Decomposition of hydrogen peroxide driven by photochemical cycling of iron species in clay

The reactivity of iron-bearing clays to catalyze the decomposition of hydrogen peroxide (H2O2) under light irradiation was investigated. Free iron oxides and structural iron in clay octahedral lattice are contained simultaneously in montmorillonite K10 (MK10), a representative natural clay mineral. By pretreatment of clay with the particular method, the reactivities of the two kinds of iron species were differentiated. It was found that free iron oxides on clay surface efficiently catalyzed the decomposition of H202 under UV light irradiation but structural iron in the octahedral lattice showed poor reactivity. This was found to result from the difference in production of Fe(II) species under UV irradiation between iron oxides and structural iron. When photoreactive substances such as N,N-dimethylaniline (DMA), rhodamine B (RhB), or malachite green (MG) were introduced, structural iron was found to promote greatly the decomposition of H202. The reduction of clay iron(II) to iron(II) is essential for the decomposition of H2O2, which is achieved by light-induced ligand to metal charge transfer (for iron oxides) or organic matters donating electrons upon irradiation (for structural iron). The light-induced redox cycling of iron did not lead to the release of iron and decomposition of H202 primarily localized on the clay surface. This work implies that iron-bearing clays could be a sink of H2O2 in the environmental system.     

超声辅助碱性过氧化氢法提取玉米皮纤维素及结构表征

以玉米皮为原料,建立了超声波辅助碱性过氧化氢法提取玉米皮纤维素的方法,在单因素实验基础上,运用响应面法对玉米皮纤维素的提取工艺进行了优化,并利用扫描电镜、傅里叶变换红外光谱仪、X-射线衍射仪、热重和粒度分析仪对玉米皮纤维素进行表征。结果表明,玉米皮纤维素最佳提取工艺条件为:超声温度为70℃、超声时间为70min、超声功率为200W、NaOH质量分数为8%、H2O2体积分数为0.7%、料液比为1:30g/mL,在此条件下纤维素含量为83.34%。表征结果表明,玉米皮纤维素表面呈现纤维素聚集结构;玉米皮纤维素分子结构没有受到破坏,具有纤维素特征吸收峰; 玉米皮纤维素的结晶结构未发生改变,玉米皮纤维素的最大热分解温度为328℃,热稳定性优于玉米皮;玉米皮纤维素粒径减小,平均粒径为111μm。     

Decomposition of hydrogen peroxide and organic compounds in the presence of dissolved iron and ferrihydrite

This work examines the contribution of solution phase reactions, especially those involving a chain reaction mechanism, to the decomposition of hydrogen peroxide (H2O2) and organic compounds in the presence of dissolved iron and ferrihydrite. In solutions at pH 4, where Fe was introduced as dissolved Fe(III), both H2O2 and 14C-labeled formic acid decomposed at measurable rates that agreed reasonably well with those predicted by a kinetic model of the chain reaction mechanism, using published rate constants extrapolated to pH 4. The ratio of the formic acid and H2O2 decomposition rates, as well as the dramatic effect of tert-butyl alcohol on these rates, confirmed that a solution chain reaction mechanism involving *OH controlled the decomposition kinetics of both compounds. In the presence of ferrihydrite as the iron source, the ratio of the rate of formic acid decomposition to that of H2O2 decomposition was significantly lower than that observed in the presence of only dissolved Fe. Moreover, neither rate diminished drastically upon addition of tert-butyl alcohol, indicating that the solution phase chain reaction is not a dominant decomposition pathway of H2O2 and formic acid. Relative decomposition rates of formic acid and a second *OH probe, benzoic acid, were consistent with oxidation of these compounds by *OH. These observations can be reproduced by a kinetic model including (a) decomposition of H2O2 at the iron oxide surface, producing *OH with lower yield than the reaction sequence with dissolved Fe, and (b) low concentrations of dissolved Fe in the presence of ferrihydrite, preventing propagation of the solution phase chain reaction.     

杨木CTMP碱性过氧化氢漂白特性的研究

在机械浆的碱性H2O2漂白过程中,会产生一定量的溶解与胶体物质（Dissolved and Colloidzl Substznces,简称DCS）。本文利用不同的分析手段（阳电荷需求量和UV吸收）研究了杨木CTMP碱性H2O2漂白过程中漂白工艺对DCS溶出及纸页性能的影响。结果表明：N2OH用量的增加以及温度升高能够促进较多DCS溶出。较高NaOH用量下,H2O2用量增加导致DCS中较多氧化木素溶出。一定温度下,延长漂白时间,也能导致较多的DCS溶出。同时,DCS的溶出有利于提高纸页白度和抗张强度。     

双氧水/甲酸预处理羊毛低温染色工艺研究

选用双氧水/甲酸对羊毛进行预处理,达到低温染色的目的.通过甲酸与双氧水协调作用,改变羊毛表层结构,使羊毛染色的温度,由传统的沸染降低到70℃,通过单因素实验、正交试验,优化工艺条件,最后得出最佳预处理工艺为:双氧水体积浓度60 mL/L,甲酸体积浓度70 mL/L,60℃水浴中保温40 min,浴比1∶100,预处理试样在70℃下染色上染百分率达到96.52％.     

The effects of alkaline hydrogen peroxide treatment on the nutritional value of tripe

Samples of tripe obtained after commercial processing with alkaline hydrogen peroxide were compared with raw tripe for nutritional quality. A large number (108) of commercial tripe samples were found to vary markedly in their protein content from 8·4 to 19·3%. The moisture content was negatively correlated with the pH of the tripe samples. However, the amino acid analyses and rat bioassays indicated that the nutritional value of the protein was not significantly decreased by the processing. Oxidation of sulphur amino acids and formation of lysino-alanine were not evident. Thiamine was completely destroyed by the processing.     

Effects of treating wheat straw with pH-regulated solutions of alkaline hydrogen peroxide on nutrient digestion by sheep

An experiment using a 4 X 4 Latin square design was to determine effects of treating wheat straw with pH-regulated (pH = 11.5) solutions of hydrogen peroxide on site and extent of nutrient digestion in multiple-fistulated sheep. Regulating reaction pH at 11.5 prevented solubilization of some cell wall hemicelluloses, resulting in improved retention of DM. Diets fed to sheep contained 33 or 70% wheat straw either untreated or treated with alkaline hydrogen peroxide. Sheep fed diets of treated wheat straw digested more DM, NDF, ADF, and cellulose anterior to the duodenum and in the total tract than when fed diets of untreated wheat straw. Apparent CP digestion before the duodenum was highest when sheep were fed the treated 33% wheat straw diet and untreated 70% wheat straw diet. Treatments did not affect apparent nutrient digestibilities in the large intestine. Ruminal pH was lower when sheep were fed the alkaline hydrogen peroxide-treated or diets containing 33% wheat straw. Ruminal ammonia concentrations were highest when sheep were fed the untreated 70% wheat straw diet. Molar proportions of ruminal acetic and propionic acids were unaffected by diet. Alkaline hydrogen peroxide treatment substantially increased susceptibility of structural carbohydrates of wheat straw to microbial degradation in the gastrointestinal tract of sheep.     

离子液体体系中过氧化氢氧化油酸合成壬二酸

以离子液体BMIMPF6为溶剂,采用钨酸为催化剂,50％的H2O2氧化油酸合成了高纯度壬二酸。通过考察催化剂用量、溶剂类型、环氧化产物碘值、离子液体循环使用次数、氧化裂解反应时间等因素对目标产物壬二酸收率及品质的影响,得出合成壬二酸的最佳条件为：60℃下,原料油酸、过氧化氢、钨酸、离子液体以1．0：3．0：0．04：1．24（摩尔比）混合反应1h后,用25％的过氧乙酸在90℃继续氧化裂解3h,可得产品壬二酸,收率为39％。产品通过FT-IR及GC-MS等手段进行了表征,纯度高达99％。环氧化产物与离子液体BMIMPF6易于分离,分离后的离子液体10次以内可以重复使用,其结构及性能基本保持不变。     

麦草生物化机浆过氧乙酸与过氧化氢漂白

研究了麦草生物化机浆CH3COOOH漂白条件以及CH3COOOH与H2O2的组合漂白.结果表明:麦草生物化机浆过氧乙酸适宜漂白条件为:3%CH3COOOH、90min、50℃、pH5.经PaP3P3a和PaP5P5a漂白,麦草生物化机浆的白度分别可达61.9%和72.1%(IS0).     

甲酸-双氧水在羊毛生物酶防毡缩整理中的应用

以生物酶进行羊毛防毡缩处理前大多要进行预处理．羊毛不耐碱，经氧化预处理易造成纤维损伤，选用甲酸为助剂进行羊毛双氧水预处理，工艺条件温和，可减少羊毛纤维的损伤，并增强防毡缩效果，还能实现低温染色，降低能耗．     

Differential effects of hydrogen peroxide and ascorbic acid on the aerobic thermosensitivity of yeast cells grown under aerobic and anoxic conditions

We have previously demonstrated that in aerobically‐grown cells of the yeast Saccharomyces cerevisiae, hydrogen peroxide (H₂O₂) increases and ascorbic acid decreases cellular thermosensitivity, as determined by the inducibility of a heat shock (HS)‐reporter gene. In this work, we reveal that the aerobic thermosensitivity of anaerobically‐grown yeast cells also increases in the presence of H₂O₂, albeit differentially between cells with two different lipid profiles. In comparison to aerobically‐grown fermenting cells treated with the same H₂O₂ concentration, both these types of anaerobically‐grown cells were found to be considerably less sensitive to aerobic heat shock and considerably more thermotolerant. Paradoxically, and in contrast to ascorbate‐pretreated aerobically‐grown yeast cells, when anaerobically‐grown cells were heat‐shocked aerobically in the presence of the same ascorbic acid concentration, they exhibited increased thermosensitivity and decreased intrinsic thermotolerance with respect to their untreated counterparts. These findings are discussed with respect to what is currently known about the redox and physiological status of yeast cells grown aerobically and cells reoxygenated following anoxic growth. Copyright © 2009 John Wiley & Sons, Ltd.     

新疆杨AHP法与KP法制浆性能对比研究

研究了沙生乔木新疆杨的化学成分及纤维形态参数,以最高温度、用碱量、蒸煮时间及过氧化氢用量为蒸煮参数,在保持升温时间和液比不变的情况下进行L.(34)碱性过氧化氢法(AHP法)蒸煮正交试验,初步分析了新疆杨的制浆性能.结果表明新疆杨原料成浆性能良好,碱性过氧化氢法原浆白度较高.在相同的打浆度和定量下,AHP法浆的浆张裂断长、耐破度和撕裂度等与KP法浆相当.     

亚麻织物的过氧化氢和过醋酸漂白

通过正交试验，优选出亚麻织物的过醋酸漂白工艺条件，并与过氧化氢的漂白效果进行对比，探讨采用过醋酸一过醋酸或过氧化氢，过醋酸工艺，对白度要求较高的亚麻产品进行复漂。     

碱法提取麸皮中阿魏酸的工艺条件研究

以小麦麸皮为原料,利用α-淀粉酶和碱性蛋白酶去除麸皮中的淀粉和蛋白质,用氢氧化钠溶液水解小麦麸皮制备阿魏酸,以阿魏酸提取量为指标通过正交实验确定最佳工艺条件。结果表明:去除50 g麦麸中的淀粉和蛋白质时,α-淀粉酶的最佳用量为3 mL,碱性蛋白酶的最佳用量为0.3 g;碱解麸皮制备阿魏酸的最佳工艺条件为:氢氧化钠质量分数为1%,料液比为1:15,碱解时间2 h,碱解温度80℃。在此条件下,阿魏酸的最佳提取量为2.47 mg/g。     

Degradation of anthocyanins in sour cherry and pomegranate juices by hydrogen peroxide in the presence of added ascorbic acid

Effects of hydrogen peroxide in the presence of ascorbic acid on the degradation of sour cherry and pomegranate juice anthocyanins were studied at three H₂O₂ concentrations (4.65, 6.98 and 9.31 mmol l⁻¹) and two ascorbic acid concentrations (60 and 80 mg l⁻¹) at 20 °C. Degradation of anthocyanins by H₂O₂ was fitted to first-order reaction kinetics in sour cherry and pomegranate juices. A similar degradation pattern was found at the 60 and 80 mg ascorbic acid levels for pomegranate juice. Degradation of sour cherry anthocyanins at the 60 mg ascorbic acid level was fitted to a second-order reaction kinetic, whereas it was a first-order reaction kinetic after a lag period occurred at the 80 mg level. Ascorbic acid, at 80 mg l⁻¹, markedly accelerated the degradation of anthocyanins in sour cherry juice at all the H₂O₂ concentrations studied. In contrast, ascorbic acid, at both 60 and 80 mg l⁻¹, protected the anthocyanins from the degradation by H₂O₂ in pomegranate juice.     

Inactivation of Escherichia coli O157:H7, Salmonella enterica serotype enteritidis,and Listeria monocytogenes on lettuce by hydrogen peroxide and lactic acid and by hydrogen peroxide with mild heat

Iceberg lettuce is a major component in vegetable salad and has been associated with many outbreaks of foodborne illnesses. In this study, several combinations of lactic acid and hydrogen peroxide were tested to obtain effective antibacterial activity without adverse effects on sensory characteristics. A five-strain mixture of Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis, and Listeria monocytogenes was inoculated separately onto fresh-cut lettuce leaves, which were later treated with 1.5% lactic acid plus 1.5% hydrogen peroxide (H2O2) at 40 degrees C for 15 min, 1.5% lactic acid plus 2% H2O2 at 22 degrees C for 5 min, and 2% H2O2 at 50 degrees C for 60 or 90 s. Control lettuce leaves were treated with deionized water under the same conditions. A 4-log reduction was obtained for lettuce treated with the combinations of lactic acid and H2O2 for E. coli O157:H7 and Salmonella Enteritidis, and a 3-log reduction was obtained for L. monocytogenes. However, the sensory characteristics of lettuce were compromised by these treatments. The treatment of lettuce leaves with 2% H2O2 at 50 degrees C was effective not only in reducing pathogenic bacteria but also in maintaining good sensory quality for up to 15 days. A < or = 4-log reduction of E. coli O157:H7 and Salmonella Enteritidis was achieved with the 2% H2O2 treatment, whereas a 3-log reduction of L. monocytogenes was obtained. There was no significant difference (P > 0.05) between pathogen population reductions obtained with 2% H2O2 with 60- and 90-s exposure times. Hydrogen peroxide residue was undetectable (the minimum level of sensitivity was 2 ppm) on lettuce surfaces after the treated lettuce was rinsed with cold water and centrifuged with a salad spinner. Hence, the treatment of lettuce with 2% H2O2 at 50 degrees C for 60 s is effective in initially reducing substantial populations of foodborne pathogens and maintaining high product quality.     

快速电化学法检测牛乳中的过氧化氢

目的 建立一种快速电化学法检测牛乳中的过氧化氢(H2O2)。方法 设计简单的三电极电化学反应池,制备普鲁士蓝(PB)修饰的石墨粉电极, 研究制得电极对H2O2的电化学响应, 用于牛乳中H2O2的快速电化学检测。结果 在?0.1 V处, 对0.2~1.4 mmol/L的H2O2具有线性响应。该电化学方法用于实际牛乳样品中H2O2的检测, 检测的回收率在91%~106%之间。结论 该H2O2电化学检测方法简单、快速、灵敏、价格低廉。