Solution and interaction of oxygen in complex liquid silver alloys

The improved classic Sieverts technique has been employed to reinvestigate the influence of temperature on the solubility of oxygen in liquid Ag?Au alloys (0 to 60 wt pct Au). Its effect is found to be slightly more pronounced at higher additions of gold as compared to results of earlier investigations. In addition the influences of temperature and composition on oxygen solubilities in multi-component Ag?O?Au?Pt?Pd alloys (0 to 12 wt pct each) have been determined. The result is found predictable by means of the recently developed “equivalence method” based only upon the knowledge of known data in ternary Ag?O?j alloys. The results of this as well as earlier investigations are evaluated on a molal basis, yielding partial molal enthalpy and entropy of solution values. Thus the “equivalence method” recently applied to solubilities and activity-coefficients at a given temperature, is found applicable to partial molal energetic data as well.     

Quantification of singlet oxygen from hematoporphyrin derivative by electron spin resonance

The mechanism of the generation and the quantitative analysis of singlet oxygen (1O2) formed by the exposure of a hematoporphyrin derivative (HpD) to light was re-evaluated by electron spin resonance (ESR) combined with 2,2,6,6,-tetramethyl-4-piperidine (TMPD). The change from TMPD to 2,2,6,6,-tetramethyl-4-piperidine-N-oxide (TAN) has been reported to depend on singlet oxygen. However, we confirmed that this reagent also react with superoxide anion (O2-) and hydroxyl radicals (OH). Therefore, the reactions between TMPD and 1O2, O2- and OH were re-examined using a kinetic approach. We found that the generation of TAN was proportional to the concentration of TMPD and HpD, as well as to the duration and strength of the illumination. The generation of TAN was not inhibited by dimethyl-sulfoxide (DMSO) or superoxide dismutase (SOD). The reaction rate between TMPD and 1O2 was determined to be 5.0 x 10(-7) M min-1. The generation of 1O2 from HpD was 2.7 x 10(-7) M min-1 under our conditions. The competitive reaction observed between 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and TMPD for O2- or OH shows that TMPD reacts with both forms of active oxygen, but gave no ESR signal. The second-order reaction rate constant of TMPD between O2- and OH was calculated as 73 M-1 s-1 and 1.5 x 10(9) M-1 s-1, respectively. The photochemical generation of 1O2 from methylene blue, another sensitizer, was also demonstrated by this method. These results show that ESR signal of TAN can be used for the highly selective monitoring of 1O2.     

Environmental Factors and the Application of Hydrogen Peroxide for the Removal of Toxic Cyanobacteria from Waste Stabilization Ponds

Toxin-producing cyanobacteria constitute a serious threat to human and environmental health. It is thus essential that an effective treatment guarantees the removal of cyanobacteria from wastewater before its inclusion in water recycling or environmental flow. Hydrogen peroxide (H2O2) has been shown to induce cyanobacterial decay in laboratory cultures. However, its application for the removal of cyanobacteria from wastewater treatment ponds under environmental conditions has not been investigated. To examine the effects of environmental factors, field trials were performed at both the mesocosm and full-scale levels. The mesocosm trial was completed under field conditions of incident radiation, with various H2O2 concentrations. A concentration of 1.1×10-4??gH2O2/μg chl-a resulted in a 32% decrease in cyanobacterial concentration after 24?h, and this approximate concentration was then applied to a wastewater treatment pond in the full-scale trial. In the full-scale experiment, intense spatial and temporal monitoring of phytoplankton concentrations and temperature throughout the pond was performed. Cyanobacterial biomass was reduced by 57% and total phytoplankton biomass by 70% within 48?h of H2O2 addition. Mixing and radiation were shown to control the depth reached by H2O2 following addition to the ponds. The synergistic effect of H2O2 addition with environmental factors increased the effectiveness of cyanobacterial removal compared with laboratory experiments. The concentration of H2O2 required for the removal of cyanobacteria under field conditions may be decreased from laboratory studies by an order of magnitude.     

流动注射—H2O2-日落黄催化光度法测定河水中铜

在硼酸缓冲溶液中,铜能对H₂O₂氧化日落黄的反应起到明显催化作用,反应产物在波长530 nm处有最大吸收峰,据此建立了流动注射-催化光度法直接测定河水中铜的方法。对流动注射系统参数进行优化,确定推动液C、显色液R₁、显色液R₂和试样S泵管流速分别为0.75 mL/min、0.30 mL/min、0.30 mL/min和0.55 mL/min,反应圈L长度为2 m,进样环体积为350 μL。对所用试剂浓度进行优化,确定日落黄浓度为0.027 g/L,H₂O₂浓度为0.005 mol/L,缓冲溶液pH 9.8。铜的浓度在20~1 000 μg/L时与峰高呈良好的线性关系,相关系数为0.999。方法的检出限为1.5 μg/L;对河水中铜进行分析,测定结果与国标法一致,相对标准偏差在0.48%~1.2%之间。     

Transient behaviour of baker's yeast during enforced periodical variation of dissolved oxygen concentration

The aim of the investigation was to find out the influence of the variation of the dissolved oxygen concentration in the microenvironment of yeast cells on their physiological behaviour in small laboratory reactors and estimate their behaviour in large industrial reactors. Since the morphology of the laboratory and industrial yeasts differed considerably, their transient behaviour was investigated and compared. For this purpose, the strain Saccharomyces cerevisiae H620 and an industrial strain were cultivated on synthetic as well as on complex medium in batch operation during periodical variation of the dissolved oxygen concentration, monitoring the most important key parameters. Also the yeast was cultivated in batch as well as in continuous operation, the cell-containing culture medium was recirculated through a nonaerated loop at different recirculation rates (residence times of the cells in the loop), and the key operation variables were monitored. It was found that the transient behaviour of laboratory and industrial yeasts differed slightly. Since cells growing in batch culture are more sensitive to dissolved oxygen concentration variation than cells growing in continuous culture, the transient behavior of cells cultivated in batch operation varied from those in continuous operation. If the anaerobic phase was longer than 1 min, ethanol was produced. However, it was consumed during the aerobiosis again, provided that phase was considerably longer than the anaerobic phase. This means that the yeast cultivation was not influenced by the periodic operation of the dissolved oxygen. Judging from the measurements in large stirred tank and airlift tower loop reactors, in general, the cells would spend more time in the aerobic than in the anaerobic flow region, and they would spend less than 1 min in the anaerobic flow region. Therefore, no considerable effect of the periodically varied dissolved oxygen concentration on the cell cultivation can be expected in large-scale reactors. In the stirred tank-loop-system at high pumping rates/high frequencies of periodically varied dissolved oxygen concentration, unexpectedly, the formation of ethanol was observed, which might be caused by stress imposed on the cells.     

Axial Dispersion and Mass Transfer Controlled Simulation Study of Chromium (VI) Adsorption onto Tree Leaves and Activated Carbon

In this paper, the feasibility and efficacy of chromium (Cr(VI)) removal using three different kinds of tree leaves viz. Emblica officinalis, Azadirachta indica, Eucalyptus agglomerata, and the activated carbon is examined through batch and continuous flow experiments. Pretreatments were given to the selected tree leaf powders to remove the natural pigments and lignin present. Batch and continuous flow experiments have been conducted to study the kinetics of adsorption, effects of pH, adsorbent dose, contact time, bed depth, flow rate, and initial Cr(VI) concentration on Cr(VI) adsorption onto the selected adsorbents. The adsorption capacity is observed higher for Emblica officinalis followed by Eucalyptus agglomerata and Azadirachta indica. The adsorption equilibrium is reached in less than 30 min and the maximum Cr(VI) uptake occurred at pH 3.0 under the test conditions. The results are also compared with the commercially available activated carbon. A mathematical model incorporating diffusion, advection, and mass transfer mechanisms available in the literature has been simplified and is then tested to simulate the laboratory and literature data. A simple method for the determination of saturation Cr(VI) concentration along the length of column has been presented. The study reveals that the model incorporating the molecular diffusion and the mass transfer mechanisms simulates better the Cr(VI) adsorption onto tree leaf powders than the literature model and the advection term plays only a negligible role due to low flow rates applied during the experiments. The model parameters, i.e., axial dispersion coefficient, “DL” and the external mass transfer coefficient, “kf” are found in the order of 10?5–10?6?m2/s and 10?9–10?11?m/s, respectively.     

The aqueous humor is capable of generating and degrading H2O2

PURPOSE: To determine the ability of the aqueous humor to generate and degrade H2O2, the effect of environmental factors such as oxygen tension and temperature, and the constituents contributing to the observed results. METHODS: Aqueous humor was carefully removed from bovine eyes within 3 hours of death. Standard and new techniques were used to follow H2O2 degradation and formation. Catalase activity was measured by H2O2 decomposition, usually at 100 microM and 10 mM H2O2, and in some cases by O2 generation. RESULTS: Bovine aqueous humor generated and degraded H2O2. The generation of H2O2 was minimal at 0 degrees C but increased as temperature increased, so that at 37 degrees C at 3 hours, approximately 90 microM H2O2 was observed. Degradation was more complex. At 0 degrees C, only a slow rate of degradation was observed. At 25 degrees C, it was more rapid, and a steady state between generation and degradation was observed at approximately 30 microM. However, at 37 degrees C, starting with 100 microM H2O2, degradation was initially rapid, but then generation became predominant and H2O2, concentration increased to more than 100 microM in 3 hours. No H2O2 was generated in the absence of O2, and H2O2 production increased with increasing O2 tension. Both low and high molecular weight components contributed to the degradation, but synthesis was completely dependent on low molecular weight constituents. Ascorbic acid and metal ions such as Cu+ made a major contribution to H2O2 production. Catalase may be the macromolecular component responsible for aqueous H2O2 decay, as evidenced by H2O2 degradation, inhibition by boiling or 3-aminotriazole, and the approximate correspondence between oxygen generation and H2O2 degradation. CONCLUSIONS: The results indicate that the aqueous humor is capable of producing levels of H2O2 that have been shown previously to cause cataract in organ culture. Changes in aqueous humor metal ion content and concentration of oxygen level have profound effects on H2O2 concentration and may effect lens viability. The variation in published H2O2 levels may in part be the result of the conditions under which the aqueous humor was obtained, stored, and used for assay. The observed steady state H2O2 concentration of 1 microM in fresh aqueous from bovine eyes must be maintained by the metabolism of surrounding tissues as well as intrinsic components capable of degrading H2O2.     

Antinuclear antibody screening by an enzyme-linked immunosorbent assay using multiple nuclear antigens

The oxidation of aminopyrine, an N-alkyl aromatic amine, by the hydroperoxidase activity of lipoxygenase was studied. Aminopyrine gave rise to a purple color in the presence of H2O2 and lipoxygenase, the color being proportional to the aminopyrine radical cation. The H2O2/aminopyrine radical cation molar ratio was 0.5. The overall reaction was considered as an enzymic-chemical second order mechanism with substrate regeneration. From the equations, the apparent constant of the radical cation's decomposition (k'app) was evaluated under different experimental conditions. It was found to be inversely proportional to the proton concentration but unaffected by the concentration of aminopyrine. These results suggest a new comprehensive mechanism for N-demethylation, which takes into account the described presence of both nitrogen- and carbon-centered radicals and the marked effect of pH on the stability of the radical cation.     

Electrolytic Oxidation of Polynuclear Aromatic Hydrocarbons from Creosote Solution Using TI/IRO2 and TI/SNO2 Circular Mesh Electrodes

The electrooxidation of polynuclear aromatic hydrocarbons (PAHs) in solution was investigated. Most of the PAHs compounds are toxic and hardly biodegradable, so that a chemical or physicochemical treatment is required. In this paper, we reported treatment of synthetic creosote oily effluent (COE) containing several PAHs by using Ti/IrO2 and Ti/SnO2 circular or cylindrical mesh anode electrodes. COE was prepared with distilled water and a commercial creosote solution in the presence of an amphoteric surfactant (CAS). In addition to anode material, different operating parameters were investigated such as current density, reaction time, recycling flow rate, and oxygen injection flow rate. The first series of experiments carried out in the recirculating batch reactor showed that circular Ti/SnO2 electrode was found to be more effective in removing PAHs than circular or cylindrical Ti/IrO2 electrodes. Current density and retention time played important roles for PAHs degradation efficiency, whereas circulation flow rate and oxygen injection slightly influenced the removal efficiency. Finally, the best and simplest operating conditions (82–84% of PAHs removal) determined for PAHs degradation in COE were obtained at a current density of 15?mA/cm2 through 90 min of treatment with a recycling rate of 3.6 L/min but without O2 injection in the close loop. Likewise, in the recirculating batch tests, PAHs decomposition exhibited behaviors of the fist-order reaction with a rate coefficient (k) of 0.015?min?1. The energy consumption was 7.5?kWh/m3. The second series of experiment using successively batch and continuous treatment of COE shows that the percentage of PAHs degradation could be maintained above 80% up to 18 h of treatment, thereafter, removal efficiency decreased owing to the formation of organic substances on the electrodes surface.     

Effect of Water Vapor on O2- Content in Ironmaking Slag

In principle,slag basicity can be expressed as the concentration of free oxygen(O2-) in the slag system.This free oxygen content is equilibrated with different silicate anions in addition to other components in the silicate-based slags.X-ray photon spectroscopy(XPS) and scanning electron microscope equipped with energy dispersive spectrometer(SEM-EDS) were used to investigate the effect of water vapor on the free oxygen content in ironmaking slags.It was found that water in the gas atmosphere plays a significant role in the silicate anion equilibria.Water decreases the amount of free oxygen in the studied slags,with the free oxygen expressed as percentage of the total oxygen decreasing in the order of the following gas mixtures:CO+CO2(44%,pH2 O = 0 k Pa) CO+CO2+H2+H2O(41%,pH2 O = 10.13 k Pa) H2+H2O(37%,pH2 O = 14.19 k Pa).The content of free oxygen ion affects the distribution of elements such as sulfur,phosphorus,and manganese.In addition,it affects the iron oxide content in the slag as well as the interaction between slag and furnace lining.     

Evaluation of UV LEDs Performance in Photochemical Oxidation of Phenol in the Presence of H2O2

A novel application of ultraviolet (UV) light emitting diodes (LEDs) as a light source for the degradation of organic contaminant has been investigated. Photocleaving of hydrogen peroxide (H2O2) via UV LEDs photolysis resulted in the generation of hydroxyl radicals. It was found that phenol removal was insignificant in the absence of hydrogen peroxide, therefore oxidation of phenol was attributed to the formed radicals. Two criteria were selected to provide detailed information on the performance of UV LEDs in phenol oxidation: (1) the reaction quantum efficiency and (2) the energy consumption. Statistical tools such as the response surface methodology and the ANOVA were applied to estimate the influence of various process parameters such as the wavelength (255, 269, and 276 nm) and H2O2 to phenol molar ratio (5, 50, and 100) on phenol degradation reaction quantum efficiency. The decay of phenol (initial concentration of 1.06 mM) was the most pronounced at 255 nm and H2O2 to phenol molar ratio of 50. Finally, the “figure-of-merit” was used to estimate the specific energy consumption of the UV LED-based process.     

Bioleaching of Sulfide Mineral in Stirred Tank Reactors Operated in a Variety of Modes

Abstract

This paper reviews analysis and modeling for the bioleaching of pyrite in stirred tank reactors operated in a variety of modes: batch, repeated-batch and continuous flow. In a batch reactor, rate data were consistent with a kinetic model assuming that the growth rate of adsorbed bacteria on the mineral surface is proportional to the product of the concentration of adsorbed cells and the fraction of adsorption sites unoccupied by cells. In this modeling, the adsorbed cell concentration was related to the free cell concentration in liquid medium through the Langmuir adsorption isotherm. The reactor model for batch operation is used to investigate the effect of solution replacement on bioleaching rate in repeated-batch reactor. Moreover, the batch model is extended to analyze and model the bioleaching in a continuous-flow tank reactor.     

Mathematical model of oxygen transport in the cerebral cortex

To estimate the magnitude of hyperemia necessary to support oxidative metabolism in the cerebral cortex during functional activation, a mathematical model of O2 transport from capillary to tissue was developed. Radial and axial gradients of O2 pressure in tissue surrounding a single capillary were calculated at normal and increased cerebral metabolic rates for O2. Cone-shaped tissue geometry and nonlinear oxyhemoglobin dissociation were assumed. Local O2 consumption was assumed to be supported with local tissue pO2 greater than 1 mmHg. The distribution of tissue pO2 was also calculated during moderate hypoxemia (paO2=42 mmHg), using experimental values of red blood cell velocity measured in individual capillaries of the rat cerebral cortex using intravital video-microscopy. The model predicted that moderate increases (相似文献   

Filtration Removals of Microorganisms and Particles

Filtration log removals (log?R’s) were determined by pilot plant seeding experiments for a selected array of organisms, i.e., protozoan cysts, algae, bacteria, and viruses, as well as turbidity/particles. Removals of these organisms and particles varied from one species to another within the range 1.4 ? log?R ? 5.1 for “reference,” i.e., specified, conditions. For other conditions, called here “excursion” conditions, log?R’s were found to be proportional to alum dose between zero and “optimum” the latter being defined as the smallest dosage that minimized filter effluent turbidity. Mono and dual media did not show performance differences, and conventional filtration showed slightly higher log?R’s than in-line filtration. The influent concentration did not show a “true” effect on log?R’s (but an “apparent” effect was seen when effluent values were consistently very low, making log?R’s proportional to influent concentration). log?R’s obtained in limited experiments at another site showed significant differences for two algae and two viruses when compared with log?R’s for reference conditions. The results illustrate the log?R variation that may be found among different groups of organisms/particles and indicate the influences of certain independent variables (e.g., influent concentration, dual media versus mono media, conventional filtration versus in-line, alum dose, zero alum dose, and filtration at a different site) on filtration removals. In addition, the importance of sampling repetitions was reinforced. The findings are significant to water treatment practice in that organism removals by filtration are likely to vary, depending on the organism/particle species as well as the filtration conditions. The implication is that a pilot plant study is advisable if confidence in log?R is desired for a given organism/particle.     

Kinetic studies on the removal of extracellular hydrogen peroxide by cultured fibroblasts

To investigate the function of antioxidant enzymes in intact cells, we examined the removal of extracellular H2O2 by cultured fibroblasts (IMR-90). H2O2 concentration dependence of the reaction rate was interpreted as that the process involves two kinetically different reactions (referred to as reactions 1 and 2). Reaction 1 was characterized by a relatively low Km value (about 40 microM), and reaction 2 by linear dependence of the rate up to 500 microM H2O2. The magnitude of reaction 1 was reduced by treatment of the cells with diethyl maleate or 6-amino-nicotinamide, while reaction 2 was inhibited by 3-amino-1,2,4-triazole treatment. It was concluded that reactions 1 and 2 are principally due to GSH peroxidase and catalase, respectively. The values of kinetic parameters were estimated by curve-fitting, and it was inferred that 80 to 90% of H2O2 is decomposed by GSH peroxidase at H2O2 concentrations lower than 10 microM. The contribution of catalase increases with the increase in H2O2 concentration. The intact cells showed a low catalase activity (about 15%), as compared with the activity found in the solubilized cells. The low catalase activity was ascribed to the latency of the enzyme caused by localization in peroxisomes. Fibroblasts also removed intracellular H2O2 generated by menadione. Treatment with diethyl maleate greatly impaired the H2O2-removing capability and caused H2O2 efflux into the medium.     

Behavior of the liquid silver electrode in a solid-oxide electrolyte concentration cell

The behavior of the liquid silver electrode in the cell (–) Ar-O₂,O(in Ag)/ZrO₂-CaO/O₂ (+) was studied as a function of the oxygen activity in silver and the temperature. The liquid metal was contained inside an impervious tube of ZrO₂+10 mole pct CaO. The cell discharges reversibly from 1000° to 1200°C. However, when the liquid silver electrode is made the cathode, diffusion overpotential appears due to a depletion of dissolved oxygen at the silver-electrolyte interface. Limiting currents are eventually observed which are directly proportional to the concentration of dissolved oxygen from 0.01 to 0.24 at. pct O. T. H. ETSELL, formerly Graduate Student, Department of Metallurgy and Materials Science, University of Toronto, Toronto, Ontario, Canada     

Modeling the Transformation of Chromophoric Natural Organic Matter during UV/H2O2 Advanced Oxidation

This research developed a differential kinetic model to predict the partial degradation of natural organic matter (NOM) during ultraviolet plus hydrogen peroxide (UV/H2O2) advanced oxidation treatment. The absorbance of 254?nm UV, representing chromophoric NOM (CNOM) was used as a surrogate to track the degradation of NOM. To obtain reaction rate constants not available in the literature, i.e., reactions between the hydroxyl radical (?OH) and NOM, experiments were conducted with “synthetic” water, using isolated Suwannee River NOM, and parameter estimation was applied to obtain the unknown model parameters. The reaction rate constant for the reaction between ?OH and total organic carbon (TOC), k?OH,TOC, was estimated at 1.14(±0.10)×104??L?mg-1?s-1, and the reaction rate constant between ?OH and CNOM, k?OH,CNOM, was estimated at 3.04(±0.33)×104??L?mol-1?s-1. The model was evaluated on two natural waters to predict the degradation of CNOM and H2O2 during UV/H2O2 treatment. Model predictions of CNOM degradation agreed well with the experimental results for UV/H2O2 treatment of the natural waters, with errors up to 6%. For the natural water with additional alkalinity, the model also predicted well the slower degradation of CNOM during UV/H2O2 treatment, owing to scavenging of ?OH by carbonate species. The model, however, underpredicted the degradation of H2O2, suggesting that, when NOM is present, mechanisms besides the photolysis of H2O2 contribute appreciably to H2O2 degradation.     

Effect of Biotrickling Filter Operating Parameters on Chlorobenzenes Degradation

In this paper the effect of operating parameters on biotrickling filter performance degrading chlorobenzene and o-dichlorobenzene mixture were studied. The large laboratory scale biofilter, total volume 40 L, filled with inert packing material was used. The biomass adaptation and cultivation were performed in a batch fermentor and were used to inoculate the biotrickling filter. After a starting period, the influence of the substrate load increase, liquid recirculation flow rate, and empty bed retention time on elimination capacity and removal efficiency were found. The most important recirculation liquid parameters were analyzed every day, that is: concentration of metabolites, dissolved organic carbon, nitrate, chloride, and biomass. A good correlation was found between intermediate concentration and the removal efficiency of the biotrickling filter. The measurements of the absorbance, very easy and rapid, can be used as a control parameter of the biofiltration efficiency.     

Elevated levels of expired breath hydrogen peroxide in bronchiectasis

Airway inflammation is important in the development and progression of many lung diseases, including bronchiectasis. Activation of inflammatory cells such as neutrophils, eosinophils, and macrophages induces a respiratory burst resulting in the production of reactive oxygen species such as hydrogen peroxide (H2O2). We have measured exhaled H2O2 in patients with documented bronchiectasis and investigated whether the concentration of H2O2 is related to the disease severity, as defined by lung function. We also investigated whether the concentrations of expired H2O2 were different in bronchiectatic patients who received inhaled corticosteroids compared with steroid-na?ve patients. In 37 patients with bronchiectasis (mean age, 45 +/- 2.5 yr; FEV1, 59 +/- 3% pred), mean H2O2 concentration in exhaled breath condensate was significantly elevated as compared with the values in 25 age-matched (mean age, 42 +/- 2 yr) normal subjects (0.87 +/- 0.01 versus 0.26 +/- 0.04 microM, p < 0.001). There was a significant negative correlation between H2O2 and FEV1 (r = -0.76, p < 0.0001). Patients treated with inhaled corticosteroids had values of H2O2 similar to those of steroid-na?ve patients (0.8 +/- 0.1 versus 0.9 +/- 0.1, p > 0.05). We conclude that H2O2 is elevated in exhaled air condensate of patients with bronchiectasis and is correlated with disease severity. Measurement of H2O2 may be used as a simple noninvasive method to monitor airway inflammation and oxidative stress.     

Hypochlorite reacts with an organic hydroperoxide forming free radicals, but not singlet oxygen, and thus initiates lipid peroxidation

The mechanism of the reaction of hypochlorite with t-butyl hydroperoxide as a model organic hydroperoxide was studied. The reaction produces chemiluminescence with rate constant 13 +/- 2 mM-1.sec-1. The chemiluminescence of this reaction was compared with that of the hypochlorite reaction with H2O2 where singlet oxygen (1O2) is formed. In the hypochlorite reaction with H2O2, the effect of hypochlorite concentration on the integrated chemiluminescence intensity is quadratic: a red filter with transmission > 600 nm did not significantly decrease the chemiluminescence intensity: substitution of D2O for H2O increased the luminescence intensity 10-fold; infrared monomol emission was observed at 1270 nm. These results confirm the formation of 1O2 during the hypochlorite reaction with H2O2. However, when t-butyl hydroperoxide was used instead of H2O2, the concentration effect significantly differed from quadratic, and the red filter decreased the luminescence intensity by approximately 99%; D2O slightly decreased the luminescence intensity. Finally, addition of t-butyl hydroperoxide to hypochlorite was not associated with monomol emission of 1O2 in the infrared region. The data exclude the possibility of singlet oxygen formation in the hypochlorite reaction with the organic hydroperoxide. According to 1H-NMR spectroscopy, di-t-butyl peroxide is the main product of the hypochlorite reaction with t-butyl hydroperoxide; its production can be explained by radical formation, i.e., by generation of t-butyloxy radical. t-Butyl hydroperoxide and cumene hydroperoxide promoted hypochlorite-induced lipid peroxidation of phospholipid liposomes. The free radical scavenger butylated hydroxytoluene completely inhibited this effect. The data suggest that organic hydroperoxides, always present in certain amounts in vivo, may be the intermediates that interact with hypochlorite-forming free radicals which are initiators of lipid peroxidation.