电解漂白

最近,美国缅因大学发表了一分电解漂白的报告,指出,电解漂白除了能提高纸浆质量外,还可以减少漂白药品的运输和貯存,减少漂白段数,缩小设备尺寸,而且从电解液回用的研究来看,废液为害问題将大大降低。 虽然,这实验是在实验室的流动电解池里进行的,但是他们认为,如果电解池有适     

靛蓝的电化学还原及其染色工艺的探讨

以贵金属氧化涂层的网状钛电极为阳极(在阳极电解池中加入35 g/L H2SO4作为电解质),Cu为阴极{在阴极电解池中加入六水硫酸铁[Fe2(SO4)3·6H2O]、三乙醇胺(TEA)、NaOH作为还原染液},饱和甘汞电极为参比电极组成电解装置进行靛蓝染料(4 g/L,放在阴极电解池中)的电化学还原染色,最佳还原染色工艺为:还原[TEA 30 g/L,Fe2(SO4)3·6H2O 5 g/L,NaOH 15 g/L,外加电压5 V,阴极面积20 cm2,35℃]→染色(35℃,70 min,浴比1:100)→在空气中自然氧化(20 min)→冷水洗→皂洗(90℃,15 min)→水洗→烘干.该工艺条件下染色织物的(⊿)K/S值为0.066,说明靛蓝电化学还原染色工艺的染色织物匀染性良好.     

什么叫库仑分析法?

在电解过程中,在电极上起反应的物质的量与通过电解池的电量成正比。在适当的条件下,测量通过电解池的电量（即库仑数）,可以求得在电极上起了反应的物质的量。利用这个原理建立起来的分析方法,称为库仑分析法。     

还原橄榄绿B的电化学还原及其染色工艺的探讨

以贵金属氧化涂层网状钛电极为阳极(在阳极电解池中加入35 g/L H2SO4作为电解质),Cu为阴极{在阴极电解池中加入六水硫酸铁[Fe2(SO4)3·6H2O]、三乙醇胺(TEA)、NaOH作为还原染液},Ag/AgCl电极为参比电极组成的电解装置中进行还原橄榄绿B染料的电化学还原染色.结果表明:在还原橄榄绿B 0.2 g/L,Fe2(SO4)3·6H2O 5 g/L,TEA 35 g/L,NaOH 13 g/L,外加电压5 V,阴极面积25cm2,40℃还原染色70 min,可以获得较好的染色效果.     

Fe3+-草酸-葡萄糖酸盐媒质的电化学还原染色工艺的研究

在以石墨电极为阴阳电极[阳极电解池中加入15 g/L H2SO4作为电解液,阴极电解池中加入Fe2(SO4)3、NaOH、C2H2O4、Ca(C6H11O7)2作为还原染液]电解装置中,进行还原大红R的电化学还原染色.结果表明:还原大红R为4g/L,Fe2(SO4)3为8g/L,NaOH为50 g/L,C2H2O4为12.6 g/L,Ca(C6H11O7)2为24.4 g/L,工作电压为4 V,还原时间为10 min,阴极面积为40 cm2时,具有良好的染色效果.     

三维电极系统降解靛蓝废水的工艺探究

为探究三维电极对电化学降解靛蓝废水的影响,在电解池中加入活性炭组成三维电极系统。比较二维电极法和三维电极法的靛蓝废水降解效率,二维电极法的脱色率为96.71%,三维电极法的脱色率98.01%。通过正交实验进一步分析NaCl质量浓度、活性炭用量、电解时间、电压对废水吸光度、COD、可生化性(BOD/COD,简写为B/C)的影响。在优选工艺条件下处理靛蓝废水,对废水吸光度、COD、B/C等3项指标进行灰色聚类分析,获得优化工艺为:电压5 V,NaCl 10 g/L,活性炭1.2 g/L,电解60 min,此时废水脱色率达到95.84%,COD去除率达到87.5%,B/C为1.57,可生化性好。     

还原大红R的电化学还原及其染色工艺的探讨

以贵金属氧化涂层网状钛电极为阳极(在阳极电解池中加入35 g/L H2SO4作为电解质);Cu为阴极{在阴极电解池中加入六水硫酸铁(Fe2(SO4)3·6H2O]、三乙醇胺(TEA)、NaOH作为还原染液};Ag/AgCI电极为参比电极组成电解装置进行还原大红R染料(0.2 g/L)的电化学还原染色.最佳还原染色工艺为:还原[Fe2(SO4)3·6H2O 5 g/L,TEA 30 g/L,NaOH 13 g/L,外加电压5 V,阴极面积30 cm2,40 ℃]一染色(40 ℃,70min.浴比1:100)→在空气中自然氧化(15 min)→冷水洗→皂洗(90℃,15 min)→水洗→烘干.该工艺条件下染色织物的ΔK/S值为0.059.说明还原大红R电化学还原染色工艺的染色织物匀染性良好.     

对称电极La_(0.75)Sr_(0.25)Cr_(1-x)Fe_(x)O_(3)-δ的电化学性能研究

文章用燃烧法制备了固体氧化物燃料电池的电极材料La_(0.75)Sr_(0.25)Cr_(1-x)Fe_(x)O_(3)-δ(x=0.4,0.5,0.6),测试La_(0.75)Sr_(0.25)Cr_(1-x)Fe_(x)O_(3)-δ的热膨胀曲线,并与固体氧化物燃料电池的电解质材料氧化钇稳定的氧化锆(YSZ)的热膨胀曲线进行对比,测试结果显示二者热膨胀系数非常接近,二者热匹配性能很好。阴极和阳极材料均采用La_(0.75)Sr_(0.25)Cr_(1-x)Fe_(x)O_(3)-δ材料,电解质用离子导电性能优越的YSZ材料,分别制备六组电解质支撑的对称电池,分别测试所制备的单电池的功率特性曲线和伏安特性曲线,结果显示,当x=0.4时并且电极材料烧结温度为1 300℃的一组电池的功率密度最大,单电池运行温度是900℃时为318 mW/cm^(2)。     

糖汁石灰澄清法联用电化学辅助过氧化氢氧化脱色工艺

以赤砂糖回溶糖浆为研究对象,利用石灰法澄清除杂后进行电化学辅助氧化脱色处理,以脱色率差值为指标,考察了电解电流强度、过氧化氢用量、电解初始p H、电解温度、电解时间5个因素对赤砂糖回溶糖浆氧化脱色的影响规律。在电解电流强度为90.0 m A、过氧化氢用量为0.9%(v/v)、电解初始p H为7.60、电解温度为30.0℃、电解时间为2.0 h的条件下;脱色率可到达44.8%,比上清汁外加过氧化氢氧化脱色率高出8.7%。结果表明,石灰法澄清联用电化学辅助氧化脱色工艺具有可行性。     

直接染料的电化学染色探讨

电化学技术的应用为柒整行业的发展提供了新的思路。本实验对棉织物进行直接染料电化学染色进行初步研究，并与传统染色进行参比对照。比较了电化学上染速率曲线和传统上染速率曲线、染色色牢度。结果表明：电化学染色上染百分率开始较传统的低，但最终的上染百分率较传统的高；电化学染色匀染性较传统的好，且两者具有同样好的色牢度。这些都说明电化学染色效果优于传统的染色效果，同时电化学染色技术可降低成本，节约能源，减少污染，是今后的发展方向之一。     

原糖溶液电解脱色的研究

阐述了原糖溶液电解脱色过程的机理,并对电解原糖浆脱色进行了实验研究,考察电解时间、电流密度、温度、锤度等因素对原糖浆脱色的影响。结果表明,电解对原糖溶液具有显著的脱色效果,对40築x的原糖溶液脱色率可以达到90%以上。     

电解法处理高浓度印染废水

采用自制试验装置，用电解法处理高浓度印染废水。通过正交试验，讨论了电压、pH值、处理时间、NaCl投加量对处理效果的影响；依据试验结果分析了电解法处理印染废水的机理。在最佳工艺条件下，即在电压25V、pH值8．0、NaCl投加量0．3g／L、循环8次、时间104min时，COD系统去除率可达90．40％，色度去除率可达100％。     

Electrodialytic Phenomena and Their Applications in the Dairy Industry: A Review

Electrodialysis (ED) is an electrochemical separation process by which electrically-charged species are transported from one solution to another. ED is a combined method of dialysis and electrolysis and can be performed with two main cell types: multi-membrane cells for dilution-concentration and water dissociation applications (membrane phenomena), and electrolysis cells for redox reactions (electrode phenomena). The dilution-concentration principle applications in the dairy industry consist mainly of the demineralization of milk or milk by-products. The use of ED with monopolar membrane for protein separation and acid caseinate production, and in bioreactors for organic acid production, is also studied in the dairy industry. The interest of ED as a membrane process has been triggered recently by the development of a new membrane type, bipolar membrane. This membrane carries out the dissociation of water molecules. ED with bipolar membranes was applied very recently to the production of lactic acid from whey product fermentation, production of caseinates, and fractionation of whey proteins. Two principle applications of electrode reactions were published: electrochemical coagulation (EC) to precipitate milk proteins, and electroreduction for the reduction of disulfide bonds in the proteins. It appears in this article that processes using membrane phenomena are more numerous and developed than electrolytic applications. This is the composition of milk and the lack of knowledge of redox reactions of the different food compounds that limit the applications and the development of electrolytic phenomena. Electrodialytic phenomena present a great potential for application in the dairy industry, and more generally, in the food industry; many of these applications have to be discovered.     

Electrodialytic phenomena and their applications in the dairy industry: a review

Electrodialysis (ED) is an electrochemical separation process by which electrically-charged species are transportedfrom one solution to another ED is a combined method of dialysis and electrolysis and can be performed with two main cell types: multi-membrane cells for dilution-concentration and water dissociation applications (membrane phenomena), and electrolysis cells for redox reactions (electrode phenomena). The dilution-concentration principle applications in the dairy industry consist mainly of the demineralization of milk or milk by-products. The use of ED with monopolar membrane for protein separation and acid caseinate production, and in bioreactors for organic acid production, is also studied in the dairy industry. The interest of ED as a membrane process has been triggered recently by the development of a new membrane type, bipolar membrane. This membrane carries out the dissociation of water molecules. ED with bipolar membranes was applied very recently to the production of lactic acid from whey product fermentation, production of caseinates, and fractionation of whey proteins. Two principle applications of electrode reactions were published: electrochemical coagulation (EC) to precipitate milk proteins, and electroreduction for the reduction of disulfide bonds in the proteins. It appears in this article that processes using membrane phenomena are more numerous and developed than electrolytic applications. This is the composition of milk and the lack of knowledge of redox reactions of the different food compounds that limit the applications and the development of electrolytic phenomena. Electrodialytic phenomena present a great potential for application in the dairy industry, and more generally, in the food industry; many of these applications have to be discovered.     

BULK MECHANICAL BEHAVIOR OF COMMERCIAL PARTICLE FOOD FOAMS

The texture of 10 commercial cereal foam products, of different composition and shape, has been evaluated through the measurement of its bulk mechanical properties using a Kramer shear cell. Force–displacement curves led to repeatable measurements, characterized by low standard deviations. Discrimination among samples and relevant mechanical variables were determined by the PCA of these curves. Most of the variability in the force–displacement curves (97%) and mechanical variables (93%) were contained in the two PC1s, and the mechanical behavior of this large variety of cereal foams texture could be explained by two variables: the energy needed for crushing (area under the force–displacement curve) and the slope ratio of the curve. These variables were then respectively related to bulk density, which increased with sugar content, and to the shape factor, evaluated through geometric approximation.

PRACTICAL APPLICATIONS

The contribution of this work to the characterization of cereal foam product texture is first, to extend the validation of the Kramer shear cell for assessing the bulk behavior of real products of irregular shape. Low standard deviation and product differentiation among 10 commercial samples shows that this method is reliable enough for quality control of cereal particle foams. Then, by its ability to determine the two most relevant variables from the texture profiles, it allows a deeper look on the relationships between mechanical properties and multi-scale structure, as shown by the relation with apparent bulk density and particle shape, and the role of sugar content. Finally, the relation with former works on cornflakes also suggests the use of these variables for assessing sample crispness.     

Differential potentiometric titration: development of a methodology for determining the point of zero charge of metal (hydr)oxides by one titration curve

A new methodology is presented, called differential potentiometric titration (DPT), which allows the determination of the point of zero charge (pzc) of metal (hydr)oxides using only one potentiometric curve. By performing extensive simulations of potentiometric titrations for various model (hydr)oxides, we found that an inflection point in a H+(cons,surf) versus pH potentiometric curve (H+(cons,surf): hydrogen ions consumed on the surface of the (hydr)oxide) and a peak in the corresponding differential curve, dH+(cons,surf)/dpH versus pH, appear at a pH equal to the pzc assumed for a model (hydr)oxide. This distinguishable peak appears at the same position irrespective of the surface ionization and the interfacial model adopted as well as the assumed ionic strength. It was found that the aforementioned peak also appears in the high-resolution differential potentiometric curves experimentally determined for four oxides (SiO2, TiO2, gamma-Al2O3, and MgO) that are widely used in various environmental and other technological applications. The application of DPT to the above-mentioned oxides provided practically the same pzc values as the corresponding ones achieved by using four different techniques as well as the corresponding isoelectric point (iep) values determined by microelectrophoresis. Differences between the pzc and iep values determined using various techniques in the case of MgO were attributed to the increasing dissolution of this oxide as pH decreases and the adsorption of cations (Mg2+, Na+) on the MgO/electrolytic solution interface.     

Electrical power from sea and river water by reverse electrodialysis: a first step from the laboratory to a real power plant

Electricity can be produced directly with reverse electrodialysis (RED) from the reversible mixing of two solutions of different salinity, for example, sea and river water. The literature published so far on RED was based on experiments with relatively small stacks with cell dimensions less than 10 × 10 cm(2). For the implementation of the RED technique, it is necessary to know the challenges associated with a larger system. In the present study we show the performance of a scaled-up RED stack, equipped with 50 cells, each measuring 25 × 75 cm(2). A single cell consists of an AEM (anion exchange membrane) and a CEM (cation exchange membrane) and therefore, the total active membrane area in the stack is 18.75 m(2). This is the largest dimension of a reverse electrodialysis stack published so far. By comparing the performance of this stack with a small stack (10 × 10 cm(2), 50 cells) it was found that the key performance parameter to maximal power density is the hydrodynamic design of the stack. The power densities of the different stacks depend on the residence time of the fluids in the stack. For the large stack this was negatively affected by the increased hydrodynamic losses due to the longer flow path. It was also found that the large stack generated more power when the sea and river water were flowing in co-current operation. Co-current flow has other advantages, the local pressure differences between sea and river water compartments are low, hence preventing leakage around the internal manifolds and through pinholes in the membranes. Low pressure differences also enable the use of very thin membranes (with low electrical resistance) as well as very open spacers (with low hydrodynamic losses) in the future. Moreover, we showed that the use of segmented electrodes increase the power output by 11%.     

Rate and extent of aqueous perchlorate removal by iron surfaces

The rate and extent of perchlorate reduction on several types of iron metal was studied in batch and column reactors. Mass balances performed on the batch experiments indicate that perchlorate is initially sorbed to the iron surface, followed by a reduction to chloride. Perchlorate removal was proportional to the iron dosage in the batch reactors, with up to 66% removal in 336 h in the highest dosage system (1.25 g mL(-1)). Surface-normalized reaction rates among three commercial sources of iron filings were similar for acid-washed samples. The most significant perchlorate removal occurred in solutions with slightly acidic or near-neutral initial pH values. Surface mediation of the reaction is supported by the absence of reduction in batch experiments with soluble Fe2+ and also by the similarity in specific reaction rate constants (kSA) determined for three different iron types. Elevated soluble chloride concentrations significantly inhibited perchlorate reduction, and lower removal rates were observed for iron samples with higher amounts of background chloride contamination. Perchlorate reduction was not observed on electrolytic sources of iron or on a mixed-phase oxide (Fe3O4), suggesting that the reactive iron phase is neither pure zerovalent iron nor the mixed oxide alone. A mixed valence iron hydr(oxide) coating or a sorbed Fe2+ surface complex represent the most likely sites for the reaction. The observed reaction rates are too slow for immediate use in remediation system design, but the findings may provide a basis for future development of cost-effective abiotic perchlorate removal techniques.     

Comparison of the Availability of Various Iron Fortificants in Bread and Milk Using an In Vitro Digestion/Caco-2 Cell Culture Method

ABSTRACT: The availabilities and dialyzabilities of various iron fortificants in bread and milk were compared using an in vitro digestion/Caco-2 cell culture model. In white bread, availability and dialyzability of electrolytic iron were lower than that of ferrous fumarate, Ferrochel®, and FeSO₄. NaFe(III)EDTA was also lower in availability than ferrous fumarate, Ferrochel®, and FeSO₄ but had the highest dialyzability. In 2% fat milk, NaFe(III)EDTA was again the highest in dialyzability but was similar in availability to ferrous fumarate, encapsulated ferrous fumarate, Ferrochel®, and FeSO₄. The results suggest that iron from NaFe(III)EDTA and electrolytic iron does not completely exchange with intrinsic iron in foods.     

Adjusting the weaning age of calves fed by automated feeders according to individual intakes of solid feed

When weaned at the ages typical of commercial dairy production, dairy calves usually show reduced growth rates, lowered energy intake, and increased behavioral signs of hunger, reflecting their difficulty in switching from a milk diet to solid feed. However, large differences exist between calves in their ability to adapt to solid feed, and automated feeders allow the age of weaning to be adjusted to an individual calf's intake of solid feed. We examined the effects of weaning according to solid feed intake on age at weaning, feed intake, and behavioral signs of hunger. In a 2×2 factorial design, 60 female Holstein calves in groups of 8 and fed milk, grain starter, and hay from automated feeders began to be weaned when their voluntary intake of grain starter was either 400g/d (high start) or 200g/d (low start), with weaning completed when their voluntary intakes of starter were either 1,600g/d (high end) or 800g/d (low end). Digestible energy intakes were calculated from milk, starter and hay intakes, corrected for body weights, calves were weighed, and the frequency of visits to the milk feeders were measured each day. The main effects and interactions between treatments were tested with ANOVA. Large differences were observed between calves in the age at which weaning was complete, with weaning completed earlier for low-end calves compared with high-end calves. No treatment effects (either of start amount or end amount) on intakes of milk, starter, or hay or on weight gains occurred. However, the calves that began weaning earlier had longer durations of weaning, greater growth rates from d 20 to 87, and were heavier on d 87, and had lower milk intakes, higher starter intakes, higher hay intakes, and a greater digestible energy intake, but showed more unrewarded visits to the milk feeder. Adjusting the age at which individual calves are weaned off milk according to their ability to eat solid feed can reduce the age at which weaning occurs while reducing the negative effects of weaning on energy intake and weight gain, although the increased visits to the milk feeder during weaning suggest that calves remain motivated to drink milk.