| 1. |
- Borah, Sandhya Banti Dutta, et al.
(författare)
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Heavy Metal Ion Sensing By Surface Plasmon Resonance on Gold Nanoparticles
- 2014
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Ingår i: ADBU Journal of Engineering Technology. - : Don Bosco University. - 2348-7305. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- Surface Plasmon resonance (SPR) based heavy metal ions sensor is one of the most sensitive sensor for detecting toxic metal ions. It is an inexpensive, portable and also feasible for real time detection. SPR sensor is a type of optical sensor in which toxic metal ions get adsorbed on the functionalized metal (mostly Au) film causes the change in refractive index of the metal (Au)-dielectric (sensing) medium. The change of the refractive index leads to a shift in the angular spectrum of the reflected light and can be accurately monitored by optical methods. In this paper,we are trying to optimize the detection level of heavy metal ions by surface plasmon resonance on gold nanoparticles using UV-VIS spectroscopy. Polymer like chitosan is being used with gold nanoparticles to detect copper and zinc ions and detection till very low concentrations of the toxic metal ions is obtained.
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| 2. |
- Ahmed, Aseel Bala, et al.
(författare)
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Microwave-enhanced degradation of phenol over Ni-loaded ZnO nanorods catalyst
- 2014
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Ingår i: Applied Catalysis B. - : Elsevier. - 0926-3373 .- 1873-3883. ; 156-157, s. 456-465
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Tidskriftsartikel (refereegranskat)abstract
- Nickel was loaded onto hydrothermally-grown ZnO nanorods on cordierite substrates and tested as catalysts in microwave-enhanced degradation of phenol from its aqueous solution (100 ppm) at 70 degrees C. Effects of metal loadings (1, 10 and 20 mM impregnation solutions) on the degradation of phenol in aqueous solution was investigated. The catalyst performances were monitored based on phenol degradation, product distributions and carbon dioxide (CO2) evolutions. Based on the type of the catalysts, two different mechanistic pathways for the decomposition were observed-through catechol and/or hydroquinone as intermediates. It was found that the 10mM nickel loaded sample catalyzed the degradation through one pathway with hydroquinone as the benzenediol intermediate formed, while the 20 mM nickel impregnated sample catalyzed the reaction through two pathways, producing catechol as well as hydroquinone by products. These differences in reaction pathways were attributed to the variation in the composition of the nickel compounds and surface structures between the two catalysts. Furthermore, the effect of hydrogen peroxide (H2O2) as an oxidant was explored. It was found that although addition of H2O2 led to an increase in the degree of phenol degradation, it also led to enhanced catalyst leaching. There was also an increase in CO2 evolution due to the addition of H2O2. It was observed that 20 mM nickel-loaded sample without the addition of H2O2 exhibited optimum performance in terms of phenol degradation and CO2 evolution with no drawback of catalyst leaching. Catalytic microwave enhanced degradation is an effective means for the removal of dissolved organic compounds from wastewater.
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| 3. |
- Al-Abri, M., et al.
(författare)
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Chlorination disadvantages and alternative routes for biofouling control in reverse osmosis desalination
- 2019
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Ingår i: npj Clean Water. - : Nature Research. - 2059-7037. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- With an ever-increasing human population, access to clean water for human use is a growing concern across the world. Seawater desalination to produce usable water is essential to meet future clean water demand. Desalination processes, such as reverse osmosis and multi-stage flash have been implemented worldwide. Reverse osmosis is the most effective technology, which uses a semipermeable membrane to produce clean water under an applied pressure. However, membrane biofouling is the main issue faced by such plants, which requires continuous cleaning or regular replacement of the membranes. Chlorination is the most commonly used disinfection process to pretreat the water to reduce biofouling. Although chlorination is widely used, it has several disadvantages, such as formation of disinfection by-products and being ineffective against some types of microbes. This review aims to discuss the adverse effect of chlorination on reverse osmosis membranes and to identify other possible alternatives of chlorination to reduce biofouling of the membranes. Reverse osmosis membrane degradation and mitigation of chlorines effects, along with newly emerging disinfection technologies, are discussed, providing insight to both academic institutions and industries for the design of improved reverse osmosis systems.
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| 4. |
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| 5. |
- Al Alawai, Reem, et al.
(författare)
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Role of bonding mechanisms during transfer hydrogenation reaction on heterogeneous catalysts of platinum nanoparticles supported on zinc oxide nanorods
- 2016
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; , s. 200-206
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Tidskriftsartikel (refereegranskat)abstract
- For supported heterogeneous catalysis, the interface between a metal nanoparticle and the support plays an important role. In this work the dependency of the catalytic efficiency on the bonding chemistry of platinum nanoparticles supported on zinc oxide (ZnO) nanorods is studied. Platinum nanoparticles were deposited on ZnO nanorods (ZnO NR) using thermal and photochemical processes and the effects on the size, distribution, density and chemical state of the metal nanoparticles upon the catalytic activities are presented. The obtained results indicate that the bonding at Pt-ZnO interface depends on the deposition scheme which can be utilized to modulate the surface chemistry and thus the activity of the supported catalysts. Additionally, uniform distribution of metal on the catalyst support was observed to be more important than the loading density. It is also found that oxidized platinum Pt(IV) (platinum hydroxide) provided a more suitable surface for enhancing the transfer hydrogenation reaction of cyclohexanone with isopropanol compared to zero valent platinum. Photochemically synthesized ZnO supported nanocatalysts were efficient and potentially viable for upscaling to industrial applications.
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| 6. |
- Al-Fori, M., et al.
(författare)
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Antifouling properties of zinc oxide nanorod coatings
- 2014
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Ingår i: Biofouling. - : Taylor & Francis. - 0892-7014 .- 1029-2454. ; 30:7, s. 871-882
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Tidskriftsartikel (refereegranskat)abstract
- In laboratory experiments, the antifouling (AF) properties of zinc oxide (ZnO) nanorod coatings were investigated using the marine bacterium Acinetobacter sp. AZ4C, larvae of the bryozoan Bugula neritina and the microalga Tetraselmis sp. ZnO nanorod coatings were fabricated on microscope glass substrata by a simple hydrothermal technique using two different molar concentrations (5 and 10 mM) of zinc precursors. These coatings were tested for 5 h under artificial sunlight (1060 W m(-2) or 530 W m(-2)) and in the dark (no irradiation). In the presence of light, both the ZnO nanorod coatings significantly reduced the density of Acinetobacter sp. AZ4C and Tetraselmis sp. in comparison to the control (microscope glass substratum without a ZnO coating). High mortality and low settlement of B. neritina larvae was observed on ZnO nanorod coatings subjected to light irradiation. In darkness, neither mortality nor enhanced settlement of larvae was observed. Larvae of B. neritina were not affected by Zn2+ ions. The AF effect of the ZnO nanorod coatings was thus attributed to the reactive oxygen species (ROS) produced by photocatalysis. It was concluded that ZnO nanorod coatings effectively prevented marine micro and macrofouling in static conditions.
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| 7. |
- Al-Hamdi, Abdullah M., et al.
(författare)
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Efficient photocatalytic degradation of phenol in aqueous solution by SnO2:Sb nanoparticles
- 2016
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 370, s. 229-236
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Tidskriftsartikel (refereegranskat)abstract
- Photodegradation of phenol in the presence of tin dioxide (SnO2) nanoparticles under UV light irradiation is known to be an effective photocatalytic process. However, phenol degradation under solar light is less effective due to the large band gap of SnO2. In this study antimony (Sb) doped tin dioxide (SnO2) nanoparticles were prepared at a low temperature (80 degrees C) by a sol-gel method and studied for its photo catalytic activity with phenol as a test contaminant. The catalytic degradation of phenol in aqueous media was studied using high performance liquid chromatography and total organic carbon measurements. The change in the concentration of phenol affects the pH of the solution due to the by-products formed during the photo-oxidation of phenol. The photoactivity of SnO2:Sb was found to be a maximum for 0.6 wt.% Sb doped SnO2 nanoparticles with 10 mg L-1 phenol in water. Within 2 h of photodegradation, more than 95% of phenol could be removed under solar light irradiation.
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| 8. |
- Al-Hamdi, Abdullah M., et al.
(författare)
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Gadolinium doped tin dioxide nanoparticles : an efficient visible light active photocatalyst
- 2015
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Ingår i: Journal of Rare Earths. - : Elsevier. - 1002-0721 .- 2509-4963. ; 33:12, s. 1275-1283
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Tidskriftsartikel (refereegranskat)abstract
- Photocatalytic degradation of phenol with sol-gel prepared rare earth doped tin dioxide (SnO2) nanoparticles was reported. Gadolinium doped tin dioxide (SnO2:Gd) nanoparticles were found to absorb higher visible light compared to lanthanum, neodymium and cerium doped materials that were studied in detail. Photocatalytic degradation of phenol under artificial white light and sunlight in the presence of SnO2: Gd nanoparticles was studied with high performance liquid chromatography (HPLC), capillary electrophoresis (CE), total organic carbon (TOC) measurements and the determination of chemical oxygen demand (COD). Clear correlations between the results obtained from these multiple measurements were found, and a kinetic pathway for the degradation process was proposed. Within 150 min of solar irradiation, the TOC of a 10 ppm phenol solution in water was reduced by 95%-99%, thus demonstrating that SnO2: Gd nanoparticles are efficient visible light photocatalysts.
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| 9. |
- Al-Hamdi, A. M., et al.
(författare)
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Intermediate formation during photodegradation of phenol using lanthanum doped tin dioxide nanoparticles
- 2016
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Ingår i: Research on chemical intermediates (Print). - : Springer Netherlands. - 0922-6168 .- 1568-5675. ; 42:4, s. 3055-3069
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Tidskriftsartikel (refereegranskat)abstract
- Lanthanum (La)-doped tin dioxide (SnO2) nanoparticles were synthesized by a modified sol–gel method at room temperature. The samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The photocatalytic activity of La:SnO2 samples were investigated by studying the degradation profile of phenol and its by-products in water. The treated samples were analyzed by HPLC–UV and a UV–Vis spectrophotometer. Benzoquinone, catechol, resorcinol, hydroquinone, acetic acid, and 2-propanol were identified as phenol degradation intermediates. Maximum concentration acquired was in the order of catechol, resorcinol, hydroquinone, and benzoquinone, which was observed in the beginning stages while iso-propanol and acetic acid were observed in the final stages of phenol degradation. We achieved a complete photodegradation of a 10 ppm aqueous phenol solution and intermediates with 0.6 % of SnO2:La nanoparticles in 120 min under artificial solar irradiation. A maximum degradation rate constant of 0.02228 min−1 of propanol and a minimum of acetic acid 0.013412 min−1 were recorded at 37 °C.
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| 10. |
- Al-Hamdi, Abdullah M, et al.
(författare)
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Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation
- 2015
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Ingår i: Journal of Alloys and Compounds. - : Elsevier. - 0925-8388. ; 618, s. 366-371
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Tidskriftsartikel (refereegranskat)abstract
- Iodine doped tin oxide (SnO2:I) nanoparticles were prepared by sol-gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO2:I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO2 nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO2 nanoparticles under similar illumination conditions.
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