Ozone Degradation of Iodinated Pharmaceutical Compounds

This study investigates the aqueous degradation of four iodinated x-ray contrast media (ICM) compounds (diatrizoate, iomeprol, iopromide, and iopamidol) by ozone and combined ozone and hydrogen peroxide. In laboratory scale experiments, second-order kinetic rate constants for the reactions of the ICM compounds with molecular ozone and hydroxyl radicals, and overall at pH 7.5, were determined. For the four ICM compounds the degradation rate constants with molecular ozone were low and in the range of 1–20?M?1?s?1, whereas the rate constants with hydroxyl radicals were in the range of 1×109–3×109?M?1?s?1. Diatrizoate had the lowest rate constant of the four compounds with respect to molecular ozone reactions. At pH 7.5, the extent of compound degradation was proportional to the applied ozone dose and inversely related to the initial compound concentration at a given ozone dose. At this pH approximately 90% of the degradation could be attributed to hydroxyl radical reactions. Enhancement of the radical mechanism by the addition of hydrogen peroxide during ozonation led to complete removal of the nonionic compounds, and >80% removal of diatrizoate, at relatively low oxidant mass ratios (H2O2/O3<0.25). A similar enhancement in compound degradation was evident with the presence of small concentrations of humic substances ( ～ 4–5?mg?L?1). Ozone oxidation led to major cleavage of the ICM compounds and the release of inorganic iodine; the proportion of iodine release was similar among the nonionic ICM compounds but much greater for diatrizoate.     

Effect of pH and Gas-Phase Ozone Concentration on the Decolorization of Common Textile Dyes

This paper presents the results of a laboratory study on the effect of pH (2, 5, and 9) and gas-phase ozone concentration (1, 7, and 11 wt?%) on the decolorization efficiency via ozonation for seven common textile dyes. Higher gas-phase ozone concentrations resulted in higher decolorization rates due to more rapid ozone transfer. Higher gas-phase ozone concentration, however, was also observed to have a positive, neutral, or negative effect on ozone dose requirements for different dyes. In general, greater ozone utilization efficiency was achieved at lower pH levels where direct ozone reactions predominate. It was observed that because ozonation can cause significant resolubilization of precipitated dyes, complete removal of dye precipitate should be accomplished prior to polishing via ozonation. The results point to the need for laboratory and/or pilot testing for dye-laden wastestreams to allow process optimization.     

Separation of cobalt and nickel by ozone oxidation

The utilization of ozone for the separation of cobalt from nickel sulfate was investigated by determining the oxidation rate for Co(II) and Ni(II) ions under various ozonation conditions at 60°C. The oxidation reaction was observed to follow a first order rate with respect to the ozone partial pressure of the O₃-O₂ mixture gas and to be promoted considerably by vigorous agitation. The oxidation rates were virtually constant down to a fairly low concentration of the oxidizable ions. Nickel ion was found to be oxidized more easily at lower pH in the mixed sulfate solutions than in solutions of a single sulfate. At pH 2.5–5.0, ozone oxidation seems to be effective to separate cobalt ions selectively from nickel sulfate solutions, due to the extremely slow oxidation of the nickel ion in comparison with cobalt.     

Ozonation of Propranolol: Transformation, Biodegradability, and Toxicity Assessment

This work studies the ozonation of the pharmaceutical propranolol (PRO) in aqueous solution. Experimental results demonstrated that ozonation was an efficient method to remove PRO, achieving its complete abatement after 8?min of treatment (ozone dose of 0.47??mmol?L-1), starting from a PRO initial concentration of 0.38??mmol?L-1. The total organic carbon (TOC) analysis indicated that 1?h of ozonation (ozone dose of 3.54??mmol?L-1) was able to achieve only about 5% of the total organic carbon removal. The ozonation of PRO aqueous solutions has not promoted a prompt increase of the ratio of biological oxygen demand to chemical oxygen demand, thus indicating the need for higher ozone doses to initiate the biodegradability enhancement. The acute toxicity increased in the first minutes of reaction with a posterior reduction to values slightly higher than the toxicity of the PRO raw solution. Some early intermediate structures were proposed, and finally, kinetic constants for the direct attack of ozone on PRO structure were calculated. These values are in the order of magnitude of 105??L?mol-1?s-1.     

Evaluating Ozone as a Remedial Treatment for Removing RDX from Unsaturated Soils

Years of wastewater discharge at the Department of Energy’s Pantex Plant have contaminated the vadose zone and underlying perched aquifer with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Because the vadose zone is acting as a continual source of groundwater contamination, removing RDX from the unsaturated zone is paramount to prevent further contamination. We determined the efficacy of ozone to degrade and mineralize RDX. Solution experiments showed that ozone (27?mg?L?1; 150?mL?min?1) was effective in mineralizing 80% of the RDX (30?mg?RDX?L?1) provided that some Pantex soil was present to buffer the solution pH. Soil columns treated with ozone produced 50% RDX mineralization within 1 day and >80% within 7 day. Experiments designed to evaluate aerobic biodegradation following partial ozonation of a RDX solution showed that ozone-generated RDX products were much more biodegradable than untreated controls in aerobic microcosms (35 versus <0.3% cumulative mineralization). These results support the use of ozone as a remedial treatment for the contaminated vadose zone at the Pantex facility.     

A kinetic model for the competitive reactions of ozone with amino acid residues in proteins in reverse micelles

Lysozyme and 10 other proteins are solubilized in reverse micelles formed by 0.1 M sodium di-2-ethyl-hexylsulfosuccinate and 2.0-2.5 M water (pH 7.4) in isooctane solvent. Exposure of the protein-containing reverse micellar solutions to ozone causes oxidative damage to the proteins, as assessed by the oxidation of tryptophan residues. The oxidation product of the protein-bound tryptophan has a molar absorption coefficient of 3275 +/- 81 M-1 cm-1 (mean +/- S.D., n = 6) at 320 nm. The product is suggested to be a Criegee ozonide or a tautomer of the Criegee ozonide and not N-formylkynurenine. Ozonation of lysozyme in reverse micelles results in the formation of hydrogen peroxide in yields of only approximately 0.07 mol/mol of tryptophan residues oxidized. The recovery of hydrogen peroxide added as an internal standard to the lysozyme-containing reverse micellar solutions ranges from 84 to 88%, whether or not the samples are subjected to ozonation. This suggests that hydrogen peroxide is neither destroyed during the process of ozonation nor consumed by the protein to a significant extent in an adventitious reaction. A kinetic model for the overall reaction of ozone with the proteins is developed, taking into account the concentrations and the reactivities of individual amino acid residues toward ozone. The model predicts the fractional reaction of ozone with tryptophan residues in the proteins, despite differences in amino acid composition, molecular weight, and tertiary structures. The lack of influence of protein structure is confirmed further by the observation that the native lysozyme (with and without external S-carboxymethylcysteine) and S-carboxymethylated lysozyme give identical values of the fractional reaction of ozone with tryptophan residues. The kinetic equations for the competitive reactions of ozone with amino acid residues in proteins, with some minor modification, are applicable to ozonations on complex mixtures of lipids, proteins, and antioxidants.     

Precipitation of K-V(V)-Oxide from V(IV) Sulfate Solution by Ozonation

Abstract

The oxidative precipitation of vanadium(IV) from its sulfate solutions with ozone has been investigated. During the ozonation, the solution pH was maintained constant by consuming the liberated hydrogen ion with drops of KOH solution. Chemical analysis of the precipitates showed that the values of x and y for the final solid product, K_xV₂O_y are from 0.30-0.47 (depending on pH) and 5.0, respectively. X-ray diffraction revealed that these potassium-incorporating vanadium(V) oxides have the basic structure of V₂O₅. The progress of oxidation of vanadium(IV) and precipitation of vanadium(V) were monitored by determining the concentrations of vanadium(IV) and vanadium(V) remaining in the solution and by ORP measurement. The rate of ozonation of vanadium(IV) increases with increasing pH, while the precipitation of vanadium(V) proceeds favourably at pH 1.5 at 25 °C and at pH 2.0 at 70 °C. A rise in temperature accelerates the oxidative precipitation of vanadium(IV) to make recovery of vanadium ion effective.     

Ozonation of Spent Reactive Dye-Baths: Effect of HCO3?/CO32? Alkalinity

The effect of carbonate and bicarbonate alkalinity (soda ash buffer as 5,180 mg/L HCO3? alkalinity at pH 7 and as 5,100 mg/L CO32? alkalinity at pH 12) on the ozonation of reactive vinylsulphone dyestuffs in a simulated spent dye-bath has been studied at varying pHs. Adsorbable organic halogen (AOX) formation due to the high chloride content of the effluent and detoxification, which was evaluated in terms of the relative toxicity index Itox determined from the ED50 values for the marine photobacteria Vibrio fischeri, were also evaluated. Highest total organic carbon (56%), chemical oxygen demand (44%), and UV254 (77%) removals were achieved at pH 7 in the presence of HCO3? alkalinity. The fastest decolorization was observed for the case pH 2, the first order decolorization rate constant found as k620 = 0.16?min?1, closely followed by the pH 12 case with soda ash (k620 = 0.12?min?1) case. No positive correlation was evident between AOX, whose maximum value (=1.3 mg/L) appeared after 40 min ozonation at pH 7 and decreased to 0.54 mg/L after 120 min treatment, and Itox, which decreased to 0.16 at t = 50?min and increased rapidly thereafter. The Itox values were more related to color abatement kinetics. The maximum relative toxicity index of Itox = 0.83 occurred after 120 min. It was also established that the presence of alkalinity in the spent reactive dye-bath had no negative impact on the oxidation rates. In contrast, its absence seriously inhibited treatment efficiency. It is speculated that, with added soda ash, the carbonate radicals HCO3? and CO3??, which are more stable and selective than OH?, were produced and promoted the oxidation process.     

活性炭催化臭氧化处理含氰废水的试验研究

研究了活性炭催化臭氧化降解低质量浓度含氰废水,考察了臭氧投加量、活性炭用量、pH值等因素对处理效果的影响.试验结果表明:活性炭对臭氧有明显的催化作用,并可以提高臭氧的利用率;在CN-初始质量浓度150 mg/L、臭氧投加量30 mg/min、活性炭14 g/L、反应30 min条件下,CN-去除率为99.8%,相对于单...     

Acute closed humeral shaft fractures treated with dynamic compression plate

BACKGROUND: To define the efficacy of dynamic compression plates (DCPs) for the treatment of closed humeral shaft fractures. METHODS: A total of 165 patients with closed humeral shaft fractures were studied retrospectively. There were 120 patients who underwent open reduction and internal fixation with DCPs and no bone grafting (BG). Forty-five patients received the same procedures with BG. The mean follow-up period was 93 months. RESULTS: In the DCP without BG group, the average blood loss was 350 ml, operation time was 105 minutes, hospital stay was 8.5 days and fracture union time was 13.5 weeks. In the DCP with BG group, the average blood loss was 525 ml, operation time was 115 minutes, hospital stay was 7.9 days and fracture union time was 9.2 weeks. CONCLUSIONS: In our experience, DCPs are effective for surgical fixation of humeral shaft fractures. Prophylactic BG is recommended for cases with more comminution.     

Ozone Inactivation Kinetics of CRYPTOSPORIDIUM in Phosphate Buffer

The rate of inactivation of Cryptosporidium parvum oocysts by ozone in 0.05 M phosphate buffer at pH 6, 7, and 8 was studied at 22 ± 1°C in batch reactors. Infectivity in neonatal CD-1 mice was used as the criterion for oocyst viability. Ozone inactivation data were fitted to the Incomplete gamma Hom (I.g.H.) and Chick-Watson (n = 1) model, both of which incorporate a first-order rate constant for the disappearance of aqueous ozone during the contact time. For a 0.05 M phosphate buffer ranging in pH from 6 to 8, a single I.g.H. model was found to adequately describe the kinetics of Cryptosporidium inactivation by ozone at 22°C. The I.g.H. model for pH 6–8 was found to provide a significantly better fit to the ozone inactivation data when compared with the Chick-Watson model. The effect of pH on ozone inactivation kinetics was associated with ozone residual stability over the pH range of 6–8. The sensitivity of Cryptosporidium to ozone at 22°C was therefore not statistically different at pH 6 when compared with pH 8. The inactivation behavior of Cryptosporidium by ozone was characterized by a tailing-off effect, with approximately equal importance of ozone concentration and contact time. The I.g.H. model for pH 6–8 can be used as an aid in the design of ozone disinfection systems, and this robust fitted model was used to formulate ozone design criteria—the initial oxone residual required for a given contact time for 1, 2, and 3 log units inactivation of Cryptosporidium at 22°C. Uncertainty associated with the ozone design criteria for 2 log units inactivation was quantified using inverse prediction intervals. An ozone design criterion was established that gives a 95% probability of achieving 2 log units inactivation of Cryptosporidium at 22°C, corresponding to an approximate safety factor of 0.7 log units.     

Antihuman immunoglobulin affinity immunoadsorption strongly decreases proteinuria in patients with relapsing nephrotic syndrome

An in vitro study was undertaken to investigate the potential for cellular telephones to interfere with representative models of presently used ICDs. Digital cellular phones (DCPs) generate strong, amplitude modulated fields with pulse repetition rates near the physiological range sensed by the ICD as an arrhythmia. DCPs with Time Division Multiple Access (TDMA) pulsed amplitude modulation caused the most pronounced effect--high voltage firing or inhibition of pacing output of the ICDs. This electromagnetic interference (EMI) occurred only when the phones were within 2.3-5.8 cm of the ICD pulse generator that was submerged 0.5 cm in 0.18% saline. ICD performance always reverted to baseline when the cellular phones were removed from the immediate proximity of the ICD. Three models of ICDs were subjected to EMI susceptibility testing using two types of digital phones and one analog cellular phone, each operating at their respective maximum output power. EMI was observed in varying degrees from all DCPs. Inhibition of pacer output occurred in one ICD, and high voltage firing occurred in the two other ICDs, when a TDMA-11 Hz DCP was placed within 2.3 cm of the ICD. For the ICD that was most sensitive to delivering unintended therapy, inhibition followed by firing occurred at distances up to 5.8 cm. When a TDMA-50 Hz phone was placed at the minimum test distance of 2.3 cm, inhibition followed by firing was observed in one of the ICDs. EMI occurred most frequently when the lower portion of the monopole antenna of the cellular phone was placed over the ICD header.     

含锑难处理金矿臭氧氧化预处理工艺研究

为解决含锑金精矿难处理的问题,对某含锑金矿进行臭氧氧化浸出锑的实验研究。实验结果表明,氧化浸出优化工艺参数：温度75 ℃,HCl浓度4.5 mol/L,浸出时间4 h,液固比10∶1,臭氧浓度121.9 g/L。在此条件下,锑的浸出率为98.13%,硫的浸出率为43.52%。经过臭氧氧化浸出处理后,矿物中的金得以在渣中富集。对原矿和浸锑渣进行硫脲浸金试验,金浸出率分别为12.36%和70.17%,表明预处理取得一定效果,实现了含锑难处理金矿中锑和金的综合回收。研究结果能为臭氧氧化浸出辉锑矿和含锑难处理金矿预处理提供理论指导。     

Effect of glycated proteins on the matrix of glomerular epithelial cells

The bactericidal activity of gaseous ozone was investigated using a commercial ozone generator. Five species of fish bacteria, Pseudomonas putida, Shewanella putrefaciens, Brochothrix thermosphacta, Enterobacter sp. and Lactobacillus plantarum, were inoculated on agar surfaces and exposed to different ozonation times in a gas chamber. Results showed ozone in relatively low concentrations (< 0.27 x 10(-3) g l-1) was an effective bactericide of vegetative cells of the five fish bacteria. The age of the cell culture was shown to influence the cell response following exposure. Survival rate was not linearly related to ozonation time, but exhibited biphasic death over an extended period. Similar bactericidal effects were observed on fish skin treated with ozone daily in the laboratory, with decreases of 1.0 log cfu cm-2 for the micro-organisms studied. Whole fish treated daily in the laboratory using a commercial ozone generator showed improved scores for sensory analyses compared with the controls. The results were statistically significant. Fish treated on board ships were also analysed for microbiological and sensory changes. Controls were obtained from a similar vessel without the ozone facility in the hold. Similar trends to those recorded in the laboratory for the microbiological and sensory results on ozonated fish were observed.     

Degradation and Mineralization of Simazine in Aqueous Solution by Ozone/Hydrogen Peroxide Advanced Oxidation

Advanced oxidation of simazine in aqueous solution by the peroxone (hydrogen peroxide/ozone) treatment was investigated using Box-Behnken statistical experiment design and response surface methodology. Effects of pH, simazine and H2O2 concentrations on percent simazine and total organic carbon (TOC) removals were investigated. Ozone concentration was kept constant at 45?mg?L?1. The optimum conditions yielding the highest simazine and TOC removals were also determined. Both simazine and peroxide doses affected simazine removal while pH and pesticide dose had more pronounced effect on mineralization (TOC removal) of simazine. Nearly 95% removal of simazine was achieved within 5 min for simazine and peroxide concentrations of 2.0 and 75?mg?L?1, respectively at pH = 7. However, mineralization of simazine was not completed even after 60 min at simazine doses above 2?mg?L?1 indicating formation of some intermediate compounds. The optimum H2O2/pH/Simazine ratio resulting in maximum pesticide (94%) and TOC removal (82%) was found to be 75/11/0.5(mg?L?1).     

Bromate Formation by Ozone-VUV in Comparison with Ozone and Ozone-UV: Effects of pH, Ozone Dose, and VUV Power

The formation of bromate by ozone–vacuum ultraviolet (VUV) (185+254??nm) process in comparison with ozone and ozone-ultraviolet (UV) (254?nm) processes of coagulated and softened water was studied. The effects of pH (7, 9, and 11), ozone dosage (1, 2, and 4?mg O3/mg C), and VUV power (30, 60, and 120?W) were investigated. Bromate concentrations formed by the ozone-VUV process were up to four and six times less than those by the ozone and ozone-UV processes, respectively. Among the variables studied, ozone dosage had the most effect on bromate formation by the ozone-VUV process. Approximately 64 and 213% increases of bromate concentration were observed when the ozone dosage was increased from 1 to 2 and 4?mg O3/mg C with VUV power of 120?W at pH 7. The bromate formation also increased as VUV power and pH increased. Hydroxyl radical exposure had a positive relationship with ozone dosage and bromate formation. Results further indicated that it might be difficult to achieve the drinking water standard for bromate and high organic matter removal concurrently.     

Effect of Temperature on Ozone Inactivation of Cryptosporidium parvum in Oxidant Demand-Free Phosphate Buffer

Ozone inactivation of Cryptosporidium parvum oocysts was studied at bench-scale in 0.05 M phosphate buffer at 1 to 37°C, pH 6–8. Animal infectivity using neonatal CD-1 mice was used for evaluation of oocyst infectiousness following treatment. Survival curves of ozone inactivation were characterized by a tail-off effect, with an initial shoulder most evident at low temperature. Temperature was a critical factor for ozone inactivation kinetics with a significant decrease of ozone efficacy at low temperature. Accounting for ozone residual stability at different pH conditions, pH was found to have no significant effect on the activation of C. parvum by ozone. Inactivation kinetics at different temperatures were expressed as an Incomplete gamma Hom model with different reaction rate constants, adjusted for water temperature using the van't Hoff-Arrhenius relationship. Between 1 and 37°C, for every 10°C decrease in the water temperature, the inactivation rate constant decreased by a factor of 2.2, corresponding to activation energy of 51.7 kJ∕mol. Ozone disinfection design criteria for 1.0 and 2.0 log-units of inactivation of Cryptosporidium were developed for various water temperatures, and 90% confidence intervals are also provided.     

Inactivation of Cryptosporidium Oocysts in a Pilot-Scale Ozone Bubble-Diffuser Contactor. II: Model Validation and Application

The axial dispersion reactor (ADR) model developed in Part I of this study was successfully validated with experimental data obtained for the inactivation of C. parvum and C. muris oocysts with a pilot-scale ozone-bubble diffuser contactor operated with treated Ohio River water. Kinetic parameters, required to model the effect of temperature on the decomposition of ozone in treated Ohio River water and oocyst inactivation, were determined from batch and semibatch ozonation experiments. The ADR model was used to simulate the effects of operating conditions (feed-gas ozone concentration, liquid flow rate, and gas flow rate), and water quality related parameters (fast ozone demand, first and second order ozone decomposition rate constants, and temperature) on the performance of the pilot-scale contactor. The model simulation provided valuable insight into understanding the performance of ozone disinfection systems and recommendations for ozone contactor design and optimization. For example, the simulation revealed that meeting inactivation requirements for C. parvum oocysts would be more challenging at relatively lower temperatures.     

Filter Sand-Phosphate Buffer Effect on 2,4-Dinitrotoluene Ozonation

The objective of this study is to evaluate the effects of different sands and phosphate buffer on ozone decomposition by measuring the observed ozone decomposition rate constant of three different natural sands at pH 7 with and without the presence of phosphate buffer and with and without sand (i.e., aqueous ozone only). In addition, this study evaluated phosphate buffer effect on the heterogeneous catalysis of ozone for the destruction of 2,4-dinitrotoluene (DNT) by measuring the observed DNT degradation rate constant (kDNT). Ozone decomposition rates in the presence of NaOH buffer and sand were up to 7.9 times greater and 3.4 times in the presence of phosphate. In the absence of phosphate, sand reduced the observed rate of DNT degradation. In the presence of phosphate, sands enhance the observed DNT degradation rate by a factor approximately proportional to their surface manganese concentration. A proposed mechanism was developed explaining the observed effects of the phosphate in a sand ozone system.