First-order Kinetics Research Articles

Dissipation, processing factors and risk assessment of chlorothalonil, chlorfenapyr and difenoconazole residues in chilli peppers from field to table

Understanding the residue fates of chlorothalonil, chlorfenapyr and difenoconazole in chilli peppers is essential for safeguarding food safety and human health. Here, the dissipation, removal and risk assessment of chlorothalonil, chlorfenapyr and difenoconazole in chilli peppers from field to table were systematically investigated. In field trials, the dissipation of chlorothalonil, chlorfenapyr and difenoconazole followed the first-order kinetics in chilli peppers, with half-lives of 6.80, 9.00 and 21.00 days, respectively. Residues of the metabolites, including 4-hydroxychlorothalonil (SDS-3701), tralopyril and difenoconazole–alcohol (CGA205375), were also detected in chilli peppers. The processing factors (PFs) in pickled chilli and chilli paste for washing, salting and fermentation were <1, with the overall process having PFs of 0.10–0.93. Chronic, acute and cumulative risk assessments indicated that dietary exposure to chlorothalonil, SDS-3701, chlorfenapyr, difenoconazole and CGA205375 was within acceptable limits of chilli pepper consumption. However, the total dietary risk of chlorothalonil and difenoconazole was alarming, with risk quotients (RQs) of 162% and 140%, respectively. The results could guide the safe and reasonable use of chlorothalonil, chlorfenapyr and difenoconazole in agriculture, as well as provide reference for assessing their residue levels in chilli products.

Ciprofloxacin removal as an emerging contaminant using electrochemical advanced reduction process: Mechanism, degradation pathway and reaction kinetic

The introduction of emerging contaminants (ECs), particularly antibiotics to the water resources has grown in recent years. Due to its widespread application and their toxicity, the ECs are one of the major environmental concerns. The present study is to evaluate the electrochemical removal of ciprofloxacin (CIP) as an emerging contaminant through the advanced reduction process (ARP). Moreover, the degradation pathway, mechanism and its kinetics have provided. In this study, the impacts of main operating variables were evaluated including pH, current density, initial pollutant concentration, sodium sulfite (Na2SO3) concentration, and time on the CIP removal through electrochemical process based-ARP. The obtained results revealed the 94.15 % CIP degradation rate under optimal conditions, at the concentration of 20 mg/L and pH 5 during 60 min. The CIP reduction followed the first-order kinetics with the rate of 0.99. In addition, the ARP along with electrochemical systems as a novel process were suggested as suitable and high efficiency technique for the CIP removal.

Comprehensive analysis of biotransformation pathways and products of chloramphenicol by Raoultella Ornithinolytica CT3: Pathway elucidation and toxicity assessment

Microbial degradation of chloramphenicol (CAP) has become important for reducing the adverse impact of environmental pollution with antibiotics. Although several pathways for CAP degradation have been identified in various bacteria, multiple metabolic pathways and their respective intermediate metabolites within a single strain are rarely reported. Here, Raoultella ornithinolytica CT3 was first isolated from silkworm excrement using CAP as the sole carbon source, and 100 mg/L CAP was almost completely degraded within 48 h. The biodegradation type of CAP followed first-order kinetics. Twenty-two CAP biotransformation products were identified using high-performance liquid chromatography and ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry. The CAP biotransformation pathways were predicted mainly in the acetylation and auxiliary pathways of propionylation and butyrylation. The toxicity of CAP biotransformation products was evaluated using the ecological structure-activity relationship (ECOSAR) model and biological indicators. The results showed that the toxicity of the intermediate metabolites changed slightly, but the final metabolite was harmless to the environment. Genomic analysis predicted that genes encoding acetyltransferase, amido-linkage hydrolase, nitroreductase, haloacetate dehalogenase, and protocatechuate 3,4-dioxygenase were associated with CAP biodegradation. This study provides new insights into the microbial degradation pathway of CAP and constitutes an ecological safety assessment for CAP-contaminated environments.

Pyrolysis mechanism of 1,1,1,2-tetrafluoroethane and 1,1,1,2-tetrafluoroethane/carbon dioxide as working fluids for transcritical power cycles: Insights from reactive force field molecular dynamics and density functional theory studies

Carbon dioxide-based mixtures in transcritical power cycle systems can enhance thermodynamic performance but may pose risks of thermal decomposition, potentially compromising system performance and safety. This study investigates the pyrolysis mechanism of 1,1,1,2-tetrafluoroethane (R134a)/carbon dioxide (CO₂), a typical CO₂-based mixture, using reactive force field molecular dynamics (ReaxFF-MD) simulations and density functional theory (DFT). ReaxFF-MD simulations are conducted at pressures ranging from 4 to 12 MPa and temperatures between 1800 K and 3200 K for various fluid compositions, including pure R134a and R134a/CO₂ mixtures at mole ratios of 0.7/0.3, 0.5/0.5, and 0.3/0.7. The effects of temperature, pressure, and composition on the thermal decomposition of both pure R134a and R134a/CO₂ mixtures are examined, with particular focus on behavior at 8 MPa. In the thermal decomposition of R134a/CO₂ mixtures, CO₂ inhibits the formation of F radicals and reduces their concentration through chemical reactions, thereby suppressing R134a decomposition. Pure R134a decomposes into primary products such as hydrogen fluoride (HF), fluorine (F), tetrafluoroethylene (C2HF4), trifluoromethyl radicals (CF3), and diatomic carbon (C2). The addition of CO2 results in the formation of additional products, including carbonyl fluoride (COF), oxygen (O), hydroxyl (HO), and formyl radicals (CHO). The decomposition pathways involve two reaction types: self-decomposition reactions dominate initially, while extraction reactions become more prominent later. Using the DFT approach, reaction energy barriers are analyzed to corroborate the ReaxFF-MD simulation findings. Moreover, the apparent activation energies for these reactions are quantified using first-order kinetics based on the Arrhenius equation, indicating that the thermal decomposition of R134a/CO2 mixtures is more challenging than that of pure R134a.

One-pot hydrothermal synthesis of g-C3N4/BiOBr/Bi2MoO6 as a Z-scheme heterojunction for efficient photocatalytic degradation of ciprofloxacin (CIP) antibiotic and Rhodamine B (RhB) dye

Photocatalytic degradation of toxic organic pollutants using natural sunlight is a rapidly advancing area of research, particularly involving binary or ternary component photocatalysts with Z-type heterojunctions. In this study, ternary g-C3N4/BiOBr/Bi2MoO6 photocatalysts were fabricated using a simple one-pot solvothermal method. The morphology and physicochemical properties of the samples were characterized using various techniques, including X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), confirming the presence of BiOBr, Bi2MoO6, and g-C3N4 components. The inclusion of g-C3N4 increased the BET surface area of the composite up to 46 m2/g, compared with BiOBr. In addition, g-C3N4 also enhanced the light absorption capability of the composite into the visible light range, while BiOBr and Bi2MoO6 significantly improved separation of electron-hole pairs, as evidenced by photoluminescence (PL) intensity. Under visible light illumination (LED lamp), the prepared photocatalyst showed high efficiency, achieving 94 % degradation of ciprofloxacin (CIP) antibiotic in 180 min and 92 % degradation of Rhodamine B (RhB) dye in 240 min. Moreover, under natural sunlight irradiation, the photocatalyst achieved degradation efficiencies of approximately 91 % for CIP and 100 % for RhB within 180 minutes. The photodegradation of the pollutants followed first-order kinetics with a Z-scheme type heterojunction. The photogenerated electrons played a crucial role as the main active species involved in detoxification of the organic contaminants. The photocatalyst exhibited excellent structural stability and good cycling ability, maintaining its original photocatalytic performance even after five cycles of use. This work demonstrates a promising strategy for developing sunlight-active ternary heterojunctions for environmental remediation.

POLYMER BIOCOMPOSITES IN THE FORM OF HYDROGEL USED FOR THE TREATMENT OF PRESSURE SORES

This paper presents research related to the development of hydrogel polymer biocomposites (chitosan and alginate) with an analgesic medication (lidocaine hydrochloride). The pharmaceutical availability of lidocaine hydrochloride from the hydrogel preparations was evaluated for transdermal systems in accordance with the Polish Pharmacopoeia, XI Edition. The rheological tests showed that these preparations had the characteristics of non-Newtonian, pseudoplastic liquids, for which the viscosity decreases as the shear rate increases. The developed hydrogel preparations showed bacteriostatic and bactericidal effects against both Escherichia coli and Staphylococcus aureus. The release of lidocaine hydrochloride from the tested hydrogel was a complex process that followed first-order kinetics. The rate of release could be influenced by appropriate selection of the composition of the biocomposite.

Kinetics of Colour, Clarity Changes and HMF Formation in Pear Juice Concentrate During Storage

In terms of providing delicious taste and excellent source of nutritional content, pears are highly consumed fruit all around the world. Pear juice concentrate (PJC) is one of the most frequently used products in the manufacturing processes of beverages, syrup base for canning fruits, vinegar, and wine. Colour, clarity, and the formation of hydroxy methyl furfural (HMF), a mark of Maillard browning reactions, were appraised as quality indices changes of PJC throughout storage. The samples were kept at 47°, 37°, and 27°C for 32 weeks and kinetic criteria were calculated for changes in color, clarity, and the generation of HMF. According to the model of zero-order reaction, the results demonstrated that the quantity of HMF rose linearly with temperature and storage period. The values of clarity and colour were both linearly reduced to align with the zero-order reaction kinetic. The dependence on temperature of the rate constant of the reactions examined and the activation energy values were calculated as 153.14, 93.81 and 61.48 kJ mol-1 for the generation of HMF, clarity, and colour changes with the help of Arrhenius equation.

PH STABILITY AND KINETICS OF pH DEACTIVATION OF CHITIN DEACETYLASE PRODUCED BY Absidia orchidis

This paper presents the influence of pH on the activity and stability of an extracellular chitin deacetylase produced by Absidia orchidis. It showed the highest activity at pH 4.0 and was most stable at pH 9.5. In addition, there was pH deactivation that could be described by first-order irreversible kinetics. The pH deactivation rate constant changed linearly with pH in the range from 4.0 to 9.0.

Unravelling charge carrier dynamics for enhancement of photocatalytic performance in Pd/MoS2 nanocomposites for water remediation of real-world pollutants

In this study, Pd/MoS2 nanocomposites were successfully synthesized incorporating Pd nanoparticles into three-dimensional (3D) flower-like MoS2 nanostructures. The controlled introduction of Pd was aimed to optimize the photocatalytic performance of the resulting nanocomposites, which exhibited exceptional efficiency in degrading various organic pollutants and antibiotic tetracycline (TC) under simulated solar light irradiation. The nanocomposites with an optimized Pd concentration of 2.5 % demonstrated outstanding photocatalytic efficiency, achieving the degradation of Rhodamine B (RhB), Methylene blue (MB), TC by 98 %, 98 %, and 96 %, respectively, with specific interval of 40, 30 and 60 min. The reaction rate constant of the Pd/MoS2 nanocomposites was measured to be 0.7798 min−1 using pseudo first-order rate kinetics. The value is about 19 times higher than that of pure MoS2 (0.00414 min−1) for degradation of RhB. The improved photocatalytic performance of these nanocomposites can be attributed to several factors. Firstly, the incorporation of Pd nanoparticles substantially enhanced their light absorption capabilities, leading to an overall increase in photocatalytic efficiency. Moreover, the presence of Pd contributed to a large surface area, further enhancing the nanocomposite's photocatalytic potential. Importantly, the formation of a built-in electric field at Pd/MoS2 interface facilitated the efficient separation of the electron-hole pairs, extending the life time of these photoinduced charge carriers. This study offers valuable insights into development of MoS2-based photocatalyst, which hold significant promise for addressing water pollution challenges and making substantial contributions to the field of water purification and environmental remediation.

Kinetic stability and bioavailability of curcumin nanoemulsions stabilized with krill oil phospholipids

Curcumin is a phenolic compound with widely reported bioactive properties. However, its low water solubility leads to low stability and bioavailability. Krill oil (KO) is a rich source of phospholipids naturally structured with omega-3 fatty acids (FA) that emerges as a suggested vehicle for curcumin. This study was aimed to prepare curcumin nanoemulsions (NE) using KO phospholipids as a surfactant to improve the absorption of curcumin after oral ingestion. NE were formulated with i) purified krill phospholipids (PCK), and ii) NE with crude KO without the addition of co-surfactants. As a reference, a NE was formulated using soy phosphatidylcholine (PC). Using 8 % of PCK and 4 cycles of ultrasound, NE with unimodal particle size dispersion were formed. The physicochemical analysis of the NE was monitored for 70 days at 4 and 30 °C; the nanoemulsified curcumin followed first-order degradation kinetics with a half-life (t1/2) for PC, KO, and PCK of 396, 328, and 162 days, respectively. TBARS values reached a maximum of 30 μM for KO and PCK NE, but according to the ABTS method, they had better antioxidant activities (>4.9 μM Trolox). Concerning pharmacokinetics, KO NE displayed the best bioavailability data with an AUC of 684.54 ± 72.62 ng h/mL, increasing five times more its absorption with respect to non-nanoemulsified curcumin. According to our data, NEs can guarantee the stability of curcumin during storage at 4 °C and improve its absorption after oral intake. Indeed, self-emulsified KO NEs enhance the bioavailability of curcumin to the same or better extent than soy PC conventional, but with the advantage of providing functional ingredients (omega-3 FA and astaxanthin).

Comparison of Combined Dissipation Behaviors and Dietary Risk Assessments of Thiamethoxam, Bifenthrin, Dinotefuran, and Their Mixtures in Tea.

In the tea-planting process, insecticides are commonly combined, potentially prolonging the pre-harvest interval and heightening the risk of dietary exposure. This study focused on three frequently used insecticides in tea cultivation: thiamethoxam, bifenthrin, and dinotefuran, aiming to investigate their dissipation behaviors and associated dietary risks upon individual and simultaneous application. The dissipation kinetics of thiamethoxam, bifenthrin, and dinotefuran were successfully characterized by first-order kinetics, yielding respective half-lives of 5.44, 9.81, and 10.16 days. Upon joint application, the dissipation half-lives of thiamethoxam and bifenthrin were notably prolonged compared with their individual applications, resulting in final concentrations after 28 days that were correspondingly elevated by 1.41 and 1.29 times. Assessment of the dietary intake risk revealed that the chronic and acute risk quotients associated with thiamethoxam and bifenthrin escalated by 1.44-1.59 times following their combined application. Although dietary risks associated with Tianmuhu white tea, as determined by the exposure assessment model, were deemed acceptable, the cumulative risks stemming from pesticide mixtures across various dietary sources warrant attention. Molecular docking analyses further unveiled that thiamethoxam and bifenthrin competitively bound to glutathione S-transferase (GST) at amino acid residues, notably at the 76th GLU and the 25th PHE, pivotal in the metabolism and absorption of exogenous substances. Moreover, the interactions between P-glycoprotein and pesticides during transport and absorption were likely to influence dissipation behaviors post-joint application. This research offers valuable insights and data support for optimizing joint pesticide application strategies and assessing risks associated with typical pesticides used in tea cultivation.

Insight into HTPB pyrolysis mechanism under high-temperature: A reactive molecular dynamics study

Hydroxyl-terminated polybutadiene (HTPB) is widely utilized in solid and hybrid rocket propellants due to its mechanical properties and combustion performance. Insight into its pyrolysis process is key to enhancing combustion efficiency in rocket engines. This study employs ReaxFF molecular dynamics (MD) simulations to explore the pyrolysis mechanism of HTPB under extreme conditions, with temperatures ranging from 1000 K to 2000 K. The results identify the primary degradation products and elucidate their formation mechanisms. The simulation reveals that C-C bond cleavage at polymerization sites is the initial step, followed by the formation of linear oligomers and butadiene. Subsequent reactions, including hydrogenation and dehydrogenation, lead to the generation of smaller molecular species. The kinetic analysis confirms that HTPB pyrolysis follows first-order reaction kinetics, with an activation energy of 8.12 kcal/mol. The findings are compared with existing experimental data, highlighting the influence of thermal environments on pyrolysis mechanisms and product distributions.

Assessment of amoxicillin (AMX) removal from aqueous medium through Rhapis-based bioretention system.

Antibiotics can be effectively removed from wastewater using constructed wetlands (C.W.s). However, little is known about using attractive garden plants in C.W.s to eliminate antibiotics. Thus, the current study aims to treat amoxicillin (AMX)-contaminated wastewater through a Rhapis excelsa-based bioretention system (BS). The investigation was done at 15days hydraulic retention time (HRT) under two conditions: set-1, varied AMX 5 to 25ppm with constant NPK (nitrogen, phosphorus, potassium) source; and set-2, varied NPK sources with constant AMX (25ppm). During the study, it was observed that in the set-1 condition with increasing AMX concentration, the removal of AMX through BS decreased; however, in the set-2 experiment, with enhancing NPK source, the performance of the BS treating 25-ppm AMX-contaminated wastewater increased. AMX removal of 2.3%, 66.3%, 60.6%, 52.2%, 46.7%, and 44.9% was achieved for control, BS-1, BS-2, BS-3, BS-4, and BS-5, respectively, during set-1 experiment. However, in the set-2 experiment, 23.4% (control), 43.3% (BS-1), 60.3% (BS-2), 75.9% (BS-3), 88.8% (BS-4), and 99% (BS-5) AMX removal were achieved. Removing pollutants like AMX, COD, PO43--P, NO3--N, and NH4+-N followed first-order kinetics. A positive correlation of COD with AMX was observed through principal component analysis and correlation matrix. The microbial community study was also covered to prioritize the role of microbes in treating AMX through BSs. The AMX treatment through Rhapis excelsa-based BS supported plant growth and development with increasing chlorophyll content, fresh weight, and C, H, N value.

Inactivation kinetics of dairy phages using photocatalytic paint under diverse environmental conditions and radiation sources

This article investigates the efficacy of a photocatalytic paint for bacteriophages inactivation under various levels of incident radiation flux, relative humidity and radiation sources. Two phages that infect lactic acid bacteria were selected: J-1, infective of Lacticaseibacillus casei ATCC 27139, and M13-G1b, infective of Streptococcus thermophilus G1b. Phage suspensions were deposited on coated and uncoated plates and exposed to radiation typically used for indoor illumination (λ = 360–720 nm). A first-order inactivation kinetics was proposed with respect to the Plaque Forming Units per mL (PFU/mL) that correlates the inactivation constant with the operating conditions. The kinetic constant of this novel model combines a potential function for the incident radiation flux and a logistic function for the relative humidity. The results showed that as these variables increased, phage inactivation turned higher for both uncoated and coated plates. Photonic and quantum efficiencies were also calculated for both phages, when treated with photocatalytic paint under UV-A radiation. The photonic efficiencies were 8.03 × 1012 PFU/Einstein for J-1 and 4.05 × 1012 PFU/Einstein for M13-G1b, while the quantum efficiencies were 1.19 × 1013 PFU/Einstein for J-1 and 6.03 × 1012 PFU/Einstein for M13-G1b. Good agreement was obtained between predictions of the proposed kinetic model and experimental data, with a Root Mean Square Error of 4.43 % for J-1 and 2.98 % for M13-G1b. The developed model would be useful to predict phage inactivation under diverse combinations of operating conditions levels in environments of dairy plants, different from those tested in this work.

Green synthesis and characterization of nano reduced graphene oxide/cerium oxide (rGO/CeO2) for Rose Bengal dye degradation

This study focuses on the synthesis and characterization of reduced graphene oxide/cerium oxide (rGO/CeO2). Cerium oxide (CeO2) was produced using a solution combustion method with Ashwagandha plant (AP) and Tartaric acid (TA) as the fuel. The nanocomposite was then synthesized via a simple reflux method. Structural, functional, and morphological analyses were performed using XRD, HR-SEM, EDAX, UV-DRS and FTIR techniques. The photocatalytic activity of rGO/CeO2 was demonstrated by degrading Rose Bengal dye (RB) at a concentration of 10 ppm over 180 min. The reaction followed first-order kinetics, achieving an impressive degradation rate of approximately 95 %. The half-life was determined to be 40.96 min, indicating efficient photocatalytic performance. The catalyst's reusability was assessed, showing consistent stability over five cycles with unchanged catalytic efficiency. This work marks the first report of RB dye degradation using an rGO/CeO2 (AP) composite.

Development and Analysis of Colon-Specific, pH-Responsive Polymer Delivery of Irinotecan Hydrochloride Tablets for Colon Cancer Treatment.

For the formulation of enteric-coated tablets containing irinotecan hydrochloride, this thesis focuses on HPMC and ethylcellulose, both of which are pH- and oxidation-resistant polymers. The integrated polymer-drug tablet mixture was coated with 15% of eudragit S100 and L100, which is a methacrylic acid copolymers, that’s soluble at pH 7. Both the physical characteristics with the invitro release kinetics pattern of the enteric-coated tablets were characterized. In the invitro release study, different pH environments were used, comparable to the gastrointestinal tract (GIT): 0.1 N HCl solution for two hours, pH 6.8 phosphate buffer for three hours, and pH 7.4 phosphate buffer for six hours. Using this device, you can simulate the pH level of the mouth, the digestive tract, and the urinary tract. As a result of consistent release studies, formulation F7 released 88.2% of the drug after 12 hours. Models such as Higuchi, Korsmeyer-Peppas, and zero-order reactions were used to analyze the GIT. This directed the development of a sustained delivery pattern that may be perfect for colonic IRT administration in the eventual treatment of colon cancer. Among the nine formulations, F7 formulated with EC and HPMC extended best sustained release pattern of drug, hence it is suitable for treating colon cancer.

Phycocyanin-Loaded Alginate-Based Hydrogel Synthesis and Characterization.

Phycocyanin was extracted from Spirulina platensis using conventional extraction (CE), direct ultrasonic-assisted extraction (direct UAE), indirect ultrasonic-assisted extraction (indirect UAE), and microwave-assisted extraction (MAE) methods at different temperatures, extraction intervals, stirring rate, and power intensities while maintaining the same algae to solvent ratio (1:15 w/v). The optimization of the extraction parameters indicated that the direct UAE yielded the highest phycocyanin concentration (29.31 ± 0.33 mg/mL) and antioxidant activity (23.6 ± 0.56 mg TE/g algae), while MAE achieved the highest purity (Rp = 0.5 ± 0.002). Based on the RP value, phycocyanin extract obtained by MAE (1:15 w/v algae to solvent ratio, 40 min, 40 °C, and 900 rpm) was selected as active compound in an alginate-based hydrogel formulation designed as potential wound dressings. Phycocyanin extracts and loaded hydrogels were characterized by FT-IR analysis. SEM analysis confirmed a porous structure for both blank and phycocyanin loaded hydrogels, while the mechanical properties remained approximately unchanged in the presence of phycocyanin. Phycocyanin release kinetics was investigated at two pH values using Zero-order, First-order, Higuchi, and Korsmeyer-Peppas kinetics models. The Higuchi model best fitted the experimental results. The R2 value at higher pH was nearly 1, indicating a superior fit compared with lower pH values.

Innovative Proniosomal Formulation of Cilnidipine, Optimization and InDepth Characterization.

This study aims to enhance the solubility and bioavailability of cilnidipine as a dual L/N-type calcium channel blocker for hypertension using proniosomes. Proniosomes are dry powders that turn into niosomes when they come into contact with water, improving drug encapsulation and stability. Different concentrations of Span-60, cholesterol, and sorbitol were tested in the Box-Behnken design. The entrapment efficiency, particle size, zeta potential, thermal characteristics, crystalline structure and in-vitro drug release were evaluated for 17 formulations. Entrance effectivity was highest in F3 at 71.83%, while a controlled released rate of over 85.28% was observed within 12 hours. The median particle size showed a moderate stability of -11.2 mV with zeta potentials indicating this fact (902.7 nm). When, cilnidipine was inserted into proniosome systems, considerable changes occurred both thermally and crystallinity-wise according to DSC as well as XRD measurements were taken during an experiment where various mathematical models showed first-order kinetics dominated among other processes involved in drug release along Higuchi’s Equation.

Biogenic fabrication of NiO-ZnO-CaO ternary nanocomposite using Azadirachta Indica (Neem) leaves extract with proficient photocatalytic degradation of rhodamine B dye

In the current study, a ternary nanocomposite (NiO–ZnO–CaO) was successfully synthesized through the co-precipitation method using Azadirachta Indica (neem) leaves extract as green approach. The characterization of prepared nanocomposite was conducted using FT-IR, XRD, SEM and EDS to determine the metal oxides absorption bands, structural properties, elemental composition, and surface morphology of the nanocomposite. FT-IR analysis revealed characteristic vibrational peaks at 621, 684, and 721 cm−1, corresponding to Ni-O, Zn-O, and Ca-O bond vibrations, respectively. XRD patterns showed distinct diffraction peaks, indicative of the hexagonal structure of ZnO and the cubic structures of NiO and CaO. EDS analysis confirmed the presence of calcium, nickel, zinc, and oxygen with weight percentages of 9.2%, 14.4%, 15.1%, and 20.9%, respectively. SEM images displayed an irregular cube like morphology with noticeable clustering within the nanocomposite. The ternary nanocomposite was employed as photocatalyst and exhibited degradation efficiency (97%) against rhodamine B dye under 180 min of irradiation time. The kinetic studies of dye on the photocatalyst surface were accurately explained by a first-order kinetics model, with all R2 &gt; 95, signifying a strong correlation between time and dye concentration. The potocatalytic degradation mechanism of ternary nanocomposite was proposed based on band positions of of NiO, ZnO and CaO forming double type II heterojunction. Furthermore, species trapping experiments employing different scavengers were carried out, revealing the active participation of OH● and O2●─ radicals in the degradation mechanism.

Investigation of the Effect of Oxide Additives on the Band Gap and Photocatalytic Efficiency of TiO2 as a Fixed Film.

The effects of various additives (Y2O3, Ga2O3, and WO3) on photocatalytic degradation efficiency under UV light-emitting diodes (LEDs) and the optical properties of TiO2 Degussa P25 were investigated using ketoprofen and diclofenac, two non-steroidal anti-inflammatory drugs commonly detected in German rivers. Experimental results demonstrated that thin films containing these additives exhibited similar photocatalytic degradation efficiencies as pure TiO2, achieving a 30% degradation of ketoprofen over 150 min. In contrast, the Y2O3/TiO2 thin film showed significantly improved performance, achieving a 46% degradation of ketoprofen in 180 min. Notably, the Y2O3/TiO2 system was three times more effective in degrading diclofenac compared to pure TiO2. Additionally, the Y2O3/TiO2 photocatalyst retained its activity over three successive cycles with only a slight decrease in efficiency. The photocatalytic degradation of both organic pollutants followed first-order kinetics with all photocatalysts. The investigation included SEM imaging to assess the surface homogeneity of the thin films and UV-vis solid-state spectroscopy to evaluate the impact of the additives on the energy band gap of TiO2.