Browsing by Author "Wijesekera, R"

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Open Access
Ball milling–A green and sustainable technique for the preparation of titanium based materials from ilmenite
(Elsevier, 2022-01-01) Thambiliyagodage, C. J; Wijesekera, R
Ilmenite is a naturally available mineral that is highly applicable in the synthesis of pure TiO2. Titania mainly presents in four polymorphs as rutile, anatase, brookite and TiO2–B. Titania could be mined from minerals such as ilmenite, leucoxene and rutile among which ilmenite is the main source. Ball milling is a mechanical activation method used before subjecting ilmenite to chemical treatment methods to produce titanium based materials. Effect of milling time, milling intensity, milling atmosphere, the introduction of reducing agents on the particle size, surface area, annealing temperature, and the crystal structure of the products are reviewed. The effect of ball milling on acid digestion of ilmenite in hydrochloric acid and sulfuric acid is discussed. Further, the effect of mechanical activation on hydrothermal treatment of ilmenite is explained in detail.
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.
Open Access
Fabrication of Fe2TiO5/TiO2 binary nanocomposite from natural ilmenite and their photocatalytic activity under solar energy
(Elsevier, 2021-01-01) Thambiliyagodage, C. J; Mirihana, S; Wijesekera, R; Madusanka, D. S; Kandanapitiye, M; Bakker, M
Heterogeneous photocatalysis is an attractive alternative route to enhance the degradation of environmental pollutants. In this work, we have fabricated Fe2TiO5/TiO2 binary nanocomposites using natural ilmenite via bottom up approach. Synthesized nanocomposites were characterized by X-ray diffractometry, X-ray fluorescence, transmission electron microscopy, Raman spectroscopy, diffuse reflectance UV–Visible spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. These nanoparticles are in the range of 40–70 nm and are of type I heterostructure with a band gap of 2.02 eV. They are sensitive to visible light and show higher photocatalytic activity under direct solar energy. Photocatalytic activity of Fe2TiO5/TiO2 was assessed using a model textile dye, methylene blue. Over a period of 2 h, 76% of methylene blue was photodegraded at a rate of 0.0084 min−1 in the presence of Fe2TiO5/TiO2.
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
Leaching of ilmenite to produce titanium based materials: a review
(Springer International Publishing, 2021-12) Thambiliyagodage, C. J; Wijesekera, R; Bakker, M. G
Naturally available ilmenite mineral is being used as a starting material to produce titanium based products that have wide applications. Transformation of ilmenite to diferent titanium based materials by strong and weak acid, and base digestion, is discussed. Efects of temperature, concentration of acid/base, reaction time on dissolution of ilmenite are extensively reviewed. Characterization of the starting materials, intermediates and the products by x-ray difraction, thermogravimetry, brunauer–emmett–teller surface area analysis, and scanning electron microscopy are presented. Further, advantages and disadvantages associated with the digestion methods are discussed.
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.