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Journal of Hazardous Materials Jun 2024Advanced oxidation processes (AOPs) based on peracetic acid (PAA) displayed great potential in removing emerging contaminants by generating HO and organic radicals....
Advanced oxidation processes (AOPs) based on peracetic acid (PAA) displayed great potential in removing emerging contaminants by generating HO and organic radicals. Performic and perpropionic acids (PFA and PPA) also act as disinfectants, but their application potential has not been investigated yet. Here, we investigated the degradation mechanism and kinetics of sulfamethoxazole (SMX) by HO, RC(O)O species (including HC(O)O, CHC(O)O and CHCHC(O)O) and RC(O)OO species (including HC(O)OO, CHC(O)OO and CHCHC(O)OO). The results show that the calculated reaction rate constants of SMX follow the order of HC(O)O > CHC(O)O > CHCHC(O)O > HO > HC(O)OO > CHC(O)OO > CHCHC(O)OO. The reactivity towards SMX is strongly correlated with the redox potentials of reactive radicals. Hence, the RCOO species play dominant roles in the purification of SMX in PFA/PAA/PPA-based AOPs. The degradation of SMX mainly proceeds via addition at the benzene ring, the hydrogen abstraction from the -NH group as well as the single electron transfer reaction. This study highlights the fundamental aspects of PFA, PAA, and PPA in the purification of sulfamethoxazole and enhances the role of organic radicals in the AOPs based on organic peracetic acids.
PubMed: 38941837
DOI: 10.1016/j.jhazmat.2024.135033 -
Inorganic Chemistry Jun 2024CYP121 is a P450 enzyme that catalyzes the intramolecular C-C coupling of its native substrate, dicyclotyrosine (cYY). According to previous suggestions, when the...
CYP121 is a P450 enzyme that catalyzes the intramolecular C-C coupling of its native substrate, dicyclotyrosine (cYY). According to previous suggestions, when the cosubstrate peracetic acid was used to generate Cpd I, the substrate cYY was suggested to participate in the cleavage of the O-O bond; however, whether cYY is involved in the formation of Cpd I and how two distant aromatic carbon atoms are activated are still unclear. Here, we constructed computational models and performed QM/MM calculations to clarify the reaction mechanism. On the basis of our calculation results, cYY is not involved in the formation of Cpd I, and the C-C coupling reaction starts from hydrogen abstraction. In the second stage, the substrate should first undergo a complex conformational change, leading to two phenolic hydroxyls of cYY close to each other. In the subsequent reaction, the resultant Cpd II again abstracts a hydrogen atom from the proximal tyrosine to generate the diradical intermediate. In addition, the C-C coupling occurs in the active site, but the final aromatization may be a nonenzymatic reaction. In general, the intramolecular C-C coupling requires two basic conditions, including the active site having good flexibility and the substrate itself having a suitable and rotatable skeleton.
PubMed: 38937145
DOI: 10.1021/acs.inorgchem.4c01943 -
Scientific Reports Jun 2024Having been successfully bred in semi-intensive and intensive aquaculture systems, oval squids of the Sepioteuthis lessoniana species complex are emerging as promising...
Having been successfully bred in semi-intensive and intensive aquaculture systems, oval squids of the Sepioteuthis lessoniana species complex are emerging as promising candidates for research and industry. Nevertheless, information about pathogens and diseases that may affect squid aquaculture remains sparse. In this study, we identify new parasitic copepod species that causes squid mortality and decreases squid hatching rates, and we also offer a solution to eliminate the pathogen during incubation of squid eggs. The newly discovered copepod Ikanecator primus gen. et sp. nov. was identified on oval squid eggs for the first time using both morphological and molecular diagnostic markers. In the genomes of the copepod and associated microbiome, we identified multiple genes for enzymes involved in cephalopod eggshell degradation in genomes of the copepod and associated microbiome. Furthermore, we conducted experiments to assess efficacy of peracetic acid in inhibiting the I. primus gen. et sp. nov. both in vitro and in vivo using immersion treatment. We established that a 2-min exposure to a concentration of 250 μl/L of peracetic acid containing product (PAA-product; 35 mg/L PAA and 15 mg/L HO) inhibited the development of nauplii in vitro. All parasites exposed to a concentration of 500 μl/L of PAA-product (70 mg/L PAA and 30 mg/L HO) were eliminated within two minutes. On top of this, the immersion treatment with 500 μl/L of PAA-product (70 mg/L PAA and 30 mg/L HO) improved survival of squid embryos and increased size of squid hatchlings compared with control and the immersion treatment with 125 μl/L of PAA-product (17.5 mg/L PAA and 7.5 mg/L HO) and the immersion treatment with 250 μl/L of PAA-product (35 mg/L PAA and 15 mg/L HO). These findings suggest that PAA holds a great potential as inhibitor and controller of parasitic copepod infections and for overall health management in cephalopod culture.
Topics: Animals; Decapodiformes; Copepoda; Peracetic Acid; Ovum; Aquaculture
PubMed: 38914681
DOI: 10.1038/s41598-024-65290-z -
Environmental Science & Technology Jun 2024Extensive research has been conducted on the utilization of a metal-based catalyst to activate peracetic acid (PAA) for the degradation of micropollutants (MPs) in...
Extensive research has been conducted on the utilization of a metal-based catalyst to activate peracetic acid (PAA) for the degradation of micropollutants (MPs) in water. Mn(II) is a commonly employed catalyst for homogeneous advanced oxidation processes (AOPs), but its catalytic performance with PAA is poor. This study showed that the environmentally friendly chelator ethylenediamine-,'-disuccinic acid (EDDS) could greatly facilitate the activation of Mn(II) in PAA for complete atrazine (ATZ) degradation. In this process, the EDDS enhanced the catalytic activity of manganese (Mn) and prevented disproportionation of transient Mn species, thus facilitating the decay of PAA and mineralization of ATZ. By employing electron spin resonance detection, quenching and probe tests, and O isotope-tracing experiments, the significance of high-valent Mn-oxo species (Mn(V)) in the Mn(II)-EDDS/PAA system was revealed. In particular, the involvement of the Mn(III) species was essential for the formation of Mn(V). Mn(III) species, along with singlet oxygen (O) and acetyl(per)oxyl radicals (CHC(O)O/CHC(O)OO), also contributed partially to ATZ degradation. Mass spectrometry and density functional theory methods were used to study the transformation pathway and mechanism of ATZ. The toxicity assessment of the oxidative products indicated that the toxicity of ATZ decreased after the degradation reaction. Moreover, the system exhibited excellent interference resistance toward various anions and humid acid (HA), and it could selectively degrade multiple MPs.
PubMed: 38913078
DOI: 10.1021/acs.est.4c00901 -
Water Research Jun 2024Krypton chloride (KrCl*) excimer lamps (222 nm) are used as a promising irradiation source to drive ultraviolet-based advanced oxidation processes (UV-AOPs) in water...
Krypton chloride (KrCl*) excimer lamps (222 nm) are used as a promising irradiation source to drive ultraviolet-based advanced oxidation processes (UV-AOPs) in water treatment. In this study, the UV/peracetic acid (PAA) process is implemented as a novel UV-AOPs for the degradation of emerging contaminants (ECs) in water. The results demonstrate that UV/PAA process exhibits excellent degradation performance for carbamazepine (CBZ), with a removal rate of 90.8 % within 45 min. Notably, the degradation of CBZ in the UV/PAA process (90.8 %) was significantly higher than that in the UV/PAA process (15.1 %) at the same UV dose. The UV/PAA process exhibits superior electrical energy per order (EE/O) performance while reducing resource consumption associated with the high-energy UV/PAA process. Quenching experiments and electron paramagnetic resonance (EPR) detection confirm that HO• play a dominant role in the reaction. The contributions of direct photolysis, HO•, and other active species (RO• and O) are estimated to be 5 %, 88 %, and 7 %, respectively. In addition, the effects of Cl, HCO, and humic acid (HA) on the degradation of CBZ are evaluated. The presence of relatively low concentrations of Cl, HCO, and HA can inhibit CBZ degradation. The UV/PAA oxidation process could also effectively degrade several other ECs (i.e., iohexol, sulfamethoxazole, acetochlor, ibuprofen), indicating the potential application of this process in pollutant removal. These findings will propel the development of the UV/PAA process and provide valuable insights for its application in water treatment.
PubMed: 38909423
DOI: 10.1016/j.watres.2024.121943 -
Water Research Jun 2024Combined sewer overflows (CSOs) introduce microbial contaminants into the receiving water bodies, thereby posing risks to public health. This study systematically...
Combined sewer overflows (CSOs) introduce microbial contaminants into the receiving water bodies, thereby posing risks to public health. This study systematically investigated the disinfection performance and mechanisms of the combined process of ultraviolet and peracetic acid (UV/PAA) in CSOs with selecting Escherichia coli (E. coli) as a target microbial contaminant. The UV/PAA process exhibited superior performance in inactivating E. coli in simulated CSOs compared with UV, PAA, and UV/HO processes. Increasing the PAA dosage greatly enhanced the disinfection efficiency, while turbidity and organic matter hindered the inactivation performance. Singlet oxygen (O), hydroxyl (OH) and organic radicals (RO) contributed to the inactivation of E. coli, with OH and RO playing the prominent role. Variations of intracellular reactive oxygen species, malondialdehyde, enzymes activities, DNA contents and biochemical compositions of E. coli cells suggested that UV/PAA primarily caused oxidative damage to intracellular molecules rather than the damage to the lipids of the cell membrane, therefore effectively limited the regrowth of E. coli. Additionally, the UV/PAA process displayed an outstanding performance in disinfecting actual raw CSOs, achieving a 2.90-log inactivation of total bacteria after reaction for 4 min. These results highlighted the practical applicability and effectiveness of the UV/PAA process in the disinfection of CSOs.
PubMed: 38909420
DOI: 10.1016/j.watres.2024.121959 -
Journal of Dairy Science Jun 2024Despite good manufacturing practices and rigorous cleaning and sanitizing procedures established in dairy processing plants, microbiological contamination remains the...
Despite good manufacturing practices and rigorous cleaning and sanitizing procedures established in dairy processing plants, microbiological contamination remains the main cause of products being non-compliant and/or atypical and hence not fit for human consumption. The objective of this study was to isolate, identify and characterize bacteria, yeasts and molds associated with substandard dairy products in Canada and to create a collection of reference isolates. In addition to conventional microbiological characterization, each isolate was tested for biofilm-forming ability and susceptibility to heat, antimicrobial agents, and common industrial disinfectants. Among the 105 microbial strains isolated from pasteurized milk, cream, and cheese samples, 24 bacterial isolates, belonging mainly to the genus Pseudomonas, were shown to be moderate or strong biofilm producers in 96-well plates and highly resistant to peracetic acid (100 ppm, 5 min contact time) and sodium hypochlorite (70 ppm, 5 min contact time). In addition, 56 bacterial isolates, including Acinetobacter baumannii, Enterobacter bugandensis, Klebsiella pneumoniae and Pseudomonas spp., were found resistant to ampicillin, fosfomycin and/or ceftriaxone, while 14 others, such as Bacillus spp. and Macrococcus spp., withstood a heat treatment equivalent to low-temperature long-time pasteurization (63°C for 30 min). This descriptive study provides new information on potential problematic microorganisms in dairies and will guide the development of novel control strategies intended to prevent and reduce microbiological contamination and the associated economic losses.
PubMed: 38908709
DOI: 10.3168/jds.2023-24506 -
ACS ES&T Water Jun 2024Combinations of UV with oxidants can initiate advanced oxidation processes (AOPs) and enhance bacterial inactivation. However, the effectiveness and mechanisms of...
Combinations of UV with oxidants can initiate advanced oxidation processes (AOPs) and enhance bacterial inactivation. However, the effectiveness and mechanisms of UV-AOPs in damaging nucleic acids (e.g., antibiotic resistance genes (ARGs)) and cell integrity represent a knowledge gap. This study comprehensively compared ARG degradation and cell membrane damage under three different UV-AOPs. The extracellular ARG (eARG) removal efficiency followed the order of UV/chlorine > UV/HO > UV/peracetic acid (PAA). Hydroxyl radical (OH) and reactive chlorine species (RCS) largely contributed to eARG removal, while organic radicals made a minor contribution. For intracellular ARGs (iARGs), UV/HO did not remove better than UV alone due to the scavenging of OH by cell components, whereas UV/PAA provided a modest synergism, likely due to diffusion of PAA into cells and intracellular OH generation. Comparatively, UV/chlorine achieved significant synergistic iARG removal, suggesting the critical role of the RCS in resisting cellular scavenging and inactivating ARGs. Additionally, flow cytometry analysis demonstrated that membrane damage was mainly attributed to chlorine oxidation, while the impacts of radicals, HO, and PAA were negligible. These results provide mechanistic insights into bacterial inactivation and fate of ARGs during UV-AOPs, and shed light on the suitability of quantitative polymerase chain reaction (qPCR) and flow cytometry in assessing disinfection performance.
PubMed: 38903200
DOI: 10.1021/acsestwater.4c00350 -
Environmental Science & Technology Jun 2024The potential of Ru(III)-mediated advanced oxidation processes has attracted attention due to the recyclable catalysis, high efficiency at circumneutral pHs, and robust...
The potential of Ru(III)-mediated advanced oxidation processes has attracted attention due to the recyclable catalysis, high efficiency at circumneutral pHs, and robust resistance against background anions (e.g., phosphate). However, the reactive species in Ru(III)-peracetic acid (PAA) and Ru(III)-ferrate(VI) (FeO) systems have not been rigorously examined and were tentatively attributed to organic radicals (CHC(O)O/CHC(O)OO) and Fe(IV)/Ru(V), representing single electron transfer (SET) and double electron transfer (DET) mechanisms, respectively. Herein, the reaction mechanisms of both systems were investigated by chemical probes, stoichiometry, and electrochemical analysis, revealing different reaction pathways. The negligible contribution of hydroxyl (HO) and organic (CHC(O)O/CHC(O)OO) radicals in the Ru(III)-PAA system clearly indicated a DET reaction via oxygen atom transfer (OAT) that produces Ru(V) as the only reactive species. Further, the Ru(III)-performic acid (PFA) system exhibited a similar OAT oxidation mechanism and efficiency. In contrast, the 1:2 stoichiometry and negligible Fe(IV) formation suggested the SET reaction between Ru(III) and ferrate(VI), generating Ru(IV), Ru(V), and Fe(V) as reactive species for micropollutant abatement. Despite the slower oxidation rate constant (kinetically modeled), Ru(V) could contribute comparably as Fe(V) to oxidation due to its higher steady-state concentration. These reaction mechanisms are distinctly different from the previous studies and provide new mechanistic insights into Ru chemistry and Ru(III)-based AOPs.
PubMed: 38899941
DOI: 10.1021/acs.est.4c02640 -
Materials (Basel, Switzerland) May 2024The sulfur in petroleum coke is harmful to carbon products, underscoring the importance of desulfurization for high-sulfur petroleum coke. This paper proposes a method...
The sulfur in petroleum coke is harmful to carbon products, underscoring the importance of desulfurization for high-sulfur petroleum coke. This paper proposes a method combining alkaline catalytic roasting with ultrasonic oxidation for the deep desulfurization of high-sulfur petroleum coke. The results show that the desulfurization rate reaches 88.99% and the sulfur content is reduced to 0.83 wt.% under a coke particle size of 96-75 μm, sodium-hydroxide-to-petroleum-coke ratio of 50%, roasting temperature of 700 °C, and holding time of 2 h. The alkali-calcined petroleum coke is ultrasonically oxidized and desulfurized in peracetic acid. The results show that, under a hydrogen peroxide content of 10%, hydrogen-peroxide-(liquid)-to-petroleum-coke (solid) ratio of 20 mL/g, acetic acid content of 5 mL, ultrasonic power of 300 W, reaction temperature of 60 °C, and reaction duration of 4 h, the sulfur content is reduced to 0.15 wt.% and the total desulfurization reaches 98.01%. Through a series of characterizations, the proposed desulfurization mechanism is verified. Alkali roasting effectively removes a significant portion of sulfur in petroleum coke. However, the elimination of certain sulfur compounds, such as the more complex thiophene, presents challenges. The thiophene content is subsequently removed via ultrasonic oxidation.
PubMed: 38893875
DOI: 10.3390/ma17112609