International Journal of Chemistry

International Journal of Chemistry | Vol. 10, No. 3, March 2019 | pp. 17–24

DOI: 10.46882/2019/IJC/000125

Article Type: Original Research Paper

Title: Kinetic Studies and Mechanistic Pathway of the Oxidation of L-Lysine by Alkaline Periodate

Names of Authors: T. M. Usman¹, A. 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 and non-metal electron transfer reactions involving amino acids yield foundational data required to map metabolic oxidation-reduction transformations in biological models. The oxidation of L-lysine by periodate ions (IO₄⁻) was investigated spectrophotometrically in an aqueous alkaline environment at a constant ionic strength of 0.20 M (NaClO₄). The reaction was monitored under pseudo-first-order conditions by tracking the absorbance decay of periodate at its wavelength maximum of 222 nm. The empirical rate law showed a first-order dependence on [IO₄⁻] and a fractional-first-order dependence on [L-lysine]. The reaction rate increased with rising hydroxyl ion concentration, revealing a base-catalyzed pathway governed by the active deprotonated amine species. Variations in the dielectric constant of the solvent medium produced significant kinetic shifts, indicating a rate-determining step involving two ionic species. Stoichiometric determinations confirmed that 1 mole of L-lysine consumed 2 moles of periodate, producing 5-aminopentanal and iodate ions as the primary end products. Thermodynamic activation parameters were computed from temperature dependence studies using the Eyring equation; the enthalpy of activation (delta H*) was 42.6 kJ/mol, and the entropy of activation (delta S*) was calculated to be -118.4 J/mol K. A plausible free-radical mechanism proceeding via an inner-sphere intermediate complex is proposed.

Keywords: Reaction kinetics; Spectrophotometry; Periodate oxidation; L-lysine; Activation parameters; Reaction mechanisms

Manuscript Timeline: Received: May 02, 2018; Revised: June 15, 2018; Accepted: July 12, 2018; Published: March 04, 2019.

Citation: Usman, T. M., & Al-Rasheed, A. M. (2019). Kinetic Studies and Mechanistic Pathway of the Oxidation of L-Lysine by Alkaline Periodate. International Journal of Chemistry, 10(3), 17–24.

International Journal of Chemistry | Vol. 10, No. 12, December 2019 | pp. 89–96

DOI: 10.46882/2019/IJC/000134

Article Type: Original Research Paper

Title: Synthesis, Microcharacterization, and Viscosity Profiling of Alginate-Graft-Polyacrylamide Superabsorbent Hydrogels

Names of Authors: J. K. Mensah¹, S. K. Roy²*

Authors’ Affiliations:
¹Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
²Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, India.

Abstract: The development of durable biopolymeric hydrogel networks is essential for agricultural soil water retention and controlled agrochemical delivery due to the requirement for specific structural coordination sites. This study describes the chemical synthesis and rheological optimization of a hybrid hydrogel fabricated via the free-radical graft copolymerization of acrylamide onto a high-viscosity sodium alginate backbone. The grafting reaction was initiated using potassium persulfate (KPS) and crosslinked via N,N'-methylenebisacrylamide (MBA) under optimized atmospheric conditions. Structural networks and morphology features were characterized using FT-IR spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Swelling kinetics were evaluated as a function of time, pH, and saline concentration. The hydrogel showed highly responsive pH-dependent swelling profiles, achieving a maximum water absorption capacity of 410 g/g at pH 7.4 due to structural carboxylate ionizations causing intermolecular chain repulsions. Rheological analysis confirmed strong non-Newtonian shear-thinning characteristics with a storage modulus (G') that remained constant up to 80°C. Batch adsorption tests showed high affinity for divalent lead and copper ions, matching the Langmuir isotherm with monolayer capacities of 72.4 mg/g and 85.6 mg/g at 298 K, confirming high remediation potential.

Keywords: Sodium alginate; Acrylamide; Graft copolymerization; Hydrogel; Viscosity profiling; Heavy metal adsorption

Manuscript Timeline: Received: March 15, 2019; Revised: April 22, 2019; Accepted: May 20, 2019; Published: December 08, 2019.

Citation: Mensah, J. K., & Roy, S. K. (2019). Synthesis, Microcharacterization, and Viscosity Profiling of Alginate-Graft-Polyacrylamide Superabsorbent Hydrogels. International Journal of Chemistry, 10(12), 89–96.

International Journal of Chemistry | Vol. 10, No. 5, May 2019 | pp. 33–40

DOI: 10.46882/2019/IJC/000127

Article Type: Original Research Paper

Title: Green Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Medium Using Extract of Musa paradisiaca Peels

Names of Authors: M. A. Haruna¹, S. Swaminathan²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Technology, Minna, Nigeria.
²Department of Chemistry, Indian Institute of Technology, Madras, 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 methanolic peel extract of Musa paradisiaca (Plantain) on carbon steel in 1.0 M HCl 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 92.5% at a dose of 2.0 g/L. Polarization diagrams established that the plant 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 = -21.4 kJ/mol), denoting a spontaneous physical adsorption mechanism driven by the presence of rich plant polyphenols.

Keywords: Carbon steel; Corrosion inhibition; Musa paradisiaca; Electrochemical impedance spectroscopy; Polarization; Adsorption isotherm

Manuscript Timeline: Received: June 05, 2018; Revised: July 18, 2018; Accepted: August 20, 2018; Published: May 04, 2019.

Citation: Haruna, M. A., & Swaminathan, S. (2019). Green Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Medium Using Extract of Musa paradisiaca Peels. International Journal of Chemistry, 10(5), 33–40.

International Journal of Chemistry | Vol. 10, No. 1, January 2019 | pp. 1–8

DOI: 10.46882/2019/IJC/000123

Article Type: Original Research Paper

Title: Phytochemical Screening, Volatile Component Identification, and In Vitro Acaricidal Efficacy of Vernonia amygdalina Essential Oils

Names of Authors: S. A. Abdulrahman¹, L. E. G. O. Santos²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Technology, Minna, Nigeria.
²Department of Organic Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.

Abstract: The widespread development of acaricide resistance among livestock ticks demands the isolation of alternative botanical formulations to minimize chemical toxicities in agrarian systems. This study describes the qualitative chemical characterization, essential oil isolation via Gas Chromatography-Mass Spectrometry (GC-MS), and in vitro acaricidal efficacy of Vernonia amygdalina (Bitter leaf) leaf extracts against Rhipicephalus microplus larvae. Essential oils obtained via hydro-distillation in a Clevenger apparatus were separated into 18 distinct peaks through GC-MS profiling, with beta-caryophyllene (38.4%), alpha-humulene (16.2%), and caryophyllene oxide (12.4%) emerging as the primary bioactive constituents. Acaricidal bioassays were performed utilizing the larval packet test across a suite of oil concentrations (5.0 to 25.0 mg/mL) over 24-hour exposure periods. The essential oil demonstrated significant lethal potency, yielding an LC50 value of 8.4 mg/mL and an LC90 value of 16.5 mg/mL against the tick larvae. A linear correlation was observed between the concentration of sesquiterpenes and larval mortality rates. This confirms that volatile sesquiterpenoids actively disrupt the respiratory and cuticle matrices of arachnid vectors, providing a sustainable botanical framework for veterinary parasite control.

Keywords: Vernonia amygdalina; Essential oils; GC-MS analysis; Beta-caryophyllene; Acaricidal bioassay; Rhipicephalus microplus

Manuscript Timeline: Received: April 02, 2018; Revised: May 15, 2018; Accepted: June 20, 2018; Published: January 03, 2019.

Citation: Abdulrahman, S. A., & Santos, L. E. G. O. (2019). Phytochemical Screening, Volatile Component Identification, and In Vitro Acaricidal Efficacy of Vernonia amygdalina Essential Oils. International Journal of Chemistry, 10(1), 1–8.

International Journal of Chemistry | Vol. 10, No. 4, April 2019 | pp. 25–32

DOI: 10.46882/2019/IJC/000126

Article Type: Original Research Paper

Title: Geochemical Speciation, Spatial Distribution, and Ecotoxicological Risk Assessments of Cadmium and Chromium in Coastal Estuaries

Names of Authors: C. I. Obi¹, S. H. Kim²*

Authors’ Affiliations:
¹Department of Pure and Industrial Chemistry, University of Port Harcourt, Port Harcourt, Nigeria.
²Department of Chemistry, Seoul National University, Seoul, South Korea.

Abstract: Total concentrations of heavy metals are insufficient to assess ecological risk in coastal bodies because environmental mobility and bioavailability depend heavily on specific chemical binding forms. This study evaluates the total concentration and geochemical speciation fractions of cadmium (Cd) and chromium (Cr) in surface sediments collected from an urban coastal estuary exposed to municipal and industrial waste discharges. Quantitative analysis was performed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) following the modified BCR three-step sequential extraction procedure. The total metal concentrations followed the sequence: Cr > Cd across all sampling locations. Spatial mapping revealed significant pollutant accumulation near industrial discharge channels. Speciation patterns demonstrated that a high proportion of cadmium (45.2%) was associated with the acid-soluble and exchangeable fractions, suggesting high structural instability and bioavailable risks to benthic organisms. Conversely, chromium was primarily bound within the residual and organic matrices, indicating low immediate mobility under baseline pH conditions. The Risk Assessment Code (RAC) calculated for cadmium indicated a high environmental hazard rating, highlighting a strong need for local effluent regulatory frameworks.

Keywords: Coastal estuary; Sediments; Heavy metals; BCR protocol; Geochemical speciation; Bioavailability

Manuscript Timeline: Received: May 11, 2018; Revised: June 22, 2018; Accepted: July 18, 2018; Published: April 02, 2019.

Citation: Obi, C. I., & Kim, S. H. (2019). Geochemical Speciation, Spatial Distribution, and Ecotoxicological Risk Assessments of Cadmium and Chromium in Coastal Estuaries. International Journal of Chemistry, 10(4), 25–32.

International Journal of Chemistry | Vol. 9, No. 8, August 2018 | pp. 57–64

DOI: 10.46882/2018/IJC/000119

Article Type: Original Research Paper

Title: Ultrasonic Speeds, Excess Volumetric Parameters, and Intermolecular Interactions of Binary Liquid Mixtures of Isobutanol with Aliphatic Amines

Names of Authors: E. C. Chiemeka¹, A. M. H. Al-Ghamdi²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Technology, Owerri, Nigeria.
²Department of Chemistry, University of Khartoum, Khartoum, Sudan.

Abstract: Experimental determination of ultrasonic velocities and fluid densities across varied temperature states yields critical baseline data needed to map hydrogen bond associations and molecular packing dynamics in multi-component chemical systems. This paper presents the measurement of ultrasonic velocity (u), density (rho), and dynamic viscosity (eta) for binary liquid mixtures of isobutanol with diethylamine, triethylamine, and cyclohexylamine across the entire composition matrix at temperatures of 298.15 K, 308.15 K, and 318.15 K under atmospheric pressure. From these raw data metrics, excess molar volumes (V^E) and excess isentropic compressibilities (kappa_s^E) were calculated. The calculated excess datasets were successfully fitted to the Redlich-Kister polynomial expression to compute the binary interaction coefficients and standard deviations. All investigated binary mixtures exhibited significant negative excess molar volumes (V^E) and negative excess isentropic compressibilities (kappa_s^E) across all composition bounds. These strong negative deviations reveal dense interstitial molecular packing and strong intermolecular hydrogen bond formation between the hydroxyl protons of isobutanol and the amine nitrogen centers, which decrease in intensity as thermal motion breaks the dipole networks.

Keywords: Ultrasonic velocity; Excess molar volume; Isentropic compressibility; Aliphatic amines; Redlich-Kister equation; Hydrogen bonding

Manuscript Timeline: Received: February 05, 2017; Revised: March 12, 2017; Accepted: April 08, 2017; Published: August 03, 2018.

Citation: Chiemeka, E. C., & Al-Ghamdi, A. M. H. (2018). Ultrasonic Speeds, Excess Volumetric Parameters, and Intermolecular Interactions of Binary Liquid Mixtures of Isobutanol with Aliphatic Amines. International Journal of Chemistry, 9(8), 57–64.