Degradation By-products Research Articles

Degradation of organic pollutants by the Cl-/PMS process.

The viewpoints on whether high concentrations of chloride ion (Cl-) promote or inhibit the oxidation activity of activated persulfates are still inconclusive. Furthermore, the degradation of organic pollutants by the persulfates in the presence of high Cl- concentrations without any activation medium has not yet been studied. In this work, the efficiency and mechanism of degradation of organic pollutants such as carbamazepine (CBZ), sulfadiazine (SDZ), and phenol (PN) by Cl--activated PMS (denoted as Cl-/PMS) were investigated. Results showed that Cl- could effectively activate PMS for the complete removal of CBZ, SDZ, and PN with reaction kinetic constants of 0.4516min-1, 0.01753min-1, and 0.06805min-1, respectively. Parameters such as PMS dose, Cl- concentration, solution pH, and initial concentrations of organic pollutants that affect the degradation efficiencies of the Cl-/PMS process were optimized. Unlike conventional activated persulfates, it was confirmed that the free chlorine was the main active species in the Cl-/PMS process. Finally, the degradation by-products of CBZ and SDZ as well as their toxicity were detected, and a possible degradation pathway for CBZ and SDZ was proposed. Though higher toxic chlorinated by-products were generated, the Cl-/PMS process was still an efficient oxidation method for the removal of organic pollutants in aqueous solutions which contain high concentrations of Cl-.

Mechanistic study of cefixime degradation with an atmospheric air dielectric barrier discharge – Influence of radical scavengers and metal ion catalyst

The ineffective removal of antibiotic residues and their metabolites by conventional wastewater treatment setups lead to their continuous discharge into the environment, causing risks to both aquatic life and human health. This study explored the use of a non-thermal plasma (NTP) generated by atmospheric air for the degradation of cefixime (CFX), a widely consumed and recalcitrant antibiotic. This study achieved a complete degradation of CFX using an NTP technology in 8 min treatment time at 6 kV and 20 kHz applied AC voltage and frequency, respectively using a high voltage alternating current power supply unit. An energy yield of 0.42 g/kWh was estimated. The degradation of the pollutant was influenced by solution flow rate, applied voltage and the solution characteristics. Five degradation by-products were identified based on quadrupole time-of-flight (Q-TOF) mass spectrum (MS) analysis and a possible degradation pathway for the pollutant was proposed. Also, radical scavenger experiments were set up to understand the specific chemical species facilitating CFX degradation. The effect of Fe2+ catalyst on the degradation of CFX was investigated in the aqueous solution. This low-cost metal ion catalyst has been known to improve the degradation of organic compounds by facilitating the oxidizing power of H2O2. Considering this, a new idea was examined in this study which was the degradation of the antibiotic in the presence of both Fe2+ catalyst and some radical scavengers (iso-propyl alcohol – IPA, tert-butyl alcohol – TBA, and sodium hydrogen carbonate – NaHCO3). When Fe2+ was introduced into CFX solutions containing TBA, IPA and NaHCO3, respectively, the degradation and kinetics increased by at least 33 %. In these mixed additives, the degradation of the pollutant was enhanced by the consumption of H2O2.

Low-Temperature Mineralization of Fluorotelomers with Diverse Polar Head Groups.

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants linked to harmful health effects. Currently employed PFAS destruction methods are energy-intensive and often produce shorter-chain and recalcitrant partially fluorinated byproducts. We report the mineralization of five fluorotelomer compounds via a base-mediated degradation using NaOH and mild temperatures (120 °C) in a mixture of DMSO:H2O (8:1 v/v). The studied fluorotelomers have varying polar head groups-carboxylic acids, sulfonic acids, alcohols, and phosphonic acids, which are the most common polar head groups used in commercial and industrial applications. The degradation intermediates and byproducts were characterized using 1H, 13C, and 19F NMR spectroscopy. Density functional theory computations at the M06-2X/6-311 + G(2d,p)-SMD-(DMSO) level were consistent with the observed intermediates and guided an overall mechanistic hypothesis. Degradation of each fluorotelomer occurs through a similar process, in which the nonfluorinated carbons and the first fluorinated carbon are cleaved from the remaining perfluoroalkyl fragment, which degrades through previously identified pathways. These findings provide important insight into PFAS degradation processes and suggest that PFAS containing at least one C-H bond within or adjacent to its fluoroalkyl chain can be degraded under these mild conditions. Many PFAS in current use as well as recalcitrant fluorinated byproducts generated from other PFAS degradation methods are candidates for this approach.

Investigation into the genotoxic impurity, 1-methyl-4-nitrosopiperazine, in rifampicin

This study assessed the presence of the genotoxic impurity 1-methyl-4-nitrosopiperazine (MNP) in 27 batches of rifampicin capsules obtained from 11 manufacturers in China. While they were below the temporary limit of 5 ppm set by the US Food and Drug Administration, the observed levels (0.33–2.36 ppm) exceeded the acceptable threshold of 0.16 ppm. Building upon preliminary findings and degradation experiments, we concluded that MNP is a by-product of the oxidative degradation of rifampicin or is introduced via oxidation or nitrosation during the synthesis process involving 1-methyl-4-aminopiperazine. The pathways of MNP formation were confirmed in this study. Furthermore, we observed that the addition of antioxidants, sealed storage, and selection of dominant crystal forms can aid in controlling MNP levels.

Efficient Nimesulide degradation via chlorination and sun-simulated radiation: Kinetic insights, reactive species formation, and application to real wastewater

Hypochlorite mediated oxidation had been established as an efficient process for degrading organic pollutants in water. In this research work, it was evaluated the synergistic potential of solar light irradiation combined with hypochlorite on a emerging contaminant model such as Nimesulide (NIM), a nonsteroidal anti-inflammatory drug. These experiments shown that at pH 3.0, where only hypochlorous acid (HOCl) prevails, the degradation constant of NIM exhibited an increase from 2.50 × 10−4 s−1 (under dark conditions) to 1.53 × 10−3 s−1 (sun-simulated radiation), signifying an approximately six-fold acceleration in degradation. Moreover, under approximately neutral pH value (7.5) wherein both HOCl and hypochlorite ion (ClO−) coexist, the enhancement observed was approximately twofold, in particular a mineralization up to 32 % was observed. This investigation also included quenching experiments conducted at varying pH levels, shedding light on the role of specific reactive species and their contributions to the degradation mechanism. The impact of synergistic effect between solar-simulated irradiation and hypochlorite systems on NIM degradation showcases a remarkable kinetic enhancement, particularly evident at lower pH values. The degradation byproducts have been identified via high resolution HPLC-MS and the main ion formed during the reaction have been monitored by IC-MS. Experiments in real sewage treatment plant waters using sun radiation revealed the promising potential and efficiency of this alternative method, despite a comparatively lower degradation rates when compared with UV lamp application. This approach offers a sustainable and economically advantageous solution for wastewater treatment.

Toxicity assessment of dioxins and their transformation by-products from inferred degradation pathways

Due to the significant POPs characteristics, dioxins caused concern in public health and environmental protection. Evaluating the toxicity risk of dioxin degradation pathways is critical. OCDD, 1,2,3,4,6,7,8-HpCDD, and 1,2,3,4,6,7,8-HpCDF, which are highly abundant in the environment and have strong biodegradation capabilities, were selected as precursor molecules in this study. Firstly, their transformation pathways were deduced during the metabolism of biometabolism, microbial aerobic, microbial anaerobic, and photodegradation pathways, and density function theory (DFT) was used to calculate the Gibbs free energy to infer the possibility of the occurrence of the transformation pathway. Secondly, the carcinogenic potential of the precursors and their degradation products was evaluated using the TOPKAT modeling method. With the help of the positive indicator (0–1) normalization method and heat map analysis, a significant increase in the toxic effect of some of the transformation products was found, and it was inferred that it was related to the structure of the transformation products. Meanwhile, the strength of the endocrine disrupting effect of dioxin transformation products was quantitatively assessed using molecular docking and subjective assignment methods, and it was found that dioxin transformation products with a higher content of chlorine atoms and molecules similar to those of thyroid hormones exhibited a higher risk of endocrine disruption. Finally, the environmental health risks caused by each degradation pathway were comprehensively assessed with the help of the negative indicator (1–2) standardization method, which provides a theoretical basis for avoiding the toxicity risks caused by dioxin degradation transformation. In addition, the 3D-QSAR model was used to verify the necessity and rationality of this study. This paper provides theoretical support and reference significance for the toxicity assessment of dioxin degradation by-products from inferred degradation pathways.

Selective oxidation decontamination in cobalt molybdate activated Fenton-like oxidation via synergic effect of cobalt and molybdenum

In this study, cobalt molybdate (CoMoO4) activated peracetic acid (PAA) was developed for water purification. CoMoO4/PAA system could remove 95% SMX with pseudo-first-order reaction rate constant of 0.15410 min−1, which was much higher than CoFe2O4/PAA, FeMoO4/PAA, and CoMoO4/persulfate systems. CoMoO4/PAA system follows a non-radical species pathway dominated by the high-valent cobalt (Co(IV)), and CH3C(O)OO• shows a minor contribution to decontamination. Density functional theory (DFT) calculation indicates that the generation of Co(IV) is thermodynamically more favorable than CH3C(O)OO• generation. The abundant Co(IV) generation was attributed to the special structure of CoMoO4 and effect of molybdenum on redox cycle of Co(II)/Co(III). DFT calculation showed that the atoms of SMX with higher ƒ0 and ƒ- values are the main attack sites, which are in accordance with the results of degradation byproducts. CoMoO4/PAA system can effectively reduce biological toxicity after the reaction. Benefiting from the selective of Co(IV) and CH3C(O)OO•, the established CoMoO4/PAA system exhibits excellent anti-interference capacity and satisfactory decontamination performance under actual water conditions. Furthermore, the system was capable of good potential practical application for efficient removal of various organics and favorable reuse. Overall, this study provides a new strategy by CoMoO4 activated PAA for decontamination with high efficiency, high selectivity and favorable anti-interference.

Multi-acrylamides improve bond stability through collagen reinforcement under physiological conditions

ObjectivesAcrylamides were shown to significantly improve bonding stability in adhesive restorations, but the reinforcement mechanism has not been fully elucidated. We tested the hypothesis that hydrogen bonding reinforcement of the collagen network (with secondary or tertiary acrylamides), as well as degree of crosslinking of the polymer network (with di- or tri-functional acrylamides), can be two of the factors at play. MethodsTwo-step total etch adhesives comprising UDMA (60 wt%) and 40 wt% of: TAAEA, TMAAEA (secondary, tertiary tri-acrylamides), BAAP, DEBAAP (secondary, tertiary di-acrylamides) or HEMA (mono-methacrylate - control) were formulated. Simulated composite restorations (n = 5) were tested after cyclic mechanical and biological (S. mutans biofilm) challenges. Gap formation before and after aging was assessed with SEM imaging. Micro-tensile bond strength (μTBS, n = 6) was assessed after seven-day incubation in water or S. mutans-containing culture medium. Collagen reinforcement was assessed with hydroxyproline assay (n = 10) and rheology (n = 3). Data were analyzed with one-way/two-way ANOVA/Tukey’s test (alpha=5%). ResultsGap formation increased and bond strength decreased for all monomers after biofilm incubation (p < 0.001). Except for DEBAAP, secondary and tertiary di/tri-acrylamides showed lower occlusal gap width values, but no significant differences overall gap length compared to HEMA. μTBS increased for tri-acrylamides compared with HEMA. Samples treated with multi-acrylamides had lower concentration of hydroxyproline (by-product of collagen degradation) (p < 0.001), except for DEBAAP, which showed values close to HEMA (p > 0.05). Dentin shear modulus increased for all acrylamides after 72 h, especially TMAAEA. SignificanceIn general, multi-acrylamides promote collagen reinforcement, leading to reduced gap formation, and stabilize the bond strength under physiological conditions.

A sustainable electrochemical strategy utilizing pulsed alternating current and dual carbon felt electrodes for enhanced degradation of organic pollutants: Oxidation performance and mechanisms

In this work, a novel electrochemical (EC) oxidation system utilizing pulsed alternating current (PAC) and dual carbon felt (CF) electrodes has been established for sustainable degradation of sulfamethoxazole (SMX) with no addition of extra oxidant. The EC/PAC system showed high degradation efficiency and energy efficiency compared to the pulsed direct current (PDC) and direct current (DC) systems. The EC/PAC process was effective across a wide pH range of 3–11 for SMX removal. The results showed that the 1O2 confined to the CF electrode surface was the dominant oxidative specie that was generated from dissolved oxygen in the system. Under PAC conditions, the cathode and anode were rapidly switched on the same CF electrode, increasing the generation of 1O2 for enhanced SMX oxidation. Furthermore, the EC/PAC system demonstrated resistance to interference from various anions of different concentration levels found in natural environment. In contrast to the EC/PDC system, the EC/PAC system emerged as a promising option for more efficient H2O2 production. High-resolution mass spectrometry results revealed the SMX degradation pathways and byproducts, which were then evaluated for toxicity removal. Overall, the EC/PAC system offers a green and sustainable solution to future wastewater treatment, with high degradation rates, energy efficiency, and sustainability.

Recyclable and biodegradable bio-based polyurethane elastomers with exceptional mechanically properties

Bio-based polyurethanes (BPUs) have garnered significant attention due to their sustainable nature and potential to replace conventional petroleum-based PUs. This study delves into the synthesis, characterization, and application of a novel BPU variant, BPUPEG, derived from A-B-A triblock polyols. DSC tests highlighted the crystallization properties of the PEG block within BPUPEG, setting it apart from other BPU samples. Structural insights were further obtained from POM and WAXS tests, revealing the nanocrystalline structures and differences among the BPU samples. Mechanical testing showcased BPUPEGs superior fracture stress and strain, emphasizing its enhanced mechanical properties. Biodegradation experiments were conducted, underscoring the environmentally benign nature of all BPUs, with BPUPEG demonstrating a slower hydrolysis rate attributed to its PEG crystalline phase. Importantly, BPUPEGs degradation byproducts were ascertained to be non-toxic, emphasizing its eco-friendly attributes. The study also explored BPUPEGs recyclability, confirming its potential for multiple reuse cycles without degradation in mechanical properties. In conclusion, BPUPEG emerges as a sustainable, high-performance BPU, holding promise for diverse applications in the future, aligning with global sustainability and carbon reduction goals.

Comparative Kinetic Analysis of Triclosan Degradation under UV-C and Simulated Solar Irradiation

This research delves deeply into the intricate degradation kinetics of triclosan, employing two distinct methodologies: UV and simulated solar irradiation. Through a comprehensive comparative analysis, the study endeavors to elucidate the efficacy of these techniques, aiming to shed light on their respective methodological strengths and limitations. The study compares the efficacy of UV and simulated solar irradiation techniques for triclosan degradation, revealing that both methods exhibit effectiveness in degrading triclosan, with variations observed in degradation rates and byproduct formation. Through a detailed examination of the kinetics of triclosan degradation, the study reveals the intricate pathways and mechanisms involved in the photodegradation process. Results highlight the influence of irradiance levels and residence times on degradation efficiency. The research identifies optimal conditions for triclosan degradation, emphasizing the importance of residence time and irradiance levels. Results show that a residence time of 4 h and an irradiance level of 450 W m−2 maximize degradation efficiency. Analysis of degradation byproducts provides insights into the transformation pathways of triclosan under UV and simulated solar irradiation, indicating the formation of 2,4-dichlorophenol, quinone, and hydroquinone as primary byproducts.

Degradable π-Conjugated Polymers.

The integration of next-generation electronics into society is rapidly reshaping our daily interactions and lifestyles, revolutionizing communication and engagement with the world. Future electronics promise stimuli-responsive features and enhanced biocompatibility, such as skin-like health monitors and sensors embedded in food packaging, transforming healthcare and reducing food waste. Imparting degradability may reduce the adverse environmental impact of next-generation electronics and lead to opportunities for environmental and health monitoring. While advancements have been made in producing degradable materials for encapsulants, substrates, and dielectrics, the availability of degradable conducting and semiconducting materials remains restricted. π-Conjugated polymers are promising candidates for the development of degradable conductors or semiconductors due to the ability to tune their stimuli-responsiveness, biocompatibility, and mechanical durability. This perspective highlights three design considerations: the selection of π-conjugated monomers, synthetic coupling strategies, and degradation of π-conjugated polymers, for generating π-conjugated materials for degradable electronics. We describe the current challenges with monomeric design and present options to circumvent these issues by highlighting biobased π-conjugated compounds with known degradation pathways and stable monomers that allow for chemically recyclable polymers. Next, we present coupling strategies that are compatible for the synthesis of degradable π-conjugated polymers, including direct arylation polymerization and enzymatic polymerization. Lastly, we discuss various modes of depolymerization and characterization techniques to enhance our comprehension of potential degradation byproducts formed during polymer cleavage. Our perspective considers these three design parameters in parallel rather than independently while having a targeted application in mind to accelerate the discovery of next-generation high-performance π-conjugated polymers for degradable organic electronics.

An analytical view of disinfectant degradation and disinfection by-product formation

An analytical view of disinfectant degradation and disinfection by-product formation

Activation of peroxymonosulfate by CoS2 loaded air-laid cloth for rapid degradation of organic pollutants in a shallow continuous flow reactor

Activation of peroxymonosulfate by heterogeneous catalyst is an efficient process for organic pollutants removal. However, it is difficult for solid-liquid separation of the heterogeneous catalysts in slurry-like batch reaction. In this work, CoS2 particles were deposited onto an air-laid cloth (denoted as CoS2-ALC) and were used as a catalyst for activation of peroxymonosulfate (PMS). Unlike traditional slurry-like batch reaction forms, a shallow continuous flow reactor was designed for the installation of a CoS2-ALC, thereby improving the activation efficiency of persulfate and rapid solid-liquid separation. The degradation kinetics constant for carbamazepine (CBZ) by the CoS2-ALC/PMS process was 0.0748 min−1, which is 374, 150, 150 times higher than that the CoS2-ALC adsorption process, PMS/ALC oxidation process and PMS alone process, respectively. The significantly enhanced degradation efficiency was due to the S in CoS2 promoting the cycling of Co2+/Co3+, thereby enhancing the generation of free radical. Parameters such as CoS2 deposition amount, PMS concentration, water flow rate, water flow height, water flow direction, solution pH, humic acid and anions that affecting the degradation efficiencies were studied. In addition, the degradation by-products of CBZ as well as their toxicity were detected, and a possible degradation pathway were proposed. Finally, expanded outdoor experiments and cycling experiment demonstrated that the CoS2-ALC/PMS process is potentially useful in practical settings of wastewater treatment.

Comparison of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS) removal in a combined adsorption and electrochemical oxidation process

This study focused on three of the most studied PFAS molecules, namely perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS). They were compared in terms of their adsorption capacity onto graphite intercalated compound (GIC), a low surface area, highly conductive and cheap adsorbent. The adsorption on GIC followed a pseudo second order kinetics and the maximum adsorption capacity using Langmuir was 53.9 μg/g for PFOS, 22.3 μg/g for PFOA and 0.985 μg/g for PFBS due to electrostatic attraction and hydrophobic interactions. GIC was added into an electrochemical oxidation reactor and >100 μg/L PFOS was found to be fully degraded (<10 ng/L) leaving degradation by-products such as PFHpS, PFHxS, PFPeS, PFBS, PFOA, PFHxA and PFBA below 100 ng/L after 5 cycles of adsorption onto GIC for 20 min followed by regeneration at 28 mA/cm2 for 10 min. PFBS was completely removed due to degradation by aqueous electrons on GIC flakes. Up to 98 % PFOA was removed by the process after 3 cycles of adsorption onto GIC for 20 min followed by regeneration at 25 mA/cm2 for 10 min. When PFBS was spiked individually, only 17 % was removed due to poor adsorption on GIC. There was a drop of 3–40 % by treating PFOS, PFOA and smaller sulfonates in a real water matrix under the same electrochemical conditions (20 mA/cm2), but PFOS and PFOA removal percentage were 95 and 68 % after 20 min at 20 mA/cm2.

Minocycline-loaded nHAP/PLGA microspheres for prevention of injury-related corneal angiogenesis

BackgroundCorneal neovascularization (CoNV) threatens vision by disrupting corneal avascularity, however, current treatments, including pharmacotherapy and surgery, are hindered by limitations in efficacy and adverse effects. Minocycline, known for its anti-inflammatory properties, could suppress CoNV but faces challenges in effective delivery due to the cornea's unique structure. Therefore, in this study a novel drug delivery system using minocycline-loaded nano-hydroxyapatite/poly (lactic-co-glycolic acid) (nHAP/PLGA) nanoparticles was developed to improve treatment outcomes for CoNV.ResultsUltra-small nHAP was synthesized using high gravity technology, then encapsulated in PLGA by a double emulsion method to form nHAP/PLGA microspheres, attenuating the acidic by-products of PLGA degradation. The MINO@PLGA nanocomplex, featuring sustained release and permeation properties, demonstrated an efficient delivery system for minocycline that significantly inhibited the CoNV area in an alkali-burn model without exhibiting apparent cytotoxicity. On day 14, the in vivo microscope examination and ex vivo CD31 staining corroborated the inhibition of neovascularization, with the significantly smaller CoNV area (29.40% ± 6.55%) in the MINO@PLGA Tid group (three times daily) than that of the control group (86.81% ± 15.71%), the MINO group (72.42% ± 30.15%), and the PLGA group (86.87% ± 14.94%) (p < 0.05). Fluorescein sodium staining show MINO@PLGA treatments, administered once daily (Qd) and three times daily (Tid) demonstrated rapid corneal epithelial healing while the Alkali injury group and the DEX group showed longer healing times (p < 0.05). Additionally, compared to the control group, treatments with dexamethasone, MINO, and MINO@PLGA were associated with an increased expression of TGF-β as evidenced by immunofluorescence, while the levels of pro-inflammatory cytokines IL-1β and TNF-α demonstrated a significant decrease following alkali burn. Safety evaluations, including assessments of renal and hepatic biomarkers, along with H&E staining of major organs, revealed no significant cytotoxicity of the MINO@PLGA nanocomplex in vivo.ConclusionsThe novel MINO@PLGA nanocomplex, comprising minocycline-loaded nHAP/PLGA microspheres, has shown a substantial capacity for preventing CoNV. This study confirms the complex's ability to downregulate inflammatory pathways, significantly reducing CoNV with minimal cytotoxicity and high biosafety in vivo. Given these findings, MINO@PLGA stands as a highly promising candidate for ocular conditions characterized by CoNV.Graphical

Enhanced degradation of Direct Red 80 dye via Fenton-like process mediated by cobalt ferrite: generated superoxide radicals and singlet oxygen.

Azo dyes, widely used in the textile industry, contribute to effluents with significant organic content. Therefore, the aim of this work was to synthesize cobalt ferrite (CoFe2O4) using the combustion method and assess its efficacy in degrading the azo dye Direct Red 80 (DR80). TEM showed a spherical structure with an average size of 33 ± 12nm. Selected area electron diffraction and XRD confirmed the presence of characteristic crystalline planes specific to CoFe2O4. The amount of Co and Fe metals were determined by ICP-OES, indicating an n(Fe)/n(Co) ratio of 2.02. FTIR exhibited distinct bands corresponding to Co-O (455cm-1) and Fe-O (523cm-1) bonds. Raman spectroscopy detected peaks associated with octahedral and tetrahedral sites. For the first time, the material was applied to degrade DR80 in an aqueous system, with the addition of persulfate. Consistently, within 60min, these trials achieved nearly 100% removal of DR80, even after the material had undergone five cycles of reuse. The pseudo-second-order model was found to be the most fitting model for the experimental data (k2 = 0.07007 L mg-1min-1). The results strongly suggest that degradation primarily occurred via superoxide radicals and singlet oxygen. Furthermore, the presence of UV light considerably accelerated the degradation process (k2 = 1.54093 L mg-1min-1). The material was applied in a synthetic effluent containing various ions, and its performance consistently approached 100% in the photo-Fenton system. Finally, two degradation byproducts were identified through HPLC-MS/MS analysis.

Construction of ternary AuPt/Bi2WO6/ZnIn2S4 heterostructures for photocatalytic degradation of tetrabromobisphenol A

How to fascinate the separation of the photogenerated electrons and holes is very crucial to enhance the photocatalysis of semiconductors. Herein we have prepared AuPt/BWO/ZIS heterostructured photocatalysts by decorating Bi2WO6 (BWO) nanoflakes and AuPt nanoparticles on the surface of ZnIn2S4 (ZIS) hierarchical microspheres. The photocatalysis of the samples was evaluated by degrading tetrabromobisphenol A under simulated-sunlight illumination. It is demonstrated that the ternary AuPt/BWO/ZIS photocatalysts exhibit obviously enhanced photocatalysis in comparison with bare BWO and ZIS as well as the binary BWO/ZIS photocatalysts. The highest photocatalysis is observed for 3%AuPt/40%BWO/ZIS, whose photodegradation performance is improved by 3.9 and 6.2 times over that of single BWO and ZIS, respectively. This phenomenon can be explained due to several reasons: the photocarriers are efficiently separated due to the charge transfer across the BWO/ZIS and AuPt/ZIS interfaces, surface plasmon resonance of AuPt nanoparticles stimulate ZIS to produce additional electron/hole pairs, and the SPR-induced electrons in the AuPt nanoparticles could also take part in the photocatalysis. Additionally, the effect of various factors on the tetrabromobisphenol A degradation was investigated; the degradation pathways of tetrabromobisphenol A and the potential toxicity of the degradation by-products were evaluated.

Effective degradation of organophosphorus pesticide by photo-Fenton and in-situ recovery/utilization of the generated phosphorus: Dual function of iron ions

Efficient recovery and utilization of the generated phosphorus during the process of organophosphorus pesticides degradation is promising but still challenging. In this study, a photo-Fenton-crystallization sequential processes were developed to achieve the degradation of organophosphorus pesticides and simultaneous recovery/utilization of the generated phosphate. In this system, iron ions exhibited dual functionality: activator of the photo-Fenton reaction and crystallizing agent of the generated phosphate and the crystals obtained were proved to be vivianite by X-ray Diffraction and Scanning Electron Microscopy. The results showed that a trichlorfon degradation rate exceeding 90% and a vivianite yield of 85.1% was achieved. Parameters such as pH and the Fe-P ratio play pivotal roles in phosphorus recovery efficiency from wastewater. In addition, the toxicity of the degradation by-products was much less than that of trichlorfon by the Toxicity Estimation Software Tool. Additionally, the recovered vivianite exhibits advantageous catalytic properties to activate peroxymonosulfate for the degradation of different pollutants. This study provides a novel perspective for the treatment and utilization of organophosphorus pesticides.

Influence of incubation period on membrane patch color for insoluble contaminant measurement in degraded hydraulic oils

Insoluble contaminants and varnish, resulting from oil degradation byproducts and sometimes depleted additive molecules, are initiated primarily due to thermal stress on the oil. This poses significant challenges in tribology, particularly for the lubrication systems of modern complex machinery, leading to severe debilitating effects such as loss of operating clearances and impaired heat transfer. Addressing varnish buildup is crucial, and timely oil analysis emerges as a valuable tool, offering essential insights into the oil degradation level and the potential presence of insoluble contaminants. Among the various laboratory testing methods available to assess varnish potential, colorimetric analysis, specifically Membrane Patch Colorimetry (MPC), is widely applied owing to its efficiency and cost-effectiveness. This study extends the application of MPC test principles, commonly utilized for turbine oils, to measure insoluble contaminants generated by degraded hydraulic fluids. Adhering to the ASTM D7843-21 standard, which stipulates the precision of this testing method for turbine oils is contingent upon the sample’s incubation period, our investigation focuses on exploring modifications to the standard 72-hour incubation period. We aim to assess the viability of shortening or extending this duration for conducting MPC tests on used hydraulic fluids, thereby potentially enhancing the precision and relevance of MPC tests in hydraulic fluid analysis.