Browsing by Author "Usgodaarachchi, L"

Now showing 1 - 11 of 11

Open Access
Efficient photodegradation activity of α-Fe2O3/Fe2TiO5/TiO2 and Fe2TiO5/TiO2 nanocomposites synthesized from natural ilmenite
(Elsevier, 2021-12-01) Thambiliyagodage, C. J; Usgodaarachchi, L; Shanitha, M; Wijesekera, R; Lansakara, B; Bakker, M
Photocatalysis is an attractive widely used environmental remediation technique. Ternary (α-Fe2O3/Fe2TiO5/TiO2) and binary (Fe2TiO5/TiO2) nanocomposites were successfully synthesized by using natural ilmenite sand as the raw material. The synthesized nanocomposites were characterized by microscopic and spectroscopic analytical techniques. Both nanocomposites were catalytically active for the photodegradation of methylene blue upon irradiation by a light source (LED and sunlight). The visible light absorption of both composites was improved by the presence of Fe2TiO5 and α-Fe2O3 which absorb in the visible. The ternary nanocomposite with type II band alignments was more active than the binary nanocomposite with type I band alignment in the visible light exposure. Under sunlight exposure, binary nanocomposites were more active than the ternary nanocomposites. Band alignment, percentage of TiO2 in the composites and the proper formation of the structure of the composites govern the photocatalytic activity. OH● is suggested as the main species responsible for the photodegradation of methylene blue.
Embargo
Efficient removal of methylene blue by turbostratic carbon/Fe3C/Fe composite synthesized by catalytic graphitization of sucrose
(Elsevier, 2021-12-07) Thambiliyagodage, C. J; Usgodaarachchi, L
Turbostratic carbon/Fe3C/Fe composite was prepared by catalytic graphitization of sucrose by α-Fe2O3. The synthesized composites were characterized by X-ray diffractometry (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). XRD patterns revealed the formation of turbostratic carbon with a d spacing of 0.3412 nm and the presence of Fe3C and Fe nanoparticles. Raman spectrum exhibited the D, G and G' peaks. XPS analysis shows the presence of graphitic carbon and +3 oxidation state of iron. Synthesized composite can remove methylene blue with an adsorption capacity of 17.8 mg/g at pH 7. Adsorption follows pseudo second order kinetics and the Langmuir isotherm model. As the synthesized composite is magnetic it could be easily separated from the mixture and could be reused effectively without significant activity loss for five cycles.
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.
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, B
The 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.
Open Access
Fabrication of r-GO/GO/α-Fe2O3/Fe2TiO5 Nanocomposite Using Natural Ilmenite and Graphite for Efficient Photocatalysis in Visible Light
(MDPI, 2023-01) Usgodaarachchi, L; Jayanetti, M; Thambiliyagodage, C; Liyanaarachchi, H; Vigneswaran, S
Hematite (α-Fe2O3) and pseudobrookite (Fe2TiO5) suffer from poor charge transport and a high recombination effect under visible light irradiation. This study investigates the design and production of a 2D graphene-like r-GO/GO coupled α-Fe2O3/Fe2TiO5 heterojunction composite with better charge separation. It uses a simple sonochemical and hydrothermal approach followed by L-ascorbic acid chemical reduction pathway. The advantageous band offset of the α-Fe2O3/Fe2TiO5 (TF) nanocomposite between α-Fe2O3 and Fe2TiO5 forms a Type-II heterojunction at the Fe2O3/Fe2TiO5 interface, which efficiently promotes electron-hole separation. Importantly, very corrosive acid leachate resulting from the hydrochloric acid leaching of ilmenite sand, was successfully exploited to fabricate α-Fe2O3/Fe2TiO5 heterojunction. In this paper, a straightforward synthesis strategy was employed to create 2D graphene-like reduced graphene oxide (r-GO) from Ceylon graphite. The two-step process comprises oxidation of graphite to graphene oxide (GO) using the improved Hummer’s method, followed by controlled reduction of GO to r-GO using L-ascorbic acid. Before the reduction of GO to the r-GO, the surface of TF heterojunction was coupled with GO and was allowed for the controlled L-ascorbic acid reduction to yield r-GO/GO/α-Fe2O3/Fe2TiO5 nanocomposite. Under visible light illumination, the photocatalytic performance of the 30% GO/TF loaded composite material greatly improved (1240 Wcm−2). Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) examined the morphological characteristics of fabricated composites. X-ray photoelectron spectroscopy (XPS), Raman, X-ray diffraction (XRD), X-ray fluorescence (XRF), and diffuse reflectance spectroscopy (DRS) served to analyze the structural features of the produced composites. © 2022 by the authors.
Open Access
Fabrication of TiO2 Spheres and a Visible Light Active α‑Fe2O3/ TiO2‑Rutile/TiO2‑Anatase Heterogeneous Photocatalyst from Natural Ilmenite
(researchgate.net, 2022-07-26) Usgodaarachchi, L; Thambiliyagodage, C; Wijesekera, R; Vigneswaran, S; Kandanapitiye, M
High-purity (98.8%, TiO2) rutile nanoparticles were successfully synthesized using ilmenite sand as the initial titanium source. This novel synthesis method was cost-effective and straightforward due to the absence of the traditional gravity, magnetic, electrostatic separation, ball milling, and smelting processes. Synthesized TiO2 nanoparticles were 99% pure. Also, highly corrosive environmentally hazardous acid leachate generated during the leaching process of ilmenite sand was effectively converted into a highly efficient visible light active photocatalyst. The prepared photocatalyst system consists of anatase-TiO2/rutile-TiO2/Fe2O3 (TF-800), rutile-TiO2/Fe2TiO5 (TFTO-800), and anatase-TiO2/Fe3O4 (TF-450) nanocomposites, respectively. The pseudo-second-order adsorption rate of the TF-800 ternary nanocomposite was 0.126 g mg–1 min–1 in dark conditions, and a 0.044 min–1 visible light initial photodegradation rate was exhibited. The TFTO-800 binary nanocomposite adsorbed methylene blue (MB) following pseudo-second-order adsorption (0.224 g mg–1 min–1) in the dark, and the rate constant for photodegradation of MB in visible light was 0.006 min–1. The prepared TF-450 nanocomposite did not display excellent adsorptive and photocatalytic performances throughout the experiment period. The synthesized TF-800 and TFTO-800 were able to degrade 93.1 and 49.8% of a 100 mL, 10 ppm MB dye solution within 180 min, respectively.
Open Access
In vitro influence of PEG functionalized ZnO–CuO nanocomposites on bacterial growth
(PubMed ID, 2024-01-14) Thambiliyagodage, C; Jayanetti, M; Liyanaarachchi, H; Ekanayake, G; Mendis, M; Usgodaarachchi, L
Polyethyleneglycol-coated biocompatible CuO–ZnO nanocomposites were fabricated hydrothermally varying Zn:Cu ratios as 1:1, 2:1, and 1:2, and their antibacterial activity was determined through the well diffusion method against the Gram-negative Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and the Gram-positive Staphylococcus aureus. The minimum inhibitory concentration and the minimum bactericidal concentration values of the synthesized samples were determined. Subsequently, the time synergy kill assay was performed to elucidate the nature of the overall inhibitory effect against the aforementioned bacterial species. The mean zone of inhibition values for all four samples are presented. The inhibitory effect increased with increasing concentration of the nanocomposite (20, 40 and 60 mg/ml) on all the bacterial species except for S. aureus. According to the MBC/MIC ratio, ZnO was found to be bacteriostatic for E. coli and P. aeruginosa, and bactericidal for S. aureus and K. pneumoniae. Zn:Cu 2:1 was bactericidal on all bacterial species. A bacteriostatic effect was observed on E. coli and P. aeruginosa in the presence of Zn:Cu 1:1 whereas, it showed a bactericidal effect on S. aureus and K. pneumoniae. Zn:Cu 1:2 exhibited a bacteriostatic effect on E. coli while a bactericidal effect was observed for E. coli, P. aeruginosa, and K. pneumoniae. The metal oxide nanocomposites were found to be more sensitive towards the Gram-positive strain than the Gram-negative strains. Further, all the nanocomposites possess anti-oxidant activity as shown by the DPPH assay.
Open Access
Photocatalytic activity of Go/Fe3O4 fabricated by Sri Lankan graphite under visible light irradiation
(Faculty of Science, University of Kelaniya, Sri Lanka, 2021-10) Usgodaarachchi, L; Thambiliyagodage, C. J
Graphene oxide (GO) was synthesized using Sri Lankan naturally available graphite by modified Hummer’s method. Fe3O4 nanoparticles were synthesized successfully by co-precipitation of Fe3+ and Fe2+ in a 2:1 molar ratio via the addition of NH4OH. Magnetically separable GO/Fe3O4 nanocomposite was fabricated by synthesizing Fe3O4 nanoparticles in the presence of GO. The synthesized nanocomposites were characterized by X-ray diffractometry (XRD), Scanning electron microscopy (SEM), and FT-IR spectroscopy. The formation of GO was confirmed by the C(002) peak at 9.39° in the XRD pattern. XRD pattern of the nanoparticles confirms the formation of crystalline Fe3O4 nanoparticles, and the diffraction peak corresponds to graphene oxide disappear in the GO/ Fe3O4 due to the absence of the folded structure of graphene oxide. SEM image of GO shows the crumpled and wrinkled lamellae structure of graphene oxide, and the images of GO/ Fe3O4 show the distribution of Fe3O4 nanoparticles with an average size of 107 nm on GO where the folded structure of GO was not present while restacking of the nanosheets, was observed. FT-IR spectrum of GO shows the presence of polar oxygenated functional groups such as carboxylic acid (-COOH), hydroxyl (-OH), and epoxy (-COC-). The photocatalytic performance of the photocatalysts was evaluated on photodegradation of methylene blue under visible light irradiation. The GO/ Fe3O4 shows better adsorption behaviour and excellent photocatalytic activity where it could be successfully used for three cycles without significant activity loss. The rate constant for the degradation of MB (0.0187 min-1 ) at the first cycle decreased to 0.0101 min-1 at the third cycle. The conversion of MB decreased from 98.31% at the first cycle to 92.15% at the third cycle. The drop in the conversion is only 6.16% going from cycle 1 to 3, which could be due to the accumulation of the MB molecules at the pore structure. The obtained high photocatalytic activity could be due to the enhanced charge separation resulted due to the presence of GO sheets and better interactions between GO and Fe 3O4.
Embargo
Photocatalytic activity of N, Fe and Cu co-doped TiO2 nanoparticles under sunlight
(Elsevier, 2021-01-01) Thambiliyagodage, C. J; Usgodaarachchi, L
Photocatalytic activity of N doped with one transition metal is well known. This article reports the synthesis of TiO2 nanoparticles doped with only N, N co-doped with Fe, N co-doped with Cu and N co-doped with both Fe and Cu by sol-gel method. Their photocatalytic activity was evaluated for the degradation of methylene blue under sunlight. Nanoparticles were characterized by X-ray diffractometry (XRD), Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and diffuse reflectance UV–visible spectroscopy (DRS). XRD analysis revealed the presence of anatase phase TiO2 nanoparticles which was confirmed by Raman spectroscopic and TEM analysis. The crystal structure has not been disturbed by doping with N, Fe and Cu as shown by both XRD and Raman analysis. TEM and SEM images exhibit the nanoparticles which are interconnected due to sintering. XPS analysis revealed the presence of the only Ti4+ in undoped TiO2 but both Ti4+ and Ti3+ are present in doped TiO2 nanoparticles. According to the DRS analysis, the band gap of all doped TiO2 is lower than that of the undoped TiO2, where N, Fe and Cu co-doped TiO2 showed the lowest band gap (2.51 eV) proving that the visible light sensitivity of TiO2 increase with metal and non-metal doping. The rate of photodegradation of methylene blue in the presence of undoped TiO2 (0.016 min−1) is higher than all the doped TiO2 nanoparticles. N doped TiO2 show the highest activity among the doped TiO2 nanoparticles (0.006 min−1). Doped TiO2 nanoparticles showed a lower photocatalytic activity due to the electron hole pair recombination and the shielding effect of the dopants.
Open Access
Synthesis and Characterization of Novel Nanomaterials for Removal of Textile Dyes in Industrial Wastewater
(SLIIT, 2022-02) Usgodaarachchi, L
Inefficient treatments and uncontrolled pollutants generation to the environment has been significantly affected the living standards in the ecosphere. The advancement in nanotechnology resulted in the effective treatment of all of the pollutants generated in the environment. In the field of textile dye removal, the special features of nanomaterials are gaining attention due to their enhanced physical, chemical and mechanical properties. Rice husk is an agricultural waste material that is used for the production of adsorbents in this study. Mesoporous silica nanoparticles were successfully synthesized by using rice husk as the raw material via a sol-gel pathway using cetyltrimethylammonium bromide (CTAB) as the structure-directing agent. The functionalization of silica nanoparticles was taken place in two pathways, such as in-situ and post functionalization methods by using 3-aminopropyltriethoxysilane (APTES) as the functionalization agent. Mesoporous silica nanoparticles were able to effectively adsorb methylene blue dye from aqueous solutions. The adsorption of MB could be best described by the pseudosecond-order model and well fitted to the Langmuir equation, with a maximum monolayer capacity of 19.26 mg/g. Photocatalytic decomposition of the organic pollutants gains emerging attention after the discovery of water splitting ability by TiO2. The high purity (98.8%, TiO2) rutile nanoparticles were successfully synthesized using ilmenite sand as the initial titanium source. This novel synthesis method was cost-effective and straightforward due to the absence of the traditional gravity, magnetic, electro statistic separation, ball milling and smelting processes. Also, highly corrosive environmentally hazardous acid leachate generated during the leaching process of ilmenite sand was effectively converted into highly efficient photocatalysts. The most efficient photocatalysts were composed of anataseTiO2/rutile-TiO2/Fe2O3, α-Fe2O3/Fe2TiO5/TiO2 and Fe2TiO5/TiO2. The synthesized nanocomposites were characterized by microscopic (SEM and TEM) and spectroscopic (XRD, Raman, XPS, FT-IR and DRS) analytical techniques. These nano heterostructures were catalytically active for the photodegradation of methylene blue upon irradiation by a light source (LED or sunlight). Efficient charge separation and limiting electron-hole recombination in photocatalyst surfaces resulted in the overall performance of synthesized material. Reduced iv graphene oxide (r-GO) has lately attracted a lot of attention to overcome limitations associated with photocatalysts. The honeycomb sp2 network structure of r-GO improves charge separation and transportation through the surface of the catalyst. The fabricated GO/Fe3O4 heterogeneous photocatalyst shows very efficient degradation performance by overcoming the limitations associated with the narrow bandgap of Fe3O4 (0.1 eV). Finally, the synthesis of graphene like materials by catalytic graphitization of sucrose by using Fe and Ti transition metals studied in this study. Herein, we reported that Fe and Ti metal oxides promoted to the graphitization process at low temperature. Sucrose mixed with only uncalcined Fe2O3 produced Fe3C, Fe, Fe3O4 dispersed on graphitic carbon, while sucrose mixed with only Fe2TiO5/TiO2 product, and mixed with uncalcined Fe2O3 and Fe2TiO5/TiO2 led to the production of TiO2, Fe3C, Fe, Fe3O4 dispersed on graphitic carbon. The most outstanding photocatalyst synthesized material composed with TiO2/Fe3C/Fe/Fe3O4–Graphitic carbon which is sun light sensing photocatalyst.
Open Access
Synthesis of mesoporous silica nanoparticles derived from rice husk and surface-controlled amine functionalization for efficient adsorption of methylene blue from aqueous solution
(Elsevier, 2021-01-01) Usgodaarachchi, L; Thambiliyagodage, C. J; Wijesekera, R; Bakker, M. G
Mesoporous silica nanoparticles (MSN) were synthesized using rice husk (RH) as the raw material via sol-gel pathway using cetyltrimethylammonium bromide (CTAB) as the structure directing agent. Silica nanoparticles were successfully functionalized with 3-aminopropyl triethoxysilane (APTES) via in-situ and post functionalization methods. Synthesized nanoparticles were characterized by X-Ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) surface area analysis. The amorphous silica nanoparticles were of 50–60 nm in diameter with a surface area of 150 m2/g, pore volume of 0.237 cm3/g and average pore size of 3.62 nm. Morphology and textural parameters were changed upon functionalization. The equilibrium adsorption capacity of MSN-A (4.94 mg/g) to adsorb 10 mg/L methylene blue (MB), was higher than in amine functionalized silica nanoparticles. The influence of experimental factors such as pH, adsorbent dosage, and initial MB concentration on adsorption of MB to MSN-A were studied. The equilibrium data for MB adsorption on mesoporous silica nanoparticles well fitted to Langmuir equation, with a maximum monolayer capacity of 19.26 mg/g. The adsorption of MB could be best described by the pseudo-second order model. The results indicate that MSN-A is a potential mesoporous material fabricated by cheap natural resources to remove MB from aqueous solutions.