VOLUME 47, NO5, OCT-2025

Thermodynamics and Reduction Kinetics of Iron(III) Benzohydroxamic Acid Complex by Hydroxylamine Hydrochloride

Using a stopped flow, the photodiode array spectrometer was employed to study the reduction kinetics of Iron(III)-Benzohydroxamic acid(BHA) complex with pH having 4.5 to 3 and temperature ranging from 298 K to 278 K. KCl was used to set the ionic strength of the system to 0.2 M. Pseudo first-order kinetics were studied to understand the reduction process. The rate constant was also calculated for 2nd order as well. It has been reported that in around 10 to 11 seconds more than half of Iron-BHA complex had been reduced while after around 120 seconds, the concentration of the complex was negligible as was completely reduced. For phase 1, the rate constant with pH 3 for temperature 278 K, 283 K, 288 K, 293 K and 298 K was 0.2120, 0.4310, 0.2900, 0.2770 and 0.5550 M-1 s-1 respectively. For pH 3.5 it is 0.1980, 0.2450, 0.3710, 0.5440 and 0.7150 M-1 s-1. It was 6.5740, 6.5740, 9.8980, 13.1500 and 18.4800 M-1 s-1 for pH 4 and for pH 4.5 it was reported to be 6.5740, 9.8980, 21.0700, 20.3400 and 35.1600 M-1 s-1 respectively. For phase 2, at pH 3 it was reported to be 0.0990, 0.1290, 0.1690, 0.2120 and 0.2750 M-1 s-1 respectively. At pH 3.5 the rate constant was 0.0850, 0.1060, 0.1320, 0.1410 and 0.1790 M-1 s-1. For pH 4, the rate was 6.5740, 6.5740, 17.1300, 25.1600 and 29.5100 M-1 s-1, while it was 6.5740, 6.5740, 10.5500, 42.8000 and 39.3700 M-1 s-1 at pH 4.5 respectively. Thermodynamic parameters were then calculated such as Change in Enthalpy, entropy and activation energy. This study elucidates the thermodynamic and kinetic parameters governing the reduction of the Iron Benzohydroxamic Acid complex. The derived thermodynamic values and proposed kinetic mechanism contribute to a deeper understanding of iron coordination chemistry and redox processes relevant to various chemical and biological systems. These findings provide a foundation for future research exploring similar metal-ligand interactions.read more

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Muhammad Perviaz, Shazia Nisar, Shazia Ishfaq, Kanwal Zahid, Muhammad Atif, Fazal Rahim, Ajmal Khan and Zulkifle Ikram

Synthesis and Characterization of Some New Analogues of Luciferin, Calculating Their Stokes Shift and Energy Band Gaps by the Tauc Plot Method

Luciferin is a chemical compound found in some living organisms. It is responsible for producing light. Due to the importance of luciferin in various applications, in this study, a series of new luciferin analogues are synthesised and characterized using different techniques, including: proton nuclear magnetic resonance (1H-NMR), carbon-13 nuclear magnetic resonance (13C-NMR), Correlation spectroscopy (COSY), Heteronuclear single quantum coherence (HSQC), Electron impact (EI) mass spectra, and Fourier transform infrared spectroscopy (FTIR). These compounds are synthesized by reacting cysteine monohydrate hydrochloride with aryl nitrile derivatives through the click reaction, using sodium bicarbonate and reflux for two days, with high yields and purity. The thiazole motif is also prepared by reacting the aldehyde with 2-aminothiophenol using urea nitrate as a catalyst with high yield, rapid, easy, quick isolation, and solvent-free. The Stokes shift for their analogues was studied and calculated. The Tauc formalism calculated the energy band gaps. The Stokes shift and the energy band gaps were almost the same value for the thiazoline motifs C3, C4, C5, and C6, which is attributed to the same chemical structures for them. Still, there is a difference for benzothiazole motifs T4, T6, as a consequence of different substitutions.read more

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Wael Sadiq Hanoon, Raed Kadhim Zaidan, Basil Ali Abdullah and Widad S. Hanoosh

New PVC Membrane-Based Ion-Selective Electrode for Ultrasensitive Detection of Bismuth(III) with Sudan I

Accurate and dependable measurement of bismuth is vital for ensuring the safety of drugs, managing industrial processes, and evaluating environmental pollution. In this study, a new potentiometric sensor that uses Sudan I as the electroactive material within poly(vinyl chloride) (PVC) membrane structure was designed. The sensor displayed a broad linear concentration range of 1.0×10-3 to 1.0×10-10 M, an ultra-low detection limit of 4.0×10⁻11 M, and a response time of 30 seconds. It retained stable performance across a pH range of 2.0–7.0 and had an operational lifetime of about one month. When compared to existing literature, the sensor's selectivity and detection limit were significantly enhanced. It was successfully utilized to determine bismuth species in pharmaceutical formulations. Potentiometric methods provide clear advantages over other analytical techniques, such as simplicity, cost-effectiveness, quick response, and high selectivity. This developed sensor is a valuable tool for bismuth(III) determination, especially in quality control and pharmaceutical analysis.read more

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Burak Aksar, Gulsah Saydan Kanberoglu and Fatih Coldur

Adsorption of RB-5 Dyestuff onto Boric Acid-Zinc Nanoalloys: Isotherm, Kinetic, and Thermodynamic Investigations

In this study, boric acid-zinc (BA-Zn) nanoalloys were employed as an adsorbent for the removal of RB-5 dyestuff from aqueous solutions. The investigation focused on analyzing the impact of the initial dyestuff concentration, solution pH, temperature, and equilibrium contact time on the adsorption process of RB-5. The adsorption behavior of RB-5 onto the surface of BA-Zn-nanoalloys was explored, with a particular emphasis on the influence of initial dyestuff concentration and solution pH. The adsorption equilibrium data were subjected to analysis using Langmuir, Freundlich, DRK, and Temkin isotherm models. The results revealed a consistent alignment of RB-5 adsorption with both Langmuir and Temkin isotherms. Notably, the Langmuir adsorption capacity of BA-Zn-nanoparticles for RB-5 adsorption was determined to be 11.77 mg/g at a temperature of 25°C. In the Temkin isotherm model, an adsorption constant (AT) of 1.003 was obtained. The calculated adsorption energy from the DR adsorption model was 1.09 kJ/mol, implying a physical interaction-driven adsorption process. The empirical data further exhibited conformity with the pseudo-second order kinetic model, reflecting the rate-limiting step and overall kinetics of the adsorption process. Complementary to this, thermodynamic parameters such as enthalpy (ΔH0), Gibbs free energy (ΔG0), and entropy (ΔS0) were evaluated to discern the energetics of BA-Zn-nanoparticle RB-5 adsorption. This study not only underscores the effectiveness of BA-Zn nanoalloys as a potential adsorbent for RB-5 dyestuff removal but also contributes to the understanding of the underlying adsorption mechanisms and energetics. The insights gained hold implications for the development of sustainable and efficient strategies for wastewater treatment and environmental protection.read more

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Hasan İLHAN, Ömer GULER, Tuncay ŞİMŞEK, Salih ALKAN

Novel Polymeric-Modified PPY@GCN Based Composite for Photocatalytic Degradation of Reactive Green 5

The widely used dye Reactive Green 5 (RG 5) endures an adverse effect on human health and water supplies, necessitating effective elimination strategies. Heterogeneous photocatalysis based on semiconductors is a sustainable approach that precisely degrades organic contaminants. The present study aims to explain and verify the effectiveness of a remarkable PPY@GCN/Bi2WO6 (PGB) composite for the environmental remediation of RG 5 dye. The graphite carbon nitride (GCN) based ternary composite (PGB) has been synthesized by the hydrothermal approach. The prepared composites were studied by using SEM/EDX to indicate morphological characteristics and elemental variations, XRD for crystalline arrangement, FTIR for functional groups, UV-VIS for absorption spectral data and PL for emission spectra. The characterization study assists the effective assembly of PGB composite on the surface of good crystallinity GCN nanosheets. The designed heterojunction enhances photocatalytic performance and increases the separation of photo-generated charges. Light activity on prepared composites and influencing parameters (pH, oxidant dosage, catalyst dose, initial RG 5 concentration, and irradiation time) were assessed in sunlight radiance. The appropriate conditions for photocatalytic breakdown were pH = 3, catalyst amount = 10 mg/L, oxidant dose = 10 mM and initial RG 5 dye concentration of 20 ppm employing a ternary PGB composite, and RG 5 dye was degraded extensively within 1 h. Under optimal conditions, the ternary PGB composite was used to accomplish 95 % degradation efficiency. The kinetic assessment indicated that experimental findings were in significant agreement with the Behnajady-Modirshahla-Ghanbery model. Reusability experiments demonstrated that catalysts may be used five times successively. Samples showed effective antibacterial properties against strains of S. aureus and E. coli and minimal cytotoxicity. A scavenging study indicated that hydroxyl radicals were the most significant reactive oxygen species involved in the photocatalytic breakdown of RG 5 dye.read more

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Raheeba Akbar, Haq Nawaz Bhatti, Muhammad Zahid, Muhammad Yasin Naz

Isolation and Characterization of Functional Oligosaccharides from Soybean Straw: Assessment of Antioxidant and Probiotic Potential

: Soybean straw was utilized as a raw material to extract hemicellulose by employing an alkaline solution. The structure of polysaccharides was analyzed using UV-visible, infrared, and nuclear magnetic resonance (NMR) one-dimensional and two-dimensional spectra. At the same time, the monosaccharide components and surface structure of xylan in soybean straw were analyzed. The in vitro antioxidant activity of soybean straw xylooligosaccharides (XOS) was evaluated using DPPH clearance and reducibility tests. Additionally, the probiotic activity of Lactobacillus acidophilus and Bifidobacterium animalis was assessed. UV-visible light scanning indicates that the proteins and nucleic acids in the hemicellulose have been removed. High-performance liquid chromatography (HPLC) analysis reveals that soybean straw hemicellulose B primarily consists of L-glucuronic acid, D-mannose, D-mannuronic acid, D-galactose, D-aminogalactose, D-glucose, D-xylose, and L-fucose, with a molar mass ratio of D-xylose at 94.33%. After hydrolysis by xylanase, oligosaccharides with a degree of polymerization of 2-3 are obtained. Scanning electron microscopy (SEM) showed that oligosaccharides were polymerized. Fourier transform infrared (FT-IR) spectroscopy, one-dimensional NMR, and two-dimensional NMR analyses indicate that XOS contain methyl and methoxy groups, and sugar residues are primarily linked through β-1-4 glycosidic bonds. In vitro antioxidant tests have shown that soybean straw oligosaccharides exhibit strong DPPH scavenging and reducing abilities. Furthermore, soybean straw oligosaccharides exhibit probiotic activity to Lactobacillus acidophilus or Bifidobacterium animalis.read more

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Wenming Jiang, Xingchen Guo, Mingxing Liao, Chunqing Hao, Jingxia Chen, Fang Li

Innovative Synthesis of Fe Doped ZnO-Zeolite Composite for Advanced Applications

This study introduces an innovative approach for synthesizing an Fe-doped ZnO-zeolite composite material with enhanced structural and functional properties targeting advanced environmental and catalytic applications. The key hypothesis of this study is that Fe doping and zeolite integration can synergistically increase the performance of ZnO by increasing the surface area, structural stability and reactivity. Fly ash-based zeolites were synthesized by fusion-assisted hydrothermal technique and employed as a support matrix for ZnO nanoparticles. ZnO was doped with varying concentrations of Fe (0.5–2 wt.%) to analyze the impact of iron incorporation on crystallinity and morphology. Subsequently, Fe-ZnO was composited with zeolite to make a hybrid material with multifunctional characteristics. Comprehensive characterizations were performed via SEM (to observe morphology and dispersion), FTIR (to confirm bonding and functional groups) and XRD (to analyze crystal structure and phase purity). XRD results confirmed the presence of wurtzite ZnO structure with no secondary phases, while SEM micrographs revealed even dispersion of Fe-ZnO on zeolite surfaces. Notably, Fe doping caused a slight shift in the diffraction peaks and reduced the crystallite size (~18–25 nm), confirming the successful incorporation of Fe into the ZnO lattice. FTIR spectra validated the coexistence of Zn–O, Fe–O, and zeolitic Si–O–Al bonds. The efficient integration of Fe-ZnO nanoparticles into the zeolite framework is confirmed by the different peaks in the Raman spectra at around 300, 445, 620, and 1050 cm⁻¹. The BET studies revealed that the Fe-ZnO/Zeolite composite has an average pore diameter of 4.7 nm and a balanced micro-mesoporous structure with an intermediate surface area. These results support the hypothesis and indicate that the Fe-ZnO/zeolite composite possesses tailored chemical and morphological properties, making it suitable for applications in adsorption, catalysis, and environmental remediation. Future work can explore optimization strategies and performance metrics for specific pollutant degradation or catalytic conversions.read more

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Akmal Shahzad Babar, Shahzad Ali Shahid Chatha and Atta Ul Haq

Fe3O4 Nanoparticles, Metal–Organic Framework of Zr and Cu, and their Composites: Synthesis, Characterization, and Photocatalytic Activity

Fe3O4 nanoparticles (a), novel Fe3O4/Zr-MOF (b) and Fe3O4/Cu-MOF (c) composites with Zr and Cu metal-organic framework Zr-MOF (d) and Cu-MOF(e) were synthesized. Fe3O4 nanoparticles Zr-MOF (d) and Cu-MOF (e) were synthesized by hydrothermal method and Fe3O4/Zr-MOF and Fe3O4/Cu-MOF composite was synthesized by sonication. The photocatalytic activity of the Fe3O4 (NPs), MOFs and the composites were investigated for degradation of methylene blue exposed to sunlight at pH 9.2. The composites were characterized by FTIR, UV-vis, TGA, SEM, and EDS spectroscopy. The composites Fe3O4/Zr-MOF and Fe3O4/Cu-MOF showed the highest efficiency of 87% and 96% respectively, whereas nanoparticle Fe3O4 (NPs) exhibited efficiency of 77%. The of MOF, Zr-MOF and Cu-MOF individually showed less efficiency of 41%, and 49% respectively. The composite Fe3O4/Zr-MOF and Fe3O4/Cu-MOF showed 1.13 and 1.24-times higher efficiency respectively over Fe3O4 (NPs) and more than double of MOF. The incorporation of Fe3O4 NPs in the Zr-MOF and Cu- MOF tune the band gap to an optimal level for radical formation and sustain required time to initiate photochemical reaction. The band gap of Fe3O4 (NPs) and Fe3O4/Cu-MOF composite is 1.95 eV and 2.54 eV respectively, whereas the band gap for TiO2 is approximately 3.2 eV which is established photo-catalyst. It is observed that Fe3O4/Cu-MOF (c) composites band gap closer to TiO2 and shows higher efficiency. These composites showed outstanding degradation efficiency than current established photocatalyst. So, these could be used industrial pollution mitigation for green environment.read more

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Reazul Hasan Riyan, Muhaimin Helal Efat, Md. Azharul Arafath and Md. Sohrab Hossain