Faculty of Humanities and Sciences
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Publication Open Access The photocatalytic and antibacterial activity of graphene oxide coupled CoOx /MnOx nanocomposites(Elsevier B.V., 2025-02) Liyanaarachchi, H; Thambiliyagodage, C; Jayanetti, M; Ekanayake, G; Wijayawardana, S; Samarakoon, UCoOx and MnOx metal oxide composites were fabricated via co-precipitation varying the Co:Mn (CM) weight ratio as 4:1, 2:1, 1:1, 1:2 and 1:4, and they hydrothermally coupled with 30 wt% of graphene oxide (GO). XRD analysis revealed the presence of Co3O4 and CoO, and Mn2O3 and Mn3O4 phases in pure CoOx and MnOx metal oxides, respectively. The irregularly shaped metal oxide nanocomposites comprised Co3O4, Mn2O3 and Mn3O4 phases and were immobilized on GO. The band gap values of the composites varied in the range of 1.86 – 2.22 eV. The highest photocatalytic activity with a rate constant of 3.5 × 10−3 min−1 was obtained with CMG (1:4). The total removal of MB increased by 55.8 % when CM (1:4) were coupled with GO. The rate of photocatalysis was dramatically increased in the presence of S2O82- and was decreased in the presence of EDTA and isopropyl alcohol. The effect of catalyst dosage was determined by varying the weight to 25, 50, 75, and 100 mg, and the dye concentration was varied in the range of 25, 50, 75 and 100 mg/L. The presence of Pb2+ and Rhodamine B decreased the photocatalytic activity, while it remained the same in the presence of Cl- and PO43- as co-pollutants. The photocatalytic activity of CMG (1:4) was reduced to 72 % upon using the catalyst for five cycles. All the synthesized nanocomposites exhibited greater sensitivity to the Gram-positive strain than the Gram-negative strains.Publication Open Access Kinetic Study of In Vitro Release of Neem from Chitosan Biopolymer and Assessment of Its Biological Effectiveness(Multidisciplinary Digital Publishing Institute (MDPI), 2025-03-06) Nishshanka, Y; Thambiliyagodage, C; Jayanetti, MThe study examined the sustained release of neem from the polymeric carrier system chitosan by varying the drug content, ionic strength of the release medium, and pH. Six different kinetic models, i.e., Korsmeyer–Peppas (KP), Peppas–Sahlin (PS), Higuchi, Hixson–Crowell, Zero order, and First order were used to investigate the drug release kinetics. Based on the R2 values, the KP and PS models were chosen from the examined models to study the drug release mechanism from the chitosan biopolymer. The values found for model parameters n and m in the KP and PS models differ noticeably, suggesting that Fickian diffusion and Case II relaxation are important components of the neem release mechanism from chitosan. At lower ionic strengths and lower pH values, neem is released from the composite mostly by Fickian diffusion. The diphenyl-2-picrylhydrazyl assay served to assess the composite’s antioxidant properties. The composite’s antioxidant properties ranged from 3.56 ± 1.89% at 10 μg/mL to 51.28 ± 1.14% at 70 μg/mL. The ability of the composite to inhibit the denaturation of egg albumin was also tested and it ranged from 59.68 ± 0.93% at 25 μg/mL to 187.63 ± 3.53% at 1600 μg/mL. The drug composite has exhibited antibacterial activity against Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, and proved to be highly effective against P. aeruginosa at lower concentrations and against S. aureus at higher concentrations. The resulting inhibition zones for P. aeruginosa at 5 and 10 mg/mL concentrations were 16.5 ± 2.25 mm, and 14.83 ± 0.6 mm, respectively, whereas for S. aureus, it was 16.67 ± 0.33 mm at 20 mg/mL. The neem–chitosan composite’s minimum inhibitory concentration/minimum bactericidal concentration ratio for K. pneumoniae, P. aeruginosa, and S. aureus was greater than 4, suggesting that they trigger bacteriostatic outcomes, whereas for E. coli, it was 4, which means that bactericidal effects were evident.Publication Embargo Heterojunction and homojunction engineering on multi-shelled confinement structure for CO2 photoreduction to CH4(Elsevier B.V., 2025-10-15) Yang, X; Yang, R; Lu, X; Cao, Y; Ye, P; Zhang, L; Li, K; Li, Z; Jiang, Y; Liu, J; Zhou, Y; Eroglu, Z; Thambiliyagodage, C; Wu, B; Metin, Ö; Zhou, Y; Zhu, WThe underdeveloped CO2 photo-reduction solid-gas mode still relies on precious metals to produce CH4. Fine-tuned ingenious structure and morphology with nonprecious metal can enable better performance with lower cost. We have synthesized and modified a TiO2 with a three-stage cavity and a three-shelled layer, loaded with In2S3 flakes only on the outermost layer. The porous hollow multi-shelled structure can give a sequence of gas diffusion from inside to outside or vice versa. Due to the confinement effect, products generated by the core can only be transferred from the inside to the outside in a unidirectional manner. The In2S3/TiO2 catalysts exhibited high performance comparable to that of conventional noble metal catalysts (e.g., Au-Ag-Pt), with a selectivity of up to 98.28 % for CH4 and a rate of 296.87 μmol·g−1·h−1 without using any co-catalyst or sacrificial agent. Systematic fundamental characterization, as well as in situ characterization and DFT calculations show that homo-junctions consisting of two crystalline phases of TiO2 contribute to the production of more *Hads and *CO. Desorbed CO can be captured and catalyzed by the outer shell In2S3/TiO2 S-scheme heterojunction during diffusion for methanation via formaldehyde intermediate. A series of photoelectrochemical characterizations also confirms that the In2S3/TiO2 hetero-junction improves light absorption and charge separation efficiency. This work provides insight into the future rational design of hollow semiconductors for artificial photosynthesis systems and selective solar fuel production.Publication Open Access Fe3O4 Chitosan Nanocomposite as a pH-Responsive Delivery System for Enhanced Delivery of Punica Granatum L. Polyphenols(American Chemical Society, 2025-10-17) Rukshan, R; Rajapaksha, N; Wijayawardana, S; Thambiliyagodage, C; Senevirathne, U; Jayanetti, M; Samarakoon, UPunica granatum extract (PG), consisting of punicalagin, ellagic acid, and gallic acid, was loaded onto an Fe3O4/Chitosan (Fe3O4@Chi) nanocomposite (Fe3O4@Chi-PG) to enhance pharmacokinetic properties. Fe3O4was synthesized via the coprecipitation method and coupled with chitosan in 2% acetic acid solution via glutaraldehyde cross-linking. The presence of interested polyphenols in the pomegranate extract was confirmed by HPLC analysis, and the extract was post-loaded to the nanocarrier. XRD confirmed the crystallographic orientation of the nanocarrier, and SEM analysis confirmed the successful coupling of Fe3O4onto the chitosan surface during the fabrication of Fe3O4@Chi. BET surface area analysis revealed the presence of micro- and mesopores in the synthesized materials. Significant reduction of the BET surface area and the pore volume of Fe3O4@Chi-PG compared to Fe3O4@Chi suggested the loading of the porous network and surface by PG. The presence of vibrational bands corresponding to the functional groups of the relevant bioactive compounds was confirmed via FT-IR analysis. The IC50values of the nanocomposite for DPPH and egg albumin denaturation assays were 18.69 and 257.69 μg/mL, respectively. The PG encapsulation efficiency of Fe3O4@Chi-PG was reported to be 86.44%. The pH-responsive release of the polyphenols was studied by fitting the release data into five kinetic models, including Korsemeyer–Peppas (KP) and Peppas–Sahlin (PS). The KP and PS models were selected to interpret the release mechanism based on the R2≥ 0.95 value. A combination of Fickian diffusion, relaxation, and swelling dominates the polyphenol release. Quasi-Fickian diffusion is responsible for the release in media with pH 1–6.7, whereas anomalous transport occurs at pH 7.4 (n = 0.46) according to the KP model. Polymer relaxation is the dominant mechanism for the release of bioactive compounds at pH 7.4, as exhibited by R/F > 1. However, the contribution of relaxation to the release of polyphenols at pH 2.5, 4, and 5.5 was negligible according to the parameters (kR= 0). Characteristics of chitosan, including protonation and deprotonation of NH2groups, surface charge of Fe3O4, ionization of COOH and OH groups of the polyphenols, and molecular weight of the active compounds, contributed to the differences in the release behavior.Publication Open Access In vitro release kinetics of bioactive compounds (gallic acid, ellagic acid, and eugenol) from chitosan polymer and the bioactivity of herb-loaded chitosan–CuO nanocomposites(Nature Research, 2025-10-13) Ekanayake, G; Wijayawardana, S; Jayanetti, M; Thambiliyagodage, C; Liyanaarachchi, H; Mendis, AThe biological efficacy of nanocomposites comprised of chitosan, CuO nanoparticles, and extracts of Phyllanthus emblica, and Syzygium aromaticum was studied. The study assessed the pH– and ionic strength-responsive controlled release of the bioactive compounds, gallic acid, ellagic acid and eugenol, from the chitosan biopolymer. Release data were fitted into zero-order, first-order, Korsmeyer–Peppas (KP), Peppas–Sahlin (PS), Higuchi, and Hixson–Crowell kinetic models to evaluate the release mechanism. According to KP and PS models (R2 ≥ 0.96), release was governed by quasi-Fickian diffusion (n < 0.43), where the diffusion occurs along with the polymer relaxation and swelling. P.emblica-coated chitosan (PeC) composite exhibited a burst release at acidic media conditions, and a quasi-Fickian diffusion at pH 5.5–7.4. Higher ionic strength caused salting-in effects for PeC in 0.4 M media, resulting in a transiently increased release. In acidic conditions, diffusion-controlled release was observed for S.aromaticum-coated chitosan (SaC) composite, with the optimal release at pH 4 media. Release was facilitated by hydrophobic nanochannels at elevated pH (8.5–10) and ionic strength of 0.5 M NaCl. The PS model’s relaxation contributions were significant at 0.4 M NaCl and 5 mg drug loading. Both composites demonstrated enhanced release at physiological conditions (0.1–0.2 M NaCl, pH 7.4). Sustained release of SaC was achieved in near-neutral/moderate ionic strength media, whereas PeC exhibited sustained release in acid/low ionic strength media. The PeC and SaC composites showed IC50 values of 10.78 µg/mL and 19.27 µg/mL for the DPPH radical scavenging ability, respectively. Recorded IC50 values for the egg albumin denaturation assay were 467 µg/mL and 390.44 µg/mL, respectively. The antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus showed maximum inhibition zones of 11.83 ± 0.06 mm (Chitosan: CuO 1:2), 12.67 ± 0.20 mm (1:4), 16.50 ± 0.09 mm (1:4), and 11.83 ± 0.08 mm (4:1), respectively. Among the herbal-coated samples, SaC exhibited the highest activity of 23.67 ± 2.84 mm against E. coliPublication Open Access Influence of ageing of graphene oxide on the properties and morphology of cement mortar(Nature Research, 2025-12-02) Suganthiny,G; Thambiliyagodage, C; Perera, S. V. T. J; Rajapakse, R. K. N. DPast studies show that Graphene Oxide (GO) enhances the structural properties of cement composites. However, GO reduces its chemical characteristics with ageing. This study determines the effects of the age of commercial and laboratory-produced GO on cementitious composites. The study considered GO of up to 35 weeks of age, and specimens were chemically characterised using various techniques. The ageing effects were evaluated using consistency, initial setting time, compressive strength, splitting tensile strength, and water absorption. The composite’s thermal resistance was also tested. GO was found to have a shelf life of 13 weeks from production to achieve favourable results. The morphology of the cement mortar was studied to determine the reason for the change in performance with GO age. This study confirms that the carbon-to-oxygen ratio (C/O) and the disorder of graphene oxide sheets (ID/IG ratio), along with the number of GO layers, govern the performance of GO-incorporated cement composites. Both ratios increase with GO age. Aged GOs in mortar increased the mean pore radius and reduced the surface area. Mortar samples with aged GOs have ettringite peaks, while early-age GO-containing samples lack ettringite peaks. Despite reduced mechanical performance with age, all mortar samples remained thermally stable at higher temperatures.Publication Open Access Fabrication of Naturally Derived Chitosan and Ilmenite Sand-Based TiO2/Fe2O3/Fe-N-Doped Graphitic Carbon Composite for Photocatalytic Degradation of Methylene Blue under Sunlight(MDPI, 2023-04-01) Mendis, A; Thambiliyagodage, C; Ekanayake, G; Liyanaarachchi, H; Jayanetti, M; Vigneswaran, Sfirst_pagesettingsOrder Article Reprints Open AccessArticle Fabrication of Naturally Derived Chitosan and Ilmenite Sand-Based TiO2/Fe2O3/Fe-N-Doped Graphitic Carbon Composite for Photocatalytic Degradation of Methylene Blue under Sunlight by Amavin Mendis 1,Charitha Thambiliyagodage 1,*ORCID,Geethma Ekanayake 1,Heshan Liyanaarachchi 1ORCID,Madara Jayanetti 1 andSaravanamuthu Vigneswaran 2,3,* 1 Faculty of Humanities and Sciences, Sri Lanka Institute of Information Technology, Malabe 10115, Sri Lanka 2 Faculty of Engineering and Information Technology, University of Technology Sydney, P.O. Box 123, Sydney, NSW 2007, Australia 3 Faculty of Sciences & Technology (RealTek), Norwegian University of Life Sciences, P.O. Box N-1432 Ås, Norway * Authors to whom correspondence should be addressed. Molecules 2023, 28(7), 3154; https://doi.org/10.3390/molecules28073154 Received: 15 March 2023 / Revised: 29 March 2023 / Accepted: 30 March 2023 / Published: 1 April 2023 (This article belongs to the Section Materials Chemistry) Download Browse Figures Versions Notes Abstract Fabrication of chitosan and ilmenite sand-based novel photocatalysts through the catalytic graphitization of chitosan is reported. Nanocomposites consisted of TiO2, Fe2O3 and Fe nanoparticles dispersed on a nitrogen-doped graphitic carbon framework. The surface area, pore volume and macropore structure of the carbon matrix is disturbed by the heterogeneously distributed nanoparticles. The extent of graphitization expanded with increasing metal loading as indicated by variation in the ID/IG ratio. The nanomaterial’s surface consists of Fe3+ and Ti4+, and graphitic, pyridinic and pyrrolic nitrogen were found in the carbon matrix. The band gap values of the composites varied in the 2.06–2.26 eV range. The photocatalytic activity of the synthesized nanomaterials was determined, and the highest rate constant for the photodegradation of methylene blue under sunlight was 4.4 × 10−3 min−1, which resulted with 10 mg/L MB and 25 mg of the best-performing catalyst. The rate constant rose with increasing concentrations of persulfate added to the medium. The rate constant greatly diminished with the addition of isopropyl alcohol as it scavenged hydroxyl radicals. The presence of co-pollutants including Pb2+, rhodamine B, PO43− and Cl− curtailed the rate of reaction. The activity reduced with an increasing number of uses of the catalyst.Publication Open Access Efficient photocatalysis of Cu doped TiO2/g-C3N4 for the photodegradation of methylene blue(Elsevier, 2023-03-06) Liyanaarachchi, H; Thambiliyagodage, C; Liyanaarachchi, C; Samarakoon, UThe release of dyes into normal water reservoirs has become a tremendous environmental problem and the development of methods to remove such dyes is essential. A novel photocatalyst was fabricated in which Cu doped to TiO2 was coupled with g-C3N4 (Cu-TiO2/g-C3N4) in different weight percentages as 10, 30 and 50%, hydrothermally. Pure TiO2 consisted of both Anatase and Rutile phases where slight lattice distortions were observed in the Cu-doped TiO2 as evidenced by the XRD and Raman analysis. Cu was present at 1.7% by weight respective to TiO2 according to the XRF analysis. Spherical and irregularly shaped aggregated Cu-doped TiO2 nanoparticles in the range of 15–55 nm were heterogeneously distributed on the g-C3N4 matrix as observed by TEM and SEM. The band gap of TiO2 (3.0 eV) was reduced to 2.67 upon doping with Cu. The band gap of g-C3N4 was found to be 2.81 eV and that of Cu-TiO2/g-C3N4 in different weight percentages were in the range of 2.82 to 2.88 eV. Synthesized photocatalysts were tested on the ability to degrade methylene blue under UV and Visible light. Cu-TiO2/50% g-C3N4 showed the highest rate constant (4.4 × 10-3 min−1) which is 5 and 9.8 times greater than TiO2 and g-C3N4, respectively. The rate constant decreased with the introduction of EDTA and Isopropyl alcohol as they scavenge holes and hydroxyl radicals, respectively. The photocatalytic activity of all the nanomaterials increased with the increasing concentration of persulfate due to the increasing concentration of SO4●- and OH● produced. Synthesized nanomaterials effectively adsorb methylene blue under dark conditions following the pseudo-second-order kinetics suggesting that methylene blue molecules were chemisorbed to the adsorbents. The adsorption rate constant resulting in the best-performing photocatalyst was 0.122 g mg−1 min−1. Hence, it is evident that Cu-TiO2/g-C3N4 can effectively degrade methylene blue.Publication Open Access Efficient photocatalysis of carbon coupled TiO2 to degrade pollutants in wastewater – A review(Elsevier, 2022-08-27) Thambiliyagodage, CWater pollution caused by human activities is a monumental problem that the world is facing today. The use of polluted water for domestic, industrial, and agricultural applications creates severe hazardous issues. Therefore, decontamination of polluted water is greatly important. The advanced oxidation process is preferred to purify contaminated water as the pollutants are completely degraded to harmless products. TiO2 is the most widely researched photocatalyst due to its chemical stability, low cost and eco-friendliness. However, the use of TiO2 is limited as it is only sensitive to UV range due to its high band gap (3.0 eV for rutile) and the possible electron-hole pair recombination. TiO2 has been coupled with carbon-based materials to enhance photocatalytic activity by enhancing charge separation and visible light absorption. This review summarizes the recent use of TiO2 coupled to activated carbon, carbon nanotubes, graphene derivatives, and g-C3N4 to degrade different pollutants found in water including dyes, pesticides, pharmaceuticals, phenols and heavy metals. The advantages and disadvantages of using each carbon-based material are discussed. Further, the challenges and opportunities associated with all the materials are presented. Finally, recommendations and possible future outlooks are briefed in this review.Publication Open Access Fabrication of dual Z-scheme g-C3N4/Fe2TiO5/Fe2O3 ternary nanocomposite using natural ilmenite for efficient photocatalysis and photosterilization under visible light(Elsevier, 2022-11-11) Thambiliyagodage, C; Liyanaarachchi, H; Kumar, A; Jayanetti, M; Usgodaarachchi, L; Lansakara, BThe advanced oxidation process is a prominent method available to remove dyes released to normal water reservoirs to alleviate water scarcity. We report the fabrication of novel g-C3N4/Fe2TiO5/Fe2O3 using natural ilmenite sand as the precursor of the metallic semi-conductors exploration of a heterostructure for photodegradation of methylene blue under sunlight. Ternary composites were synthesized by varying g-C3N4 with respect to Fe2TiO5/Fe2O3 and varying Fe2TiO5/Fe2O3 with respect to g-C3N4 where the varying component was varied as 8, 24 and 40%, respect to the constant material. The hybridization of the three semi-conductors has been confirmed by the microscopic, chemical, and structural analyses. X-ray diffraction patterns show the presence of all three g-C3N4, Fe2TiO5 and α-Fe2O3 while the transmission electronic microscopic and scanning electronic microscopic images show the heterogeneous distribution of the metal oxide nanoparticles on g-C3N4 matrix forming the composite. HRTEM images further reveal the junction of Fe2TiO5 and α-Fe2O3. X-ray photoelectron spectra show the existence of s-triazine and heptazine rings in the composites with Fe3+ and Ti4+ as the only oxidation states of Fe and Ti. Fe2TiO5/Fe2O3/40% g-C3N4 with bandgap of 2.63 eV calculated by diffuse reflectance UV-Visible spectroscopy showed the highest photocatalytic activity (0.009 min−1) being 1.3 times greater than the Fe2TiO5/Fe2O3 nanoparticles. Enhanced photocatalytic activity over the fabricated composites was observed due to the increased visible light absorption, efficient charge separation and improved charge transportation. g-C3N4 coupled with 40% Fe2TiO5/Fe2O3 showed the highest antibacterial activity against gram-negative E.Coli. The synthesis of dual Z-scheme g-C3N4/Fe2TiO5/Fe2O3 ternary composite provides new sights in developing novel photocatalysts using natural ilmenite sand for environmental applications.