International Journal of Chemistry

International Journal of Chemistry | Vol. 15, No. 6, June 2024 | pp. 41–48

DOI: 10.46882/2024/IJC/000188

Article Type: Original Research Paper

Title: Thermodynamic Modeling, Kinetic Runs, and Multilayer Adsorption of Acid Yellow 36 Dye onto Modified Bentonite Clay

Names of Authors: A. D. Yusuf¹, M. A. Al-Ghamdi²*

Authors’ Affiliations:
¹Department of Industrial Chemistry, Federal University of Technology, Yola, Nigeria.
²Department of Chemistry, Qatar University, Doha, Qatar.

Abstract: The release of highly stable anionic azo dyes like Acid Yellow 36 from textile processing factories causes significant environmental and toxicity hazards in surface water channels. This study examines the adsorptive uptake performance of a surfactant-modified bentonite clay (SMB) prepared via chemical functionalization with hexadecyltrimethylammonium bromide (HDTMA-Br). The structural parameters of raw and modified clays were characterized using X-ray diffraction (XRD) and FT-IR spectroscopy. Adsorption operations were conducted via batch runs, monitoring changes in contact time, solution pH, initial dye loading concentrations, and system temperatures. The equilibrium datasets fit closely with the Freundlich isotherm model, demonstrating successful multilayer dye attachment onto the hydrophobic surfactant bilayers. Kinetic parameters matched the intra-particle diffusion expressions alongside a pseudo-second-order mechanism, showing that chemisorption reactions controlled the mass transfer rates. Thermodynamic constants showed that the adsorption process was endothermic (delta H° = 22.4 kJ/mol) and caused an increase in system randomness at the solid-solution interface (delta S° = 74.2 J/mol K). Negative values of Gibbs free energy (delta G°) spanning from -2.4 to -5.8 kJ/mol across the 298 to 328 K range confirmed process spontaneity, positioning SMB as an affordable material for industrial dye wastewater treatment.

Keywords: Bentonite clay; Surfactant modification; Acid yellow 36; Adsorption isotherm; Chemisorption; Thermodynamic parameters

Manuscript Timeline: Received: September 10, 2022; Revised: October 22, 2022; Accepted: November 15, 2022; Published: June 03, 2024.

Citation: Yusuf, A. D., & Al-Ghamdi, M. A. (2024). Thermodynamic Modeling, Kinetic Runs, and Multilayer Adsorption of Acid Yellow 36 Dye onto Modified Bentonite Clay. International Journal of Chemistry, 15(6), 41–48.

International Journal of Chemistry | Vol. 15, No. 1, January 2024 | pp. 1–8

DOI: 10.46882/2024/IJC/000183

Article Type: Original Research Paper

Title: Transesterification Kinetics, Thermodynamic Modeling, and Engine Emissions of Methyl Esters from Ricinodendron heudelotii Seed Oil

Names of Authors: M. C. Okonkwo¹, T. H. Nguyen²*

Authors’ Affiliations:
¹Department of Industrial Chemistry, Enugu State University of Science and Technology, Enugu, Nigeria.
²Department of Chemical Engineering, Hanoi University of Science and Technology, Hanoi, Vietnam.

Abstract: Utilizing non-edible agricultural crop lipids as chemical feedstocks for alternative biodiesel synthesis promotes green energy targets without competing with global food security reservoirs. This study investigates the transesterification kinetics and chemical properties of biodiesel synthesized from essessang (Ricinodendron heudelotii) seed oil. Because of an elevated initial free fatty acid content (5.84 mg KOH/g), a two-step acid-base catalyzed transesterification route was deployed. The first step reduced the acid value below 1.0 mg KOH/g using 1.2% v/v sulfuric acid in methanol, followed by standard base-catalyzed transesterification with sodium methoxide. Fatty acid methyl ester (FAME) yield was optimized at 93.8% using a 6:1 methanol-to-oil molar ratio, a catalyst concentration of 1.0 wt% NaOH, and a process temperature of 60°C for 90 minutes. Kinetic analysis confirmed that the transesterification process followed pseudo-first-order reaction mechanics with an activation energy of 41.5 kJ/mol. Fuel properties of the prepared biodiesel, including kinematic viscosity (4.32 mm²/s at 40°C), flash point (164°C), and cetane number (53), matched international ASTM D6751 regulatory specifications. Diesel engine tests using a B20 blend showed a 14.5% reduction in smoke opacity compared to conventional diesel.

Keywords: Ricinodendron heudelotii; Biodiesel; Transesterification; Reaction kinetics; Activation energy; Fuel properties

Manuscript Timeline: Received: July 02, 2022; Revised: August 14, 2022; Accepted: September 10, 2022; Published: January 04, 2024.

Citation: Okonkwo, M. C., & Nguyen, T. H. (2024). Transesterification Kinetics, Thermodynamic Modeling, and Engine Emissions of Methyl Esters from Ricinodendron heudelotii Seed Oil. International Journal of Chemistry, 15(1), 1–8.

International Journal of Chemistry | Vol. 15, No. 11, November 2024 | pp. 81–88

DOI: 10.46882/2024/IJC/000193

Article Type: Original Research Paper

Title: Adsorptive Sequestration of Toxic Divalent Lead Ions Using Xanthated Rice Straw Biomass

Names of Authors: E. N. Chidi¹, L. M. van der Westhuizen²*

Authors’ Affiliations:
¹Department of Pure and Industrial Chemistry, Nnamdi Azikiwe University, Awka, Nigeria.
²Department of Chemical Engineering, Stellenbosch University, Stellenbosch, South Africa.

Abstract: Heavy metal contamination of surface waters by industrial manufacturing operations requires the development of low-cost, chemically stable, and highly active biosorption matrices. This investigation reports the adsorptive efficiency of a modified agricultural adsorbent derived from rice straw prepared via chemical modification with carbon disulfide under alkaline conditions (xanthation). The chemical transformations and surface porous architectures of the matrix were examined through scanning electron microscopy (SEM) and FT-IR spectroscopy. The analytical data confirmed that the xanthation process successfully integrated sulfur-rich dithiocarbonate active ligand networks across the cellulosic biomass strands. Batch extraction experiments evaluated parameters of solution pH, equilibrium contact time, adsorbent dosage, and initial Pb(II) concentrations. Maximum lead adsorption occurred at an optimum solution pH of 5.5, using an equilibrium contact period of 90 minutes. Equilibrium data matched the Langmuir model closely, showing a maximum monolayer adsorption capacity of 58.45 mg/g at 298 K. Sorption kinetics followed a pseudo-second-order model with a high correlation coefficient (R² > 0.998), proving that chemical surface complexation reactions controlled the mass transfer rates. Thermodynamic parameters confirmed process spontaneity and endothermic characteristics, highlighting this modified biomass as an affordable choice for industrial water treatment.

Keywords: Rice straw; Xanthation; Lead removal; Adsorption kinetics; Chemisorption; Wastewater treatment

Manuscript Timeline: Received: June 02, 2023; Revised: July 15, 2023; Accepted: August 10, 2023; Published: November 09, 2024.

Citation: Chidi, E. N., & van der Westhuizen, L. M. (2024). Adsorptive Sequestration of Toxic Divalent Lead Ions Using Xanthated Rice Straw Biomass. International Journal of Chemistry, 15(11), 81–88.

International Journal of Chemistry | Vol. 15, No. 4, April 2024 | pp. 25–32

DOI: 10.46882/2024/IJC/000186

Article Type: Original Research Paper

Title: Development and Validation of a Spectrophotometric Method for Quantitative Determination of Levofloxacin in Tablet Dosage Forms

Names of Authors: E. O. Effiong¹, J. M. S. Cardoso²*

Authors’ Affiliations:
¹Department of Chemistry, University of Uyo, Uyo, Nigeria.
²Department of Pharmacy, University of Coimbra, Coimbra, Portugal.

Abstract: Developing rapid, low-cost analytical protocols is essential for routine quality monitoring and the detection of substandard antibiotic formulations in clinical testing laboratories. This paper describes the development and validation of a simple UV-Vis spectrophotometric method for the quantification of levofloxacin in commercial tablet dosage forms. The analytical procedure relied on the reaction of levofloxacin with iron(III) chloride in an acidic medium, generating a highly stable yellow-colored complex monitored spectrophotometrically at its absorption maximum of 385 nm. Method validation parameters followed the International Council for Harmonisation (ICH) guidelines. Excellent linearity was established over a concentration range of 2.0 to 25.0 mg/L with a correlation coefficient (R²) of 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were determined to be 0.08 mg/L and 0.24 mg/L, respectively. Precision assessments yielded relative standard deviations (RSD) below 1.8%. The validated method was successfully applied to screen five commercial brands of levofloxacin tablets, producing recovery percentages between 98.6% and 101.4% with no interference from common tablet excipients, making it suitable for routine quality control setups.

Keywords: UV-Vis spectrophotometry; Levofloxacin; Complexation; Method validation; Pharmaceuticals; Quality control

Manuscript Timeline: Received: August 14, 2022; Revised: September 25, 2022; Accepted: October 15, 2022; Published: April 02, 2024.

Citation: Effiong, E. O., & Cardoso, J. M. S. (2024). Development and Validation of a Spectrophotometric Method for Quantitative Determination of Levofloxacin in Tablet Dosage Forms. International Journal of Chemistry, 15(4), 25–32.

International Journal of Chemistry | Vol. 15, No. 7, July 2024 | pp. 49–56

DOI: 10.46882/2024/IJC/000189

Article Type: Original Research Paper

Title: Green Synthesis of Silver-Palladium Bimetallic Nanoparticles Using Extract of Juniperus procera and Their Catalytic Efficiencies

Names of Authors: S. I. Musa¹, K. A. Al-Jubouri²*

Authors’ Affiliations:
¹Department of Chemistry, University of Jos, Jos, Nigeria.
²Department of Chemistry, University of Baghdad, Baghdad, Iraq.

Abstract: The biological synthesis of bimetallic noble metal nanoparticles using medicinal plant extracts offers an eco-friendly and economically sustainable alternative to traditional chemical reduction protocols. This study details the green synthesis of stable silver-palladium (Ag-Pd) alloy nanoparticles utilizing the aqueous leaf extract of Juniperus procera as both a reducing and stabilizing agent. The bioreduction process was monitored via UV-Vis spectrophotometry, which revealed the gradual decay and disappearance of the metal precursor bands over 60 minutes. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses showed highly spherical nanoparticles with an average particle diameter of 16 nm. X-ray diffraction (XRD) patterns confirmed the alloyed crystalline structure of the biosynthesized bimetallic system. Fourier-transform infrared (FT-IR) spectroscopy indicated that water-soluble biomolecules, primarily flavonoids and terpenoids within the leaf matrix, were responsible for capping and protecting the nanoparticles against structural agglomeration. The catalytic efficiency of the synthesized Ag-Pd nanoparticles was evaluated by tracking the reduction of rhodamine 6G dye by sodium borohydride (NaBH₄) in an aqueous system. In the absence of a catalyst, the reaction proceeded slowly, but the introduction of bimetallic nanoparticles accelerated the degradation process, achieving 97.4% decolorization within 10 minutes, outperforming monometallic controls.

Keywords: Bimetallic nanoparticles; Green synthesis; Juniperus procera; Alloy structure; Heterogeneous catalysis; Rhodamine 6G degradation

Manuscript Timeline: Received: October 12, 2022; Revised: November 24, 2022; Accepted: December 18, 2022; Published: July 08, 2024.

Citation: Musa, S. I., & Al-Jubouri, K. A. (2024). Green Synthesis of Silver-Palladium Bimetallic Nanoparticles Using Extract of Juniperus procera and Their Catalytic Efficiencies. International Journal of Chemistry, 15(7), 49–56.

International Journal of Chemistry | Vol. 15, No. 2, February 2024 | pp. 9–16

DOI: 10.46882/2024/IJC/000184

Article Type: Original Research Paper

Title: Kinetic Studies and Free-Radical Mechanisms of the Alkaline Permanganate Oxidation of L-Tryptophan

Names of Authors: T. M. Usman¹, F. M. Al-Rasheed²*

Authors’ Affiliations:
¹Department of Chemistry, Bayero University, Kano, Nigeria.
²Department of Chemistry, King Saud University, Riyadh, Saudi Arabia.

Abstract: The kinetics of transition metal electron transfer reactions involving basic amino acids yield essential data required to map biochemical oxidation paths and structural intermediate transformations. The oxidation of L-tryptophan by permanganate ions (MnO₄⁻) was investigated spectrophotometrically in an aqueous sodium hydroxide medium at a constant ionic strength of 0.20 M (NaClO₄). The reaction progress was monitored under pseudo-first-order conditions by following the absorbance decay of MnO₄⁻ at its absorption maximum of 525 nm. The empirical rate law showed a first-order dependence on [permanganate] and a fractional-first-order dependence on [L-tryptophan]. The reaction rate increased with rising hydroxyl ion concentration, revealing a base-catalyzed pathway driven by the active unprotonated amine species. Variations in ionic strength produced positive kinetic shifts, indicating a rate-determining step involving two similarly charged ionic species. Stoichiometric determinations confirmed that 1 mole of L-tryptophan consumed 2 moles of permanganate, producing indole-3-acetaldehyde and Mn(II) species as the primary end products. Thermodynamic activation constants calculated from temperature-dependence datasets using the Eyring equation yielded an enthalpy of activation (delta H*) of 45.8 kJ/mol and an entropy of activation (delta S*) of -112.4 J/mol K, supporting an inner-sphere mechanism.

Keywords: Reaction kinetics; Spectrophotometry; Permanganate oxidation; L-tryptophan; Activation parameters; Reaction mechanisms

Manuscript Timeline: Received: July 10, 2022; Revised: August 20, 2022; Accepted: September 15, 2022; Published: February 07, 2024.

Citation: Usman, T. M., & Al-Rasheed, F. M. (2024). Kinetic Studies and Free-Radical Mechanisms of the Alkaline Permanganate Oxidation of L-Tryptophan. International Journal of Chemistry, 15(2), 9–16.