Sporicidal action of ozone and hydrogen peroxide: a comparative study.

Elimination of contaminating spores on packaging materials and food-contact surfaces remains a challenge to the food industry. Hydrogen peroxide and chlorine are the most commonly used sanitizers to eliminate these contaminants, and ozone was recommended recently as an alternative. Hence, we compared the sporicidal action of ozone and hydrogen peroxide against selected foodborne spores of Bacillus spp. Under identical treatment conditions, 11 microg/ml aqueous ozone decreased spore counts by 1.3 to 6.1 log10 cfu/ml depending upon the bacterial species tested. Hydrogen peroxide (10%, w/w), produced only 0.32 to 1.6 log10 cfu/ml reductions in spore counts. Thus, hydrogen peroxide, at approximately 10,000-fold higher concentration, was less effective than ozone against Bacillus spores. Resistance of spores to ozone was highest for Bacillus stearothermophilus and lowest for B. cereus. Therefore, spores of B. stearothermophilus are suitable for testing the efficacy of sanitization by ozone. Electron microscopic study of ozone-treated B. subtilis spores suggests the outer spore coat layers as a probable site of action of ozone.     

Kinetic mechanism for predicting secondary organic aerosol formation from the reaction of d-limonene with ozone

A semi-explicit mechanism of d-limonene was developed and tested against experimental results obtained from large outdoor Teflon film chambers at the University of North Carolina (UNC) smog chamber facility. The model couples gas-phase reactions with partitioning processes and possible particle-phase reactions. The model not only tracks the gas-phase ozonolysis reaction of d-limonene, but also provides a reasonable prediction of the secondary aerosol mass production under different conditions. Limononaldehyde was the major identified product, followed by limona-ketone, referred to here as keto-limonene, keto-limononaldehyde, limononic acid, and keto-limononic acid. Identified particle-phase products accounted for about 60% of the observed particle mass in the initial stages of the reaction. Model sensitivity was tested and discussed with respect to effects of temperature, humidity, water uptake, and reactant concentrations.     

Degradation of ozone-refractory organic phosphates in wastewater by ozone and ozone/hydrogen peroxide (peroxone): the role of ozone consumption by dissolved organic matter

Ozonation is very effective in eliminating micropollutants that react fast with ozone (k > 10(3) M(-1) s(-1)), but there are also ozone-refractory (k < 10 M(-1) s(-1)) micropollutants such as X-ray contrast media, organic phosphates, and others. Yet, they are degraded upon ozonation to some extent, and this is due to (?)OH radicals generated in the reaction of ozone with organic matter in wastewater (DOM, determined as DOC). The elimination of tri-n-butyl phosphate (TnBP) and tris-2-chloroisopropyl phosphate (TCPP), added to wastewater in trace amounts, was studied as a function of the ozone dose and found to follow first-order kinetics. TnBP and TCPP concentrations are halved at ozone to DOC ratios of ～0.25 and ～1.0, respectively. The (?)OH rate constant of TCPP was estimated at (7 ± 2) × 10(8) M(-1) s(-1) by pulse radiolysis. Addition of 1 mg H(2)O(2)/L for increasing the (?)OH yield had very little effect. This is due to the low rate of reaction of H(2)O(2) with ozone at wastewater conditions (pH 8) that competes unfavorably with the reaction of ozone with wastewater DOC. Simulations based on the reported (No?the et al., ES&T 2009, 43, 5990-5995) (?)OH yield (13%) and (?)OH scavenger capacity of wastewater (3.2 × 10(4) (mgC/L)(-1) s(-1)) confirm the experimental data. Based on a typically applied molar ratio of ozone and H(2)O(2) of 2, the contribution of H(2)O(2) addition on the (?)OH yield is shown to become important only at high ozone doses.     

Elimination of Listeria monocytogenes biofilms by ozone, chlorine, and hydrogen peroxide

This study evaluated the efficacy of ozone, chlorine, and hydrogen peroxide to destroy Listeria monocytogenes planktonic cells and biofilms of two test strains, Scott A and 10403S. L. monocytogenes was sensitive to ozone (O3), chlorine, and hydrogen peroxide (H2O2). Planktonic cells of strain Scott A were completely destroyed by exposure to 0.25 ppm O3 (8.29-log reduction, CFU per milliliter). Ozone's destruction of Scott A increased when the concentration was increased, with complete elimination at 4.00 ppm O3 (8.07-log reduction, CFU per chip). A 16-fold increase in sanitizer concentration was required to destroy biofilm cells of L. monocytogenes versus planktonic cells of strain Scott A. Strain 10403S required an ozone concentration of 1.00 ppm to eliminate planktonic cells (8.16-log reduction, CFU per milliliter). Attached cells of the same strain were eliminated at a concentration of 4.00 ppm O3 (7.47-log reduction, CFU per chip). At 100 ppm chlorine at 20 degrees C, the number of planktonic cells of L. monocytogenes 10403S was reduced by 5.77 log CFU/ml after 5 min of exposure and by 6.49 log CFU/ml after 10 min of exposure. Biofilm cells were reduced by 5.79 log CFU per chip following exposure to 100 ppm chlorine at 20 degrees C for 5 min, with complete elimination (6.27 log CFU per chip) after exposure to 150 ppm at 20 degrees C for 1 min. A 3% H2O2 solution reduced the initial concentration of L. monocytogenes Scott A planktonic cells by 6.0 log CFU/ml after 10 min of exposure at 20 degrees C, and a 3.5% H2O2 solution reduced the planktonic population by 5.4 and 8.7 log CFU/ml (complete elimination) after 5 and 10 min of exposure at 20 degrees C, respectively. Exposure of cells grown as biofilms to 5% H2O2 resulted in a 4.14-log CFU per chip reduction after 10 min of exposure at 20 degrees C and in a 5.58-log CFU per chip reduction (complete elimination) after 15 min of exposure.     

Evaluation of gaseous ozone and hydrogen peroxide treatments for reducing Fusarium survival in malting barley

The use of Fusarium-infected barley for malting can lead to mycotoxin production and decreased malt quality. Methods for treatment of Fusarium-infected barley might prevent these safety and quality defects and allow use of otherwise good-quality barley. Gaseous ozone and hydrogen peroxide (HP) were evaluated for effectiveness in reducing Fusarium survival while maintaining germinative energy (GE) in barley. Gaseous ozone treatments (GOT) included concentrations of 11 and 26 mg/g for 0, 15, 30, and 60 min. HP treatments included 0, 5, 10, and 15% concentrations with exposure times of 0, 5, 10, 15, 20, and 30 min. For GOT, in naturally Fusarium-infected barley, a statistically significant (P < 0.05) decrease (24 to 36%) of Fusarium survival occurred within 15 min of exposure at either concentration. GE was significantly (P < 0.05) affected by 30 min at both concentrations in naturally Fusarium-infected barley, but not in sound barley. GOT did not cause any significant (P > 0.05) effect on GE in sound barley at either concentration over the full 30-min exposure time. For HP, Fusarium survival was significantly decreased (50 to 98%) within 5 min of exposure. With the exception of two treatments (10 and 15% HP agitated for 20 min), GE was not statistically significantly different from the control in naturally Fusarium-infected barley. In sound barley, HP had no significant (P > 0.05) effect on GE. The results suggest that GOT and HP might have potential for treatment of Fusarium-infected malting barley.     

汉麻纤维的超声波/双氧水脱胶工艺研究

汉麻纤维是一种功能型和环保型纺织纤维,其胶质含量较高,致使脱胶效果不佳,严重制约了对其的开发利用.通过超声波预处理并结合双氧水氧化脱胶,探讨影响脱胶效果的因素,得出最佳脱胶工艺条件:超声波频率60 kHz,处理时间55 min,双氧水用量5%,硅酸钠用量2%,渗透剂JFC用量2%,NaOH用量3%,煮练温度90℃,煮练时间60 min.在此工艺条件下,汉麻纤维的共生物杂质总含量由原来的30.49%下降到8.75%,断裂强度保持在4.5 cN/dtex以上,其可纺性以及纤维品质均有明显改善.     

羊绒的双氧水/角蛋白酶抗起毛起球整理

采用双氧水与角蛋白酶联合处理羊绒织物,以提高羊绒织物的抗起毛起球性能.试验结果表明:双氧水体积分数30 mL/L,50℃氧化处理40 min,角蛋白酶质量分数2.0％,50℃酶处理25 min,经氧化/角蛋白酶联合作用,织物的抗起毛起球性能可达到3.5级,符合羊绒制品的服用性能要求.     

过氧化氢降解水不溶性条斑紫菜多糖

研究了以过氧化氢降解水不溶性条斑紫菜多糖的影响因素,并用液相色谱、红外光谱、紫外光谱法对降解产物进行检测得到蛋白质含量和总糖含量。结果表明,多糖降解的最适条件为:过氧化氢质量分数为1.8%,温度60℃,时间6.0 h;产物包含3种低聚糖组分,可能为双糖、双糖衍生物或聚合度不低于3的低聚糖;产物主要是β-糖苷键连接的吡喃型低聚糖,具有硫酸基和3,6-内醚半乳糖结构;产物含有蛋白质2.12%,总糖93.66%。     

微波/双氧水处理羊毛的染色性能

羊毛织物经微波/双氧水预处理后,采用丽雅伦活性染料、兰纳素活性染料、派拉丁1∶1型金属络合染料和依素伦1∶2型金属络合染料进行轧染染色,并微波固色。扫描电镜和X射线衍射技术分析表明,羊毛纤维表面鳞片结构损伤明显,但结晶指数有所提高;对纤维物理机械性能影响较小,K/S值和透染性提高,可提高得色量。     

氢氧直接合成过氧化氢贵金属催化剂研究进展

综述了近年来国内外在氢氧直接合成过氧化氢方面的研究进展,包括Pd催化剂的活性组分、Au催化剂、载体、反应介质的研究进展.重点探讨了Pd基催化剂活性态及其改性对氢氧直接合成过氧化氢活性的影响.指出非贵金属掺杂的负载型双金属催化剂及其改性、催化机理研究将是氢氧直接合成过氧化氢催化剂研究的发展方向.     

红松松塔多糖过氧化氢法脱色工艺的研究

优化红松松塔粗多糖过氧化氢脱色法的工艺条件。本实验采用过氧化氢法对红松松塔多糖进行脱色研究,利用单因素和正交试验研究了过氧化氢浓度、脱色时间、脱色温度和pH值对红松松塔粗多糖脱色工艺的影响。研究结果表明,过氧化氢法最佳脱色工艺条件为过氧化氢浓度6％、时间60min、温度80℃和pH值11。该研究对生产出高品质的红松松塔多糖有显著的推动作用。     

过氧化氢脱毛技术（Ⅰ） 影响脱毛效果的几种因素

以毛干损伤率、掉毛程度为考察指标,主要研究了在过氧化氢脱毛过程中几种控制因素对脱毛效果的影响规律。     

Degradation of curdlan using hydrogen peroxide

Curdlan, a linear glucan interconnected by β-(1 → 3) linkages, is soluble in alkaline solutions but not in water, which limits its wide application, particularly in the food industry. In this study, curdlan was subjected to oxidative degradation using hydrogen peroxide (H₂O₂). The optimal hydrolysis conditions were determined, and the results were as follows: reaction time, 40 min; temperature, 60 °C; H₂O₂ concentration, 1.5% (v/v); and NaOH concentration, 2.5 M. Under these optimised conditions, the maximum dextrose equivalent value (13.49%) was obtained. The composition and the structure of the hydrolysates were characterised by high-performance liquid chromatography and Fourier-transform infra-red spectroscopy, respectively. The hydrolysates were filtered, neutralised with HCl, concentrated to ∼12% (w/v), desalted, and freeze dried to yield a water-soluble, white powder. The (1 → 3)-β-d-glucan oligosaccharide content of the product was 98.6% and the yield was 91.4% (w/w).     

涤棉织物双氧水/尿素活化氧化前处理体系

采用双氧水/尿素活化氧化体系对涤棉混纺织物进行一浴一步法轧蒸前处理,探讨双氧水、尿素、去油剂用量、汽蒸时间、轧余率对织物退浆率、退浆废水中PVA降解率、毛效和白度的影响.试验结果表明,65/35涤棉织物的优化前处理工艺为:双氧水60 mL/L,尿素112.5 g/L,去油剂2 g/L,pH值5～6,二浸二轧(轧余率100%),100℃汽蒸30 min;90/10涤棉织物为:双氧水80 mL/L,尿素150 g/L,去油剂2 g/L,PH值5～6,二浸二轧(轧余率100%),100℃汽蒸20 min.处理后涤棉织物的退浆率和PVA降解率均较高,且毛效、白度等指标完全满足后续加工要求.     

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％.     

碎米荠多糖的过氧化氢脱色方法研究

为了脱除碎米荠多糖液中的色素,以过氧化氢(H2O2)为脱色剂,选择脱色时间、脱色温度、pH值和过氧化氢的质量百分比浓度等因素为试验因素,进行单因素试验,以此为基础进行4因素4水平的正交试验.结果表明,在脱色时间6～7 h、室温、pH4～5和过氧化氢的质量百分比浓度为6%～7%的脱色条件下,可以有效地脱除碎米荠多糖液中的色素.     

Mechanisms of hydrogen peroxide decomposition in soils

The rates and mechanisms of hydrogen peroxide (H2O2) decomposition were examined in a series of soil suspensions at H2O2 concentrations comparable to those found in rainwaters. The formation of hydroxyl radical (OH) as a possible decomposition intermediate was investigated using a new, highly sensitive method. In surface soils with higher organic matter or manganese content, H2O2 usually decayed rapidly, with disproportionation to water and dioxygen dominating the decomposition, whereas the formation of the hydroxyl radical (OH) represented <10% of the total H2O2 decomposed. In contrast, for soils with lower organic matter content, H2O2 usually decayed much more slowly, but OH was a major product of the H2O2 decomposed. The decomposition was principally associated with soil particles, not the soil supernatant. Different sterilization techniques indicated that decomposition of H2O2 was at least partly due to biological activity. Because the loss of H2O2 can largely be accommodated by the production of O2 and OH within these soils, our results suggest that disproportionation through a catalase-type mechanism and the production of OH through a Haber-Weiss mechanism represent the principal routes through which H2O2 is lost.     

Chemiluminescent determination of hydrogen peroxide in water

A method for determining low concentrations of hydrogen peroxide (H₂O₂) in water, based on the chemiluminescent oxidation of 3-aminophthalhydrazide (luminol) by H₂O₂ in the presence of a copper ion catalyst, is described. Levels of H₂O₂ down to 3 × 10^-8 mol/1 (1 ppb) can be determined. The method may be used to monitor the amount of residual H₂O₂ in aseptically filled packages sterilized with H₂O₂ before filling.     

Trichloroethylene degradation in a coupled anaerobic/aerobic reactor oxygenated using hydrogen peroxide

In this work, trichloroethylene (TCE) degradation under combined anaerobic-aerobic conditions was studied in an ethanol-fed biofilm reactor oxygenated using hydrogen peroxide. The reactor was inoculated with a biomass originating from an anaerobic digestor. Granulated peat was added to the reactor as a substratum for biofilm development. Extensive characterization of reactor populations using activity tests and PCR analysis revealed the development of a mutualistic consortium, particularly methanotrophic and methanogenic microorganisms. This consortium was shown to degrade TCE by a combination of reductive and oxidative pathways. A near complete degradation of TCE at a load of 18 mg L(R)(-1) day(-1) was evidenced by a stoichiometric release of inorganic chloride.