Kinetic Studies Research Articles

Removal of Tetracycline Using Tungsten Disulfide/Graphene Oxide as Photocatalyst: Effect of Light Irradiation and Kinetic Studies

Once widely utilised in both human and veterinary medicine, tetracycline antibiotics are now recognised as major environmental pollutants with detrimental effects on the environment and human health. Concerns regarding allergic responses, gastrointestinal problems, and diseases resistant to antibiotics are raised by their persistence in soil, groundwater, and surface water. The production of a tungsten disulfide-graphene oxide nanocomposite for tetracycline degradation under varied light sources is presented in this work. The successful incorporation of tungsten disulfide on graphene oxide structures was confirmed by characterization using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-ray Diffraction (XRD). This revealed characteristic peaks for hydroxyl (3328 cm–1), carbonyl (1732 cm–1), alkene (1583 cm–1), and ether (1044 cm–1) bonds, as well as sulphur bonding (500 to 739 cm–1). With a d-spacing of 2.24 nm, the tungsten disulphide-graphene oxide nanocomposite had a strong peak at 2θ = 15.5˚corresponds to the (002) plane, as shown by X-ray diffraction. A distinctive GO peak was found at 2θ = 10.1˚, which corresponds to the plane (002). With light emitting diodes (95.67%), fluorescent lights (81.28%), and ultraviolet-visible light (88.09%), the nanocomposite in a photoreactor showed excellent photocatalytic efficiency. The better performance of the tungsten disulfide-graphene oxide nanocomposite under varying illumination circumstances, as determined by the Langmuir-Hinshelwood (LH) model, presents a viable and sustainable option for tetracycline degradation in water purification. This technique tackles a long-term strategy for tetracycline photocatalytic degradation in water purification under different illumination scenarios. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Thermodynamic and Kinetic Studies on the Pyrophoricity of Uranium Flakes

The objective of this work was to arrive at quantitative estimates of pyrophoricity of uranium in different geometries. The major source of heat generation was identified to be exothermic chemical reactions of uranium with moist air. Time evolution of temperature was studied for uranium considering 3D conduction and convection heat loss routes using Finite Element Analysis. Auto ignition temperature for uranium flakes was quantified using heat balance equation and was found to be around 500 K. Excess heat generation rates needed to cause auto ignition of uranium flakes at room temperature were also estimated. The major sources of excess heat leading to its ambient ignition could be attributed to friction and other exothermic chemical reactions of process impurities in uranium.

Diffusion-Induced Ordered Nanowire Growth: Mask Patterning Insights

Innovative methods for substrate patterning provide intriguing possibilities for the development of devices based on ordered arrays of semiconductor nanowires. Control over the nanostructures’ morphology in situ can be obtained via extensive theoretical studies of their formation. In this paper, we carry out an investigation of the ordered nanowires’ formation kinetics depending on the growth mask geometry. Diffusion equations for the growth species on both substrate and nanowire sidewalls depending on the spacing arrangement of the nanostructures and deposition rate are considered. The value of the pitch corresponding to the maximum diffusion flux from the substrate is obtained. The latter is assumed to be the optimum in terms of the nanowire elongation rate. Further study of the adatom kinetics demonstrates that the temporal dependence of a nanowire’s length is strongly affected by the ratio of the adatom’s diffusion length on the substrate and sidewalls, providing insights into the proper choice of a growth wafer. The developed model allows for customization of the growth protocols and estimation of the important diffusion parameters of the growth species.

Adsorption Isotherm, Kinetic and Thermodynamic Studies for Removal of Fluoride Ions from Drinking Water Using Modified Natural Pumice

This study aimed to modify pumice using aluminum chloride as an adsorbent for defluoridation. Batch and column experiments were carried out to evaluate the effects of pH, initial fluoride concentration, contact time, dose, and temperatur. The modified pumice adsorbent showed good fluoride removal in both batch and column studies. Fluoride up-take was observed to be effective >7%, at pH 6.5-7.5, and adsorption equilibrium time was observed at 60 min. the adsorption results were modelled using kinetic and isotherm models. Experimental data indicated that fluoride adsorption follows the second pseudo-order kinetics model (R2 > 0.99) and fits well with both the Freundlich and Langmuir isotherm models, which showed favorability for the adsorption of fluoride with a maximum capacity of 0.083 mg/g. The negative values of ∆Ho and ∆Go indicate that the adsorption process was feasible, exothermic, and spontaneous. The column performance showed the best fluoride uptake efficiency, with a breakthrough capacity of 0.48 mg/g. The %R was approximately %100 using0.1M NaOH. Fluoride levels in real wells water decreased dramatically (e.g. 4.1-0.88, 7.1-1.54, and 6.2-1.46 mg/L). The results revealed that modified pumice has the potential for fluoride removal from drinking water.

Kinetic and Mechanistic Studies of Native Chemical Ligation with Phenyl α-Selenoester Peptides

Kinetic and Mechanistic Studies of Native Chemical Ligation with Phenyl α-Selenoester Peptides

Inhibitory Potential of N-Methyl Formanilide on Mild Steel Corrosion in Sulfuric Acid: Quantum Chemical and Experimental Perspectives

Technological progress has led to increased use of metals and alloys such as aluminum, brass, bronze and mild steel. While mild steel is favoured for its availability, low cost and excellent mechanical properties, it is prone to corrosion. This study aims to reduce the corrosion of mild steel in sulfuric acid using N-methyl formanilide (NMF) as an inhibitor. The effectiveness of NMF was evaluated using gravimetric method (weight loss) and electrochemical impedance spectroscopy (EIS). Surface analyses were conducted using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The study examined the performance of NMF at different temperatures (298 K to 338 K) and varying inhibitor concentrations. The results indicated that the percentage inhibition efficiency (%IE) of NMF increased with higher concentration but decreased with temperature. The NMF formed a protective layer on mild steel through physical adsorption, which was confirmed by El-Awady adsorption isotherm and comparing it with other adsorption models. The kinetic and thermodynamic studies were also performed, with activation energy (Ea) and adsorption free energy (ΔG°ads) being calculated. These findings were further validated using the AM1 quantum mechanical method, revealing the promising results for the investigation.

Adsorption of ortho-Nitrophenol from Aqueous Solution using Phosphated Biomass of Ailanthus excelsa: Kinetic and Equilibrium Studies

This study interprets phosphated biomass of Ailanthus excelsa (PBAE) as a eco-friendly, inexpensive and potential adsorbent for adsorption of ortho-nitrophenol (ONP) from aqueous solution by using batch adsorption method. The prepared biosorbent was characterized using a variety of techniques such as Brunauer Emmett Teller (BET), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). As a function of many process parameters including material dose, contact time, concentration, pH and temperature, batch studies were conducted. It was found that a pH of 6.0, a biosorbent dosage of 0.050 g and an initial phenol concentration of 25 mg/L and temperature 298 K were the best conditions for ONP removal. The maximum sorption was found to be 95.28%. Adsorption data was better fitted to the Langmuir, Freundlich, Temkin and Dubinin Radushkevich isotherms. It was demonstrated that the sorption rate follows the pseudo-second order kinetics and intraparticle diffusion theory and the biosorption process was spontaneous and exothermic in nature.

Adsorption Kinetics Studies for Groundwater Remediation: A Study on Environmental and Economic Sustainability

Adsorption Kinetics Studies for Groundwater Remediation: A Study on Environmental and Economic Sustainability

Slow release of NPK fertilizer using biodegradable porous carriers synthesized from agricultural waste

This study investigates the synthesis of porous biodegradable materials from rice bran and pineapple waste to determine their potential as carriers for slow-release NPK (Nitrogen, Phosphorus, Potassium) fertilizers. Through gel formation, solvent exchange, and carbonization; agro-waste gets converted into highly porous materials. A further examination of these materials demonstrates their adsorption capability and efficacy in progressive NPK fertilizer release. Experimental results show that both rice bran and pineapple waste-derived materials are effective slow-release fertilizer carriers. However, comparative investigation shows that rice bran-based material has better slow-release properties than its pineapple waste-derived counterpart. Here we also include the kinetic study of the release rate of NPK fertilizers which turned toward a Pseudo-zero order of release rate. This study emphasizes the necessity of repurposing agricultural byproducts for sustainable material synthesis, which contributes to the advancement of green chemistry and provides eco-friendly fertilizer delivery systems.

Preparation and Formation Mechanism of β-SiC Coatings Using a SiCl4-CH4-H2-N2 System.

The mechanism of β-SiC preparation via chemical vapor deposition (CVD) of the SiCl4-CH4-H2-N2 system remains unclear. Consequently, the change of molar Gibbs free energy of the CVD β-SiC chemical reaction in the SiCl4-CH4-H2-N2 system has been studied by the Helsinki Software Corporation (HSC) Chemistry code for the first time. The role of nitrogen in the reaction was confirmed. Seven potential reaction pathways of CVD β-SiC were presented, and the thermodynamic equilibrium components of each reaction were calculated systematically. The most viable reaction pathway and corresponding optimal temperature range for CVD β-SiC were determined. In addition, a kinetic study of CVD β-SiC was conducted. The microscopic morphology and crystal structure of β-SiC coatings prepared on the graphite surface at different temperatures were charactered by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman, etc. Ultimately, through SEM, XRD, and Raman observation, uniform and dense β-SiC coatings with fine grains and high crystallinity were successfully obtained. Furthermore, large β-SiC-coated graphite trays with diameters of 230 and 465 mm were prepared by CVD using the SiCl4-CH4-H2-N2 system, and the average thickness of β-SiC was about 100.6 μm. This study provides a theoretical basis and technical recommendations for the fabrication of SiC-coated graphite trays used in metal-organic chemical vapor deposition (MOCVD) equipment.

Close‐packed One‐dimensional Coordination Polymer Cathode with Fast Kinetics for Sodium‐ion Batteries

Sustainable sodium‐ion batteries (SIBs) have gained tremendous attention; however, the large‐sized Na+ poses serious challenges on the development of inorganic‐based cathodes. To overcome the issues, metal–organic electrode materials are appealing because they combine attractive characteristics of organic redox centers (e.g., flexibility, highly reversible redox properties, fast kinetics (regardless of size and charge of guest ions), structural/redox tunability, and resource abundance) with structural stability arising from metal‐ligand coordination. Herein, a one‐dimensional copper‒benzoquinoid coordination polymer (CP), [CuL(Py)2]n, (LH4 = 1,4‐dicyano‐2,3,5,6‐tetrahydroxybenzene, Py = pyridine) is investigated as cathode for SIBs. As opposed to most CPs reported for SIBs which possess high porosity and surface area, this close‐packed CP can deliver discharge capacity as high as 277 mAh g‒1 at 2C (~523 mA g‒1), and at extremely high rates of 50C and 300C (~13 and 78 A g‒1), reversible capacities of 131 and 74 mAh g‒1 still can be delivered, respectively. The transport kinetics of Na+ in [CuL(Py)2]n is found to be even faster than that of Li+ despite the close‐packed structure. The mechanistic and kinetic studies have been performed. The findings gained in this work undoubtedly unravel a potential design strategy for high‐performance metal–organic electrode materials for emerging post‐Li‐ion batteries.

Kinetic study and optimization of ginger mediated ochratoxin A reduction: An eco-friendly approach including toxicity evaluation.

Ochratoxin A (OTA) is a toxic secondary metabolite synthesized by certain fungal strains of Penicillium and Aspergillus and is characterized as a Group 2B carcinogen. OTA infiltrates food and feeds through diverse chains, posing health risks to humans and animals. Herein, seven distinct edible plant materials were screened for their OTA reduction activity. Amidst them, ginger juice in aqueous (2.5%, v/v) showed the highest OTA reduction (95.63%), following first-order reaction kinetics (R2 = 0.92) with 0.72 d-1 rate constant. OTA reduction activity of ginger juice was substantially compromised in the presence of salt (> 2.5%) and temperature (> 40 °C). The response surface methodology-based approach employing Box-Behnken experimental design revealed an integrated effect of temperature, pH, and salt concentrations on OTA reduction (27.44-100%) by ginger juice. In addition, heat treatment (100 °C) and dialysis (12-14 kDa cutoff) of ginger juice implied the inclusion of heat-stable small molecules in reducing OTA. Ginger-treated OTA ameliorated hepatocellular carcinoma (HepG2) cell viability and diminished reactive oxygen species (ROS) levels compared to native OTA. In zebrafish embryos, OTA-induced teratogenic effects, diminished hatching (22.91%), and elevated ROS levels leading to embryo mortality (75%), which was significantly reversed by OTA treated with ginger, underscoring the curtailed toxicity of OTA-converted products by ginger.

Evaluation of Biochemical Methane Potential and Kinetics of Organic Waste Streams for Enhanced Biogas Production

Organic waste has the potential to produce methane gas as a substitute for petrol-based fuels, while reducing landfilling and possible environmental pollution. Generally, anaerobic digestion (AD) is used only in wastewater treatment plants as a tertiary stage of sewage sludge treatment, generating a fraction of the energy that such process plants require. In this study, four different wastes—food waste (FW), dairy industry waste (DIW), brewery waste (BW), and cardboard waste (CBW)—were tested for biogas production. The biochemical methane potential (BMP) of each sample was evaluated using an automatic methane potential system (AMPTS). Operating parameters such as pH, temperature, total solids, and volatile solids were measured. Experiments on the anaerobic digestion of the samples were monitored under mesophilic conditions (temperature 37 °C, retention time 30 days). Specific methane yields (SMYs), as well as the theoretical methane potential (BMPth), were used to calculate the biodegradability of the substrates, obtaining the highest biodegradability for BW at 95.1% and producing 462.3 ± 1.25 NmL CH4/g volatile solids (VS), followed by FW at an inoculum-to-substrate ratio (ISR) of 2 at 84% generating 391.3 NmLCH4/g VS. The BMP test of the dairy industry waste at an inoculum-to-substrate ratio of 1 was heavily inhibited by bacteria overloading of the easily degradable organic matter, obtaining a total methane production of 106.3 NmL CH4/g VS and a biodegradability index of 24.8%. The kinetic modeling study demonstrated that the best-fitting model was the modified Gompertz model, presenting the highest coefficient of determination (R2) values, the lowest root means square error (RMSE) values for five of the substrates, and the best specific biogas yield estimation with a percentage difference ranging from 0.3 to 3.6%.

Efficient Capture of Phosphate From Aqueous Media Using Bimetallic La‐Zr‐MOF

ABSTRACTDeposition of excessive phosphate in natural water column caused several issues, like the eutrophication and destruction of aquatic ecosystems. Adsorption has been an effective and convenient method for phosphate elimination. Herein, a novel bimetallic metal–organic framework adsorbent, namely, La‐Zr‐MOF, was prepared, and the morphology, crystallite, characteristic functional groups, specific surface area, and composite material surfaces were analyzed using XRD, FT‐IR, SEM‐EDS, and BET. The adsorption performance of the adsorbent was systematically evaluated by batch adsorption experiments, and the adsorption thermodynamic and kinetic properties were analyzed. The results reveal that La‐Zr‐MOF exhibits a high selectivity and sorption performance for phosphate, and the adsorption of La‐Zr‐MOF follows the Langmuir and pseudo–second‐order models; the phosphate removal procedure is a chemisorption accompanied by an endothermic reaction, and the maximum capacity was 127.7 mg g−1. Combined with batch adsorption experiments, kinetic and thermodynamic studies and various characterization analyses together revealed the phosphate removal mechanism, mainly ligand exchange and electrostatic interactions.

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.

Adsorption of amoxicillin by chitosan and alginate biopolymers composite beads.

Due to its widespread use and incomplete breakdown in the human body, amoxicillin has been detected in receiving water bodies. This raises significant concerns, like the promotion of antibiotic resistance, toxicity towards aquatic life, disruption of the natural balance of microbial communities within these water bodies, and the struggle of effectively removal by the traditional wastewater treatment plants. Consequently, exploring new processes to complement the existing methods is crucial. Adsorption, a promising highly efficient, selective, and versatile technique, can effectively remove contaminants, making it useful in various industries such as water treatment, pharmaceuticals, and environmental remediation. Several adsorbents are documented in the literature for drug adsorption; however, their fabrication often involves more complex steps and substances compared to chitosan and alginate, which are natural polymers that are biocompatible, non-toxic, and biodegradable. Their tunable properties and ease of modification enhance their efficacy in environmental remediation. Therefore, the novelty of this article is to understand the interaction of amoxicillin with chitosan and alginate adsorbents easily synthetized using the dripping technique. This approach allows us to explore basic principles that can be applied to more complex systems in future studies. The optimal pH for both beads was found to be 4, with adsorption capacities of 74.2 ± 0.3mgg-1 for alginate and 80.4 ± 0.2mgg-1 for chitosan, using 1g of adsorbent. Kinetics studies indicated that external diffusion governs adsorption for alginate, while internal diffusion governs adsorption for chitosan. This approach underscores the potential of chitosan and alginate beads as effective adsorbents for mitigating antibiotic contamination in water systems, offering a sustainable complement to traditional treatment methods.

Potential of convective drying in valorization of broccoli leaves: kinetic study, bioaccessibility of phenolic compounds and structural characteristics

Potential of convective drying in valorization of broccoli leaves: kinetic study, bioaccessibility of phenolic compounds and structural characteristics

Process Intensification and Reaction Kinetics for Synthesis of 5‐Hydroxymethyl Furfural Using DICAT‐1 Solid Acid Catalyst in a Batch Reactor

Abstract5‐HMF is a potential platform multifaceted molecule for various industrial applications and can be produced from biomass‐based hexose sugars. In the present study, the indigenously prepared catalyst DICAT‐1 (an acronym derived from DBT‐ICT Center for Energy Biosciences Catalyst #1) has been explored for fructose dehydration, using isopropyl alcohol (IPA) as a green and low boiling point (LBP) organic solvent. The exploration of heterogeneous DICAT‐1 adds specific advantages for 5‐HMF synthesis in terms of high yield, conversion, selectivity, catalyst separation, recycle, reuse, and so forth. Different variants of DICAT‐1, such as DICAT‐1A, DICAT‐1B, DICAT‐1C, and DICAT‐1D, having variable surface acidity were tested for fructose dehydration in the presence of IPA. Of the tested variants, DICAT‐1C provides good yield and selectivity of 5‐HMF. Thus, further process optimization study was conducted to obtain maximum yield, conversion, and selectivity using DICAT‐1C. The intensified process provides maximum 78% yield of 5‐HMF with 83% fructose conversion and 94% selectivity. The catalyst recyclability study showed the consistency in 5‐HMF yield, conversion, and selectivity for five consecutive recycle runs. The study of reaction kinetics showed the first‐order kinetics with an activation energy of 13.16 kJ/mole by using DICAT‐1C catalyst. Thus, the use of easily recyclable and robust catalyst provides an efficient route for production of 5‐HMF in presence of green solvent.

Growth and Production Kinetics, Extraction, and Characterization of Microbial Biosurfactants

The present study emphasizes the Growth, production and characterization of the biosurfactant produced by Pseudomonas aeruginosa, Micrococcus luteus and Serratia marcescens. These three isolates study for growth Kinetics and production kinetics. HPLC analysis of biosurfactant shows major peak and minor peak with different retention time on the basis of sample spend a different amount of time on the column according to its chemical composition.

Optimization, Kinetic and Thermodynamic Study of Rhodamine B Removal by Zinc Chloride-activated Arachis hypogaea (Groundnut Husk) biochar

Adsorption of dye from industrial effluent before discharge into the environment has become a major challenge to the food, pharmaceutical, textile, photographic and cosmetic industries. This has led scientists to the search for suitable green solutions. Carbonized and zinc chloride activated Arachis hypogaea (groundnut husk) in a 1:1 ratio was used as an adsorbent for the removal of Rhodamine B from aqueous solution. The adsorbent was characterized by ash content, bulk density, moisture content, pH, Iodine number, surface area and functional group analyses. Key parameters such as initial pH, initial concentration of Rhodamine B dye, temperature and contact time were investigated. The equilibrium data obtained were correlated with Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. It was found that both the Freundlich and Langmuir isotherms fit well to the data. The Langmuir isotherm model best describes the uptake of Rhodamine B onto zinc chloride activated groundnut husk biochar with R2 > 0.997. Maximum Rhodamine B. dye removal was observed at a pH of 11.0, with an adsorbent dosage of 1.0 g, a contact time of 125 min, an initial dye concentration of 20 mg/L and a temperature at 315 K. The efficiency of zinc chloride activated groundnut husk biochar for Rhodamine B removal was 99.55% for dilute solutions at 50 g/L. The Fourier Transform Infrared (FTIR) spectra recorded before and after activation showed the numbers of functional groups available for Rhodamine B. molecules to bind onto in the studied adsorbent. The kinetic data were best described by the pseudo-first-order and pseudo second-order models, while the thermodynamic studies indicated a spontaneous and endothermic nature in the adsorption of Rhodamine B by the zinc chloride modified groundnut husk. This research clearly details an innovative approach to utilizing carbonized and zinc chloride-activated Arachis hypogaea (groundnut husk) as an eco-friendly adsorbent for the removal of Rhodamine B from industrial effluents.