International Journal of Chemistry

International Journal of Chemistry | Vol. 3, No. 2, February 2012 | pp. 10–17

DOI: 10.46882/2012/IJC/000041

Article Type: Original Research Paper

Title: Green Synthesis of Zinc Oxide Nanoparticles Using Aqueous Leaf Extract of Citrus sinensis and Their Photocatalytic Activity

Names of Authors: S. I. Musa¹, O. R. Popoola²*

Authors’ Affiliations:
¹Department of Chemistry, University of Jos, Jos, Nigeria.
²Department of Chemistry, Ekiti State University, Ado-Ekiti, Nigeria.

Abstract: The biological synthesis of metal oxide nanoparticles using plant extracts represents an eco-friendly and sustainable alternative to traditional chemical preparation methods. This study describes the green synthesis of zinc oxide nanoparticles (ZnO-NPs) using the aqueous leaf extract of Citrus sinensis (Sweet orange) as a reducing and capping agent. The formation of the nanoparticles was monitored via UV-Vis spectrophotometry, which revealed a characteristic absorption peak at 368 nm. X-ray diffraction (XRD) analysis confirmed the crystalline nature of the ZnO-NPs, showing a hexagonal wurtzite structure with an average crystallite size of 24 nm. Fourier-transform infrared (FT-IR) spectroscopy indicated that hydroxyl and carbonyl groups from the plant polyphenols and flavonoids were actively involved in stabilizing the nanoparticle matrix. The photocatalytic efficiency of the synthesized ZnO-NPs was evaluated by monitoring the degradation of Methyl Orange dye under natural solar irradiation. The biosynthesized nanoparticles achieved 94.2% decolorization of the dye within 90 minutes of exposure. Kinetic modeling established that the photocatalytic breakdown followed the Langmuir-Hinshelwood pseudo-first-order model with a rate constant of 0.028 min⁻¹, proving that these green catalysts are highly efficient for treating textile industry organic pollutants.

Keywords: Zinc oxide nanoparticles; Green synthesis; Citrus sinensis; Crystalline structure; Photocatalytic degradation; Methyl orange

Manuscript Timeline: Received: June 05, 2011; Revised: July 18, 2011; Accepted: August 12, 2011; Published: February 03, 2012.

Citation: Musa, S. I., & Popoola, O. R. (2012). Green Synthesis of Zinc Oxide Nanoparticles Using Aqueous Leaf Extract of Citrus sinensis and Their Photocatalytic Activity. International Journal of Chemistry, 3(2), 10–17.

International Journal of Chemistry | Vol. 3, No. 9, September 2012 | pp. 90–97

DOI: 10.46882/2012/IJC/000048

Article Type: Original Research Paper

Title: Electrochemical Properties and Supercapacitive Performance of Polypyrrole-Graphene Oxide Nanocomposite Electrodes

Names of Authors: U. B. Aliyu¹, L. O. Ndidi²*

Authors’ Affiliations:
¹Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.
²Department of Chemistry, Federal University of Technology, Owerri, Nigeria.

Abstract: High-efficiency electrical energy storage requires supercapacitor electrodes that combine high pseudocapacitance with rapid electric double-layer charge transfer and mechanical stability. This study presents the preparation and electrochemical testing of polypyrrole-graphene oxide (PPy-GO) nanocomposites synthesized via the in situ chemical oxidative polymerization of pyrrole monomers on graphene oxide sheets. The morphological configurations and structural properties of the hybrid matrices were examined through transmission electron microscopy (TEM), FT-IR, and Raman spectroscopy. TEM images revealed a uniform distribution of amorphous PPy particles along the highly wrinkled GO layers. Electrochemical properties were investigated via cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) in a 1.0 M KCl electrolyte. The PPy-GO electrode delivered a maximum specific capacitance of 385 F/g at a current density of 0.5 A/g, outperforming standalone pure PPy (185 F/g). Electrochemical impedance spectroscopy (EIS) plots showed a very low internal resistance of 0.35 ohms. Long-term cycle testing showed that the nanocomposite maintained 86.4% of its initial capacitance after 1500 continuous cycles, making it a viable candidate for micro-supercapacitor assemblies.

Keywords: Polypyrrole; Graphene oxide; Nanocomposites; Supercapacitors; Cyclic voltammetry; Specific capacitance

Manuscript Timeline: Received: September 12, 2011; Revised: October 25, 2011; Accepted: November 10, 2011; Published: September 09, 2012.

Citation: Aliyu, U. B., & Ndidi, L. O. (2012). Electrochemical Properties and Supercapacitive Performance of Polypyrrole-Graphene Oxide Nanocomposite Electrodes. International Journal of Chemistry, 3(9), 90–97.

International Journal of Chemistry | Vol. 3, No. 12, December 2012 | pp. 114–121

DOI: 10.46882/2012/IJC/000051

Article Type: Original Research Paper

Title: Green Synthesis of Palladium Nanoparticles Using Phoenix dactylifera Aqueous Extract and Catalytic Hydrogenation of Nitroarenes

Names of Authors: S. I. Musa¹, H. Al-Masri²*

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

Abstract: The biological synthesis of noble metal nanoparticles using desert plant matrices offers a sustainable approach to green heterogeneous catalysis. This study presents the green synthesis of stable palladium nanoparticles (PdNPs) utilizing the aqueous seed extract of Phoenix dactylifera (Date palm) as a powerful reducing and stabilizing agent. The bioreduction process was monitored via UV-Vis spectrophotometry, which revealed the complete disappearance of the palladium chloride absorption band within 45 minutes. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses showed spherical palladium nanoparticles with an average diameter of 12 nm. X-ray diffraction (XRD) patterns confirmed the highly crystalline, face-centered cubic lattice profile of the biosynthesized metallic palladium. Fourier-transform infrared (FT-IR) spectroscopy indicated that water-soluble polyphenols and reducing sugars within the date seed matrix were responsible for capping and protecting the PdNPs against structural agglomeration. The catalytic efficiency of the synthesized PdNPs was evaluated by tracking the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride (NaBH₄) in an aqueous system. In the presence of the green catalyst, the reaction achieved 98.4% conversion within 8 minutes. The hydrogenation kinetics conformed tightly to the pseudo-first-order kinetic model with a rate constant of 0.312 min⁻¹, indicating excellent catalytic potential for industrial nitro-aromatic wastewater treatment.

Keywords: Palladium nanoparticles; Green synthesis; Phoenix dactylifera; Crystalline structure; Heterogeneous catalysis; Nitroarenes

Manuscript Timeline: Received: June 15, 2012; Revised: July 28, 2012; Accepted: August 20, 2012; Published: December 04, 2012.

Citation: Musa, S. I., & Al-Masri, H. (2012). Green Synthesis of Palladium Nanoparticles Using Phoenix dactylifera Aqueous Extract and Catalytic Hydrogenation of Nitroarenes. International Journal of Chemistry, 3(12), 114–121.

International Journal of Chemistry | Vol. 3, No. 6, June 2012 | pp. 42–49

DOI: 10.46882/2012/IJC/000045

Article Type: Original Research Paper

Title: Distribution and Health Risk Profiling of Polycyclic Aromatic Hydrocarbons in Well Water Sourced from Urban Hubs

Names of Authors: T. H. Awotunde¹, S. C. Chika²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Agriculture, Abeokuta, Nigeria.
²Department of Chemistry, University of Ilorin, Ilorin, Nigeria.

Abstract: Leaching of hazardous organic industrial residues into urban shallow well water resources poses a severe threat to public health in municipal settlements. This study screens the spatial distribution, origin indicators, and health risk profiles of 16 priority polycyclic aromatic hydrocarbons (PAHs) across twenty shallow wells in a highly populated urban hub. Water samples were gathered during the dry and wet seasons, and quantified via Gas Chromatography-Mass Spectrometry (GC-MS). Total PAH concentrations ranged from 12.4 to 56.8 ng/L, with lower molecular weight structures like phenanthrene and fluoranthene emerging as the dominant species. Diagnostic ratio calculations (phenanthrene/anthracene and fluoranthene/pyrene) indicated that the PAHs were primarily pyrogenic in origin, driven by the incomplete combustion of fossil fuels and urban municipal refuse dumps. Seasonal assessments revealed significantly higher PAH migration during the rainy period, indicating rain-induced runoff and soil leaching pathways. Carcinogenic potency evaluations and Lifetime Cancer Risk (LCR) indices for adult consumption routes fell within the safe benchmark threshold of 1 in 1,000,000, but presented an escalating trend near active commercial automobile repair centers.

Keywords: Polycyclic aromatic hydrocarbons; Groundwater; Gas chromatography-mass spectrometry; Diagnostic ratios; Pyrogenic sources; Cancer risk assessment

Manuscript Timeline: Received: August 02, 2011; Revised: September 12, 2011; Accepted: October 04, 2011; Published: June 03, 2012.

Citation: Awotunde, T. H., & Chika, S. C. (2012). Distribution and Health Risk Profiling of Polycyclic Aromatic Hydrocarbons in Well Water Sourced from Urban Hubs. International Journal of Chemistry, 3(6), 42–49.

International Journal of Chemistry | Vol. 3, No. 8, August 2012 | pp. 82–89

DOI: 10.46882/2012/IJC/000047

Article Type: Original Research Paper

Title: Mechanochemical Optimization and Structural Characterization of Metakaolin-Based Geopolymer Cements Containing Rice Husk Ash

Names of Authors: T. S. Ani¹, Y. M. Sani²*

Authors’ Affiliations:
¹Department of Electronic and Chemical Engineering, Enugu State University of Science and Technology, Enugu, Nigeria.
²Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.

Abstract: Incorporating industrial and agricultural amorphous silica wastes into geopolymer binders reduces production costs while enhancing mechanical strengths. This study examines the structural synthesis and properties of binary geopolymer cements produced via the alkaline activation of blends of metakaolin (MK) and rice husk ash (RHA) at ratios of 100:0 to 60:40. The geopolymerization process was initiated using an activating solution of sodium silicate and sodium hydroxide with an overall liquid-to-binder ratio of 0.45. Structural changes were monitored using XRD, FT-IR, and Scanning Electron Microscopy (SEM). FT-IR results confirmed the successful framework incorporation of silicates derived from RHA, as shown by a shift in the asymmetric stretching band of Si-O-T bonds to 980 cm⁻¹. Compressive strength measurements demonstrated that samples prepared with 20% RHA achieved a maximum strength of 46.8 MPa after 28 days of ambient curing, which was 15% higher than pure metakaolin binders. SEM imaging revealed a denser, less porous aluminosilicate gel network, confirming that RHA acts as an efficient supplementary silica source for green building materials.

Keywords: Geopolymer; Metakaolin; Rice husk ash; Alkaline activation; Compressive strength; Microstructure

Manuscript Timeline: Received: September 05, 2011; Revised: October 18, 2011; Accepted: November 04, 2011; Published: August 02, 2012.

Citation: Ani, T. S., & Sani, Y. M. (2012). Mechanochemical Optimization and Structural Characterization of Metakaolin-Based Geopolymer Cements Containing Rice Husk Ash. International Journal of Chemistry, 3(8), 82–89.

International Journal of Chemistry | Vol. 3, No. 11, November 2012 | pp. 106–113

DOI: 10.46882/2012/IJC/000050

Article Type: Original Research Paper

Title: Synthesis, Characterization, and Anti-malarial Efficacy of Novel Quinine-Based Transition Metal Complexes

Names of Authors: A. A. Yusuf¹, M. T. Garba²*

Authors’ Affiliations:
¹Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.
²Department of Pharmacology and Therapeutics, Ahmadu Bello University, Zaria, Nigeria.

Abstract: The development of drug resistance by Plasmodium falciparum strains has created an urgent need to modify classic antimalarial scaffolds to enhance their clinical efficacy. This study details the synthesis and molecular characterization of novel copper(II), zinc(II), and iron(II) complexes coordinated with quinine ligands. The synthesized metal-drug complexes were characterized using elemental analysis, molar conductance, magnetic moment measurements, and FT-IR spectroscopy. Analytical data established a 1:1 metal-to-drug ratio for all synthesized entities, conforming to a general structural formula of [M(Q)Cl₂], where Q represents the neutral quinine molecule. FT-IR spectra established that quinine behaves as a bidentate ligand, coordinating to the metal centers via the quinoline nitrogen and the secondary hydroxyl oxygen atoms. In vivo antimalarial evaluation was conducted against Plasmodium berghei infected mice using the 4-day suppressive test. Oral administration of the copper(II)-quinine complex at a dose of 20 mg/kg produced a 92.4% reduction in parasitemia levels, outperforming standalone uncoordinated quinine (74.5%). This enhanced clearance is attributed to increased lipophilicity upon chelation, which facilitates metal-drug penetration across the erythrocyte membrane.

Keywords: Quinine; Metal complexes; Parasitemia clearance; FT-IR spectroscopy; Plasmodium berghei; Chelation therapy

Manuscript Timeline: Received: October 20, 2011; Revised: November 28, 2011; Accepted: December 15, 2011; Published: November 02, 2012.

Citation: Yusuf, A. A., & Garba, M. T. (2012). Synthesis, Characterization, and Anti-malarial Efficacy of Novel Quinine-Based Transition Metal Complexes. International Journal of Chemistry, 3(11), 106–113.