International Journal of Chemistry

International Journal of Chemistry | Vol. 13, No. 8, August 2022 | pp. 57–64

DOI: 10.46882/2022/IJC/000166

Article Type: Original Research Paper

Title: Green Corrosion Mitigation of Carbon Steel in Acidic Medium Using Leaf Extract of Moringa oleifera

Names of Authors: M. A. Haruna¹, S. K. Bhattacharya²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Technology, Minna, Nigeria.
²Department of Chemistry, Indian Institute of Technology, Kharagpur, India.

Abstract: The utilization of toxic synthetic chemical inhibitors in industrial acid descaling operations creates substantial environmental and safety hazards, driving research into sustainable green alternatives. The corrosion mitigation performance of the aqueous leaf extract of Moringa oleifera (MO-Extract) on carbon steel in 0.5 M H₂SO₄ was investigated via gravimetric weight loss and electrochemical test protocols. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements were recorded across varying inhibitor dosages (0.2 to 2.0 g/L) and system temperatures (303 to 333 K). Weight loss metrics revealed that protection efficiency increased with extract concentration, peaking at 91.4% at a dose of 2.0 g/L. Polarization diagrams established that MO-Extract functions as a mixed-type inhibitor, suppressing both anodic iron dissolution and cathodic hydrogen gas evolution pathways. EIS scans confirmed that charge-transfer resistance (Rct) increased with higher extract amounts, indicating the formation of a robust organic protective film on the steel face. The adsorption behavior of the bioactive compounds conformed to the Langmuir isotherm model, yielding a negative standard free energy of adsorption (delta G°ads = -20.8 kJ/mol), denoting a spontaneous physical adsorption mechanism driven by the presence of rich plant polyphenols.

Keywords: Carbon steel; Corrosion inhibition; Moringa oleifera; Electrochemical impedance spectroscopy; Polarization; Adsorption isotherm

Manuscript Timeline: Received: August 14, 2021; Revised: September 25, 2021; Accepted: October 15, 2021; Published: August 03, 2022.

Citation: Haruna, M. A., & Bhattacharya, S. K. (2022). Green Corrosion Mitigation of Carbon Steel in Acidic Medium Using Leaf Extract of Moringa oleifera. International Journal of Chemistry, 13(8), 57–64.

International Journal of Chemistry | Vol. 13, No. 4, April 2022 | pp. 25–32

DOI: 10.46882/2022/IJC/000162

Article Type: Original Research Paper

Title: GC-MS Chemical Profiling, Total Phenolic Mapping, and Larvicidal Efficacy of Ocimum suave Leaf Essential Oils

Names of Authors: S. A. Abdulrahman¹, G. E. D. M. Santos²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Technology, Minna, Nigeria.
²Department of Chemistry, University of Campinas, Campinas, Brazil.

Abstract: The rampant spread of vector-borne illnesses in tropical eco-zones demands the identification of alternative botanical formulations to minimize chemical insecticide hazards in agricultural and aquatic systems. This research reports the qualitative chemical characterization, volatile compound identification via Gas Chromatography-Mass Spectrometry (GC-MS), and in vitro larvicidal efficacy of Ocimum suave leaf essential oil against Culex quinquefasciatus fourth-instar larvae. Essential oils obtained via hydro-distillation in a Clevenger apparatus were separated into 22 distinct peaks through GC-MS profiling, with methyl eugenol (45.8%), beta-caryophyllene (14.2%), and eugenol (11.5%) emerging as the primary bioactive constituents. Larvicidal bioassays were conducted utilizing contact toxicity tests across a suite of oil concentrations (20 to 100 mg/L) over 24-hour exposure periods. The essential oil demonstrated significant lethal potency, yielding an LC50 value of 42.6 mg/L and an LC90 value of 78.4 mg/L against the mosquito larvae populations. A linear correlation was observed between the concentration of oxygenated phenylpropanoids and larval mortality rates. This confirms that volatile aromatic components actively disrupt the respiratory and acetylcholinesterase enzymes of the larvae, providing a sustainable botanical framework for vector population management.

Keywords: Ocimum suave; Essential oils; GC-MS analysis; Methyl eugenol; Larvicidal bioassay; Culex quinquefasciatus

Manuscript Timeline: Received: June 15, 2021; Revised: July 28, 2021; Accepted: August 22, 2021; Published: April 02, 2022.

Citation: Abdulrahman, S. A., & Santos, G. E. D. M. (2022). GC-MS Chemical Profiling, Total Phenolic Mapping, and Larvicidal Efficacy of Ocimum suave Leaf Essential Oils. International Journal of Chemistry, 13(4), 25–32.

International Journal of Chemistry | Vol. 13, No. 1, January 2022 | pp. 1–8

DOI: 10.46882/2022/IJC/000159

Article Type: Original Research Paper

Title: Synthesis, Structural Elucidation, and Antifungal Kinetics of Novel Streptomycin-Based Transition Metal Complexes

Names of Authors: A. A. Yusuf¹, P. K. Ghosh²*

Authors’ Affiliations:
¹Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.
²Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India.

Abstract: The emergence of drug resistance among opportunistic fungal strains requires the structural modification of classic aminoglycoside derivatives via coordination to transition metal ions to boost clinical performance. This research outlines the synthesis, structural characterization, and in vitro antifungal testing of novel copper(II), nickel(II), and cobalt(II) complexes coordinated with streptomycin ligands. The synthesized coordination compounds were profiled utilizing elemental analysis, molar conductance measurements, magnetic susceptibility, and FT-IR spectroscopy. Analytical metrics established a 1:1 metal-to-ligand stoichiometric coordination pattern for all complexes, corresponding to a general structural configuration of [M(STR)Cl₂], where STR represents the neutral streptomycin molecule. Molar conductance tests in DMSO indicated a non-electrolytic nature. FT-IR spectra confirmed that streptomycin acts as a bidentate ligand, binding to the metal centers via the guanidino ring nitrogen and the carbonyl oxygen atoms. In vitro antifungal evaluation was conducted against Candida albicans and Aspergillus niger isolates via the disk diffusion test. The copper(II)-streptomycin complex demonstrated a two-fold increase in mycelial growth inhibition compared to standalone uncoordinated streptomycin, which is explained via cell permeability and chelation principles.

Keywords: Streptomycin; Metal complexes; Antifungal activity; FT-IR spectroscopy; Candida albicans; Chelation theory

Manuscript Timeline: Received: February 12, 2020; Revised: March 20, 2020; Accepted: April 15, 2020; Published: January 03, 2022.

Citation: Yusuf, A. A., & Ghosh, P. K. (2022). Synthesis, Structural Elucidation, and Antifungal Kinetics of Novel Streptomycin-Based Transition Metal Complexes. International Journal of Chemistry, 13(1), 1–8.

International Journal of Chemistry | Vol. 13, No. 10, October 2022 | pp. 73–80

DOI: 10.46882/2022/IJC/000168

Article Type: Original Research Paper

Title: Synthesis, Molecular Docking, and Enzymatic Screening of Novel Quinoline-Linked Chalcone Derivatives

Names of Authors: O. M. Kolawole¹, E. C. J. Smith²*

Authors’ Affiliations:
¹Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria.
²Department of Chemistry, University of Manchester, Manchester, United Kingdom.

Abstract: Inhibiting acetylcholinesterase (AChE) represents a vital clinical strategy for managing Alzheimer's disease by maintaining systemic acetylcholine neurotransmitter levels in brain tissue. In this work, five novel quinoline-linked chalcone derivatives were synthesized via Claisen-Schmidt condensation of quinoline-2-carboxaldehyde with various substituted acetophenones in the presence of potassium hydroxide catalysts. The molecular structures of the synthesized targets were verified using elemental analysis, FT-IR, and ¹H-NMR spectroscopy. In vitro AChE enzyme inhibition assays revealed that compound 3d, bearing a p-chlorosubstituent, possessed the highest inhibitory potency, showing an IC50 value of 7.8 μM compared to the donepezil clinical standard (IC50 = 2.1 μM). To investigate specific binding modes, in silico molecular docking simulations were run inside the catalytic active site of human AChE using AutoDock Vina software. The computational docking models demonstrated that the chalcone carbonyl forms stable hydrogen bonds with Gly121 and Ser203 residues. The quinoline ring extensions fit well into the peripheral anionic site, engaging in significant edge-to-face pi-pi stacking interactions with Trp286. These structural contacts stabilize the ligand-protein topology, explaining the low inhibition constants and presenting a potential scaffold for further antidementia drug design.

Keywords: Quinoline; Chalcones; Acetylcholinesterase; Enzyme inhibition; Molecular docking; Alzheimer's disease

Manuscript Timeline: Received: September 10, 2021; Revised: October 22, 2021; Accepted: November 15, 2021; Published: October 05, 2022.

Citation: Kolawole, O. M., & Smith, E. C. J. (2022). Synthesis, Molecular Docking, and Enzymatic Screening of Novel Quinoline-Linked Chalcone Derivatives. International Journal of Chemistry, 13(10), 73–80.

International Journal of Chemistry | Vol. 13, No. 3, March 2022 | pp. 17–24

DOI: 10.46882/2022/IJC/000161

Article Type: Original Research Paper

Title: Adsorptive Sequestration of Hexavalent Chromium Using Thiol-Functionalized Sugarcane Bagasse 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 South Africa.

Abstract: Heavy metal contamination of surface waters by industrial chrome plating 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 sugarcane bagasse prepared via chemical modification with thioglycolic acid. 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 thiolation process successfully integrated sulfur-rich thiol (-SH) functional ligand networks across the cellulosic biomass structure. Batch extraction experiments evaluated parameters of solution pH, equilibrium contact time, adsorbent dosage, and initial Cr(VI) concentrations. Maximum chromium adsorption occurred at an acidic pH of 2.0, using an equilibrium contact period of 90 minutes due to the protonation of surface functional groups. Equilibrium data matched the Langmuir model closely, showing a maximum monolayer adsorption capacity of 54.45 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 material for industrial water treatment plant design.

Keywords: Sugarcane bagasse; Thiolation; Hexavalent chromium; Adsorption kinetics; Chemisorption; Wastewater treatment

Manuscript Timeline: Received: June 02, 2021; Revised: July 15, 2021; Accepted: August 10, 2021; Published: March 08, 2022.

Citation: Chidi, E. N., & van der Westhuizen, L. M. (2022). Adsorptive Sequestration of Hexavalent Chromium Using Thiol-Functionalized Sugarcane Bagasse Biomass. International Journal of Chemistry, 13(3), 17–24.

International Journal of Chemistry | Vol. 12, No. 3, March 2021 | pp. 17–24

DOI: 10.46882/2021/IJC/000147

Article Type: Original Research Paper

Title: Thermodynamic Modeling, Kinetic Runs, and Multilayer Adsorption of Acid Blue 92 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 Blue 92 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 blue 92; Adsorption isotherm; Chemisorption; Thermodynamic parameters

Manuscript Timeline: Received: July 20, 2020; Revised: August 28, 2020; Accepted: September 15, 2020; Published: March 04, 2021.

Citation: Yusuf, A. D., & Al-Ghamdi, M. A. (2021). Thermodynamic Modeling, Kinetic Runs, and Multilayer Adsorption of Acid Blue 92 Dye onto Modified Bentonite Clay. International Journal of Chemistry, 12(3), 17–24.