International Journal of Chemistry

International Journal of Chemistry | Vol. 7, No. 3, March 2016 | pp. 17–24

DOI: 10.46882/2016/IJC/000090

Article Type: Original Research Paper

Title: Thermodynamic Modeling, Kinetic Runs, and Multilayer Adsorption of Malachite Green Dye onto Modified Montmorillonite 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 cationic triphenylmethane dyes like Malachite Green 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 montmorillonite clay (SMM) 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 SMM as an affordable material for industrial dye wastewater treatment.

Keywords: Montmorillonite clay; Surfactant modification; Malachite green; Adsorption isotherm; Chemisorption; Thermodynamic parameters

Manuscript Timeline: Received: July 20, 2015; Revised: August 28, 2015; Accepted: September 15, 2015; Published: March 04, 2016.

Citation: Yusuf, A. D., & Al-Ghamdi, M. A. (2016). Thermodynamic Modeling, Kinetic Runs, and Multilayer Adsorption of Malachite Green Dye onto Modified Montmorillonite Clay. International Journal of Chemistry, 7(3), 17–24.

International Journal of Chemistry | Vol. 7, No. 10, October 2016 | pp. 73–80

DOI: 10.46882/2016/IJC/000097

Article Type: Original Research Paper

Title: Mechanochemical Properties and Microstructural Performance of Slag-Based Geopolymer Grout Reinforced with Nano-Silica Particles

Names of Authors: T. S. Ani¹, M. F. de Oliveira²*

Authors’ Affiliations:
¹Department of Electronic and Chemical Engineering, Enugu State University of Science and Technology, Enugu, Nigeria.
²Department of Chemical Engineering, Instituto Superior Técnico, Lisbon, Portugal.

Abstract: Developing high-performance geopolymer grouts from industrial wastes decreases production carbon footprints, though enhancing mechanical integrity requires structural optimization via reactive nanomaterial additives. This research tracks the structural development and mechanical profiles of geopolymer cements synthesized from ground granulated blast furnace slag (GGBS) integrated with nano-silica (nano-SiO₂) particles at dosages from 0% to 3.0% by weight. Alkaline activation was executed utilizing structural mixtures of sodium silicate and 12 M sodium hydroxide solutions. Hardening kinetics and microstructural phases were analyzed using X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, and Scanning Electron Microscopy (SEM). FT-IR spectra demonstrated the formation of a rigid silicate network, indicated by the prominent framework stretching bands shifting to 1012 cm⁻¹. Compressive strength experiments showed that grout cubes prepared with 2.0% nano-silica substitution reached a maximum compressive value of 58.4 MPa after 28 days of curing at room temperature, outperforming pure slag controls. SEM characterization revealed a highly dense matrix featuring intense structural crosslinking of calcium silicate hydrate (C-S-H) gel structures, which significantly reduces internal cracking.

Keywords: Geopolymer grout; Slag activation; Nano-silica; Compressive strength; Microstructure; C-S-H gel networks

Manuscript Timeline: Received: January 14, 2016; Revised: February 18, 2016; Accepted: March 12, 2016; Published: October 05, 2016.

Citation: Ani, T. S., & de Oliveira, M. F. (2016). Mechanochemical Properties and Microstructural Performance of Slag-Based Geopolymer Grout Reinforced with Nano-Silica Particles. International Journal of Chemistry, 7(10), 73–80.

International Journal of Chemistry | Vol. 7, No. 4, April 2016 | pp. 25–32

DOI: 10.46882/2016/IJC/000091

Article Type: Original Research Paper

Title: Green synthesis of Platinum Nanoparticles Using Aqueous Bark Extract of Prunus africana and Their Heterogeneous Catalytic Efficiency

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 platinum 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 platinum nanoparticles (PtNPs) utilizing the aqueous bark extract of Prunus africana 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 platinum chloride precursor band over 60 minutes. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses showed highly spherical nanoparticles with an average particle diameter of 14 nm. X-ray diffraction (XRD) patterns confirmed the face-centered cubic crystalline structure of the biosynthesized metallic platinum. Fourier-transform infrared (FT-IR) spectroscopy indicated that water-soluble biomolecules, primarily pentacyclic triterpenes and phytosterols within the bark matrix, were responsible for capping and protecting the PtNPs against structural agglomeration. The catalytic efficiency of the synthesized PtNPs was evaluated by tracking the reduction of eosin Y dye by sodium borohydride (NaBH₄) in an aqueous system. In the absence of a catalyst, the reaction proceeded slowly, but the introduction of PtNPs accelerated the degradation process, achieving 97.4% decolorization within 10 minutes. The dye degradation kinetics conformed strictly to the pseudo-first-order kinetic model with a rate constant of 0.284 min⁻¹, indicating excellent catalytic potential for chemical waste neutralization.

Keywords: Platinum nanoparticles; Green synthesis; Prunus africana; Biosynthesis; Heterogeneous catalysis; Eosin Y degradation

Manuscript Timeline: Received: October 12, 2015; Revised: November 24, 2015; Accepted: December 18, 2015; Published: April 02, 2016.

Citation: Musa, S. I., & Al-Jubouri, K. A. (2016). Green synthesis of Platinum Nanoparticles Using Aqueous Bark Extract of Prunus africana and Their Heterogeneous Catalytic Efficiency. International Journal of Chemistry, 7(4), 25–32.

International Journal of Chemistry | Vol. 7, No. 2, February 2016 | pp. 9–16

DOI: 10.46882/2016/IJC/000089

Article Type: Original Research Paper

Title: Synthesis, Computational Modeling, and Enzymatic Inhibition Screening of Novel Coumarin-Linked Hydrazone Derivatives

Names of Authors: O. M. Kolawole¹, E. R. Watson²*

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

Abstract: Inhibiting alpha-glucosidase represents a critical therapeutic target for managing postprandial hyperglycemia in type 2 diabetes mellitus. In this work, five novel coumarin-linked hydrazone derivatives were synthesized via the condensation of 3-acetylcoumarin with various substituted benzohydrazides in the presence of catalytic glacial acetic acid. The molecular frameworks of the synthesized targets were verified using elemental analysis, FT-IR, and ¹H-NMR spectroscopy. In vitro alpha-glucosidase enzyme inhibition assays revealed that compound 3c, bearing a p-nitro substituent, possessed the highest inhibitory potency, showing an IC50 value of 12.4 μM, compared to the acarbose clinical standard (IC50 = 38.2 μM). To investigate specific binding configurations, in silico molecular docking simulations were run inside the catalytic domain of alpha-glucosidase using AutoDock Vina software. The computational docking models demonstrated that the coumarin lactone carbonyl forms stable hydrogen bonds with Asp214 and Arg315 residues. The aromatic ring extensions fit well into the hydrophobic pocket, engaging in significant pi-pi stacking interactions with Phe178. These structural contacts stabilize the ligand-protein topology, explaining the sub-micromolar inhibition constants and presenting a potential scaffold for further antidiabetic drug design.

Keywords: Coumarin; Hydrazones; Alpha-glucosidase; Enzyme inhibition; Molecular docking; Antidiabetic drug design

Manuscript Timeline: Received: June 12, 2015; Revised: July 25, 2015; Accepted: August 18, 2015; Published: February 06, 2016.

Citation: Kolawole, O. M., & Watson, E. R. (2016). Synthesis, Computational Modeling, and Enzymatic Inhibition Screening of Novel Coumarin-Linked Hydrazone Derivatives. International Journal of Chemistry, 7(2), 9–16.

International Journal of Chemistry | Vol. 7, No. 9, September 2016 | pp. 65–72

DOI: 10.46882/2016/IJC/000096

Article Type: Original Research Paper

Title: Assessing the Hydrocarbon Tolerance and Phytoremediation Trait of Arachis hypogaea L. in Diesel Oil Spiked Soils

Names of Authors: O. F. Olawal¹, J. de Koning²*

Authors’ Affiliations:
¹Department of Plant Biology, University of Ilorin, Ilorin, Nigeria.
²Department of Environmental Sciences, Wageningen University, Wageningen, Netherlands.

Abstract: The accidental leakage of diesel fuel from commercial storage tanks damages agricultural soil porosity and introduces toxic aromatic hydrocarbons into arable land, demanding green restoration strategies. This controlled study investigates the growth kinetics and remediation efficiency of Arachis hypogaea L. (Groundnut) cultivated in soils artificially spiked with varying concentrations of automotive diesel oil (1.0% to 4.0% w/w). Plant structural indices, remaining soil total petroleum hydrocarbon (TPH) concentrations, and root zone microbial populations were quantified over a 90-day developmental period. Arachis hypogaea demonstrated strong physiological tolerance, maintaining high root nodulation indices across all diesel loading levels below 3.0%. Gas Chromatography (GC-FID) profiling showed a 74.2% reduction in soil TPH content within the rhizosphere of cultivated systems, compared to minimal attenuation (22.5%) in unplanted controls. Soil microbiological testing revealed a five-fold expansion of heterotrophic degradation bacteria within the legume root matrix. This confirms that root exudates and symbiotic nitrogen-fixing bacteria actively interact to stimulate microbial proliferation, accelerating the degradation of complex petroleum structures in contaminated agricultural terrains.

Keywords: Diesel fuel; Arachis hypogaea; Total petroleum hydrocarbons; Soil phytoremediation; Rhizosphere effect; Legume symbiosis

Manuscript Timeline: Received: December 08, 2015; Revised: January 20, 2016; Accepted: February 15, 2016; Published: September 09, 2016.

Citation: Olawal, O. F., & de Koning, J. (2016). Assessing the Hydrocarbon Tolerance and Phytoremediation Trait of Arachis hypogaea L. in Diesel Oil Spiked Soils. International Journal of Chemistry, 7(9), 65–72.

International Journal of Chemistry | Vol. 7, No. 6, June 2016 | pp. 41–48

DOI: 10.46882/2016/IJC/000093

Article Type: Original Research Paper

Title: Isolation, Structural Profiling, and Optimizing Kinetics of Amylolytic Complexes Sourced from Thermophilic Aspergillus Strains

Names of Authors: C. N. Nwosu¹, H. M. Sato²*

Authors’ Affiliations:
¹Department of Biochemistry, Nnamdi Azikiwe University, Awka, Nigeria.
²Department of Biotechnology, Tokyo Institute of Technology, Tokyo, Japan.

Abstract: The industrial saccharification of starch into simple glucose syrups requires robust amylolytic enzymes that can resist thermal denaturation during high-temperature steam liquefaction loops. This study details the isolation, microstructural profiling, and kinetic optimization of high-yielding alpha-amylase complexes produced by a thermophilic fungal strain sourced from processing soil surrounding artisanal cassava processing mills. Enrichment culturing was executed in starch-infused Mandels' media at 50°C, isolating a dominant strain identified via internal transcribed spacer (ITS) rRNA gene sequencing as Aspergillus fumigatus strain Cassava-A1. Response surface methodology optimized solid-state fermentation yields using wheat bran matrices. Maximum alpha-amylase activity (54.5 U/mL) was achieved at an incubation temperature of 50°C, an initial substrate pH of 6.0, and a fermentation period of 96 hours. Biochemical characterization showed that the crude enzyme complex retained over 85% of its initial catalytic activity across a temperature range of 45 to 65°C and a pH stability window of 5.5 to 7.0 for 24 hours. The high thermal stability of this enzyme system, along with its independence from calcium ions, makes it a viable candidate for bio-refinery industrial operations.

Keywords: Alpha-amylase; Aspergillus fumigatus; Solid-state fermentation; Thermal stability; Kinetic optimization; Starch saccharification

Manuscript Timeline: Received: November 10, 2015; Revised: December 18, 2015; Accepted: January 14, 2016; Published: June 03, 2016.

Citation: Nwosu, C. N., & Sato, H. M. (2016). Isolation, Structural Profiling, and Optimizing Kinetics of Amylolytic Complexes Sourced from Thermophilic Aspergillus Strains. International Journal of Chemistry, 7(6), 41–48.