Reaction Order Research Articles

Synthesis and Performance Study of Self-Degradable Gel Plugging Agents Suitable for Medium- and Low-Temperature Reservoirs.

Aiming at the problems of current similar hydrogel plugging agents, such as poor breaking performance, nonspontaneous degradation, and reservoir pollution which have been plaguing their application in temporary plugging operations, this study has synthesized a cross-linking agent for hydrogels with dimethylaminoethyl acrylate and dibromo-p-xylene as raw materials. With Fourier transform infrared, 1H nuclear magnetic resonance, and thermogravimetric analyses as representations of the structure and thermal stability of the cross-linking agent, a set of self-degrading hydrogel systems has been developed with the cross-linking agent as the core so as to make evaluations on the temperature resistance, plugging performance, and core damage performance of the hydrogel and conduct a study on its gelation kinetics. The research results show that the cross-linking agent shows good thermal stability. When applied in the hydrogel system, the hydrogel has shown high temperature resistance, maintaining gel strength for 5-10 days at 50-90 °C, with viscosity after complete degradation lower than 10 mPa·s. The excellent bearing strength of the hydrogel system has led to a core damage rate below 5%. The study on gelation kinetics of the hydrogel system shows that, with the increase in the concentration of the cross-linking agent, the gelation time of the hydrogel system is shortened, with the reaction order between the cross-linker concentration and the gelation time at about 0.6 under the condition of 50-90 °C.

Quantitative Kinetic Insights from Operando-UV/Vis Spectroscopy: An Application to NH3-SCR of NOx on Cu-CHA Catalysts.

We employ UV/Vis Diffuse Reflectance spectroscopy directly coupled with a packed bed flow reactor to extract quantitative kinetic information. We use as a show-case the CuII/CuI redox dynamics during the reduction half cycle of the NH3-Selective Catalytic Reduction (SCR) on Cu-CHA catalysts. Our measurements enable quantification of the fraction of oxidized Cu, reconstructed by Multivariate Curve Resolution (MCR) together with monitoring of the gas-phase evolution during the reaction. These data both on the dynamics of the gas-phase and of the active site oxidation state have been used to assess the reduction half cycle rate equation and estimate the rate constant. Our results in terms of reaction orders and kinetic constant are in line with previous findings in the literature. Overall, our results demonstrate that the combined analysis of the UV spectra and of the gas-phase dynamics provides converging and unparalleled kinetic insight: this approach effectively resolves ambiguities concerning RHC kinetics and mechanism. More in general, this work provides evidence that operando spectroscopy can be used to extract quantitative kinetic information on catalytic cycles.

Co-Extraction of Aluminum and Silicon and Kinetics Analysis in Carbochlorination Process of Low-Grade Bauxite.

Addressing the issue that the Bayer process is not suitable for low-grade bauxite, carbochlorination was proposed to recover aluminum and silicon from low-grade bauxite. This study focused on the behavior of aluminum and silicon during the carbochlorination process of low-grade bauxite. The impact of various process parameters on the chlorination efficiency was investigated, and the chlorination mechanism and kinetics of aluminum and silicon chlorination in bauxite were analyzed and discussed. Under optimal experimental conditions, the chlorination efficiency of Al2O3 and SiO2 reached 94.93% and 86.32%, respectively. The carbochlorination of aluminum and silicon in bauxite adhered to a shrinking, unreacted core model governed by gas diffusion within the product layer. This process can be bifurcated into two stages. Additionally, calculations were conducted to determine the apparent activation energy and reaction order of the chlorination processes involving Al2O3 and SiO2. Examining the chlorination mechanism revealed that the bauxite carbochlorination encompasses transformations among various minerals. Notably, the aluminum component prefers to participate in the carbothermal chlorination reaction over silicon.

Quantitative Kinetic Insights from Operando‐UV/Vis Spectroscopy: An Application to NH3−SCR of NOx on Cu‐CHA Catalysts

AbstractWe employ UV/Vis Diffuse Reflectance spectroscopy directly coupled with a packed bed flow reactor to extract quantitative kinetic information. We use as a show‐case the CuII/CuI redox dynamics during the reduction half cycle of the NH3‐Selective Catalytic Reduction (SCR) on Cu‐CHA catalysts. Our measurements enable quantification of the fraction of oxidized Cu, reconstructed by Multivariate Curve Resolution (MCR) together with monitoring of the gas‐phase evolution during the reaction. These data both on the dynamics of the gas‐phase and of the active site oxidation state have been used to assess the reduction half cycle rate equation and estimate the rate constant. Our results in terms of reaction orders and kinetic constant are in line with previous findings in the literature. Overall, our results demonstrate that the combined analysis of the UV spectra and of the gas‐phase dynamics provides converging and unparalleled kinetic insight: this approach effectively resolves ambiguities concerning RHC kinetics and mechanism. More in general, this work provides evidence that operando spectroscopy can be used to extract quantitative kinetic information on catalytic cycles.

Highly accurate heat release rate marker detection in NH3–CH4 cofiring through machine learning and domain knowledge-based selection integration

Ammonia emerges as a promising substitute for traditional fuels, offering a potential reduction in fossil fuel consumption and the associated emissions. Given its weak reactivity, an effective strategy to harness the potential of ammonia involves cofiring it with methane, to establish a self-sustaining combustion process. The understanding of heat release rate (HRR) in the cofiring process of ammonia and methane is crucial for burner design. This study introduces novel HRR indicators through a machine learning-based approach, focusing on species significantly contributing to HRR. Kinetic analysis is carried out utilizing a one-dimensional freely propagating flame model, applying a mechanism including 59 species and 356 reactions. Domain knowledge-based feature selection narrows down the search space, enhancing computational efficiency during HRR indicator identification. A random forest model is then employed to identify radical/radical combinations and their respective reaction orders, representing HRR optimally based on mean decrease impurity. The proposed HRR markers are [CH4]0·76[OH]1.08, [HCO]0·65[NO]0.24, [CH3]0.65[O]0.63, [NH2][O]0.59, and [NH3]0·93[OH]0.96. The root mean square error for each marker was extracted and compared with literature data, demonstrating higher reliability of the proposed indicators over those previously suggested. Additionally, the paper concludes with a discussion of the feasibility of measuring these markers from an experimental perspective.

Demystifying group-4 polyolefin hydrogenolysis catalysis: Gaseous propane hydrogenolysis mechanism over the same catalysts

A kinetic/mechanistic investigation of gaseous propane hydrogenolysis over the single-site heterogeneous polyolefin depolymerization catalysts AlS/ZrNp2 and AlS/HfNp2 (AlS = sulfated alumina, Np = neopentyl), is use to probe intrinsic catalyst properties without the complexities introduced by time- and viscosity-dependent polymer medium effects. In a polymer-free automated plug-flow catalytic reactor, propane hydrogenolysis turnover frequencies approach 3,000 h-1 at 150 °C. Both catalysts exhibit approximately linear relationships between rate and [H2] at substoichiometric [H2] with rate law orders of 0.66 ± 0.09 and 0.48 ± 0.07 for Hf and Zr, respectively; at higher [H2], the rates approach zero-order in [H2]. Reaction orders in [C3H8] and [catalyst] are essentially zero-order under all conditions, with the former implying rapid, irreversible alkane binding/activation. This rate law, activation parameter, and DFT energy span analysis support a scenario in which [H2] is pivotal in one of two plausible and competing rate-determining transition states-bimolecular metal-alkyl bond hydrogenolysis vs. unimolecular β-alkyl elimination. The Zr and Hf catalyst activation parameters, ΔH‡ = 16.8 ± 0.2 kcal mol-1 and 18.2 ± 0.6 kcal mol-1, respectively, track the relative turnover frequencies, while ΔS‡ = -19.1 ± 0.8 and -16.7 ± 1.4 cal mol-1 K-1, respectively, imply highly organized transition states. These catalysts maintain activity up to 200 °C, while time-on-stream data indicate multiday activities with an extrapolated turnover number ~92,000 at 150 °C for the Zr catalyst. This methodology is attractive for depolymerization catalyst discovery and process optimization.

Synthesis of hydrogels from biomaterials and their potential application in tissue engineering

In this study, a series of hydrogels were synthesized from chitosan(s) that was crosslinking with glutaraldehyde at different concentrations. Ascorbic acid in an acidic medium was used to facilitate non-covalent interactions. The chitosan(s) was obtained from shrimp cytoskeleton; while ascorbic acid was extracted from xoconostle juice. The hydrogel reaction was monitored by UV–vis spectroscopy (550 nm) to determine the reaction kinetics and reaction order at 60 °C. The hydrogels structures were characterized by NMR, FT-IR, HR-MS and SEM, while the degree of cross-linking was examined with TGA-DA. The extracellular matrices were obtained as stable hydrogels where reached maximum crosslinking was of 7 %, independent of glutaraldehyde quantity added. The rheological properties showed a behavior of weak gels and a dependence of crosslinking agent concentration on strength at different temperatures. The cytotoxicity assay showed that the gels had no adverse effects on cellular growth for all concentrations of glutaraldehyde.

Intrinsic kinetics of steam methane reforming over a monolithic nickel catalyst in a fixed bed reactor system

The intrinsic kinetics of steam methane reforming were experimentally investigated using a monolithic nickel-based catalyst in a specially designed fixed bed system. All kinetic tests were performed under various operating conditions: steam to carbon ratio of 2 to 5, methane volumetric concentration in feed gas of 3 % to 9 %, temperature of 500 to 650 °C, and typical biogas compositions with N2 dilution (carbon dioxide 35.7–55.6 %, methane 44.4–64.3 %, with 86–91 % nitrogen dilution). A deconvolution process was applied during the rate calculation and the reaction orders with respect to different gases were determined, coupled with thermodynamic system analysis. The reaction mechanism was then proposed and a Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model was established, followed by kinetic parameter estimations for the model and a further model validation with experimental data. Based on the model, the intrinsic kinetic of SMR reaction using monolithic catalysts was described. The validity and feasibility of applying the faster approach for kinetic parameter estimation were demonstrated, and this work is the first demonstration of a complex reaction system. Also, the reaction mechanism appeared to show a suitably high correlation with alternative and more sustainable methane sources (i.e. biogas).

Co-pyrolysis Behavior of Coal and Biomass: Synergistic Effect and Kinetic Analysis.

Co-pyrolysis of coal and biomass is an efficient way to utilize resources. This study investigates the co-pyrolysis behavior and kinetics of coal and biomass using thermogravimetric analysis (TGA) and TG-FTIR. Co-pyrolysis of coal and biomass exhibits a synergistic effect. When the biomass is 25%, the weight loss increases, showing a positive synergistic effect. When the biomass is 50%, it exhibits a negative synergistic effect. Increasing the heating rate can promote the generation of a synergistic effect. Co-pyrolysis involves two central pyrolysis stages: stage III (250-380 °C) and stage IV (380-550 °C). Friedman, FWO, KAS, and STA methods are used to calculate the activation energy for stages III and IV. The activation energy (E α) for co-pyrolysis is higher than that for coal or biomass pyrolysis alone. A positive synergistic effect is observed in stage III, while a negative synergistic effect is noted in stage IV. The master curve method determines an accurate reaction order (n) and pre-exponential factor (A) value of Coal75-Bio25. In stage III, E α = 238.81 kJ/mol, n = 2.4, A = 1.30 × 1021 s-1. In stage IV, E α = 37 8.01 kJ/mol, n = 4.0, A = 1.10 × 1027 s-1. The kinetic parameters in stage IV are significantly higher than those in stage III. TG-FTIR is used to analyze the synergistic effect of co-pyrolysis. Compared with coal and biomass pyrolysis separately, the Coal75-Bio25 pyrolysis process releases less CO2 and more CH4. These findings support the synergistic effect of coal and biomass during co-pyrolysis.

Regularities in mercury cation sorption by a lignin-based sulfur-containing sorbent

The unfavorable environmental situation in the town of Usolye-Sibirskoye (Irkutsk Oblast, Russia) determines the relevance of investigating and applying a new lignin-based sulfur-containing sorbent for purification of groundwater from mercury compounds. The sorbent was synthesized on the basis of waste products of epichlorohydrin (1,2,3-trichloropropane), sulfur, and lignin. The IR spectrum of the sorbent under study showed the presence of an S–S bond in the region of 445–465 cm-1. Intensive absorption of Hg2+ ions in the regions of 2800–2950 cm-1 (valence vibrations of C–H bonds in CH and CH2 groups) and 1460 cm-1 (deformation vibrations in CH2 group) was observed. Absorption of Hg2+ ions by lignin fragments was accompanied by a change in the vibration band of S–S bonds, which splits into two bands of higher frequencies than the νS–S band in the original sorbent. The optimum sulfur content, which ensures the maximum sorption activity of the sorbent, was found to be 53.25%. The mercury sorption isotherms at 20 and 60 °C are described by parabolic dependencies with determination coefficients of 98.9 and 98.6 %, respectively. The kinetic curve at 20 °C and 40 °C is approximated by a hyperbola and a cubic polynomial with determination coefficients of 97.9 and 96.2 %, respectively. The reaction order (first order at 20 °C and second order at 40 °C) and the reaction rate constant (0.0876 min-1 at 20 °C and 0.00014 min-1 at 40 °C) were determined. At 20 °C, the sorption rate of Hg2+ was established to be significantly higher and the sorption time to be faster than those at 40 °C. Therefore, mercury sorption by the proposed sorbent should be carried out at 20 °C in order to reduce energy consumption.

Process and kinetics of ammonium sulfide removal of zinc, nickel and cobalt from manganous sulfate electrolyte

In producing electrolytic manganese and manganese-based lithium batteries, Manganous sulfate solution serves as a crucial intermediate material. During the preparation of manganese sulfate solution by acid leaching, the removal of impurities such as zinc, nickel, and cobalt ions by sulfide precipitation is essential for obtaining high-quality metallic manganese and high-purity manganese sulfate. The results show that when the temperature is 45 °C, the pH is 5.60, the ammonium sulfide dosage is 40 %, the time is 5 min, and the rotation speed is 650 rpm, the sulfidation rates of zinc, nickel and cobalt are 99.07 %, 89.30 %, and 87.70 % respectively. At this time, the loss rate of manganese in the solution after sulfide impurity removal is 11.45 %, and the manganese-impurity ratio is 80.00. Response surface methodology analysis revealed that temperature, pH, and ammonium sulfide concentration significantly affected the manganese loss rate. After process optimization, at a temperature of 32.70 °C, a pH of 5.20, and an ammonium sulfide concentration of 32.73 %, the manganese loss rate decreased to 6.05 %, while the removal rates of Ni, Co, and Zn were 75.35 %, 60.80 %, and 99.51 %, respectively. In the Manganous sulfate electrolyte with or without ammonium sulfate, the sulfide precipitation processes of zinc, nickel and cobalt ion are all first-order reactions, and the reaction order is zinc > nickel > cobalt. More importantly, the density functional theory (DFT) calculation results also confirmed the formation sequence of zinc sulfide > nickel sulfide > cobaltous sulfide, which supported the experimental results well. This study will lay the foundation for process optimization and mechanism elucidation of impurity ions in ammonium sulfate electrolyte precipitated by ammonium sulfate.

Diethyl Sulfide Oxidation with Sodium Peroxoborate in Water–Acetonitrile System. Kinetics and Mechanism

In aqueous solutions of acetonitrile (1 vol%), the rate of oxidation of diethyl sulfide with sodium peroxoborate, Na2[B2(O2)2(OH)4]∙6H2O, in the pH range of 8.5–11 is significantly higher than the oxidation rate in water and exceeds the rate of reaction of Et2S with hydrogen peroxide in the H2O–MeCN system. The reaction order with respect to the substrate, which is close to zero, suggests that the limiting stage of the process is the reaction of peroxoborate anions with MeCN, leading to the formation of active boron peroxyimidates, which then react in a rapid stage with Et2S.

Insights into the oxidative thermal stability of mesoporous triazine‐based organic polymers: Kinetics and thermodynamic parameters

AbstractThis study investigates the thermal degradation kinetics of mesoporous triazine‐based polymers, namely triazine‐amine and triazine‐ether polymers. The synthesis, physicochemical characterization, and catalytic applications of these polymers were discussed in our previous report. Herein, the thermal stability parameters, including kinetic triplets and thermodynamic parameters, were determined using thermogravimetric analysis (TGA) and non‐isothermal mathematical approximations such as Coats‐Redfern, Broido, and Horowitz–Metzger methods. Triazine‐ether polymers exhibit thermal stability within the range of 200°C–300°C, while triazine‐amine polymer demonstrates superior thermal stability, reaching up to 450°C. According to the Coats‐Redfern method, the degradation follows reaction orders of 0.5 ≤ n ≤ 1. The activation energy of triazine‐amine polymer is notably high, particularly at the third degradation stage (e.g., 89.0 kJ/mol by the Broido method), attributed to its high nitrogen content. Conversely, the higher carbon content of triazine‐ether polymers reduces their activation energy to approximately 30 kJ/mol at all stages and thus, facilitates the degradation process. Thermodynamically, the degradation process is favorable yet non‐spontaneous, with intermediate states of the polymers exhibiting higher entropy, indicative of their enhanced degradation capability.

Parameter estimation of epoxy resin cure kinetics by dynamics DSC data

AbstractThis study focused on determining the curing kinetic parameters of amine‐epoxy resin by performing dynamic DSC tests. The Kissinger and Crane equations were used to determine the activation energy, the pre‐exponential factor, and the reaction order as kinetic parameters for curing. The Ozawa equation was also used to determine the activation energy that changes at different levels of cure during the reaction. The average activation energy obtained by the Ozawa method was compared with the Kissinger activation energy. In addition, the T‐β extrapolation method was used to determine the optimum curing temperature. The kinetic parameters obtained from the Kissinger and Crane equations were used in the nth‐order kinetic model to predict the degree of cure at a given time and temperature. The linear regression fitting method was used in Minitab software to determine the curing parameters. The results were evaluated based on the fitting parameters. This study provides a theoretical basis for the curing mechanisms of epoxy matrix fiber composites used in the manufacture of wind turbine blades.

A clean metallurgical process for vanadium precipitation from vanadium-rich solutions

Ammonium salt vanadium precipitation process has excellent performance in industrial production, but its shortcomings such as high cost and environmental impact are not conducive to sustainable development. In this paper, ethylenediamine was selected as the precipitant, and vanadate was precipitated from acidic simulated vanadium-rich solutions by the ammonium salt precipitation process. The high purity V2O5 product was obtained after calcination. Under optimal conditions, the precipitation rate of vanadium reached 94.8 %, and the purity of vanadium was as high as 99.1 %. The vanadium precipitation product was hexamethyl ammonium, and the vanadium product was V2O5. It can be derived by the differential method that the reaction order was n = 2.4, the reaction rate equation was CV-1.4=kt+a, and the apparent activation energy was 27.8097 kJ/mol, which can be classified as the diffusion-controlled reaction. This innovative process enables a savings of 5050 yuan per ton of V2O5. On this basis, a complete V2O5 production process with zero waste discharge was designed.

Evaluation of pyrolysis characteristics and kinetic parameters from several prospected biomass residues by thermogravimetric analysis

Abstract With fossil fuel supplies dwindling and persistent environmental concerns surrounding their consumption, biomass has emerged as a highly promising renewable energy source. Understanding the characteristics of biomass pyrolysis is crucial as it provides valuable insights and guidance for designing and optimizing the pyrolysis process. In this regard, a thermogravimetric assessment was conducted to evaluate the pyrolysis characteristics and kinetic parameters of four prospective biomass sources: Yang Na wood (Dipterocarpus alatus), palmyra palm shell, cotton stalk, and spent coffee grounds with a condition temperature range of 33 °C to 700 °C and a heating rate of 10 °C·min-1 in a nitrogen atmosphere. The kinetic parameters were evaluated using the Coats and Redfern methods, employing various reaction order models. The activation energy and pre-exponential factor were determined for the active pyrolysis stage. The results revealed that the high heating values for all samples ranged from 18.20 to 23.00 MJ·kg-1. Additionally, the onset temperature fell within the range of 243 to 254 °C, while the offset temperature ranged from 365 to 452 °C for all samples. The conversion rate at the offset temperature was 0.67 for Yang Na wood, 0.62 for palmyra palm shell, 0.65 for cotton stalk, and 0.74 for spent coffee grounds. Moreover, the activation energies were measured as 46.47 kJ·mol-1 for Yang Na wood, 52.46 kJ·mol-1 for palmyra palm shell, 64.20 kJ·mol-1 for cotton stalk, and 69.01 kJ·mol-1 for spent coffee grounds. The higher activation energy corresponded to a higher pre-exponential factor. In conclusion, the pyrolysis characteristics and kinetic parameters of the four types of biomasses have been found to be favourable, indicating their potential for promotion and application as a raw material for the pyrolysis process.

Highly Efficient Phosphazene-Derivative-Based Flame Retardant with Comprehensive and Enhanced Fire Safety and Mechanical Performance for Polycarbonate.

Polycarbonate (PC) as a widely used engineering plastic that shows disadvantages of flammability and large smoke production during combustion. Although many flame-retardant PCs have been developed, most of them show enhanced flame retardancy but poor smoke suppression or worsened mechanical performance. In this work, a novel nitrogen-phosphorus-sulfur synergistic flame retardant (Pc-FR) was synthesized and incorporated into PC with polytetrafluoroethylene (PTFE). The extremely low content of PC-FR (0.1-0.5 wt%) contributes significantly to the flame retardancy, smoke suppression and mechanical performance of PC. PC/0.3 wt% Pc-FR/0.3 wt% PTFE (PC-P0.3) shows the UL-94 V-0 and LOI of 33.5%. The PHRR, THR, PSPR, PCO and TCO of PC-P0.3 decreased by 39.44%, 14.38%, 17.45%, 54.75% and 30.61%, respectively. The impact strength and storage modulus of PC-P0.1 increased by 7.7 kJ/m2 and 26 MPa, respectively. The pyrolysis mechanism of PC-P0.3 is also revealed. The pyrolysis mechanism of PC-P0.3 is stochastic nucleation and subsequent growth and satisfies the Aevrami-Erofeev equation. The reaction order of PC-P0.3 is 1/2. The activation energy of PC-P0.3 is larger than PC-0, which proves that the Pc-FR can suppress the pyrolysis of the PC. This work offers a direction on how to design high-performance PC.

Towards microwave-assisted methane pyrolysis. Kinetic investigations of a Fe/C catalyst using thermogravimetric analysis coupled with gas chromatography

Methane pyrolysis (MP) is one of enabling technologies in the economy transition from fossil to renewable fuels. Although the technology has its undoubted advantages, the cost of producing hydrogen with MP is still higher than that using Steam Methane Reforming (SMR). Remote and contactless catalyst heating by microwaves can significantly intensify methane pyrolysis and reduce these costs. One of the catalysts that can be utilized in the microwave-assisted MP is the Fe/C catalyst. The current work presents a reference study of the MP kinetics on the dedicated Fe/C catalyst under conventional (non-microwave) heating. The kinetic data determined in this work are necessary for appropriate modelling and design of the microwave-assisted MP reactor. Experiments were carried out using thermogravimetric analysis coupled with gas chromatography. The reaction order with respect to methane and the activation energy were found to be 0.6, and 71 kJ/mol, respectively. The effects of CO2 concentration and temperature on the regeneration of the catalyst were also demonstrated.

ELECTROSYNTHESIS OF Cu2O IN THE Cu(s)|CuSO4(aq)|Fe(s) REACTOR AND DEGRADATION POTENT FOR METHYLENE BLUE

Research on Cu synthesis2O uses the electrolysis method in the Cu(s)|CuSO4(aq)|Fe(s) system and degradation tests on methylene blue. Cu2O is a blackish-red solid which has properties as a semiconductor with a band gap of around 2-2.2 eV. These transition metal oxides are widely used as catalysts, solar cell components, and photodetectors. This research aims to synthesize Cu2O with variations in electrolysis time, determine the characteristics of Cu2O using FTIR and XRD, and test the degradation of methylene blue. The method used is electrolysis with a fixed potential and time variations. Research stages include solution preparation, determination of decomposition potential, electrolysis of samples under various conditions, and analysis. The results of determining the decomposition potential are used as the application potential value in the copper electrolysis process, namely 3.25 V. Sample electrolysis was carried out at a potential of 3.25 V, solution pH 4.0 in a volume of 100 mL at 30, 60, 90, and 120 respectively. and 150 minutes. The products obtained were analyzed using Fourier Transform Infra-Red (FTIR) and X-ray diffraction (XRD). The results of FTIR analysis show that before calcination there is a Cu-O functional group with a wave number of 477.23 cm-1 and after calcination, there is a Cu-O functional group with a wave number of 538.28 cm-1 which indicates the formation of oxide. The results of XRD analysis show that the value of 2θ before calcination is 36.553; 50,481 ; 62.855 which shows the peak of Cu and after calcination 29.928; 36,027 ; 61.568 shows the Cu2O peak. The highest photocatalytic activity test results for Cu2O against methylene blue were 85.96%. The rate of degradation of methylene blue by Cu2O follows the second order reaction rate equation with the R2 value and reaction rate constant being 0.9418 and 0.00769572 L mol-1 s-1, respectively.

Kinetic Study of the Extraction of the Osmium (VI) Sulfite Complex by Tri-Octylamine from Sulfurous Solutions

ABSTRACT To develop effective technologies for extracting osmium from solutions obtained in the process of processing intermediate products of copper production, their intensification, selection of equipment, it is necessary to know the kinetic parameters of the extraction process. However, there are no data on the kinetics of osmium extraction with amines from sulfate solutions. For the first time, kinetic regularities of the extraction of the osmium (VI) sulfite complex [OsO2(SO3)2(H2O)2]2- from sulfuric acid solutions with tri-octylamine (TОA) [Alamine 336] were revealed using a Lewis diffusion cell. To clarify the mechanism of extraction of the osmium (VI) sulfite complex from sulfurous solutions, one of the necessary conditions is to determine the type of equation for the kinetics of the extraction reaction, the values of its parameters and an assessment of the region of its occurrence. The apparent extraction rate constant is (4.60 ± 0.18)∙10−6 m∙s−1. Orders were established for the reacting components: the interaction of TOA with the sulfite complex [OsO2(SO3)2(H2O)2]2- proceeds according to the reactions of the first order with respect to the metal and the second order with respect to the extractant. The value of the apparent activation energy 29 kJ/mol was determined. The process is performed in the diffusion-kinetic region and is limited by mass transfer through the interfacial area. The composition of the extractable complex was determined by the dilution method. The compound was isolated in an individual state, studied by the elemental chemical method, UV- and IR-spectroscopy, and its composition was installed: (ТОАН)2[OsO2(SO3)2(H2O)2].