富硒蛹虫草中硒多糖的分离与分析

在对人工栽培的富硒蛹虫草中分离提取了水溶性硒多糖,富硒蛹虫草硒多糖的分离纯化方法是采用水提醇沉工艺,粗硒多糖得率为5.76%。系统研究了富硒蛹虫草硒多糖的浸提、纯化、分离条件,苯酚硫酸法测定了富硒蛹虫草的多糖含量为47.5%,分子荧光法测定硒多糖中含硒量为92.3 mg·kg-1。     

大蓟多糖提取分离及含量测定

用水提-醇沉法从大蓟中提取多糖,脱脂、去蛋白,经冷冻干燥后得到粗多糖。通过苯酚-硫酸法测定糖的含量,粗多糖得率为6.5%。再采用DEAE-纤维素离子交换柱层析进一步分离纯化,得到5个次级组分DJ1,DJ2,DJ3,DJ4和DJ5。其中得率最高的是DJ2组分,为8.06‰。     

益母草多糖的抗氧化性

测定益母草多糖含量和研究其多糖的抗氧化性.利用水提醇沉法提取粗多糖,并利用Sevage法脱蛋白对其进行纯化;采用苯酚-硫酸法测定益母草多糖样品中纯多糖的含量并采用邻苯三酚自氧化法和水杨酸法分别研究益母草多糖清除O2-·和·OH的效果.益母草提取所得多糖样品中纯多糖含量达48.5％,益母草多糖具有较强的清除O2-·和·OH的作用.     

香菇多糖L-2A的结构表征

从香菇子实体中提取纯化得到香菇多糖级分L-2A,利用紫外光谱、红外光谱、凝胶渗透色谱和气相色谱分析其结构特征.香菇多糖L-2A糖含量为90.14%;重均分子量是2.03×10 5道尔顿;具有D-葡萄吡喃糖构型,单糖组成主要是由吡喃型葡萄糖组成;香菇多糖L-2A多糖含有o-糖苷键,且主要是o-Ser连接方式;具有与刚果红结合的螺旋结构.香菇多糖L-2A为首次从香菇子实体中分离得到.     

ICP-MS法测定茶叶及其多糖提取物中的降血糖相关性元素

采用微波溶样ICP-MS法测定了江西婺源绿茶茶叶、茶叶温水及热水浸提液和茶多糖中降血糖相关性元素(ERBS)的含量,探讨了ERBS含量与茶叶品质老嫩以及茶多糖中ERBS含量与茶叶中ERBS总量的关系。结果表明,茶叶品质老嫩不同,茶叶以及茶多糖中各ERBS含量存在一定差异,由品质差的茶叶提取得到的茶多糖中的ERBS的量较高。茶叶中结合于多糖中的各ERBS占相应ERBS总量的比例在0.03%～9.57%之间,与元素种类、茶叶品质有关。结合于多糖中的ERBS占茶叶ERBS总量的比例,鄣山特级和五级茶分别为1.11%和2.10%,对孤山老叶茶,为0.85%。测定结果可以作为选择提取茶多糖茶叶原料的依据,也可为研究茶多糖可能的降血糖机理提供可靠的无机元素方面的数据。     

白灵菇多糖的提取及含量的测定

苯酚-硫酸分光光度法测定白灵菇中多糖含量。测定波长485nm,多糖换算因子f=1.59,在5.00—70.00μg/mL范围内吸光度与被测物含量呈良好的线性关系,相关系数r=0.9998,方法的回收率在96.66%—102.33%%之间,相对标准偏差RSD在2.01%—3.10%之间。测定结果表明,白灵菇中含有丰富的多糖。本法简便、准确、重现性好,可作为白灵菇多糖含量的测定方法。     

南瓜生长过程中多糖含量的测定

苯酚-硫酸分光光度法测定了南瓜中多糖含量。测定波长为485nm,多糖换算因子f=2.97,在5.00—70.00μg/mL范围内呈良好的线性关系,相关系数r=0.9998,方法的回收率在96.0%—101.7%之间,相对标准偏差RSD在2.07%—3.12%之间。结果表明,南瓜多糖在南瓜生长40天后几乎不再发生变化。本法简便、准确、重现性行好,可作为南瓜中多糖含量的测定方法。     

黑龙江膜荚黄芪多糖及微量元素Fe、Zn、Cu和Mn的测定

采用水提醇沉法制备黄芪多糖提取物,苯酚-硫酸分光光度法测定多糖的含量,在0.00-0.14mg/mL线性范围内具有良好的线性关系,回收率在94.81%-103.50%.测定黄芪多糖含量为4.3%.采用校准曲线法,用空气-乙炔火焰原子吸收光谱法测定样品中Fe、Zn、Cu和Mn的含量,膜荚黄芪中微量元素含量较高.     

褐蘑菇多糖提取及含量的测定

采用水提醇沉法从褐蘑菇中提取水溶性多糖,通过苯酚-硫酸比色法在490nm波长处测定多糖含量。在5.00—40.00μg/mL范围内,葡萄糖质量浓度与吸光度呈良好线性关系,相关系数r=0.9981,回收率在97.82%—103.09%之间,相对标准偏差RSD为2.24%（n=5）,褐蘑菇多糖含量为3.01%。方法操作简单、显色稳定、准确度高,可作为褐蘑菇多糖工业化生产的常规检测方法。     

分光光度法测定沙棘叶多糖含量

经苯酚-硫酸显色,用分光光度法测定沙棘叶多糖含量。测定波长490nm,葡萄糖含量在10.0—71.0μg/mL范围内与吸光度呈良好的线性关系,r=0.9981,多糖换算因子f为3.271。测得不同月份同一片植株沙棘叶多糖含量分别为:5月份3.39%,7月份3.94%,9月份4.42%,平均回收率为99.07%,RSD为3.22%。     

Ultrasound induced cleaning of polymeric nanofiltration membranes

Cleaning of the flat sheet nanofiltration membranes, using backflushing, chemical cleaning, and ultrasonication operated individually as well as in combination with chemicals, has been studied in the present work. Identical hydrophilic polyamide membranes were fouled individually using an aqueous solution containing a single dye, an aqueous solution containing a mixture of dyes, and a synthetically prepared petroleum refinery effluent. Effect of different parameters such as the concentration of cleaning solution, contact time, frequency, and power of ultrasound on the efficacy of membrane cleaning has been studied. Optimal cleaning was achieved under sonication conditions of frequency of 24 kHz and power dissipation of 135 W. It was demonstrated that application of sonication under optimum conditions without chemical agents, gave about 85% water flux recovery. In the case of combined chemical and ultrasonic treatment, it was clearly observed that the use of chemical agent increased the efficacy of ultrasonic cleaning. The hybrid method recovered the initial water flux to almost 90% based on the use of 1.0 M aqueous NaOH and 4 min of sonication. Overall, the use of aqueous NaOH in combination with sonication showed a better efficiency for cleaning than the individual processes thus demonstrating a new avenue for membrane cleaning.     

Membrane cleaning with ultrasonically driven bubbles

A laboratory filtration plant for drinking water treatment is constructed to study the conditions for purely mechanical in situ cleaning of fouled polymeric membranes by the application of ultrasound. The filtration is done by suction of water with defined constant contamination through a membrane module, a stack of five pairs of flat-sheet ultrafiltration membranes. The short cleaning cycle to remove the cake layer from the membranes includes backwashing, the application of ultrasound and air flushing. A special geometry for sound irradiation of the membranes parallel to their surfaces is chosen. Two frequencies, 35 kHz and 130 kHz, and different driving powers are tested for their cleaning effectiveness. No cleaning is found for 35 kHz, whereas good cleaning results are obtained for 130 kHz, with an optimum cleaning effectiveness at moderate driving powers. Acoustic and optic measurements in space and time as well as analytical considerations and numerical calculations reveal the reasons and confirm the experimental results. The sound field is measured in high resolution and bubble structures are high-speed imaged on their nucleation sites as well as during their cleaning work at the membrane surface. The microscopic inspection of the membrane surface after cleaning shows distinct cleaning types in the cake layer that are related to specific bubble behaviour on the membrane. The membrane integrity and permeate quality are checked on-line by particle counting and turbidity measurement of the permeate. No signs of membrane damage or irreversible membrane degradation in permeability are detected and an excellent water permeate quality is retained.     

Direct contact ultrasound for fouling control and flux enhancement in air-gap membrane distillation

Air Gap Membrane distillation (AGMD) is a thermally driven separation process capable of treating challenging water types, but its low productivity is a major drawback. Membrane fouling is a common problem in many membrane treatment systems, which exacerbates AGMD’s low overall productivity. In this study, we investigated the direct application of low-power ultrasound (8–23 W), as an in-line cleaning and performance boosting technique for AGMD. Two different highly saline feedwaters, namely natural groundwater (3970 μS/cm) and RO reject stream water (12760 μS/cm) were treated using Polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) membranes. Theoretical calculations and experimental investigations are presented, showing that the applied ultrasonic power range only produced acoustic streaming effects that enhanced cleaning and mass transfer. Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy (ATR FT-IR) analysis showed that ultrasound was capable of effectively removing silica and calcium scaling. Ultrasound application on a fouled membrane resulted in a 100% increase in the permeate flux. Cleaning effects accounted for around 30–50% of this increase and the remainder was attributed to mass transfer improvements. Contaminant rejection percentages were consistently high for all treatments (>99%), indicating that ultrasound did not deteriorate the membrane structure. Scanning Electron Microscopy (SEM) analysis of the membrane surface was used to confirm this observation. The images of the membrane surface demonstrated that ultrasound successfully cleaned the previously fouled membrane, with no signs of structural damage. The results of this study highlight the efficient and effective application of direct low power ultrasound for improving AGMD performance.     

Ultrasound-enhanced membrane-cleaning processes applied water treatments: influence of sonic frequency on filtration treatments

Ultrasound (US) cleaning technique was applied to remove fouling of ultrafiltration (UF) and microfiltration (MF) membranes which were used to treat peptone and milk aqueous solutions, respectively. Membrane operations were performed by cross-flow filtration with 60 kPa operating pressure in an US field. The US employed had 28, 45 and 100 kHz frequency with 23 W/cm(2) output power. For each polymeric membrane made of polysulfone UF and cellulose MF, cleaning experiments were carried out with and without US after fouling. The fouled UF and MF membranes showed volume flux decline, but the membrane property was recovered by US irradiation. It was found in 28 kHz frequency that water cleaning was effective for recovery of declined condition due to fouling. Also, US-enhanced permeability of membranes was discussed in both membrane systems. We observed that US decreased the fouling condition in both membrane systems when US was irradiated before fouling. It was found that 28 kHz frequency US could enhance formation of the fouled layer in both filtration systems of peptone and milk solution.     

Study and optimization of the ultrasound-enhanced cleaning of an ultrafiltration ceramic membrane through a combined experimental–statistical approach

Membrane fouling is one of the main drawbacks of ultrafiltration technology during the treatment of dye-containing effluents. Therefore, the optimization of the membrane cleaning procedure is essential to improve the overall efficiency. In this work, a study of the factors affecting the ultrasound-assisted cleaning of an ultrafiltration ceramic membrane fouled by dye particles was carried out. The effect of transmembrane pressure (0.5, 1.5, 2.5 bar), cross-flow velocity (1, 2, 3 m s⁻¹), ultrasound power level (40%, 70%, 100%) and ultrasound frequency mode (37, 80 kHz and mixed wave) on the cleaning efficiency was evaluated. The lowest frequency showed better results, although the best cleaning performance was obtained using the mixed wave mode.A Box–Behnken Design was used to find the optimal conditions for the cleaning procedure through a response surface study. The optimal operating conditions leading to the maximum cleaning efficiency predicted (32.19%) were found to be 1.1 bar, 3 m s⁻¹ and 100% of power level.Finally, the optimized response was compared to the efficiency of a chemical cleaning with NaOH solution, with and without the use of ultrasound. By using NaOH, cleaning efficiency nearly triples, and it improves up to 25% by adding ultrasound.     

The optimisation of ultrasonic cleaning procedures for dairy fouled ultrafiltration membranes

Ultrafiltration (UF) of whey is a major membrane based process in the dairy industry. However, commercialization of this application has been limited by membrane fouling, which has a detrimental influence on the permeation rate. There are a number of different chemical and physical cleaning methods currently used for cleaning a fouled membrane. It has been suggested that the cleaning frequency and the severity of such cleaning procedures control the membrane lifetime. The development of an optimal cleaning strategy should therefore have a direct implication on the process economics. Recently, the use of ultrasound has attracted considerable interest as an alternative approach to the conventional methods. In the present study, we have studied the ultrasonic cleaning of polysulfone ultrafiltration membranes fouled with dairy whey solutions. The effects of a number of cleaning process parameters have been examined in the presence of ultrasound and results compared with the conventional operation. Experiments were conducted using a small single sheet membrane unit that was immersed totally within an ultrasonic bath. Results show that ultrasonic cleaning improves the cleaning efficiency under all experimental conditions. The ultrasonic effect is more significant in the absence of surfactant, but is less influenced by temperature and transmembrane pressure. Our results suggest that the ultrasonic energy acts primarily by increasing the turbulence within the cleaning solution.     

Experimental aspects of ultrasonically enhanced cross-flow membrane filtration of industrial wastewater

Ultrasound based on-line cleaning for membrane filtration of industrial wastewater was studied. An ultrasonic transducer was assembled in the membrane module in order to get an efficient cleaning of membranes in fouling conditions. The focus of the studies was on the effects of the ultrasound propagation direction and frequency as well as the transmembrane pressure. The more open the membrane was the easier the membrane became plugged by wastewater colloids, when the ultrasound propagation direction was from the feed flow side of the membrane. If the membrane was tight enough, the ultrasound irradiated from the feed side of the membrane increased the flux significantly. However, in the circumstances studied, the power intensity needed during filtration was so high that the membranes eroded gradually at some spots of the membrane surface. It was discovered that the ultrasonic field produced by the used transducers was uneven in pressurised conditions. On the other hand, the ultrasound treatment at atmospheric pressure during an intermission pause in filtration turned out to be an efficient and, at the same time, a gentle method in membrane cleaning. The input power of 120 W (power intensity of 1.1 W/cm2) for a few seconds was sufficient for cleaning. The flux improvement was significant when using a frequency of 27 kHz but only minor when using 200 kHz.     

Cleaning efficiency enhancement by ultrasounds for membranes used in dairy industries

Membrane cleaning is a key point for the implementation of membrane technologies in the dairy industry for proteins concentration. In this study, four ultrafiltration (UF) membranes with different molecular weight cut-offs (MWCOs) (5, 15, 30 and 50 kDa) and materials (polyethersulfone and ceramics) were fouled with three different whey model solutions: bovine serum albumin (BSA), BSA plus CaCl₂ and whey protein concentrate solution (Renylat 45). The purpose of the study was to evaluate the effect of ultrasounds (US) on the membrane cleaning efficiency. The influence of ultrasonic frequency and the US application modes (submerging the membrane module inside the US bath or applying US to the cleaning solution) were also evaluated. The experiments were performed in a laboratory plant which included the US equipment and the possibility of using two membrane modules (flat sheet and tubular). The fouling solution that caused the highest fouling degree for all the membranes was Renylat 45. Results demonstrated that membrane cleaning with US was effective and this effectiveness increased at lower frequencies. Although no significant differences were observed between the two different US applications modes tested, slightly higher cleaning efficiencies values placing the membrane module at the bottom of the tank were achieved.     

Role of cleaning methods on bond quality of Ti coated glass/imidex system

Thin film materials are widely used in the fabrication of semiconductor microelectronic devices. In thin film deposition, cleanliness of substrate surface have become critically important as over 50% of yield losses in integrated circuit fabrication are caused by microcontamination [1]. There are many wafer cleaning techniques. The most successful approach for silicon wafer cleaning technique is RCA clean [2]. But for glass substrate it is still not known which procedure of cleaning is the best. This paper provides an understanding of the right way of glass wafer cleaning method, with a focus towards identifying good bond strength. Two wafer cleaning techniques have been used for cleaning glass substrates in the context of laser micro-joining of dissimilar substrates. First cleaning procedure involves two steps, first cleaning in acetone solution and then in DI water solution. After each step dried with N₂. Second cleaning procedure involves four steps, first cleaning with 1% Alconox solution, second in DI water, third in acetone solution and finally in a methanol solution and dried with N₂ after each step. Deposition of Ti thin film on top of these two types of substrate using DC magnetron sputtering method also showed better adhesion of Ti film on glass for the second type of cleaning method. Scanning electron microscopy (SEM) analyses of the lap shear tested failed surfaces for these two kinds of samples revealed strong bond for samples prepared by second cleaning method compared to first cleaning method. Characterization of these two sets of samples using X-ray photoelectron spectroscopy (XPS) has shown excellent contamination removal for the second cleaning method. This modification is believed to be due to reduction of carbon contamination.     

Cleaning results of new and fouled nanofiltration membrane characterized by contact angle, updated DSPM, flux and salts rejection

In membrane process industries, membrane cleaning is one of the most important concerns from both economical and scientific points of view. Though cleaning is important to recover membrane performance, an inappropriate selection of cleaning agents may result into unsatisfactory cleaning or irreparable membrane.In this study the cleaning performance has been studied with measurements of membrane contact angle, Updated Donnan steric partitioning pore model (UDSPM) and salt rejection as well as flux measurement. Thin film nanofiltration (NF) membranes such as DK, HL and DL provided by GE Osmonics are used in this study. Tests were carried out with virgin DK, HL and DL as well as fouled DK membranes. Several cleaning agents were investigated; some of them were analytical grade such as HCl, NaOH and others such as SDS, mix agents were commercial grade agents that are already in use in commercial plants. Contact angle, DSPM and salt rejection as well as flux of virgin and fouled membranes before and after chemical cleaning were measured and compared. The contact angle measurements with and without chemical cleaning of different virgin and fouled membranes revealed very interesting results which may be used to characterise the membrane surface cleanliness. The contact angle results revealed that the cleaning agents are found to modify membrane surface properties (hydrophobicity/hydrophilicity) of the treated and untreated virgin and fouled membranes. The details of these results were also investigated and are reported in the paper. However, UDSPM method did not give any valuable information about pore size of the untreated and treated NF membranes. The salt rejection level of monovalent and divalent ions before and after cleaning by high and low pH cleaning agents is also investigated and is reported in the paper.