Peracetic Acid Solution Research Articles

Evaluation of self-heating models for peracetic acid using calorimetry

Abstract Thermal analysis of peracetic acid (PAA) with respect to the explosive properties was performed using calorimetry. The exothermic characteristics and thermal runaway profiles of PAA solutions were acquired through differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2). The results revealed significant enthalpy changes and gas eruption for PAA solutions that were subjected to free-radical induced and autocatalytic reactions. The reaction kinetics and order of various PAA solutions were elucidated using calorimetry.

Processability and mechanical properties of bioplastics produced from decoloured bloodmeal

AbstractBloodmeal is a protein‐rich coproduct of the meat industry and can be converted into a thermoplastic. A solution of peracetic acid can be used to degrade colored compounds in bloodmeal, yielding a light yellow material. This causes an increase in β‐sheets in the protein's secondary structure, but the addition of sodium dodecyl sulfate (SDS) and triethylene glycol (TEG) reduced α‐helical and β‐sheet content, thereby increasing random coils. Without SDS, chains were less capable of folding into these structures, preventing sufficient intermolecular interactions and chain entanglement, leading to low specific mechanical energy input (SME) during extrusion, and poor consolidation. The whiteness of molded samples showed no correlation with SME during extrusion or the degree of consolidation after extrusion; however, they were observed to have a higher level of whiteness with increasing TEG content and should be considered as a secondary process not directly linked to extrusion. Increasing the amount of water during extrusion increased the Young's modulus (E) by facilitating formation of new interactions, while increasing TEG decreased E as a result of plasticization. The action of SDS on destabilizing electrostatic and hydrophobic interactions was beneficial to extrusion, although it had no further effect during injection molding. TEG had virtually no effect on tensile strength, although it was required for flow and facilitated the formation of strong interactions after water had been evaporated during conditioning.

Influence of peracetic acid modification on the physicochemical properties of activated carbon and its performance in the ozone-catalytic oxidation of gaseous benzene

Coal based activated carbon (AC) was pretreated by peracetic acid solution and used for supporting Mn catalyst towards oxidation of gaseous benzene by catalytic ozonation. The as-obtained activated carbon was characterized by XPS, BET, SEM, and TG technologies. It indicates that peracetic acid solution modification not only raised the quantity of chemisorbed oxygen or water, and hydroxyl group on activated carbon material surface, but also increased the specific surface area and benzene adsorption capacity of activated carbon. Benzene could be completely removed in 300min and CO2 selectivity reached to 61.9% over Mn/AC-modified catalyst. A possible catalytic ozonation mechanism of activated carbon which was treated by peracetic acid solution supported Mn catalyst for oxidation of benzene was proposed.

Identification and biocide susceptibility of dominant bacteria after cleaning and disinfection of broiler houses

Hygiene in animal production is key for both farm management and food safety. Cleaning and disinfection (C&D) of broiler houses is essential to manage farm hygiene. Still high levels of total aerobic flora after C&D in broiler houses are reported. However, little is known about the microbial composition after cleaning (AC) and after disinfection (AD). In addition, the question why some bacterial species/isolates are still present AD whereas others are killed remains.The study was carried out in 4 broiler houses. Sampling was performed AC and AD. The disinfectant was based on hydrogen peroxide and peracetic acid. Enumerations were carried out for total aerobic flora, Enterococcus spp. and Enterobacteriaceae. The dominant bacteria present was assessed by (GTG)5 analysis and 16S rRNA gene sequence analysis. Moreover, minimum bactericidal concentration (MBC) tests were carried out on 18 selected isolates belonging to the Enterobacteriaceae family and 10 Enterococcus faecium isolates.A wide variety of bacteria were detected AC and AD. In total, 363 and 255 isolates were identified AC and AD, respectively, resulting in a total of 109 identified species. The most dominant bacteria belonged to Brevibacterium, Brachybacterium, and Staphylococcus AC and Bacillus, Brevibacterium, and Staphylococcus AD. At both sampling moments, Enterococcus faecium was dominant among the Enterococcus spp. isolates. On the selective medium for Enterobacteriaceae, the genera Enterobacter and Pantoea and Aeromonas (non Enterobacteriaceae) were dominant AC while Escherichia, Lelliottia, and Pantoea were dominant AD. In addition, species pathogenic to poultry and humans were identified not only AC but also AD. MBC results showed no trend in selection of less susceptible isolates for the used disinfectant AD compared to AC. Finally, the recommended concentration of the disinfectant (i.e., 0.5% commercial solution of hydrogen peroxide and peracetic acid) seemed too low to kill Enterobacteriaceae.

Nanocellulose Produced from Rice Hulls and its Effect on the Properties of Biodegradable Starch Films

Rice hull is a residue from agro-industry that can be used to produce nanocellulose. We produced nanocellulose from rice hulls through bleaching (with a 5% NaOH solution followed by a peracetic acid solution) and acid hydrolysis at a mild temperature (45oC) followed by ultrasonication. We investigated the microstructure, crystallinity and thermal stability of these materials and studied their effects on the properties of starch films. After bleaching, the compact structure around the cellulosic fibers was removed, and the lignin content of the residue decreased from 7.22 to 4.22%. The obtained nanocellulose presented a higher crystallinity (up 70%), higher thermal stability than the raw material and lignin contents below 0.35%. The nanocellulose formed interconnected webs of tiny fibers (< 100 nm in diameter), which decreased the opacity, water vapor permeability and improved the mechanical properties when added as reinforcement in the starch films.

Biofilm-producing ability and efficiency of sanitizing agents against Prototheca zopfii isolates from bovine subclinical mastitis

The objectives of the present study were to evaluate (1) the capacity of the microalga Prototheca zopfii isolated from subclinical bovine mastitis cases to form biofilms; and (2) the resistance of these isolates to sanitizing agents. Ten isolates of P. zopfii from cows with subclinical mastitis (somatic cell count >200×103 cells/mL), distributed in 5 dairy farms, were evaluated for their capacity to form biofilms in polystyrene microplate assays and stainless steel coupons, at 25°C and 37°C ± 1°C. Prototheca zopfii were isolated from milk samples via microbiological culture and analyzed by 18S rRNA gene sequencing. Biofilm formation on the coupons was observed by scanning electron microscopy. The resistance to sanitizing agents was assessed using the biofilm-forming P. zopfii isolates in stainless steel coupon assays, which were subjected to 3 sanitizers: peracetic acid, sodium hypochlorite, and iodine solution. To evaluate resistance to the sanitizers, the minimum inhibitory concentration (MIC) technique was performed using decreasing concentrations of the sanitizing agents (20, 10, 5, 2.5, 1.25, 0.625, 0.312, 0.156, 0.078, 0.039, and 0.019g/L). After inoculating the isolates, all concentrations were evaluated at 3 distinct incubation periods (24, 48, and 72 h) to assess the effect of incubation time on the MIC. Using the polystyrene microplate assays, 1 isolate showed weak biofilm production, 5 moderate, and 4 strong, when incubated at 25°C ± 1. For isolates incubated at 37°C ± 1, 6 showed weak biofilm production and 4 moderate. All P. zopfii isolates (n=10) had the capacity to form biofilms on stainless steel coupons. The longer the incubation period of the P. zopfii isolates at different dilutions, the greater the concentrations of sanitizer needed to prevent growth of the microalgae under the tested conditions. We detected a significant effect of sanitizer and time of incubation (24, 48, and 72 h) on MIC values against P. zopfii isolates. The isolates were sensitive in vitro to peracetic acid (MIC90 ≥0.019g/L), sodium hypochlorite (MIC90 ≥0.312g/L), and iodine solution (MIC90 ≥0.625g/L), after 24 h of incubation (where MIC90=concentration needed to inhibit 90% of isolates). Of the tested sanitizers, peracetic acid had the greatest efficiency against P. zopfii. We conclude that P. zopfii isolates are capable of biofilm production, which may contribute to their persistence in a milking and dairy environment.

Fatores relacionados à troca das soluções de desinfecção dos aparelhos endoscópicos

Objective: To identify the factors related to the replacement of disinfection solutions of endoscopes devices. Method: A quantitative study carried out at an endoscopy service in the city of Belo Horizonte, belonging to the Brazilian National Health System, in the period from March 28, 2012 to March 20, 2013. It was carried out a documentary analysis of test records for daily monitoring of chemical disinfection processes in that particular sector. Descriptive statistics were used with frequency distribution and central trend measurements. Results: The following factors related to the replacement of the disinfecting solution of peracetic acid were identified: minimum solution concentration inferior to the required (75%), volume below the ideal amount (15%), presence of deposits and accidental solution spillage, both at 5%. The extra cost estimated on the unnecessary exchanges reached 66.6%. Conclusion: There is a prior need to review the planning and protocols of the service.

Thermal hazards of a green antimicrobial peracetic acid combining DSC calorimeter with thermal analysis equations

Peracetic acid (PAA) is a widely used green antimicrobial agent of the environmental protection chemicals, whose registered applications have expanded to include in sanitation at food processing and pasteurizers in beverage plants, agricultural premises, wineries and breweries, as well as the disinfection of medical supplies, to prevent biofilm formation in pulp industries, and as a water purifier and disinfectant. The thermal reactivity and hazard characteristics were evaluated for PAA solutions by calorimetry analysis methodology, where the thermal reaction and kinetic data were programmed by differential scanning calorimetry. The thermal stability screening test was able to determine the self-decomposition of PAA solutions, and to observe the initial exothermic temperature (Ti) and heat of decomposition (ΔHd). The thermokinetic parameters of PAA were also calculated according to the experimental data by temperature programming and thermal analysis model with Arrhenius equation. The purpose of this study was to elucidate the self-heating exothermic excursions associated with the various PAA solutions via C++ programming language. Understanding the thermal decomposition hazard of PAA was beneficial to proactive safety protocol for the industrial process, storage, as well as transportation.

Peracetic acid oxidation of saline waters in the absence and presence of H ₂O ₂: secondary oxidant and disinfection byproduct formation.

Peracetic acid (PAA) is a disinfectant considered for use in ballast water treatment, but its chemical behavior in such systems (i.e., saline waters) is largely unknown. In this study, the reactivity of PAA with halide ions (chloride and bromide) to form secondary oxidants (HOCl, HOBr) was investigated. For the PAA-chloride and PAA-bromide reactions, second-order rate constants of (1.47 ± 0.58) × 10(-5) and 0.24 ± 0.02 M(-1) s(-1) were determined for the formation of HOCl or HOBr, respectively. Hydrogen peroxide (H2O2), which is always present in PAA solutions, reduced HOCl or HOBr to chloride or bromide, respectively. As a consequence, in PAA-treated solutions with [H2O2] > [PAA], the HOBr (HOCl) steady-state concentrations were low with a limited formation of brominated (chlorinated) disinfection byproducts (DBPs). HOI (formed from the PAA-iodide reaction) affected this process because it can react with H2O2 back to iodide. H2O2 is thus consumed in a catalytic cycle and leads to less efficient HOBr scavenging at even low iodide concentrations (<1 μM). In PAA-treated solutions with [H2O2] < [PAA] and high bromide levels, mostly brominated DBPs are formed. In synthetic water, bromate was formed from the oxidation of bromide. In natural brackish waters, bromoform (CHBr3), bromoacetic acid (MBAA), dibromoacetic acid (DBAA), and tribromoacetic acid (TBAA) formed at up to 260, 106, 230, and 89 μg/L, respectively for doses of 2 mM (ca. 150 mg/L) PAA and [H2O2] < [PAA]. The same brackish waters, treated with PAA with [H2O2] ≫ [PAA], similar to conditions found in commercial PAA solutions, resulted in no trihalomethanes and only low haloacetic acid concentrations.

Antimicrobial activity of Chlorhexidine, Peracetic acid and Sodium hypochlorite/etidronate irrigant solutions against Enterococcus faecalis biofilms.

To evaluate the antimicrobial effect of 2.5% sodium hypochlorite alone (NaOCl) and associated with 9% HEBP (NaOCl/HEBP), 2% peracetic acid (PAA) and 2% chlorhexidine (CHX), on the viability of Enterococcus faecalis biofilms attached to dentine. Biofilms of E.faecalis were grown on the surface of dentine blocks for 5days and then exposed to the irrigating solutions for 3min. Distilled water was used as the control. The total biovolume and the percentage of dead cells of the infected dentine were measured by means of confocal microscopy and the live/dead technique. Nonparametric tests were used to determine statistical differences (P<0.05). NaOCl and the NaOCl/HEBP mixture were associated with a significantly greater percentage of dead cells, followed by PAA (P<0.05). No significant antimicrobial effect of CHX was observed in comparison with the control group. Total biovolume decreased significantly in NaOCl, NaOCl/HEBP and PAA solutions in comparison with the CHX and control groups. NaOCl alone or associated with HEBP were the most effective irrigant solutions in dissolving and killing E.faecalis biofilms.

Influence of Concentration and Agitation of Sodium Hypochlorite and Peracetic Acid Solutions on Tissue Dissolution.

To evaluated the tissue dissolution of sodium hypochlorite (NaOCl) and peracetic acid (PA) solutions at different concentrations, with or without ultrasonic agitation. The following solutions were analyzed: 2.5% NaOCl, 0.5, 1 and 2% PA, 1% PA associated with 6.5% hydrogen peroxide (HP) and saline. Fragments of bovine pulp tissue with 25 ± 2g mg were immersed into test tubes containing 4 mL of the solutions for 10 minutes. In the groups with agitation, pulp tissues were submitted to 2 cycles of 1 minute of ultrasonic agitation. The specimens were weighed after the removal from the solutions. The percentage of mass loss was calculated according to the difference of mass before and after exposure to solutions. Data were submitted to ANOVA and Tukey tests (p < 0.05). A total of 2.5% NaOCl with or without agitation showed the higher tissue dissolution (between 64.5 and 67% of mass reduction) (p < 0.005). By comparing the PA solutions, the concentrations of 1 and 2% with or without agitation and the concentration of 0.5% with agitation showed similar dissolution activity (between 35.4 and 44% of mass reduction). The use of the ultrasonic agitation promoted an increase of the dissolution ability only for 0.5% PA. Peracetic acid solution has pulp tissue dissolution. However, this ability is lower than 2.5% NaOCl solution. The sodium hypochlorite solution shows higher ability to dissolve tissue than PA.

Selective Oxidation of Methane to Methanol with Organic Oxidants Catalyzed by Iodine in Non-Aqueous Acetic Acid Medium

Various organic oxidants including tert-butyl peroxybenzoate, tert-butyl hydroperioxide (TBHP), hydrogen peroxide-urea adduct, dicumyl peroxyide and peracetic acid solution were studied for the oxidation of methane to methanol via methyl acetate catalyzed by iodine in non-aqueous acetic acid medium. Among these organic oxidants investigated, tert-butyl hydroperioxide (TBHP) exhibited the highest methane conversion. The effects of various kinetic factors on the catalytic behavior of the TBHP-I2 system were investigated, and a quantitative yield of methyl acetate (18.9%) based on methane has been obtained under the optimized conditions. A possible mechanism involving electrophilic displacement has been suggested for this reaction.

Force decay in orthodontic elastomeric chains after immersion in disinfection solutions

Aim: To evaluate the force decay of orthodontic elastomeric chains after immersion in disinfecting solutions. Methods: One-hundred and fifty segments of elastomeric chains were divided in 3 groups: Control group – no disinfection; Chlorhexidine group - disinfection in 0.12% chlorhexidine digluconate solution; and Peracetic acid group - disinfection in 0.2% peracetic acid solution. Elastomeric chains of 14 mm were stretched up to 20 mm and the given force (kgf) was evaluated in an Instron universal testing machine at the following intervals: 1 h, 1 day, 7, 14, 21 and 28 days after the immersion in the disinfecting solutions. Data (kgf) were analyzed statistically by Analysis of Variance and Tukey’s test at a 5% significance level. Results: Both groups presented similar force decay along 7 days and remained stable up to 28 days. Force degradation was observed in the first hours of activation (~50%). Conclusions: It may be concluded that there were no significant differences among the investigated groups, in most interval times, indicating that both chemical solutions can be used for previous disinfection of orthodontic elastomeric chains.

Evaluation of 0.5% peracetic acid and 2.5% sodium hypochlorite on smear layer removal of root canal instrumented by three rotary systems

Objective: The aim of this study was to evaluate the effect of 0.5% peracetic acid solution and 2.5% sodium hypochlorite solution on smear layer removal of root canal walls after rotary instrumentation. Material and methods: Sixty single-rooted human teeth with standardized length had their canals instrumented by three rotary systems (Biorace, MTwo and Endowave), varying the irrigation solution, as follows (n=10): G1- Biorace System + 0.5% peracetic acid solution; G2- Biorace System + 2.5% sodium hypochlorite solution; G3- MTwo System + 0.5% peracetic acid solution; G4- MTwo System + 2.5% sodium hypochlorite solution; G5- Endowave System + 0.5% peracetic acid solution; G6- Endowave System + 2.5% sodium hypochlorite solution. After instrumentation, the roots were cleaved and the dentin walls were evaluated by SEM at x500 and x2000 magnification for assessing the cleaning of the root canals at the cervical, middle and apical thirds. The analyzed area was quantified according to the total number of tubules present and the percentage of open tubules at each region. Data were submitted to statistical analysis by ANOVA and Tukey tests, at the significance level of 5%. Results: There were no statistical significant differences among the experimental groups. In all groups the smear layer removal at cervical and medium thirds was higher than that of apical third. Conclusion: It was concluded that the cleaning obtained at the apical third was lower in all groups studiedand neither the instrumentation technique nor the irrigating solution was able to promote total smear layer removal from root canal walls. KEYWORDS: Peracetic acid; Root canal irrigants; Scanning electron microscopy; Sodium hypochlorite.

Comparison of Physicochemical Characteristics of Microcrystalline Cellulose from Four Abundant Kenyan Biomasses

Microcrystalline cellulose (MCC) powders extracted from banana stem, rice straws, water hyacinth and papyrus reeds were investigated for their physicochemical properties. Preparation of the MCC was carried out using the alkali hydrolysis process followed by further treatment using peracetic acid. The lignocellulosic biomasses were first treated with aqueous sodium hydroxide to remove lignin and hemicelluloses followed by further treatment with a solution of peracetic acid at 80 0 C for 2 hours to remove residual lignin and hemicellulose. The obtained cellulose was then bleached with 20% hydrogen peroxide to whiten the products. Further treatment of cellulose with 2.5N hydrochloric acid converted it into microcrystalline cellulose. MCC from rice straws was modified with citric acid and its characteristics compared to unmodified cellulose. Physical characteristics of the microcrystalline cellulose were determined by obtaining the bulk densities, tapped densities, Carr's index, Hausner's ratio and wettability. Further characterization was done using FTIR spectrophotometer, Differential Scanning Calorimeter, Thermal Gravimetric Analysis and Scanning Electron Microscope (SEM). Apart from the SEM micrographs, MCC parameters of the four biomasses determined were

The Role of Peracetic Acid in Bloodmeal Decoloring

AbstractHydrogen peroxide (HP) can degrade soluble heme, forming yellow or colorless degradation products. Thermal treatment during bloodmeal production changes the conformation of oxyhemoglobin trapping heme in hydrophobic protein regions or forms methemoglobin (metHb) heme which catalytically removes HP. As a result, HP can only degrade a portion of the heme present in bloodmeal leading to poor decoloring. Equilibrium peracetic acid (PAA) solutions can effectively decolor bloodmeal. This work assessed the ability of PAA to decolor bloodmeal and the mechanism by which it occurs. The inability of HP to decolor bloodmeal is determined by the fact that it is unable to permanently degrade metHb heme, or hydrophobically trapped heme. Addition of organic acids to HP led to significant swelling of the protein chains but also to poorer decoloring and lower HP consumption compared to PAA. This suggested that in the case of PAA solutions, where bleaching was facile, the reason PAA solutions are capable of decoloring bloodmeal was due to the action of the PAA molecule against heme, whereas HP and acetic (ethanoic) acid played only minor roles in total bleaching. The decolored protein powder has reduced odor and whiter color, and is suitable for applications such as bioplastics.

800 - Morphological analysis of gutta-percha points subjected to different treatments and influence on obturation sealing

Objective: This study evaluated the morphological changes in scanning electron microscopy (SEM), which occur on the surface of gutta-percha points at times exceeded those recommended. Methods: 2% chlorhexidine (CLX), 2.5% sodium hypochlorite (NaOCl), 2%peracetic acid (PA) and 0.25% peracetic acid (SAP) solutions were used in periods of 1 minute, 30 minutes, 6 hours and 12 hours. Groups were divided according to the solution and disinfection period (n=12). Results: The results indicated that there was statistically significant difference between the solutions and periods tested. In 1 minute, all solutions do not differ from the control. After 30 minutes, the SAP significantly alter the morphology of the points. The test energy dispersive spectrometry (EDS) indicated that all the solution periods alter the chemical composition of gutta-percha points. The relationship of disinfection on microleakage of filling was also evaluated in groups that suffered disinfection for 12 hours. The SAP group showed statistically significant difference compared to control, because 100% of its roots showed infiltration. The other groups of CLX, NaOCl and AP, although not statistically significant, were respectively 9, 8 and 8 out of 12 of his roots with infiltration. Conclusion: Concluded that the disinfection process can cause morphological changes if the immersion period is exceeded and that, in addition to altering the chemical composition of gutta-percha, these solutions can influence the sealing of the filling.

Study on Sterile Anti-Shedding UV Ink Used on PE Bottle Cap

Sterile anti-shedding UV ink used on PE bottle cap was developed. The ink can be soaked in peracetic Acid solution with the concentration at 1800ppm for four hours’ sterilization under the constant temperature 90 °C, and there was no deinking phenomenon. The ink was prepared by mixed experimental method. The influence of prepolymer, monomer and photoinitiator on the UV ink properties such as curing speed, adhesion and solvent resistance were discussed. The optimum formulation of this sterile ink was as follow: PEA is 22.5%, PUA is 22.5%, TMPTA is 13.5%, DPGDA is 13.5%, 907 is 3%, ITX is 3%, carbon soot is 18%, defoamer is 4%. Under this condition, the properties of UV curing ink were as follow: curing time 10s, adhesion level 3 and good solvent resistance. The ink was an environmental ink used on plastic bottle cap.

Validation of peracetic acid as a sporicide for sterilization of working surfaces in biological safety cabinets

Objectives: This study aimed to validate the use of peracetic acid as sporicide agent to decontaminate the working surface of a laminar flow biological safety cabinet (BSC), as an alternative to glutaraldehyde, including the selection of the disinfecting agent, the method of application, and the contact time. Materials and methods: The test organism was the spore-forming bacterium Bacillus atrophaeus ATCC 9372, which is a surrogate for an important infectious agent. Spore cultures were prepared from B. atrophaeus and used them to test the sporicidal efficacy of peracetic acid on a BSC stainless steel surface. The performance of the sterilant was assessed by determining minimal inhibitory concentration (MIC) and by microbial challenge in conditions that mimicked surface contamination. It was used 2.0% glutaraldehyde solution as the control. Results: The range of MICs was 0.6-1.1% for the control and 0.003n0.006% for the 0.2% peracetic acid solution. The 0.2% peracetic acid was an effective sterilant against B. atrophaeus spores (6-7 log spores, under defined conditions of use) after 40 min contact time, which was double that recommended on the product label. Conclusion: It was conclude that while the results of official methods can help to evaluate how products will perform, they are not usually reproducible in real-life user conditions and environments. Validation tests must be carried out to ensure the efficacy and safety of surface decontamination procedures.

Effect of NaCl on the Corrosion of Cold Rolled Steel in Peracetic Acid Solution

Effect of NaCl on the Corrosion of Cold Rolled Steel in Peracetic Acid Solution