International Journal of Chemistry

International Journal of Chemistry | Vol. 4, No. 1, January 2013 | pp. 1–8

DOI: 10.46882/2013/IJC/000052

Article Type: Original Research Paper

Title: Phytochemical Screening, Volatile Fingerprinting, and Antiprotozoal Capacity of Crude Extracts from Carica papaya Seeds

Names of Authors: A. E. Ogunkoya¹, J. M. S. Cabral²*

Authors’ Affiliations:
¹Department of Chemistry, Ekiti State University, Ado-Ekiti, Nigeria.
²Department of Bioengineering, Instituto Superior Técnico, Lisbon, Portugal.

Abstract: Carica papaya seeds are frequently utilized in traditional tropical medicine as an anthelmintic agent, yet their volatile bioactive profiles require deep chromatographic mapping to clarify structural efficacy. This investigation reports the qualitative phytochemical screening, volatile constituent identification via Gas Chromatography-Mass Spectrometry (GC-MS), and in vitro antiprotozoal capacity of hexane, ethyl acetate, and methanol seed extracts. Qualitative testing revealed a heavy presence of alkaloids, benzyl glucosinolates, phenolics, and flavonoids concentrated within the semi-polar ethyl acetate fraction. GC-MS profiling of the ethyl acetate extract identified 15 prominent peaks, with benzyl isothiocyanate (38.42%), oleic acid (22.15%), and palmitic acid methyl ester (12.30%) emerging as the primary bioactive components. The antiprotozoal potential was evaluated in vitro utilizing susceptibility assays against Giardia lamblia trophozoites, benchmarked against metronidazole. The ethyl acetate extract displayed the highest antiprotozoal activity, yielding an IC50 value of 15.8 μg/mL, compared to 2.4 μg/mL achieved by the standard drug. A linear correlation was observed between the concentration of benzyl isothiocyanate and protozoal cell mortality, validating that thiocyanate derivatives act as the driving contributors to structural cellular disruption, lending scientific validation to traditional medical usage.

Keywords: Carica papaya; Seed extract; Gas Chromatography-Mass Spectrometry; Benzyl isothiocyanate; Antiprotozoal activity; Giardia lamblia

Manuscript Timeline: Received: July 02, 2012; Revised: August 14, 2012; Accepted: September 10, 2012; Published: January 03, 2013.

Citation: Ogunkoya, A. E., & Cabral, J. M. S. (2013). Phytochemical Screening, Volatile Fingerprinting, and Antiprotozoal Capacity of Crude Extracts from Carica papaya Seeds. International Journal of Chemistry, 4(1), 1–8.

International Journal of Chemistry | Vol. 4, No. 2, February 2013 | pp. 9–16

DOI: 10.46882/2013/IJC/000053

Article Type: Original Research Paper

Title: Isolation, Screening, and Kinetic Optimization of Cellulase Complexes Sourced from Thermophilic Fungal Strains

Names of Authors: C. N. Nwosu¹, H. A. Tanaka²*

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

Abstract: Industrial saccharification of tough lignocellulosic biomass requires robust cellulolytic enzymes that can resist thermal denaturation under operational refinery configurations. This study focuses on the selective isolation, biochemical screening, and thermal kinetic optimization of high-yielding cellulolytic fungal strains sourced from geothermal hot spring soils. Soil suspensions underwent enrichment culturing in Mandels' mineral media containing microcrystalline cellulose at elevated temperatures. Two distinct fungal strains displaying large hydrolysis zones via Gram's iodine clearing tests were isolated. The highest-yielding strain was identified morphologically and via genetic sequencing as Aspergillus fumigatus. Optimization experiments under solid-state fermentation showed that maximum endoglucanase and exoglucanase production occurred at a temperature of 45°C and a medium pH of 5.0 after 96 hours of incubation. Utilizing agricultural cotton residues as alternative substrates induced a high enzyme yield (6.2 U/mL) compared to wood sawdust (2.1 U/mL). The crude cellulase complex retained over 85% of its initial catalytic activity across a temperature stability range of 40 to 60°C for 24 hours, establishing an exceptionally stable enzyme framework for economic bioethanol manufacturing tracks.

Keywords: Thermophilic fungi; Aspergillus fumigatus; Solid-state fermentation; Cellulase; Thermal stability; Bioethanol production

Manuscript Timeline: Received: July 11, 2012; Revised: August 20, 2012; Accepted: September 15, 2012; Published: February 06, 2013.

Citation: Nwosu, C. N., & Tanaka, H. A. (2013). Isolation, Screening, and Kinetic Optimization of Cellulase Complexes Sourced from Thermophilic Fungal Strains. International Journal of Chemistry, 4(2), 9–16.

International Journal of Chemistry | Vol. 4, No. 3, March 2013 | pp. 17–24

DOI: 10.46882/2013/IJC/000054

Article Type: Original Research Paper

Title: Synthesis, Structural Characterization, and Dynamic Swelling of Chitosan-Graft-Polyacrylamide Hydrogels for Heavy Metal Extraction

Names of Authors: J. K. Mensah¹, S. Chatterjee²*

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: Developing high-capacity polymeric adsorbents from biopolymer backbones is essential for green remediation of heavy metals from industrial effluents. This study describes the chemical synthesis and structural optimization of a crosslinked hydrogel prepared via the free-radical graft copolymerization of acrylamide onto a highly purified chitosan backbone. The reaction was initiated using ammonium persulfate (APS) and crosslinked via N,N'-methylenebisacrylamide (MBA). The structural configuration of the chitosan-graft-polyacrylamide (Ch-g-PAM) matrix was verified through FT-IR spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Swelling kinetics were systematically evaluated across varying solution pH (2.0 to 10.0) and ionic strengths. The hydrogel displayed sensitive pH-dependent swelling profiles, achieving a maximum water absorption capacity of 310 g/g at pH 5.5 due to the complete protonation of amine functional groups causing maximum polymer chain expansion. Batch adsorption tests showed that the Ch-g-PAM hydrogel possessed high affinity for copper(II) and lead(II) ions in aqueous solutions. The adsorption data matched the Langmuir isotherm model with maximum monolayer adsorption capacities of 54.5 mg/g for Cu(II) and 82.6 mg/g for Pb(II) at 298 K, presenting an effective bio-sorption framework.

Keywords: Chitosan; Acrylamide; Graft copolymerization; Hydrogel; pH-sensitive swelling; Heavy metal adsorption

Manuscript Timeline: Received: August 05, 2012; Revised: September 18, 2012; Accepted: October 12, 2012; Published: March 02, 2013.

Citation: Mensah, J. K., & Chatterjee, S. (2013). Synthesis, Structural Characterization, and Dynamic Swelling of Chitosan-Graft-Polyacrylamide Hydrogels for Heavy Metal Extraction. International Journal of Chemistry, 4(3), 17–24.

International Journal of Chemistry | Vol. 4, No. 4, April 2013 | pp. 25–32

DOI: 10.46882/2013/IJC/000055

Article Type: Original Research Paper

Title: Spatial Analysis, Speciation, and Bioavailability of Mercury Contamination in Well Water Networks near Landfills

Names of Authors: T. H. Awotunde¹, L. A. Rossi²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Agriculture, Abeokuta, Nigeria.
²Department of Environmental Chemistry, University of São Paulo, São Paulo, Brazil.

Abstract: Municipal landfill leachate containment failures result in toxic heavy metal migrations into shallow groundwater aquifers, creating chronic ingestion risks. This study monitors the spatial variations, chemical speciation, and bioavailability indices of toxic mercury (Hg) compounds across twenty household well water sources positioned around a major urban dumpsite. Water monitoring was carried out over consecutive wet and dry cycles. Total mercury levels and organic methylmercury fractions were quantified utilizing cold vapor atomic fluorescence spectrometry (CV-AFS). Total mercury concentrations ranged from 0.45 to 4.85 μg/L, with 35% of monitored groundwater sites surpassing the strict WHO drinkable contaminant threshold of 6.0 μg/L. Speciation analysis showed that inorganic Hg(II) was the dominant species, though methylmercury accounted for up to 12.5% of total burden profiles at down-gradient coordinates. Seasonal mapping confirmed elevated total mercury mobilization during the rainy period, indicating rain-induced plume leaching. Chronic Daily Intake (CDI) projections and Hazard Quotient (HQ) risk parameters for child consumption cohorts surpassed 2.5 near historical waste dump boundaries, emphasizing an immediate public healthcare concern and a need for local membrane filtration arrays.

Keywords: Groundwater pollution; Mercury speciation; Methylmercury; Atomic fluorescence spectrometry; Landfill leachate; Hazard quotient

Manuscript Timeline: Received: August 14, 2012; Revised: September 25, 2012; Accepted: October 15, 2012; Published: April 05, 2013.

Citation: Awotunde, T. H., & Rossi, L. A. (2013). Spatial Analysis, Speciation, and Bioavailability of Mercury Contamination in Well Water Networks near Landfills. International Journal of Chemistry, 4(4), 25–32.

International Journal of Chemistry | Vol. 4, No. 7, July 2013 | pp. 49–56

DOI: 10.46882/2013/IJC/000058

Article Type: Original Research Paper

Title: Electrochemical Performance and Supercapacitive Characterization of Polyrhodanine-Carbon Nanotube Thin Film Electrodes

Names of Authors: U. B. Aliyu¹, J. Y. Lee²*

Authors’ Affiliations:
¹Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.
²Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore.

Abstract: Fabricating highly efficient electrochemical energy storage units requires the development of hybrid polymer electrodes that exhibit high specific capacitance and fast ion diffusion kinetics. This research details the synthesis and electrochemical characterization of polyrhodanine-multiwalled carbon nanotube (PRHD-MWCNT) thin-film nanocomposites prepared via in situ chemical oxidative polymerization pathways. The surface topology and morphological features of the hybrid films were analyzed using field emission scanning electron microscopy (FESEM), FT-IR, and Raman spectroscopy. FESEM imaging confirmed that a highly continuous, ultra-thin polyrhodanine layer was uniformly deposited across the conductive multiwalled carbon nanotube skeletal network. Electrochemical performance was investigated via cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) loops in a 1.0 M HCl electrolyte system. The optimized PRHD-MWCNT hybrid electrode delivered a maximum specific capacitance of 412 F/g at a current density of 1.0 A/g, which was substantially higher than standalone pure polyrhodanine films (145 F/g). Electrochemical impedance spectroscopy (EIS) data showed a very low charge-transfer resistance of 0.38 ohms, confirming accelerated ionic transport across the polymeric interface. Cyclic stability evaluations proved that the composite material retained 89.2% of its capacitive profile after 2000 continuous cycles.

Keywords: Polyrhodanine; Carbon nanotubes; Thin films; Supercapacitors; Cyclic voltammetry; Specific capacitance

Manuscript Timeline: Received: October 02, 2012; Revised: November 15, 2012; Accepted: December 04, 2012; Published: June 15, 2013.

Citation: Aliyu, U. B., & Lee, J. Y. (2013). Electrochemical Performance and Supercapacitive Characterization of Polyrhodanine-Carbon Nanotube Thin Film Electrodes. International Journal of Chemistry, 4(7), 49–56.

International Journal of Chemistry | Vol. 4, No. 5, May 2013 | pp. 33–40

DOI: 10.46882/2013/IJC/000056

Article Type: Original Research Paper

Title: Assessing the Hydrocarbon Tolerance and Phytoremediation Trait of Ricinus communis L. in Polycyclic Aromatic Hydrocarbon Spiked Soils

Names of Authors: O. F. Olawal¹, G. de Metru²*

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

Abstract: Persistent organic pollutants like polycyclic aromatic hydrocarbons (PAHs) accumulate inside industrial soil sub-surfaces, requiring cost-effective vegetative extraction strategies. This controlled study investigates the growth kinetics and remediation efficiency of Ricinus communis L. (Castor bean) cultivated in soils artificially spiked with varying concentrations of phenanthrene (100 to 500 mg/kg) and pyrene (50 to 250 mg/kg). Plant structural indices, remaining soil PAH concentrations, and root zone microbial populations were quantified over a 90-day developmental period. R. communis demonstrated strong physiological tolerance, maintaining high root-to-shoot biomass ratios across all phenanthrene loading levels. High-Performance Liquid Chromatography (HPLC) profiling showed a 78.4% reduction in soil phenanthrene and a 62.5% reduction in pyrene concentrations within the rhizosphere of cultivated systems, compared to minimal attenuation in unplanted controls. Soil microbiological testing revealed a five-fold expansion of heterotrophic degradation bacteria within the castor root matrix. This confirms that root exudates actively stimulate microbial proliferation, accelerating the degradation of complex polycyclic aromatic structures in contaminated industrial terrains.

Keywords: Ricinus communis; Phenanthrene; Pyrene; Soil phytoremediation; Rhizosphere effect; Microbial degradation

Manuscript Timeline: Received: September 02, 2012; Revised: October 12, 2012; Accepted: November 05, 2012; Published: May 02, 2013.

Citation: Olawal, O. F., & de Metru, G. (2013). Assessing the Hydrocarbon Tolerance and Phytoremediation Trait of Ricinus communis L. in Polycyclic Aromatic Hydrocarbon Spiked Soils. International Journal of Chemistry, 4(5), 33–40.