First-order Reaction Kinetic Model Research Articles

Degradation of ribavirin by Fe2+/PS oxidation technology: performance, mechanism and toxicity control

During the COVID-19 pandemic, the extensive use of ribavirin (RBV) raised concerns about its environmental residues and associated risks, necessitating remedial actions. This study investigates the degradation efficiency, mechanism, and biotoxicity of RBV using ferrous (Fe2+) activated persulfate (PS) advanced oxidation technology (Fe2+/PS oxidation). Experiments conducted under various conditions revealed that at pH = 3, PS concentration of 4 mM, PS/Fe2+ molar ratio of 2:1, and citric acid of 0.5 mM with Fe2+ added twice, the degradation rate of RBV reached 98.70 %. The degradation process of RBV by Fe2+/PS from 0 to 5 mins followed a first-order reaction kinetics model. The presence of halide ions (Cl-, Br-, I-) was found to inhibit the degradation efficiency. The active species involved were identified as SO4-·, ·OH, 1O2, and FeO2+, with SO4-· and ·OH being the most significant. Moreover, the products of ribavirin were determined and their degradation pathways were proposed. Dehydration, deamidation, C-N bond breaking and hydroxylation were the major pathways. Additionally, toxicity assessment showed that Fe2+/PS oxidation reduced the inhibition rate of bioluminescence in Vibrio fischeri from 31.58 % to 3.88 %, effectively controlling RBV toxicity during the reaction. This study provides insights into managing water environmental risks associated with pharmaceutical residues in the post-pandemic era.

Preparation and Properties of Cotton Fabric Photocatalyzed by Ag-Doped Madder-Sensitized TiO2

In this study silver nanoparticles (NP) were grown in-situ on the surface of madder-sensitized TiO2 by an in-situ reduction method using silver nitrate as a silver source and a honeysuckle extract as a reducing agent. Silver doped madder-sensitized TiO2 nanoparticles were then prepared, supported on the surface of cotton fabrics to prepare photocatalytic cotton fabrics with high-efficiency self-cleaning properties and excellent antibacterial properties. transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses showed that elemental Ag NPs were deposited on the surface of the madder-sensitized TiO2, and that Ag-doped madder-sensitized TiO2 NPs were successfully loaded on the cotton fabric surface. The results of UV-Visible diffuse reflectance spectroscopy (UV-Vis-DRS) and Photoluminescence Spectroscopy (PL) showed that Ag-doping could further reduce the band gap of madder-sensitized TiO2 than pure TiO2. The absorption of light in the photocatalytic system was increased, and the recombination of electron-hole pairs was effectively inhibited. Compared with madder-sensitized TiO2 photocatalyzed cotton fabric, the degradation rate of nano-Ag-doped madder-sensitized TiO2 photocatalytic cotton fabric for methylene blue (MB) was increased by 10.66% within 2 h, and the degradation process was in line with the first-order reaction kinetic model. After 5 times of washing, the photocatalytic cotton fabric still had excellent photocatalytic performance. Its antibacterial rates against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reached 100 and 99.99%, respectively. In addition, it had good wrinkle resistance and UV protection properties, but the cross-linking modification reduced the breaking strength by about 14%.

Changes in food quality and characterization under thermal accumulation conditions during Chinese cooking.

Chinese cooking is the primary treatment method for table food in China. The process is complex and large-scale, which is important to the macroeconomy and national nutrition and health. First, this article puts forward the concept of thermal accumulation for Chinese cooking by taking pork tenderloin fried at different oil temperatures, explaining changes in moisture content, hardness, and color with different thermal accumulation conditions, and measuring kinetic parameters. The variations of L* and b* obtained by the experimental results belong to the first-order reaction kinetic model, while the changes in water content and shear force belong to the zero-order reaction kinetic model. Simultaneously, the superheat value is used as a thermal accumulation indicator, combined with sensory evaluation to determine that the Z value of the human sensory overheating of pork tenderloin is 99°C, and O s,max (Z = 99°C, the reference temperature is 110°C) is 5.86 min.

Copyrolysis characteristics of polyvinyl chloride, polyethylene and polypropylene based on ReaxFF molecular simulation

Reactive force field molecular dynamics (ReaxFF MD) simulation was used to study the copyrolysis behaviour of waste plastics i.e., polyvinyl chloride (PVC), polyethylene (PE), and polypropylene (PP) from three perspectives: (1) gas phase products, (2) reaction route, and (3) activation energy. The results demonstrate that the thermogravimetric (TG) experiment's findings and the weight loss characteristics of PVC/PE/PP copyrolysis obtained by ReaxFF MD simulation were consistent. Copyrolysis changed the amount of gas phase products generated, the direction of free radical movement, and the range of temperatures at which they were produced in considerable quantities. Due to the transfer of chloride (Cl) radicals, both PE and PP had a detrimental synergistic impact on the production of hydrogen chloride (HCl). Based on the first-order reaction kinetics model, the copyrolysis of waste plastics significantly lowered the total activation energy of the mixture, and the activation energy of PVC/PE/PP ternary blend system decreased most significantly.

One-pot ternary sequential reactions for photopatterned gradient multimaterials

One-pot ternary sequential reactions for photopatterned gradient multimaterials

Residue Determination Method and Photolysis Process of Picoxystrobin in Three Soils by QuEchers and HPLC/MS

ABSTRACT The dissipation and residue of picoxystrobin in three different soils (Xerosols, Yermosols and Chernozem) was investigated. An easy-to-implement and sensitive method was established to determine picoxystrobin in the three different soils via modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) combined with HPLC (high-performance liquid chromatography). The photodegradation process of picoxystrobin in three different soils was detected by HPLC-mass spectrometry. The linearity of picoxystrobin detection was studied in the range of 0.3–10 mg/L (0.3, 0.5, 1, 2 and 10 mg/L), good linearity was obtained and the correlation coefficients (R2) was 0.9999. The recoveries of picoxystrobin ranged from 78.4% to 106.4% and relative standard deviation of 0.67%-4.46% in three kinds of soil spiked at 0.5, 1, and 2 mg/kg. The results of the recovery study indicated that the method meets the precision and accuracy requirements for picoxystrobin in the three different soils. The photodegradation experiments revealed that the compound had a degradation half-life ranging from 3.80–4.29 days. The rule of photodegradation of picoxystrobin on the surface of three soils was consistent with first-order reaction kinetic model. Finally, two possible routes of picoxystrobin fragmentation were indicated by mass spectrometry. This work will provide a theoretical reference for the analysis of picoxystrobin residues in soil and practical applications.

Kinetic Investigation for Chemical Depolymerization of Post-Consumer PET Waste Using Sodium Ethoxide

Reaction kinetics provides significant insights into the reaction rate and mechanism to control a chemical reaction. In the present work, the detailed kinetics of glycolytic depolymerization of post-consumer polyethylene terephthalate (PET) waste in the presence of sodium ethoxide (EtONa) was investigated. The glycolysis experiments were conducted in a batch reactor over a temperature range of 160 to 197 °C. The confirmation of the product, the bis(2-hydroxyethyl)terephthalate monomer, was carried out using nuclear magnetic resonance spectroscopy, high-performance liquid chromatography, differential scanning calorimetry, and X-ray diffraction techniques. Investigations on the influence of particle size and temperature showed that conversion increased with a decrease in particle size and increasing temperature. Equilibrium conversions were found at different temperatures, and a van ’t Hoff plot was used to confirm that the depolymerization reaction is endothermic. Gibbs’ free energy was used to calculate the ceiling temperature (TC = 156 °C). Three kinetic models were tested for their applicability. It was found that the EtONa-catalyzed glycolysis of PET follows a first-order reversible reaction kinetic model at higher temperatures (170–197 °C). However, a heterogeneous shrinking core mechanism was applicable in a lower temperature range (160–170 °C). The kinetic evaluation revealed that the PET glycolysis reaction consists of heterogeneous and homogeneous mechanisms depending upon the depolymerization stages at various temperatures.

Enhanced photocatalytic activity of Fe-, S- and N-codoped TiO2 for sulfadiazine degradation.

The online version contains supplementary material available at 10.1007/s13762-023-04771-6.

Study on decolorization of methylene blue with a kind of electrolytic active water

Electrolytic active water was prepared by electrolytic treatment of sodium chloride aqueous solution using a self-made device. In order to investigate the properties of electrolytic active water , the pH value, available chlorine contents and decolorization ability on methylene blue solution were tested and compared with that of sodium hypochlorite aqueous solution. Experimental results showed that the electrolytic active water has higher oxidation capacity and decolorization efficiency for methylene blue compared with sodium hypochlorite solution, implying maybe other reactive oxygen species components besides hypochlorite existed in the electrolytic active water. The electrolytic active water was stable under long-term storage, and mechanical force with oxidation activity did not decrease. In addition, the decolorization kinetics of methylene blue in the electrolytic active water was explored, and it was found that, in general, the decolorization reaction of methylene blue in electrolytic active water was consistent with the first-order reaction kinetics model, but when the pH value of electrolytic active water solution was weakly alkaline or neutral, the decolorization reaction of methylene blue was closer to the second-order reaction kinetics model.

Ceramic ozone catalytic coupling incineration ash and excess sludge recycling with ceftriaxone sodium wastewater treatment: Performance and mechanism

Highly efficient and economic treatment of wastewater sludges and wastewater containing ceftriaxone sodium (CRO) in one way is a challenging issue in the water treatment field. Therefore, a waste-recycling strategy of reasonably manufactured ceramic ozone catalyst (COC) with low cost and high value was proposed, which solved the difficult problems of sludge and incineration ash disposal and CRO removal. In view of the complex reaction among the components, the recovery heat conversion mechanism of inorganic substances forming crystalline ceramic skeleton, heavy metals solidifying stably and forming catalytic sites, and organic substances pore-forming in the whole material composition is expounded. COC has excellent catalytic performance. Under the optimal reaction conditions, the removal rate of CRO is 97.87 %, which accords with the first-order reaction kinetic model. The free radical quenching study and electron spin resonance (ESR) analysis show that the main free radical in the COC/O3 system is •O2–. The degradation intermediates in various time periods were identified by LC-MS analysis, while the degradation and transformation ways of CRO were put forward. The excellent catalytic performance can be attributed to the synergistic effect of electronic mediator CO, CC functional group adsorption and catalytic electron transfer mechanism of MgFe2O4, MnFe2O4, Fe2O3 and TiO2. In addition, COC has excellent repeatability, stability and environmental safety. The benefits of waste recycling are obvious.

Study on Pyrolysis-Mechanics-Seepage Behavior of Oil Shale in a Closed System Subject to Real-Time Temperature Variations.

In situ mining is a practical and feasible technology for extracting oil shale. However, the extracted oil shale is subject to formation stress. This study systematically investigates the pyrolysis–mechanics–seepage problems of oil shale exploitation, which are subject to thermomechanical coupling using a thermal simulation experimental device representing a closed system, high-temperature rock mechanics testing system, and high-temperature triaxial permeability testing device. The results reveal the following. (i) The yield of gaseous hydrocarbon in the closed system increases throughout the pyrolysis reaction. Due to secondary cracking, the production of light and heavy hydrocarbon components first increases, and then decreases during the pyrolysis reaction. The parallel first-order reaction kinetic model shows a good fit with the pyrolysis and hydrocarbon generation processes of oil shale. With increasing temperature, the hydrocarbon generation conversion rate gradually increases, and the uniaxial compressive strength of oil shale was found to initially decrease and then increase. The compressive strength was the lowest at 400 °C, and the conversion rate of hydrocarbon formation gradually increased. The transformation of kaolinite into metakaolinite at high temperatures is the primary reason for the increase in compressive strength of oil shale at 400–600 °C. (ii) When the temperature is between 20 and 400 °C, the magnitude of oil shale permeability under stress is small (~10−2 md). When the temperature exceeds 400 °C, the permeability of the oil shale is large, and it decreases approximately linearly with increasing pore pressure, which is attributed to the joint action of the gas slippage effect, adsorption effect, and effective stress. The results of this research provide a basis for high efficiency in situ exploitation of oil shale.

Efficient Interfacial Charge Transfer Based on 2D/2D Heterojunctions of Fe-C3N4/Ti3C2 for Improving the Photocatalytic Degradation of Antibiotics.

Graphitic carbon nitride (g-C3N4) has shown to be a promising photocatalyst that, however, suffers from strong charge recombination and poor conductivity, while MXenes have shown to be perfect cocatalysts for the photocatalytic process but show poor stability. In this study, we successfully constructed 2D/2D heterojunctions of Fe-C3N4/Ti3C2 for the photocatalytic degradation of antibiotics. In this study, multilayer Ti3C2 was obtained by etching Ti3AlC2, and then Fe-C3N4/Ti3C2 photocatalyst was prepared by the one-pot microwave method and high-temperature calcination method. The synthesized samples were characterized by XRD, SEM, TEM, XPS, TGA, BET, DRS, PL, and other means. The photocatalytic degradation of tetracycline hydrochloride by Fe-C3N4/Ti3C2 was in accordance with the first-order reaction kinetics model, and the apparent rate constant k was 2.83, 2.06, and 1.77 times that of g-C3N4, Fe-C3N4, and g-C3N4/Ti3C2, respectively. Through the mechanism study, it was shown that the most active species in the reaction system was • O2 −, while h+ and •OH had a relatively lower effect on the degradation system.

A mathematical model to predict the color change of fresh dough sheets under fluctuation temperatures

The objective of this work was to establish a mathematical model to predict the color change of fresh dough sheets under fluctuation temperatures. The changes of color expressed in the parameters (L*, a*, b* and TCD) of green tea and turmeric dough sheets were measured at 5, 10, 20, 30 and 40 °C, respectively, and then the change models were established by zero- and first-order reaction kinetics model. The results showed that the first-order reaction kinetics model (all R2 > 0.9) fitted well the change of color parameter L* while the other parameters were not well fitted by zero- and first-order reaction kinetics model. Furthermore, the temperature-dependent reaction rate was assessed by the Arrhenius equation and showed better performance. Finally, a dynamic prediction model of parameter L* combining the first-order reaction kinetics model with the Arrhenius equation was established under fluctuation temperatures. The validation results showed that changes of parameter L* under fluctuation temperatures could be predicted accurately by the model. This study will may be useful to determine consumption time and shelf life under the dynamic product distribution channel by providing real-time indication of quality of fresh noodle products.

Simulation and reaction parameter estimation in subsurface flow constructed wetland for greywater treatment

Subsurface flow constructed wetland (SSFCW) is widely adopted for the removal of BOD5 and TKN from greywater. The design of SSFCW is normally based on thumb rules or using a first-order reaction kinetic model. However, the applicability of this model is system/environment-specific which necessitates the assessment of the potential applicability of other reaction kinetic models. In the present study, experiments were planned on SSFCW during initial and established phases to collect the data on BOD and TKN for assessing the system-specific application of plug flow, K-S* and CSTRs in series models. The reaction rate parameters along the length of SSFCW and overall for the system were estimated. There was no variation in values of rate parameter along the length in an initial phase, but the values increased along the length of SSFCW in established phase. Further, the applicability of these models was assessed for predicting BOD5 in SSFCW based on error analysis. And overall reaction rate parameters were estimated. Based on the average absolute error and RMS error it is concluded that plug flow and K-S* reaction kinetic models are more applicable for BOD5. The volumetric reaction rate parameter is recommended to be 0.612/day (plug flow) and 0.742/day (K-S*) for the design of SSFCW in tropical climate for BOD5 removal. The volumetric reaction rate parameter for TKN removal by plug flow model is recommended to be 0.389/day.

Effective degradation of hydrolyzed polyacryamide (HPAM) in a simultaneous combination of acoustic cavitation and microbubbles ozonation: Process optimization and degradation mechanism

Managing environmental contamination with hydrolyzed polyacryamide (HPAM) is essential due to its persist long with slow biodegradability influence on the environment. In this study, the simultaneous combination of acoustic cavitation and microbubbles ozonation (US/O3) was applied to generate additional highly reactive hydroxyl radicals (·OH) and thus to enhance the degradation of HPAM. Compared with the two separated degradation process methods, the coupled method exerts a synergistic effect on the decomposition of HPAM, with an enhancement factor of 1.50. Effects of aeration pattern, ultrasound irradiation, operating temperature, initial HPAM concentration, and valance state of cations on the removal of HPAM were investigated intensively. An increase in valance state of cations contributes to HPAM removal. The maximum HPAM degradation, chemical oxygen demand (CODcr) removal and viscosity reduction of the HPAM wastewater were 97.35%, 89.01% and 93.25%, respectively. The degradation of HPAM conformed to the first-order reaction kinetic model. Removal of HPAM followed hydroxyl radical mechanism. The degradation mechanism of HPAM was also discussed with the change of FTIR and UV–Visible spectra of HPAM in investigated processes. The main reaction intermediates, such as heptanoic anhydride, oleamide, myristamide, acetic acid, acetamide, and propanamide, are identified and a possible degradation pathway is proposed during the US/O3 process. The process was proved to be a suitable technique for dealing with HPAM-containing wastewater.

Study on ultrasonic / hydraulic cavitation field for enhanced degradation of ceflor masonry in water

Based on ultrasonic cavitation, with low concentration of levofloxacin hydrochloride solution and cavitation product analysis, the degradation rules of levofloxacin hydrochloride were studied by ultrasonic, zero valent iron and zero valence iron (US / Fe0). The results showed that zero-valent iron promotes the degradation of levofloxacin hydrochloride solution by ultrasonic cavitation, and the degradation reaction fits the first-order reaction kinetic model, with a degradation rate constant of 6.3710-3min-1. Under the reaction conditions, the biodegradability of levofloxacin hydrochloride solution was significantly improved, and after 270min minutes of the reaction, the solution BOD5 / CODcr was increased from 0 to 0.421.

Use of image analysis to determine the shelf-life of an apple compote with wine

This research aimed to understand how the storage conditions change the appearance of an apple compote added with white wine (ACWW) during storage at different temperatures (20, 30, and 40 °C) for 63 days. Microbiological quality, color parameters, and pH were monitored. The CIE L*, a*, and b* color variables were measured through image analysis. The parameters associated with the color changes during storage were the most critical quality indices of the ACWW, especially the overall color difference (ΔE), since it presented the larger velocity constants, fitting to the first-order reaction kinetic model. Therefore, ΔE was selected as a critical parameter to estimate shelf-life but fitted with the first-order fractional conversion model, which provided a shelf-life of 45.64 days at 20 °C. The shelf-life decreased with increasing storage temperature. In conclusion, the results demonstrated the applicability of the image analysis and the kinetics-based accelerated shelf-life testing approach to obtain faster insight into quality attributes changes, mainly color changes in compotes and similar products.

Pesticide production wastewater treatment by Electro-Fenton using Taguchi experimental design.

In this study, the electro-Fenton (EF) method was applied to remove total organic carbon (TOC) from the pesticide production wastewater containing tricyclazole (TC). Statistical Taguchi method was used to optimize the treatment performance. Analysis of variance (ANOVA) indicated that the polynomial regression model fitted experimental data with R2 of 0.969. The optimal conditions for eliminating 75.4% TOC and 93.7% TC were 0.2 mM of Fe2+, 990 mg/L of Na2SO4, 180 min of reaction time at pH 3 with 2.22 mA/cm2 of current density. The removal of TC present in the wastewater followed the first-order reaction kinetic model (R2 = 0.993); while that was the second-order kinetic model in the case of the TOC removal (R2 = 0.903). In addition, the experimental results and theory approaches (density functional theory and natural bond orbital calculations) also showed the C-N bond breaking and nitrate ions cleavage to ammonia. Acute toxicity of the pesticide wastewater after treatment (PWAT) on microcrustaceans showed that the treated wastewater still exhibited high toxicity against D. magna, with LC50 values of 3.84%, 2.68%, 2.05%, and 1.78% at 24 h, 48 h, 72 h, and 96 h, respectively.

Synthesis of KBiO3/Nano-Ag3PO4 Composite Photocatalyst and its Application for Degradation of Organic Pollutant under visible light

In this work, a novel composite photocatalyst, KBiO3/nano-Ag3PO4 (K/Ag catalyst), was synthesized, and efficiently degraded methylene blue (MB) under visible light. The various properties of photocatalyst were measured by modern analytical techniques, such as XRD, FT-IR, SEM, XPS, and UV-Vis. We also utilized Density functional theory calculation (DFT) to investigate the photocatalytic degradation mechanism in this reaction process. The multiple characterization findings demonstrated that K/Ag composite catalyst was successfully synthesized using Ag3PO4 and KBiO3, and it displayed excellent absorption for visible light. The photocatalytic results confirmed that K/Ag catalyst greatly promoted the degradation of MB under visible light. The first-order reaction kinetics model could satisfactorily describe the apparent photocatalytic degradation process in this system. In addition, adding electron capture agents to the photocatalytic system highly decreased the degradation efficiencies of target pollutant. Moreover, K/Ag composite catalyst exhibited perfect photocatalyst stability after recycling three times. Through calculating the band structure, Density of States (DOS) and work function, KBiO3 and Ag3PO4 could be considered as n type and p type semiconductor material, respectively. When the composite catalyst was exposed to light, the light-excited electrons would be appeared in both the conduction bands. Furthermore, the transfer trend of electrons and holes made photogenerated electrons concentrate on the conduction band of n type KBiO3, and photogenerated holes concentrate on the valence band of p type Ag3PO4, and thereby greatly improve the photocatalytic efficiency.

Degradation of Tryptophan by UV Irradiation: Influencing Parameters and Mechanisms

The chlorination of dissolved amino acids can generate disinfection by-products (DBPs). To prevent the formation of DBPs, we examined the UV-induced degradation of tryptophan (Trp). In order to further understand the impact of UV disinfection on Trp, the effects of initial concentrations of Trp, pH, temperature, concentrations of NO3−, HCO3− and Cl− on Trp removal were investigated, and a degradation mechanism was also proposed. The results demonstrated that degradation fitted a pseudo first-order reaction kinetic model. The degradation of Trp was mainly caused by direct UV degradation. The apparent rate constant kobs decreased with the increase in initial Trp concentration and increased with increases in pH and temperature. The thermal degradation activation energy was 19.65 kJ/mol. Anions in water also had a significant influence on the degradation of Trp. HCO3− and NO3− contributed to the kobs of Trp, but Cl− inhibited the degradation rate. By electron paramagnetic resonance (EPR) spectroscopy, ·OH was proven to be formed during the degradation of Trp by UV. Based on the intermediate products of C11H15NO3, C10H15N and C9H13N detected by LC-MS-MS, the degradation pathway of Trp was speculated.