International Journal of Chemistry

International Journal of Chemistry | Vol. 3, No. 10, October 2012 | pp. 98–105

DOI: 10.46882/2012/IJC/000049

Article Type: Original Research Paper

Title: Acoustic Velocities, Volumetric Properties, and Intermolecular Interactions of Binary Solvent Systems of Methanol with Alkyl Acetates

Names of Authors: E. C. Chiemeka¹, A. B. Adekunle²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Technology, Owerri, Nigeria.
²Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria.

Abstract: Ultrasonic velocity and density measurements provide a reliable method for evaluating molecular packaging and specific dipole interactions within binary liquid mixtures. This study presents the experimental determination of ultrasonic speed (u), density (rho), and viscosity (eta) for binary systems of methanol with methyl acetate, ethyl acetate, and propyl acetate over the full composition matrix at temperatures of 298.15 K and 308.15 K under atmospheric pressure. From these basic data, excess molar volumes (V^E) and excess isentropic compressibilities (kappa_s^E) were calculated. The calculated excess data were fitted to the Redlich-Kister polynomial equation to estimate the binary interaction coefficients and standard standard deviations. All investigated mixtures exhibited negative values for both V^E and kappa_s^E across the entire composition spectrum. These negative deviations indicate strong structural interactions, compact molecular packaging, and hydrogen bonding between the hydroxyl proton of methanol and the ester carbonyl centers. The magnitude of these negative parameters increased with ester chain length, confirming that enhanced hydrophobic properties reinforce intermolecular dipole associations in solution.

Keywords: Ultrasonic velocity; Excess molar volume; Isentropic compressibility; Binary mixtures; Redlich-Kister equation; Molecular interactions

Manuscript Timeline: Received: October 15, 2011; Revised: November 22, 2011; Accepted: December 12, 2011; Published: October 04, 2012.

Citation: Chiemeka, E. C., & Adekunle, A. B. (2012). Acoustic Velocities, Volumetric Properties, and Intermolecular Interactions of Binary Solvent Systems of Methanol with Alkyl Acetates. International Journal of Chemistry, 3(10), 98–105.

International Journal of Chemistry | Vol. 3, No. 4, April 2012 | pp. 26–33

DOI: 10.46882/2012/IJC/000043

Article Type: Original Research Paper

Title: Optimization of Enzymatic Hydrolysis of Rice Straw for Bioethanol Production Using Crude Fungal Enzymes

Names of Authors: C. N. Nwosu¹, K. A. Boateng²*

Authors’ Affiliations:
¹Department of Biochemistry, Nnamdi Azikiwe University, Awka, Nigeria.
²Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.

Abstract: Converting lignocellulosic agricultural residues into fermentable reducing sugars requires highly active and stable cellulolytic enzyme complexes. This study focuses on the optimization of the enzymatic hydrolysis of alkali-pretreated rice straw using crude cellulase systems obtained from Aspergillus niger via solid-state fermentation. The rice straw was pretreated with 2.0 M NaOH at 80°C for 2 hours to remove lignin and increase surface accessibility. Enzymatic saccharification parameters, including enzyme loading, substrate concentration, incubation temperature, and saccharification period, were evaluated systematically. Maximum reducing sugar yield was achieved using an enzyme loading of 25 U/g of substrate and a 5% w/v substrate concentration at an operating temperature of 45°C and pH 5.0 after 72 hours. Under these optimized conditions, the glucose yield reached a peak concentration of 28.5 mg/g of dry substrate, representing a cellulose conversion efficiency of 74.2%. High-Performance Liquid Chromatography (HPLC) profiling of the hydrolysate confirmed that glucose and cellobiose were the primary monosaccharides produced. The low accumulation of fermentation inhibitors like furfural suggests that this optimized hydrolysate is highly suitable for downstream bioethanol fermentation processes.

Keywords: Rice straw; Fungal cellulase; Alkaline pretreatment; Enzymatic hydrolysis; Glucose yield; Bioethanol

Manuscript Timeline: Received: July 10, 2011; Revised: August 22, 2011; Accepted: September 14, 2011; Published: April 02, 2012.

Citation: Nwosu, C. N., & Boateng, K. A. (2012). Optimization of Enzymatic Hydrolysis of Rice Straw for Bioethanol Production Using Crude Fungal Enzymes. International Journal of Chemistry, 3(4), 26–33.

International Journal of Chemistry | Vol. 3, No. 7, July 2012 | pp. 50–57

DOI: 10.46882/2012/IJC/000046

Article Type: Original Research Paper

Title: Assessing the Hydrocarbon Biodegradation and Phytoremediation Trait of Zea mays L. in Spent Engine Oil Polluted Soil

Names of Authors: O. F. Olawal¹, K. C. Onyekwelu²*

Authors’ Affiliations:
¹Department of Plant Biology, University of Ilorin, Ilorin, Nigeria.
²Department of Electronic and Chemical Engineering, Enugu State University of Science and Technology, Enugu, Nigeria.

Abstract: The discharge of spent engine oil from mechanical workshops destroys soil structure and introduces non-volatile organic pollutants into agricultural lands, demanding remediation. This field study investigates the plant growth response and hydrocarbon degradation capacity of Zea mays L. (Maize) grown in soils artificially contaminated with spent engine oil at levels of 2.0% to 6.0% w/w. Plant vegetative parameters, total petroleum hydrocarbons (TPH), and soil microbial populations were monitored over a 12-week cultivation cycle. Z. mays showed high tolerance to oil stress up to a 4.0% threshold, beyond which significant drops in stem height and dry biomass occurred. Gas Chromatography (GC-FID) analysis showed a 72.4% reduction in soil TPH content within the rhizosphere of Z. mays pots, compared to a baseline 26.5% reduction observed in unplanted control soil systems. Microbial enumerations revealed a four-fold increase in the population of hydrocarbon-utilizing bacteria (HUB) within the rhizosphere, confirming that root exudates actively stimulate microbial proliferation, accelerating the degradation of complex oil hydrocarbons.

Keywords: Spent engine oil; Zea mays; Total petroleum hydrocarbons; Phytoremediation; Rhizosphere; Hydrocarbon-utilizing bacteria

Manuscript Timeline: Received: August 11, 2011; Revised: September 20, 2011; Accepted: October 10, 2011; Published: July 05, 2012.

Citation: Olawal, O. F., & Onyekwelu, K. C. (2012). Assessing the Hydrocarbon Biodegradation and Phytoremediation Trait of Zea mays L. in Spent Engine Oil Polluted Soil. International Journal of Chemistry, 3(7), 50–57.

International Journal of Chemistry | Vol. 3, No. 1, January 2012 | pp. 1–9

DOI: 10.46882/2012/IJC/000040

Article Type: Original Research Paper

Title: Thermodynamic Modeling, Desorption Kinetics, and Multilayer Adsorption of Congo Red onto Modified Kaolinite Clay

Names of Authors: A. D. Yusuf¹, T. S. Ani²*

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

Abstract: The discharge of highly stable anionic azo dyes like Congo Red from textile processing factories presents severe remediation challenges for municipal sanitation networks. This study examines the adsorptive uptake performance of a surfactant-modified kaolinite clay (SMK) optimized via chemical treatment with cetyltrimethylammonium bromide (CTAB). Structural parameters of raw and functionalized clays were characterized using X-ray diffraction (XRD) and FT-IR spectroscopy. Adsorption operations were conducted via batch runs, monitoring shifts in contact period, baseline 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° = 18.5 kJ/mol) and caused an increase in system randomness at the solid-solution interface (delta S° = 64.2 J/mol K). Negative values of Gibbs free energy (delta G°) spanning from -1.8 to -4.5 kJ/mol confirmed process spontaneity, positioning SMK as an affordable material for dye wastewater treatment.

Keywords: Kaolinite clay; Surfactant modification; Congo red; Adsorption isotherm; Chemisorption; Thermodynamic parameters

Manuscript Timeline: Received: May 12, 2011; Revised: June 26, 2011; Accepted: July 15, 2011; Published: January 03, 2012.

Citation: Yusuf, A. D., & Ani, T. S. (2012). Thermodynamic Modeling, Desorption Kinetics, and Multilayer Adsorption of Congo Red onto Modified Kaolinite Clay. International Journal of Chemistry, 3(1), 1–9.

International Journal of Chemistry | Vol. 3, No. 5, May 2012 | pp. 34–41

DOI: 10.46882/2012/IJC/000044

Article Type: Original Research Paper

Title: Synthesis, Characterization, and Swelling Kinetics of Carboxymethyl Cellulose Grafted Polyacrylic Acid Hydrogels

Names of Authors: J. K. Mensah¹, M. A. Idowu²*

Authors’ Affiliations:
¹Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
²Department of Environmental Management, Federal University of Agriculture, Abeokuta, Nigeria.

Abstract: Smart polymeric hydrogels that respond to environmental changes find valuable applications in controlled drug delivery and agricultural soil hydration. This study describes the synthesis and swelling optimization of a biodegradable hydrogel prepared via the graft copolymerization of acrylic acid (AA) onto a carboxymethyl cellulose (CMC) backbone. The reaction was performed in an aqueous medium using potassium persulfate (KPS) as a free-radical initiator and N,N'-methylenebisacrylamide (MBA) as a crosslinker. The structural configuration of the CMC-g-PAA hydrogel was confirmed using Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Swelling kinetics were evaluated as a function of time, solution pH (2.0 to 12.0), and external salt concentrations. The hydrogel exhibited highly sensitive pH-dependent swelling behavior, showing maximum water absorption capacity (420 g/g) at pH 7.4 due to the complete ionization and electrostatic repulsion of carboxylate anions. Conversely, swelling was strongly suppressed in highly acidic media and in the presence of multivalent cations (Al³⁺ and Ca²⁺). Kinetic modeling confirmed that the water diffusion process followed a second-order swelling model, establishing its suitability for moisture retention matrices.

Keywords: Carboxymethyl cellulose; Acrylic acid; Graft copolymerization; Hydrogel; pH-sensitive swelling; Kinetic modeling

Manuscript Timeline: Received: July 15, 2011; Revised: August 28, 2011; Accepted: September 18, 2011; Published: May 04, 2012.

Citation: Mensah, J. K., & Idowu, M. A. (2012). Synthesis, Characterization, and Swelling Kinetics of Carboxymethyl Cellulose Grafted Polyacrylic Acid Hydrogels. International Journal of Chemistry, 3(5), 34–41.

International Journal of Chemistry | Vol. 3, No. 3, March 2012 | pp. 18–25

DOI: 10.46882/2012/IJC/000042

Article Type: Original Research Paper

Title: Biochemical Assessment and Nutritional Mineral Fingerprinting of Indigenous Leafy Vegetables from Eastern Nigeria

Names of Authors: A. E. Ogunkoya¹, I. J. Okoye²*

Authors’ Affiliations:
¹Department of Chemistry, Ekiti State University, Ado-Ekiti, Nigeria.
²Department of Pure and Industrial Chemistry, Nnamdi Azikiwe University, Awka, Nigeria.

Abstract: Indigenous wild leafy vegetables serve as vital micronutrient and mineral reservoirs in rural diets, yet comprehensive biochemical profiling of lesser-known varieties remains incomplete. This research evaluates the nutritional composition, mineral profile, and anti-nutritional factors of three popular indigenous vegetables (Gongronema latifolium, Vernonia amygdalina, and Telfairia occidentalis) harvested in Eastern Nigeria. Proximate analysis established high crude fiber contents ranging from 8.4% to 12.5% on a dry weight basis, alongside moderate crude protein profiles (16.4% to 22.8%) and very low lipid concentrations (1.2% to 2.5%). Mineral profiling using Atomic Absorption Spectrophotometry (AAS) demonstrated that calcium was the most abundant macro-element (420 to 680 mg/100g), followed by magnesium and potassium, while toxic heavy metals like lead and cadmium were below hazardous detection thresholds. Quantified antinutritional matrices showed low baseline levels of oxalates (2.1 to 3.4 mg/g), phytates (1.8 to 2.9 mg/g), and saponins (0.5 to 1.2 mg/g). These antinutrient concentrations fell well within safe human consumption guidelines and dropped further during traditional cooking procedures, confirming that these vegetables are excellent dietary tools for mitigating micronutrient deficiencies.

Keywords: Leafy vegetables; Proximate analysis; Mineral profile; Antinutrients; Food chemistry; Micronutrient deficiency

Manuscript Timeline: Received: June 12, 2011; Revised: July 24, 2011; Accepted: August 20, 2011; Published: March 07, 2012.

Citation: Ogunkoya, A. E., & Okoye, I. J. (2012). Biochemical Assessment and Nutritional Mineral Fingerprinting of Indigenous Leafy Vegetables from Eastern Nigeria. International Journal of Chemistry, 3(3), 18–25.