30.1±2.1)℃,跨膜压差控制在(1.58±0.02)×106 Pa的恒定体积渗滤操作模式下,膜通量无衰减,稳定在(29.4±1.8) L/(m2·h),经3倍体积纳滤渗滤操作后,低聚木糖纯度由原料的83.33%（DP2到DP6低聚木糖/总糖）上升至92.54%,木二糖损失率为12.45%（对原料中的木二糖）,总糖回收率为88.39%（对原料中的总糖）。纳滤分离模型的研究为低聚木糖溶液的渗滤纯化和浓缩模拟并精确优化工艺提供了参数基础,使用纳滤膜在渗滤操作模式下,可以高效脱除单分子糖,同时低聚木糖损失较小。 相似文献
8.
为研究磁化甘蔗混合汁微滤膜分离过程,分析膜面吸附作用对传质过程的影响。以甘蔗混合汁为原料,研究了磁化甘蔗混合汁在微滤过程中质量传递模型。在不考虑膜表面层的吸附作用下,0.45和0.20μm陶瓷微滤膜分离的传质系数分别为-81.406和-83.130,回归方程的决定系数R2分别为0.921和0.920,P值分别为0.002和0.010;考虑膜表面层的吸附作用,0.45和0.20μm陶瓷微滤膜分离的传质系数分别为-323254.006和573281.937,吸附系数分别为0.995和0.994,回归方程的决定系数R2分别为0.939和0.999,P值分别为0.015和0.0008,可见,对于上述磁化条件和膜分离过程进出口操作压力差0.03~0.04 MPa,控制温度(35±1)℃,全回流试验条件下,膜面吸附作用对微滤膜分离过程传质模型影响显著(P0.05)。该研究有助于微滤膜分离设备的选型设计参数和操作条件的优化。 相似文献
9.
为模拟磁化甘蔗汁微滤膜分离过程,建立了磁化微滤膜分离过程的的膜通量的无量纲数学模型。该研究以磁场、微滤膜器和膜管的参数、微滤膜的操作条件和料液的流体力学性质为影响因素,根据π定理,因次一致性和流动相似理论建立了磁化微滤膜操作过程的膜通量的无量纲模型,并以甘蔗混合汁为原料进行了模型的求解与验证。结果表明:关于磁化甘蔗混合汁微滤过程所建立的多元回归模型的决定系数R2值为0.905,标准误差为0.173,模型精度较高。该模型可预测膜器条件、操作条件和磁场强度等参数条件下的磁化糖汁微滤膜分离过程的膜通量,为磁化陶瓷微滤膜装置的设计和操作工艺条件的确定提供了简便的计算方法。 相似文献
10.
利用海水汲取液的沼液正渗透浓缩技术 总被引：1，自引：2，他引：1
为实现沼液浓缩以提高其应用价值,该试验以海水作为汲取液,采用正渗透技术对山东某海滨猪场的沼液进行浓缩。试验结果表明,正渗透浓缩倍数为2时的膜通量最高可达到9.5 L/(m2·h);沼液浓缩后的总含盐量、总钾、总磷、总氮、化学需氧量的回收率均可以达到96.7%以上,在保证较高膜通量的条件下沼液体积最高可减小为原液的1/4;对数据拟合分析的结果表明,在沼液浓缩倍数为3时,正渗透膜具有较高的浓缩效率,可达到3.9 L2/(m2·h·g)。综上,采用正渗透技术对沼液进行浓缩的方式是可行的,这不仅缓解了沼液不能及时消纳所造成的资源浪费,而且还可以提高沼液作为肥料的应用价值。 相似文献
11.
Concord grape juice with 20% polymeric and 60% monomeric anthocyanin (Acy) forms was ultrafiltrated using polyvinylidene fluoride flat sheet membranes ranging from 10 to 1000 K molecular weight cutoff (MWCO) to obtain different permeate and retentate fractions. Permeate flux, membrane resistance, Acy rejection, fouling, Acy content and composition, color properties, and antioxidant activity (AOX) were characterized. Results showed that permeate flux declined with lower MWCO, while membrane resistance increased and related exponentially with fouling. Anthocyanin membrane rejection differed for polymeric and monomeric Acy forms. Polymeric Acy increased (36-66%) and monomeric Acy decreased (12-20%) in retentate fractions with membrane pore size of <100K MWCO, while polymeric Acy decreased (11-28%) and monomeric Acy increased (5-7%) in permeate fractions. Fraction properties showed that AOX related linearly with the total phenolic content, while lightness and chroma color properties related linearly to the monomeric Acy content. These results indicate that ultrafiltration can be used to tailor monomeric and polymeric Acy fractions with potential effects in color and bioactive properties. 相似文献
12.
Kulbhushan Samal Kuntal Maiti Kaustubha Mohanty Chandan Das 《Water, air, and soil pollution》2018,229(3):96
The performance of spinning basket membrane (SBM) module was tested for the separation of polyvinyl alcohol (PVA) from wastewater. The SBM performance was examined using 50 kDa polyethersulfone ultrafiltration membrane under different parametric conditions. Also, the effects of rotational speed and transmembrane pressure on permeate flux and PVA rejection were investigated. The rotational speed played a significant role in decreasing membrane fouling by reducing the particle deposition on the membrane surface due to enhanced turbulence and shear force. Also, the in-built hydrodynamic cleaning facility of the SBM module allowed easy cleaning of the membrane. The steady-state value of percentage rejection of PVA was above 90% when the steady-state permeate flux value was above 54% of its initial value. The results suggested that spinning basket membrane module was efficient as well as economical for the separation of PVA from aqueous solution. 相似文献
13.
During ultrafiltration of orange juice with inorganic membranes, heating of the juice prior to the filtration experiment resulted in a significant increase of the fouling indices. The effect of the irreversible fouling (Rif) was always high, whereas the reversible fouling (Rrf) depended on the treatment. It was clearly seen that fouling was reduced after pectin degradation, but the heat treatment applied to the juice before filtration still resulted in reduced fluxes. It is suggested that pectins and proteins that undergo flocculation/coagulation during the heat treatment tend to interact with the membrane-filtering layer and to cause reduction of permeation flux. To clean the membrane to restore its pure water flux, close to the initial one, a proteolitic enzyme detergent wash was needed. 相似文献
14.
Graphene oxide (GO)-based membranes provide an encouraging opportunity for oil-in-water emulsion separation with high separation efficiency. In this work, novel hierarchically structured membrane consisting of GO and halloysite nanotubes (HNTs) was successfully fabricated by vacuum-assisted filtration method. XRD and TEM measurements showed the successful intercalation of HNTs into the interlayers of GO nanosheets. With the incorporation of the one-dimensional hollow tubular structure halloysite nanotubes, GO-HNTs(GOH) membrane possessed combined advantages of high oil rejection rate and excellent fouling resistance properties. The permeate fluxes increased from 286.6 L/(m2·h) for GO membrane to 716 L/(m2·h) for GOH membrane. The results indicate that the GOH membranes have great potential applications in water purification and wastewater treatment. 相似文献
15.
Hubert B Baron A Le Quere JM Renard CM 《Journal of agricultural and food chemistry》2007,55(13):5118-5122
The polyphenol contents and colors of cider apple juices were compared before (NCM, not clarified must) and after five clarification treatments: enzymatic depectinization by pectinases followed by (i) sedimentation (depectinized and decanted juice), (ii) tangential microfiltration (microfiltered juice) or (iii) fining using gelatin (gelatin-treated juice); (iv) enzymatic gelification of pectin by pectin methylesterase followed by natural keeving by a cider manufacturer (producer keeved juice), or (v) flotation (floated with nitrogen gas juice). The pressing of the apples led to the highly selective extraction of the flavan-3-ols with the lowest molecular weights: In the apples, the number average degree of polymerization of the flavanols was 14.7, and it dropped to 2.2 in the NCM. Keeving had the highest impact on the reduction of both flavanol content and number average degree of polymerization. The flavanol concentrations were decreased in the permeate by fining (30%) much more than by depectinization. The clarification step led to a further decrease of the number average degree of polymerization. Hydroxycinnamic acids were less affected by the extraction process (with extraction yields >50%) and not affected by clarification. The color evolved with all treatments: L*, a*, b*, and chromaticity distance index measures indicated a reduction of orange-yellow saturation except after sedimentation. 相似文献
16.
超滤（ultrafiltration，UF）能有效浓缩沼液，但透过液中仍含有大量养分，可进一步采用纳滤（nanofiltration，NF）等精密膜浓缩利用。NF膜的孔径会直接影响膜的截留特性和通量，从而影响浓缩性能。为了探究NF膜孔径对沼液浓缩过程养分富集效果和膜污染行为的影响，该研究以鸡粪沼液的UF透过液为研究对象，分别采用800 D、500 D、100 D的NF膜（平均膜孔径分别为2.0、1.0、0.5 nm）进行浓缩，重点分析养分截留效果和膜污染特征。结果表明：不同孔径的NF膜均能高效截留化学需氧量（chemical oxygen demand，COD）和总磷（total phosphorus，TP），截留率可达68%以上，但对总氮（total nitrogen，TN）和总钾（total potassium，TK）的截留较低，仅为19%～35%。随着膜孔径降低，NF对COD、TN、TP、TK的截留效果略有提高，但整体差异不明显。不同孔径NF膜在沼液浓缩过程均出现了明显的水通量降低。与1.0 nm的NF膜相比，0.5 nm膜较小的孔径和2.0 nm膜较大的初始通量均会导致膜表面有机-无机致密污染层的形成，从而造成水通量快速降低；而1.0 nm膜表面形成的以无机晶体为主的污染层较为疏松，通量下降较为缓慢。综合养分截留效果和水通量变化规律，确定孔径为1.0 nm的NF膜更适用于浓缩沼液的UF透过液，研究结果可为推动沼液膜浓缩的发展与工程应用提供理论与技术支撑。 相似文献
17.
超滤技术对草莓汁中重要芳香成分影响的研究 总被引：6，自引：1，他引：6
选用“宝交早生”草莓为原料研究了超滤技术对草莓汁中重要芳香成分的影响及主要原因。在聚砜（ＰＳ）、磺化聚砜（ＳＰＳ）、聚砜－磺化聚砜共混膜（ＰＳ－ＳＰＳ）三种超滤膜的比较中筛选出适宜草莓汁澄清的ＰＳ膜和ＰＳ－ＳＰＳ共混膜；采用同时蒸馏萃取（ＳＤＥ）法提取、浓缩果汁中芳香成分，作气谱分析，比较超滤前后芳香成分的变化，共混膜对芳香成分的保留率优于ＰＳ单一膜，酸类、醇类芳香成分的保留优于酯类的保留。实验确定了超滤中引起芳香成分损失的三种因素：超滤膜的吸附作用、筛分作用、超滤中循环处理引起的挥发作用。 相似文献
18.
Doherty WO 《Journal of agricultural and food chemistry》2011,59(5):1829-1836
It is accepted that the efficiency of sugar cane clarification is closely linked with sugar juice composition (including suspended or insoluble impurities), the inorganic phosphate content, the liming condition and type, and the interactions between the juice components. These interactions are not well understood, particularly those between calcium, phosphate, and sucrose in sugar cane juice. Studies have been conducted on calcium oxide (CaO)/phosphate/sucrose systems in both synthetic and factory juices to provide further information on the defecation process (i.e., simple liming to effect impurity removal) and to identify an effective clarification process that would result in reduced scaling of sugar factory evaporators, pans, and centrifugals. Results have shown that a two-stage process involving the addition of lime saccharate to a set juice pH followed by the addition of sodium hydroxide to a final juice pH or a similar two-stage process where the order of addition of the alkalis is reversed prior to clarification reduces the impurity loading of the clarified juice compared to that of the clarified juice obtained by the conventional defecation process. The treatment process showed reductions in CaO (27% to 50%) and MgO (up to 20%) in clarified juices with no apparent loss in juice clarity or increase in residence time of the mud particles compared to those in the conventional process. There was also a reduction in the SiO2 content. However, the disadvantage of this process is the significant increase in the Na2O content. 相似文献
19.
Mondor M Ippersiel D Lamarche F Boye JI 《Journal of agricultural and food chemistry》2004,52(23):6991-6996
Soy protein concentrates produced by combining electroacidification and dead-end ultrafiltration with a membrane of 100 kDa (pH 7 and 6) were compared with concentrates produced by ultrafiltration (pH 9) and a traditional acid precipitation procedure at pH 4.5. Mineral removal during ultrafiltration (mainly potassium, phosphorus, and calcium) was enhanced for the pH 6 electroacidified extract, compared to the extract at pH 9. This yielded a concentrate with improved solubility characteristics. The solubility for the concentrate prepared at pH 6 was enhanced by as high as 45% when compared to the concentrate at pH 9. The concentrate produced according to the traditional acid precipitation process showed mineral contents and solubility profile similar to those of the pH 6 concentrate, but required twice as much water during the process. The effect of electroacidification treatments on ultrafiltration permeate flux was quantified through the measurement of the different hydraulic resistances. Cake resistance was the main resistance to the permeate flux, and it was minimum at pH 9, maximum at pH 7, and intermediate at pH 6. 相似文献