Showing papers by "Puangrat Kajitvichyanukul published in 2016"
TL;DR: The rate of inactivation of S. aureus using the doped TiO2 nanoparticles in the presence of visible light is greater than that of E. coli and the band gap narrowing of N-dopedTiO2 can induce more visible light absorption and leads to the superb antibacterial properties of this material.
Abstract: The Ni-doped and N-doped TiO2 nanoparticles were investigated for their antibacterial activities on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria. Their morphological features and characteristics such as particle size, surface area, and visible light absorbing capacity were compared and discussed. Scanning electron microscopy, X-ray diffraction, and UV–visible spectrophotometry were used to characterize both materials. The inactivation of E. coli (as an example of Gram-negative bacteria) and S. aureus (as an example of Gram-positive bacteria) with Ni-doped and N-doped TiO2 was investigated in the absence and presence of visible light. Antibacterial activity tests were conducted using undoped, Ni-doped, and N-doped TiO2. The N-doped TiO2 nanoparticles show higher antibacterial activity than Ni-doped TiO2. The band gap narrowing of N-doped TiO2 can induce more visible light absorption and leads to the superb antibacterial properties of this material. The complete inactivation time for E. coli at an initial cell concentration of 2.7 × 104 CFU/mL was 420 min which is longer than the 360 min required for S. aureus inactivation. The rate of inactivation of S. aureus using the doped TiO2 nanoparticles in the presence of visible light is greater than that of E. coli. The median lethal dose (LD50) values of S. aureus and E. coli by antibacterial activity under an 18-W visible light intensity were 80 and 350 mg/ml for N-doped TiO2, respectively.
60 citations
TL;DR: This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH•), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N- doped TiO2, and C,N co-dopes prepared by the sol–gel method.
Abstract: This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH(•)), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N-doped TiO2, and C,N co-doped TiO2 prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy were used to analyze the titania. The rate of formation of OH(•) for each type of titania was determined, and the OH-index was calculated. The kinetics of as-synthesized TiO2 catalysts in photocatalytic oxidation of 2-chlorophenol (2-CP) under visible light irradiation were evaluated. Results revealed that nitrogen was incorporated into the lattice of titania with the structure of O-Ti-N linkages in N-doped TiO2 and C,N co-doped TiO2. Carbon was joined to the Ti-O-C bond in the C-doped TiO2 and C,N co-doped TiO2. The 2-CP adsorption ability of C,N co-doped TiO2 and C-doped TiO2 originated from a layer composed of a complex carbonaceous mixture at the surface of TiO2. C,N co-doped TiO2 had highest formation rate of OH(•) and photocatalytic activity due to a synergistic effect of carbon and nitrogen co-doping. The order of photocatalytic activity per unit surface area was the same as that of the formation rate of OH(•) unit surface area in the following order: C,N co-doped TiO2 > C-doped TiO2 > N-doped TiO2 > undoped TiO2.
51 citations
TL;DR: In this article, a titania-impregnated chitosan/xylan hybrid film was prepared by adding of titanium dioxide in the mixture solution of chitosa and xylan in acetic acid.
46 citations
TL;DR: In this paper, a rotating disc photocatalytic reactor for water treatment is described, where a thin film of liquid becomes entrained on the disc enhancing the high efficacy in chromium (VI) removal from wastewater during the rotation of the disc.
Abstract: A new photocatalytic reactor design for water treatment was characterised by the use of rotating disc photocatalytic reactor. In this study, TiO2 was immobilised on stainless steel disc by sol-gel method. Experiments in a reactor containing 20 rotating disc with UV light irradiation at the wavelength of 380 nm were performed. The effect of the wastewater flow rate and rotating disc speed on photocatalytic reduction of chromium(VI) over TiO2/stainless steel disc was determined. The chromium(VI) was effectively reduced in a wide range, and the rate of photocatalytic reduction increases with an increase of rotating speed and flow rate. A thin film of liquid becomes entrained on the disc enhancing the high efficacy in chromium (VI) removal from wastewater during the rotation of the disc. The kinetics study of this photoreactor was also investigated.
2 citations
TL;DR: In this article, the ability of iron nanoparticles in paraquat degradation using heterogeneous Fenton and photo-Fenton processes was investigated, and the results showed that the photo-fenton reaction provided higher efficiency in removing paraquats than the Fenton process.
Abstract: This work was aimed to investigate the ability of iron nanoparticles in paraquat degradation using heterogeneous Fenton and photo-Fenton processes. The iron nanoparticles were synthesised and their sizes are in the nanometre range of 10-30 nm. SEM, TEM, and XRD were used to characterise the obtained materials. From XRD analysis and the Fe(II)/Fe(III) ratio, the iron nanoparticles are predominantly of magnetite phase. Results from Fenton reaction at pH3 show that paraquat with initial concentrations in range of 60-100 ppm has been degraded with the removal percentages in the range of 43.7-75.8%. In photo-Fenton process at pH3, the paraquat removal percentages were 70.9-99.1% for initial paraquat concentrations as of 100-300 ppm. The photo-Fenton reaction using iron nanoparticles provided higher efficiency in paraquat removal than the Fenton process. Results from this work can benefit further for application of iron nanoparticles in pesticides removal from water and wastewater.
2 citations
TL;DR: In this paper, a composite material between activated carbon (AC) and iron oxide in nanoscale was used to remove paraquat from contaminated water, and the surface area of AC/iron oxide nanoparticles was in the range of 754.39 to 775.81 mµ/g.
Abstract: A composite material between activated carbon (AC) and iron oxide in nanoscale was used to remove paraquat from contaminated water. The surface area of AC/iron oxide nanoparticles was in the range of 754.39 to 775.81 m²/g for the ratio 1:1 to 10:1 AC:iron oxide nanoparticles. The maximum adsorption capacity was found at pH 11. Adsorption of paraquat increases with increase in temperature indicating an endothermic process. Sorption behaviour of paraquat onto AC/iron oxide nanoparticles was evaluated using the Langmuir and Freundlich isotherm. The adsorption behaviour of paraquat was well described by Freundlich isotherm indicated that AC/iron oxide nanoparticles posed heterogeneous surface with heterolayer paraquat coverage on the surface of composite material. First and second order kinetic models were tested. The paraquat adsorption rate fits a pseudo-second-order kinetic model where the rate-limiting step is assumed to be chemical sorption between the adsorbate and adsorbent. The AC/iron oxide nanoparticles can readily be separated from the solution using a permanent magnet.
1 citations
TL;DR: In this article, a green synthesis of silver nanoparticles from radish juice and tea extracts was reported to achieve higher levels of inhibition of E. coli than that of Staphylococcus aureus.
Abstract: Silver nanoparticles (AgNPs) have antibacterial properties and are widely used for water disinfection. This technology is commercially applied in point-of-use water treatment as a post-treatment for filtrate water. However, the current process of synthesizing AgNPs has several disadvantages including the use of hazardous chemicals, consumption of a large amount of energy and the formation of hazardous byproducts. Here, we report an alternative and green synthesis using plant extracts. In this work, the plant extracts came from radish (R) and tea (T), and the AgNPs were derived from a microwave irradiation method. The AgNPs synthesized by chemical-based microwave irradiation (Ag-C) were also used as a control material. The novel method produced a smaller size of nanostructures with good dispersion ability and less agglomeration than those from chemical synthesis. The antibacterial properties of AgNPs on Gram-negative bacteria Escherichia coli ( E. coli ) and Gram-positive bacteria Staphylococcus aureus ( S. aureus ) were investigated. The results revealed that AgNPs from both green synthesis and chemical-based methods inactivated both types of bacteria. The green-synthesized AgNPs from radish juice provided a higher percentage of inhibition of E. coli than that of S. aureus . The inactivation rates of the AgNPs increased with increasing concentration of AgNPs. As the concentration of the Ag/AgCl-R and Ag-R increased from 150 μg/mL to 300 μg/mL, complete inactivation required a reduced time for the reaction from 300 minutes to only 30 minutes. Finally, the Ag/AgCl-R and Ag-R offered high antibacterial activity while the Ag-T provided the lowest antibacterial activity. This work provides an alternative method for the eco-synthesis of antibacterial nanomaterials for water treatment.