Browsing by Author "Liyanaarachchi, C"

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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, U
The 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.
Open Access
Efficient Visible-Light Photocatalysis and Antibacterial Activity of TiO2-Fe3C-Fe-Fe3O4/Graphitic Carbon Composites Fabricated by Catalytic Graphitization of Sucrose Using Natural Ilmenite
(American Chemical Society, 2022-07-26) Thambiliyagodage, C; Usgodaarachchi, L; Jayanetti, M; Liyanaarachchi, C; Kandanapitiye, M; Vigneswaran, S
Dyes in wastewater are a serious problem that needs to be resolved. Adsorption coupled photocatalysis is an innovative technique used to remove dyes from contaminated water. Novel composites of TiO2-Fe3C-Fe-Fe3O4dispersed on graphitic carbon were fabricated using natural ilmenite sand as the source of iron and titanium, and sucrose as the carbon source, which were available at no cost. Synthesized composites were characterized by X-ray diffractometry (XRD), Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence spectroscopy (XRF), and diffuse reflectance UV-visible spectroscopy (DRS). Arrangement of nanoribbons of graphitic carbon with respect to the nanomaterials was observed in TEM images, revealing the occurrence of catalytic graphitization. Variations in the intensity ratio (ID/IG), Laand LD, calculated from data obtained from Raman spectroscopy suggested that the level of graphitization increased with an increased loading of the catalysts. SEM images show the immobilization of nanoplate microballs and nanoparticles on the graphitic carbon matrix. The catalyst surface consists of Fe3+and Ti4+as the metal species, with V, Mn, and Zr being the main impurities. According to DRS spectra, the synthesized composites absorb light in the visible region efficiently. Fabricated composites effectively adsorb methylene blue via π-πinteractions, with the absorption capacities ranging from 21.18 to 45.87 mg/g. They were effective in photodegrading methylene blue under sunlight, where the rate constants varied in the 0.003-0.007 min-1range. Photogenerated electrons produced by photocatalysts captured by graphitic carbon produce O2•-radicals, while holes generate OH•radicals, which effectively degrade methylene blue molecules. TiO2-Fe3C-Fe-Fe3O4/graphitic carbon composites inhibited the growth of Escherichia coli (69%) and Staphylococcus aureus (92%) under visible light. Synthesized novel composites using natural materials comprise an ecofriendly, cost-effective solution to remove dyes, and they were effective in inhibiting the growth of Gram-negative and Gram-positive bacteria.