Degradation Process Research Articles

Properties and kinetic behavior of free and immobilized laccase from Oudemansiella canarii: Emphasis on the effects of NaCl and Na2SO4 on catalytic activities

Studies have highlighted the great potential of Oudemansiella canarii laccase in degrading synthetic dyes for reducing their toxicity. Immobilization of enzymes improves usability in degradation processes and the present work succeeded in immobilizing this laccase onto MANAE-agarose. Immobilization improved pH, thermal, and storage stabilities. Both, free and immobilized enzymes presented Michaelis-Menten kinetics with the substrate 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with Km values of 0.056 ± 0.003 and 0.195 ± 0.022 mM, respectively. Immobilization increased Vmax 1.27-fold. NaCl caused incomplete (hyperbolic) inhibition, which was satisfactorily described by the one-substrate one-modifier mechanism. Immobilization reduced the maximal inhibition by NaCl from 80.2 to 55.7 %. The effect of Na2SO4 was predominantly stimulation, but inhibition of the free enzyme occurred at high substrate concentrations. Stimulation of the immobilized enzyme by Na2SO4 was much more pronounced. It strongly depended on the substrate concentration and was much stronger (up to 300 %) at low substrate concentrations. The combined effects of substrate and sulfate on the immobilized laccase could be satisfactorily described by the one-substrate one-modifier mechanism. The modified response of the immobilized O. canarii laccase to NaCl and Na2SO4 considerably favors its use as a tool in bioremediation processes because environmental contamination by salts frequently represents a strong operational challenge.

Removal of antibiotics from aquaculture wastewater using a continuous flow/EC/PMS coupled system

The electricity activated peroxomonosulfate (ion) coupled system (EC/PMS) has important application value in water pollution treatment. However, the traditional batch system commonly used in this coupled system poses significant challenges in treating large volume and low concentration aquaculture wastewater, such as poor mass transfer, long treatment time, and increased risk of secondary pollution. Therefore, this study proposed to introduce the continuous flow operation mode into the EC/PMS system to form a continuous flow electrocatalytic peroxomonosulfate (ion) (CF/EC/PMS) coupling system, achieving 100 % removal of tetracycline (TC) with an initial concentration of 2 mg/L. Subsequently, through cathodic optimization, an 85 % removal efficiency was achieved for antibiotics with secondary pollution risks, such as norfloxacin and NOR. It is worth noting that the secondary pollutants (such as fluoride ions, F−) generated during the degradation process have also successfully achieved a removal efficiency of 70 %. In this system, singlet oxygen (1O2) was the main active species. This system has advantages such as a processing volume of at least 3L, a wide pH range (3–9), low oxidant dosage (PMS = 2 mM), and low energy consumption (EEO = 0.018 kWh/m3 log). The coupling system effectively removes the main pollutants, and the optimized cathode coupling system achieves safe removal of fluorinated drugs, reducing the risk of secondary pollution. In summary, this study has the characteristics of low cost and engineering applicability, providing a promising method for economically, efficiently, and environmentally friendly treatment of aquaculture wastewater.

A remaining useful life prediction method of aluminum electrolytic capacitor with adaptive degradation model selection

The degradation process of aluminum electrolytic capacitors(AECs) usually exhibits characteristics such as non-linearity and multi-stage. These degradation features lead to the difficulty to accurately predict the remaining useful life(RUL) of the whole degradation process of AECs. To address this, by dividing the capacitor degradation process into two stages, a two-stage RUL prediction method for AECs considering multiple degradation models is proposed in this paper.In the offline parameter estimation phase, the initial degradation model parameters of two stages are estimated using two-step maximum likelihood estimation combined with particle swarm optimization(PSO) algorithm. In the dynamic parameter updating phase, a sequential Bayesian method is used to update the model parameters. To select the optimal degradation model, an evaluation method based on historical RUL similarity is proposed to calculate the fitness of each model. Finally, the effectiveness of the method is verified on NASA’s accelerated degradation data set and several widely used methods are used for comparison. The experimental results show that the proposed method has higher accuracy, which proves the superiority of the method.

Multi-axial fatigue of high-strength concrete: Model-enabled interpretation of punch-through shear test response

This paper aims to fill the gap in multi-axial fatigue characterization of concrete by presenting a comprehensive numerical analysis of data from the punch-through shear test (PTST), which allows control over combined shear and compression loads in the tested ligament. To accurately reproduce the degradation process in this multi-axial configuration, a material model must capture two key effects: (i) dissipative behavior at the inter-aggregate level during subcritical pulsating loading and (ii) fatigue-induced tri-axial stress redistribution in the test ligament. The recently published MS1 model by the authors effectively incorporates these features, thereby enabling a deeper interpretation of the experimental data. The former effect is seamlessly integrated into the model using the Lemaitre-type fatigue hypothesis, facilitating the direct derivation of general evolution equations. The latter effect is efficiently represented through the microplane homogenization framework. The model’s predictions for PTST response under monotonic shear loading with varying levels of radial confinement align well with experimental results. Similarly, the simulated fatigue response accurately reproduces the experimentally observed S-N (Wöhler) curves. Further studies demonstrate the model’s ability to predict the effect of fatigue loading sequence. A thermodynamically-based formulation provides an energetic interpretation of this effect, offering a quantitative breakdown of energy dissipation attributed to individual dissipative mechanisms over the lifetime of the material. The studies show that damage-induced dissipation remains almost constant regardless of different fatigue loading histories.

Type-II heterojunction Se-g-C3N4/ZnO coupled MnCo2O4 photocatalyst for enhanced levofloxacin hydrochloride degradation activated by peroxymonosulfate

The advanced oxidation process induced by photocatalysis under visible light undoubtedly possesses greater application potential and cost-effectiveness due to the high excitation energy supply costs. Here, we proposed a novel Type-II heterojunction Se-g-C3N4/ZnO (Se-CN/ZnO) and MnCo2O4 (MCO) photocatalyst for the efficient degradation of levofloxacin hydrochloride (LEV) activated by peroxymonosulfate (PMS) under sunlight. Analysis results confirmed the oxidation process was executed by Se-CN/ZnO synergistic MCO-activated PMS for the responsive degradation of LEV, achieving a removal efficiency greater than 98.6 % within 15 min (kinetic rate constant Kobs = 0.299 min−1), under optimal conditions ([Se-CN/ZnO (300 °C)]0 = 46 mg, [MCO]0 = 1.6 mg, [PMS]0 = 0.27 mM, [Aeration rate]0 = 146 mL/min, pH = 5.5). Effective interfacial transfer and spatial segregation of the photogenerated electron-hole were attributed to the stabilized Type-II energy band structure of Se-CN/ZnO, the rapid cyclic redox of metal ions Mnn+(n = 2,3,4) and Com+(m = 2,3) promoted the activation of PMS reduction of LEV through synergistic action of various endogenous substances. Analysis of the contribution of reactive oxygen species by electron paramagnetic resonance substantiated the dominant role of ·OH and O2·-, and the superiority of the degradation process was further validated with the analysis of the non-toxic and ecological safety characteristics of intermediates. The recommended method of eco-friendly and stable catalytic performance of LEV has engineering application prospects that are incomparable to many publicly available treatment methods.

Deep Variational Network Toward Blind Image Restoration.

Blind image restoration (IR) is a common yet challenging problem in computer vision. Classical model-based methods and recent deep learning (DL)-based methods represent two different methodologies for this problem, each with their own merits and drawbacks. In this paper, we propose a novel blind image restoration method, aiming to integrate both the advantages of them. Specifically, we construct a general Bayesian generative model for the blind IR, which explicitly depicts the degradation process. In this proposed model, a pixel-wise non-i.i.d. Gaussian distribution is employed to fit the image noise. It is with more flexibility than the simple i.i.d. Gaussian or Laplacian distributions as adopted in most of conventional methods, so as to handle more complicated noise types contained in the image degradation. To solve the model, we design a variational inference algorithm where all the expected posteriori distributions are parameterized as deep neural networks to increase their model capability. Notably, such an inference algorithm induces a unified framework to jointly deal with the tasks of degradation estimation and image restoration. Further, the degradation information estimated in the former task is utilized to guide the latter IR process. Experiments on two typical blind IR tasks, namely image denoising and super-resolution, demonstrate that the proposed method achieves superior performance over current state-of-the-arts.

Electrochemical activation of periodate with graphite electrodes for degradation of high concentrations of thiocyanogen (SCN−) in mineral processing tail liquid

Cyanide has been widely used in gold extraction due to its cost-effectiveness, high selectivity and recovery. Regrettably, its wide application also leads to the presence of a large amount of thiocyanogen (SCN−) in the tail liquid of mineral processing plants, which affects the quality of the effluent water, and thus poses a threat to the ecological environment and human health. This paper investigates the degradation of high concentration of SCN− in water using electrochemical oxidation/periodate (E-GP/PI) system. A degradation rate of 90.25 % of SCN− was achieved by optimising various operating parameters. The effects of organic matter and typical heavy metal ion concentrations on the degradation of SCN− were investigated, and it was found that Cu2+ was able to promote the degradation of SCN− through the formation of stable complexes with SCN−, which enhanced the degradation rate to 96.48 %. However, the presence of Octadecyltrimethylammonium bromide (OTAB) and butylxanthin hindered the degradation process, where 500 mg/L of OTAB reduced the degradation rate of SCN− to 80.88 %, while 100 mg/L of butylxanthin reduced the degradation rate to 78.66 %. On this basis, experiments were carried out using real wastewater samples and SCN− degradation efficiencies of about 90 % were obtained. Afterwards, through electron paramagnetic resonance analysis, free radical burst, ion chromatograph and other research techniques, IO3 and O2– were obtained as the main drivers of SCN− degradation and SCN− degradation pathways were elucidated. Finally, the E-GP/PI system was shown to be effective in reducing the ecotoxicity of SCN− by increasing the 24-h LC50 from 12.5 % to 48.5 % in a toxicity test with daphnia. This study provides a new idea for the green and efficient treatment of SCN− rich beneficiation tail liquid.

Continuous-flow degradation of Orange I using CoFe2O4-loaded activated carbon catalyst: Optimization of reaction parameters and toxicity prediction

Orange I (OI) azo dyes produce toxic aromatic compounds in water, making solutions an important issue. In this study, we employed the urea combustion method to load CoFe2O4 particles onto activated carbon (CFO-AC-500). Subsequently, the catalyst was incorporated into a column continuous flow device, testing the effects of multi water parameters and toxicity, and predicting the degradation process on the catalytic degradation of OI for peroxymonosulfate (PMS) activation. In CFO-AC-500/PMS continuous reactor, it showed a satisfied OI removal of more than 82 % of the OI at a flow rate of 73.6 mL/min in 240 min. Also, response surface methodology (RSM) was employed to optimize the operating conditions, with model fitting results demonstrating that the OI removal rate could reach 95.07 % under specific conditions. ESR analyses revealed that the degradation of OI was primarily governed by free radicals (SO4•-, HO• and O2•-) and non-radical pathways (1O2). The biological toxicity of degraded OI was significantly reduced. This innovative CFO-AC-500/PMS continuous flow system can provide an effective new method for the degradation of difficult-to-treat pollutants in practical applications.

Kinetics of continuously catalyzed peroxymonosulfate in a fixed-bed reactor

Most studies have been conducted in batch reactors. Therefore, understanding the catalytic reaction kinetics and mass transfer in continuous catalytic reactors is essential for the design of heterogeneous catalysts and optimisation of catalytic degradation processes in heterogeneous systems. In this research, granular catalysts (Co-600/AlSi-0.25/AP) is used to investigate the kinetic constants and mass transfer resistance for the continuous catalytic decomposition of peroxymonosulfate (PMS) and degradation of p-nitrophenol (PNP) in a fixed bed reactor. The flow rate is 5 mL/min and reaction temperature is 30 °C, intrinsic kinetic constants of PMS decomposition and PNP degradation are 48 and 195 kg−1·min−1·L, respectively, which are 20–30 times of the apparent kinetic constants of PMS decomposition and PNP degradation in fixed bed reactors, respectively. The decomposition rates of PMS and PNP are controlled by mass transfer, and the reaction takes place in the diffusion-controlled regime. The mass transfer kinetic model based on the plug-flow model shows a good agreement between the calculated data and the experimental data. Which indicate that PMS decomposition and pollutant degradation in a fixed-bed reactor can be predicted by mass transfer kinetic modelling, guide the design of catalysts and the optimisation of heterogeneous catalytic reaction system in a fixed-bed reactor.

Novel 3D plate-like g-C3N4/BiOCl heterojunction as a highly efficient photocatalyst for the degradation of carbofuran in wastewater under visible light irradiation

The g-C3N4/BiOCl (gCN-BCl) heterojunction photocatalyst was synthesized using a low-temperature precipitation method for effective photocatalytic degradation of carbofuran (CBF). All gCN-BCl composites demonstrate greater efficacy in removing CBF compared to its individual constituents. The synergistic effect of incorporating the 0D structured BiOCl onto the 2D structured g-C3N4 was comprehensively examined using various microscopic, X-ray, and spectroscopic analytical techniques. Additionally, optical and photoelectrochemical analyses were conducted. The findings validated that the interaction between the two semiconductors at the heterointerfaces enhanced remarkable physical and structural stability, promoted high charge separation and transfer properties, and improved photocatalytic degradation. Under optimal conditions, 5-gCN-BCl (0.25 g/L) achieved a CBF (5 mg/L) removal efficiency of 95.7 % under visible light irradiation of 120 min, achieving 3.1- and 5.9-times higher degradation rate than the pure BiOCl and g-C3N4, respectively. The radical trapping experiments indicated that the h+ and •O2− were the primary reactive species involved in the CBF degradation. Furthermore, the potential toxicity of CBF and its intermediates was assessed, revealing that the photocatalytic degradation process significantly lowered the ecotoxicity of pesticide wastewater. The potency of 5-gCN-BCl was also evaluated in tap water and real wastewater samples, with CBF degradation efficiencies of 85.8 %, 47.6 %, and 38.7 % in tap water, municipal, and pesticide industry wastewater, respectively. Additionally, artificial neural network (ANN) modeling was employed to predict and optimize the photocatalytic degradation process, providing further insights into the system’s performance. The outcomes of this work offer valuable insights into the development of heterojunction photocatalysts with superior stability and efficacy for eliminating pesticides from water bodies.

Mobilization and enrichment of geogenic iodine in a floodplain groundwater system: New insights from sources and characterization of dissolved organic matter.

High iodine groundwater occurs widely in the lower reaches of Yellow River floodplain, which has aroused public concern. The biogeochemical behavior of dissolved organic matter (DOM) plays a crucial role in the mobilizing iodine from aquifer media. In this study, the molecular composition of DOM in groundwater characterized by FT-ICR-MS, and the optical properties of organic matter obtained by combining three-dimensional fluorescence spectroscopy and parallel factor analysis (EEM ⁃ PARAFAC), were used to elucidate the effect of DOM on the migration and enrichment of iodine in groundwater in the eastern Henan Plain, which is located in the lower reaches of Yellow River floodplain, Northern China. The results show that，the total iodine concentration in groundwater in the study area is ranged from 4.68 to 1598 μg/L, and the average value was 216.4 μg/L. High iodine groundwater shows a distribution pattern along the Paleochannels of Yellow River, which is closely related to the richness of organic matter in the buried sediments of the Paleochannels of Yellow River. Organic matter in the sedimentary aquifers plays an important role in regulating the mobilization and enrichment of iodine, and its degradation process is conducive to the release of iodine. DOM components in high iodine groundwater are more homogeneous, more unsaturated, and has more aromatic molecules than those in low iodine groundwater. The activation of organic iodine in groundwater system may be accompanied by the degradation of N+ aliphatic compounds (CHON, CHONSP and CHON) and the formation of oxygen-poor highly unsaturated phenols (CHOSP, CHOP and CHOS) organic compounds. In addition to biodegradation, the adsorption of iron oxide rich in sedimentary aquifers can partially remove the high AI and O/C components of DOM in groundwater and enrich the remaining OPHUP components. The findings provide new insights into the coupling mechanism between iodine release and DOM in aquifers.

Investigation of removing orange II azo dye from wastewater through an oxidation process

Rapid industrial growth in Bangladesh, especially in the textile industry, has led to water pollution from toxic azo dyes like orange-II, which are harmful to ecosystems and enter the food chain via irrigation. This study examined the use of chemical coagulation (using C6H11NO4X2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{C}}_{6} {\ ext{H}}_{11} {\ ext{NO}}_{4} {\ ext{X}}_{2}$$\\end{document} and FeCl3·6H2O\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{FeCl}}_{3} \\cdot 6{\ ext{H}}_{2} {\ ext{O}}$$\\end{document}) and advanced oxidation process (using NaOCl\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NaOCl}}$$\\end{document}) to treat orange-II dye for irrigation. However, C6H11NO4X2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{C}}_{6} {\ ext{H}}_{11} {\ ext{NO}}_{4} {\ ext{X}}_{2}$$\\end{document} and FeCl3·6H2O\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{FeCl}}_{3} \\cdot 6{\ ext{H}}_{2} {\ ext{O}}$$\\end{document} showed limited effectiveness in removing orange-II dye across various pH (3, 6, 9, and 12) levels. In contrast, NaOCl\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NaOCl}}$$\\end{document} achieved significant dye removal rates of over 90–99%. The study focused on high color removal, limited ClO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{ClO}}_{2}$$\\end{document} and neutral pH after the test. Variables included NaOCl\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NaOCl}}$$\\end{document} doses (0.5 ml, 2.5 ml, and 5 ml), orange II dye doses (50 mg, 100 mg, and 150 mg) under different pH (3, 6, 8, 9 and 12) conditions. The manuscript is the first to assess orange-II dye using higher doses (2.5 ml and 5 ml) of NaOCl\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NaOCl}}$$\\end{document} compared to other studies, as an alkaline chemical to neutralize pH levels post-test. The highest dye removal occurred at pH 9 with similar results at other pH levels except pH 12. However, despite effective color removal, the pH remained alkaline at pH 8, 9, and 12 after the test. Hence, optimal experimental conditions of operational parameters were pH = 3 or 6, 2.5 ml NaOCl\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NaOCl}}$$\\end{document} dose with 100 mg/L or 150 mg/L dye doses. Further research is recommended on the degradation process, toxicological analysis of the final product, and cost-effectiveness for safe irrigation water.

Identification of fibrosis-associated lncRNAs in diabetic cardiomyopathy patients.

Our study endeavours to ascertain the plasma-derived long noncoding ribonucleic acids (lncRNA) and messenger RNA (mRNA) expression profiles through gene microarray analysis, aiming to elucidate their potential biological roles in the development and progression of diabetic cardiomyopathy (DCM), particularly with respect to myocardial fibrosis. We conducted gene chip experiments to discern differences in lncRNA and mRNA expression profiles between diabetic cardiomyopathy and type 2 diabetes mellitus (T2DM). Differentially expressed mRNAs were subjected to functional enrichment analysis, thereby enabling the identification of key genes. Subsequently, we established an interaction network connecting lncRNAs with mRNAs. To validate myocardial fibrosis-related mRNAs, we further developed a rat model of diabetic cardiomyopathy. We identified 688 differentially expressed lncRNAs and 341 differentially expressed mRNAs, which were primarily enriched in creatine metabolism, small guanosine triphosphate hydrolase (GTPase)-mediated signal transduction, and fatty acid degradation processes. Our analyses revealed 8 core genes (SMD11, DRG1, RPS26, EIF2S1, UBE3A, CEBPZ, NUP153, and EMD) associated with diabetic cardiomyopathy. An investigation into the lncRNA-mRNA coexpression network underscored 4 lncRNAs (lnc-NEK10-3, lnc-KDM4A-2, lnc-PCYOX1-3, and lnc-CDCP2-1) as significantly linked to differentially expressed fibrosis-associated mRNAs. The expression levels of transmembrane protein 173 (TMEM173) and toll-like receptor 7 (TLR7) were found to be significantly higher in DCM compared to normal controls, whereas cathepsin L1 (CTSL) and forkhead box O3 (FOXO3) displayed significantly lower expression levels relative to those of normal controls. Our study disclosed a subset of lncRNAs and mRNAs that are implicated in diabetic cardiomyopathy and myocardial fibrosis, thereby presenting themselves as promising biomarkers and therapeutic targets for the management of both diabetic cardiomyopathy and myocardial fibrosis.

Quantitative Effects of Ecuadorian Silicon-Aluminum Materials on the Degradation Rate and Mechanical Strength Enhancement of Recycled Polyethylene

This study presents an innovation in the use of a native Ecuadorian nanoporous material known as allophane for the reprocessing of greenhouse plastics to obtain a functional polymer that allows for reuse, improving its mechanical properties and/or increasing its lifespan. By achieving this objective, three problems are simultaneously addressed: 1) the need to recycle used plastics in a prominent Ecuadorian flower company committed to environmental preservation, 2) the scientific viability work carried out by the Central University of Ecuador, and 3) the industrial application of recycled plastics and pellet production. Blown film extrusion was used to prepare low-density polyethylene sheets with different amounts of Ecuadorian allophane microparticles (30±5 micrometers) (0.1%, 0.3%, and 0.5% by weight). Mechanical property studies were conducted following ASTM D 882 standards, and thermal stability was characterized using thermogravimetry. The results showed an increase in elongation at break and Young's modulus percentages as the concentration of the additive increased, demonstrating its physical-chemical compatibility. Additionally, the effect on the polymer’s thermal degradation was analyzed, resulting in a directly proportional relationship between activation energy and the concentration of the material. Finally, these results demonstrate that allophane as an additive enhances the mechanical properties of recycled low-density polyethylene (12-36%) and accelerates its thermal degradation process, reducing environmental impact.

Reliability analysis for binary Lévy degradation processes using characteristic functions

AbstractMany engineering systems experience complex degradation processes along with random shocks that often pose a risk to the safe and reliable operations of the system. The analysis of dependence among multiple degradation processes has been a challenging task in the field of reliability engineering. To study dependence behaviors and jump uncertainties among degradation processes, one of the effective approaches is to model these degradation processes using multidimensional Lévy subordinators. However, a critical obstacle arises in determining the convergent mathematical form of the reliability function under Lévy measures and distributions. To obtain a closed form of reliability function, this study investigates the Lévy measure and the characteristic function of multiple dependent degradation processes. Each degradation process is modeled by a one‐dimensional Lévy subordinator utilizing the marginal Lévy measure and characteristic function. The dependence among all dimensions is described by the Lévy copula and the associated multidimensional Lévy measure. For a two‐dimensional case, we derive the reliability function and probability density function (PDF) from the characteristic function and the inverse Fourier transform. Numerical examples are provided to demonstrate the proposed models for reliability and lifetime analysis of multidimensional degradation processes in engineering systems.

Upcycling of steel slag to activate persulfate for the degradation of chlortetracycline hydrochloride: performance and mechanism

ABSTRACT Steel slag has great potential as an Fe-based heterogeneous Fenton-like catalyst because of its high iron content and low cost. However, the iron compounds are often encapsulated by calcium or silicon compounds in the steel slag. Herein, steel slag powder was acid-modified with salicylic acid to remove some Ca–Si compounds and thus expose more iron active sites. The results showed that the calcium content significantly decreased from 36.33 to 20.54% after modification, and more transition metals of Fe and Mn with catalytic activities were exposed simultaneously. During the activation of peroxysulphate, the conversion of Fe(Ⅱ) to Fe(Ⅲ) occurs and large amounts of •OH and 1O2 are produced as the main reactive oxygen species. The removal rates of CTC and TOC are 93.42 and 46.05%, respectively, and a degradation process may also be inhibited by CO32−, H2PO4−, and humic acid (HA). The degradation pathways of CTC mainly include both dechlorination and demethylation. In addition, salicylic acid-modified steel slag shows good repeated usability, and its removal ability is maintained at higher than 80% after four times of recycling. This study provides a new idea for designing an efficient and cheap catalyst to treat organic wastewater.

Oxidative degradation of chitosan by Fe-MCM-41 heterogeneous Fenton-like system

We herein disclosed an efficient multiphase Fenton-like catalytic system for oxidative degradation of chitosan. By utilizing Fe-MCM-41, featured with regular mesoporous structure and high specific surface area, the activation efficiency of H2O2 was significantly enhanced and the chitosan degradation efficiency proved by 28.1% higher than the conventional system using H2O2 alone. Under optimized conditions (5 g/L chitosan, 0.5 g/L Fe-MCM-41, 0.16 mol/L CH3COOH, 0.86 mol/L H2O2, 50 °C, 140 min), the viscosity reduction rate of chitosan reached an impressive 98.2%. Among the catalysts tested, Fe-MCM-41 with a loading factor of x = 0.12 demonstrated optimal degradation performance. After four recycles, the degradation efficiency maintained > 93.6%, demonstrating its excellent stability and recyclability for potential industrial applications. Kinetic studies provided further elucidation of the reaction mechanism, which indicated that the degradation process of chitosan followed a first-order kinetic model, with an apparent activation energy (Ea) of 48.91 kJ/mol. This novel and efficient strategy for chitosan degradation, addressed the challenges of catalyst recovery and secondary pollution typically associated with traditional Fenton systems, and posed broad application potential for polysaccharide material processing.

Degradation of norfloxacin by the synergistic effect of micro-nano bubbles and sodium hypochlorite: kinetics, influencing factors and pathways.

This study thoroughly investigated the degradation of norfloxacin (NOR) under the influence of micro-nanobubbles (MNBs) and sodium hypochlorite (NaClO), focusing on their synergistic effects. The impact of various environmental factors, including NaClO concentration, pH, inorganic anions, and surfactants, on NOR degradation efficiency within the MNBs/NaClO system was systematically assessed. The basic properties of the MNBs/NaClO system and the degradation kinetics of NOR were explored. The degradation products and pathways of NOR were explored to reveal the degradation mechanism of antibiotics in the MNBs/NaClO system by employing density functional theory (DFT) and high-performance liquid chromatography-mass spectrometry (HPLC-MS). The redox potential of the MNBs/NaClO system exhibited significantly superior properties than the single system, with bubble sizes predominantly in the nanoscale. The degradation kinetics of NOR adhered to a pseudo-first-order reaction model, with optimal degradation occurring at a 0.025% NaClO volume concentration. Acidic conditions promoted the degradation of NOR, and alkaline conditions inhibited the degradation of NOR. Inorganic anions PO43-, HCO3-, and CO32- in the water matrix led to strong inhibition of NOR degradation. Cationic surfactants accelerated the degradation process of NOR, while anionic and nonionic surfactants had a consistent inhibitory effect on the degradation of NOR. Based on the degradation behavior, three potential pathways for NOR degradation were proposed: quinolone group transformation, defluorination reaction, piperazine ring cracking and quinolone ring decomposition. This research contributes a novel technical approach for addressing antibiotic pollution and offers a theoretical framework for understanding the fate of antibiotics in the environment.

Analysis of fatigue degradation process and modelling of an elliptical crack in the locking system of a PET bottle blower

In the dynamic world of Polyethylene Terephthalate (PET) bottle production, ensuring the reliability of blow molding machines is paramount, particularly the locking mechanisms that endure significant cyclic loads during operation. This study investigates the fatigue degradation and crack propagation within the locking system of a two-cavity, 2-liter PET bottle blow molder. By modeling an elliptical crack in the most stressed component, we explore the complex stress distribution and the impact of repeated opening and closing cycles on the system’s integrity. Utilizing advanced finite element analysis (FEA), our research provides a comprehensive understanding of the stress intensity factors and safety margins under varying loading conditions. The results not only enhance predictive maintenance strategies but also offer valuable insights into extending the operational lifespan of these machines, thereby improving safety and reliability in industrial applications. This study opens new avenues in the field of component lifespan prediction. By combining artificial intelligence, machine learning, and innovative materials, it aims to improve the reliability and lifespan of PET blow molders.

Green biogenic synthesis of magnetite nanoparticles from indigenous banksia ashbyi leaf for enhanced sonochemical dye degradation

Abstract Developing alternative green and sustainable technologies to prevent, reduce, and remove dyes present in effluents generated by the textile industry is of global importance. Since, elevated levels of dyes present a significant biological hazard due to their toxicity toward aquatic life and ecosystems in general. In this study, magnetite (Fe3O4) nanoparticles (MNPs) were successfully synthesized using a co-precipitation method that used indigenous Banksia Ashbyi (BA) leaf extracts to modulate the particle size and size distribution. The MNPs were identified and characterized by UV–visible spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, thermo-gravimetric analysis (TGA), and electron microscopy. FTIR analysis showed the characteristic peak at 551 cm-1, which signified the presence of the Fe–O bond, hence MNPs. Analysis of the UV–visible spectrum revealed a board absorption band and an optical band-gap energy of 2.65 eV. Microscopy revealed that the MNPs were spherical and tended to agglomerate, while XRD analysis confirmed their crystalline nature, with the smallest crystallite size determined to be between 16 and 18 nm. The catalytic activity of MNPs by themselves and in the presence of ultrasonic irradiation for the degradation of a commercially available navy blue RIT was demonstrated by using UV-visible spectroscopy and kinetic modeling. This study found that there was a synergistic effect when ultrasonic irradiation was used during the dye degradation process, which increased the percentage of dye removal to 89.8% within 25 minutes. These results suggest that the synthesized MNPs have the potential to treat wastewater containing commercial organic dyes.