| 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. |
- 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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| 3. |
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| 4. |
- Al-Hinai, Muna H., et al.
(författare)
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Antimicrobial Activity Enhancement of Poly(ether sulfone) Membranes by in Situ Growth of ZnO Nanorods
- 2017
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Ingår i: ACS Omega. - : AMER CHEMICAL SOC. - 2470-1343. ; 2:7, s. 3157-3167
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Tidskriftsartikel (refereegranskat)abstract
- Composite poly(ether sulfone) membranes integrated with ZnO nanostructures either directly blended or grown in situ have enhanced antibacterial activity with improved functionality in reducing the biofouling in water treatment applications. The pore structure and surface properties of the composite were studied to investigate the effect of the addition of ZnO nanostructures. The hydrophilicity of the blended membranes increased with a higher content of ZnO nanoparticles in the membrane (2-6%), which could be further controlled by varying the growth conditions of ZnO nanorods on the polymer surface. Improved water flux, bovine serum albumin rejection, and inhibition of Escherichia coli bacterial growth under visible light irradiation was observed for the membranes decorated with ZnO nanorods compared to those in the membranes simply blended with ZnO nanoparticles. No regrowth of E. coli was recorded even 2 days after the incubation.
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| 5. |
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| 6. |
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| 7. |
- Al-Naamani, Laila, et al.
(författare)
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Nanocomposite Zinc Oxide-Chitosan Coatings on Polyethylene Films for Extending Storage Life of Okra (Abelmoschus esculentus)
- 2018
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 8:7
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Tidskriftsartikel (refereegranskat)abstract
- Efficiency of nanocomposite zinc oxide-chitosan antimicrobial polyethylene packaging films for the preservation of quality of vegetables was studied using okra Abelmoschus esculentus. Low density polyethylene films (LDPE) coated with chitosan-ZnO nanocomposites were used for packaging of okra samples stored at room temperature (25 degrees C). Compared to the control sample (no coating), the total bacterial concentrations in the case of chitosan and nanocomposite coatings were reduced by 53% and 63%, respectively. The nanocomposite coating showed a 2-fold reduction in total fungal concentrations in comparison to the chitosan treated samples. Results demonstrate the effectiveness of the nanocomposite coatings for the reduction of fungal and bacterial growth in the okra samples after 12 storage days. The nanocomposite coatings did not affect the quality attributes of the okra, such as pH, total soluble solids, moisture content, and weight loss. This work demonstrates that the chitosan-ZnO nanocomposite coatings not only maintains the quality of the packed okra but also retards microbial and fungal growth. Thus, chitosan-ZnO nanocomposite coating can be used as a potential coating material for active food packaging applications.
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| 8. |
- Al-Sabahi, Jamal, et al.
(författare)
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Efficient visible light photocatalysis of benzene, toluene, ethylbenzene and xylene (BTEX) in aqueous solutions using supported zinc oxide nanorods
- 2017
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 12:12
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Tidskriftsartikel (refereegranskat)abstract
- Benzene, toluene, ethylbenzene and xylenes (BTEX) are some of the common environmental pollutants originating mainly from oil and gas industries, which are toxic to human as well as other living organisms in the ecosystem. Here we investigate photocatalytic degradation of BTEX under visible light irradiation using supported zinc oxide (ZnO) nanorods grown on glass substrates using a microwave assisted hydrothermal method. ZnO nanorods were characterized by electron microscopy, X-ray diffraction (XRD), specific surface area, UV/visible absorption and photoluminescence spectroscopy. Visible light photocatalytic degradation products of BTEX are studied for individual components using gas chromatograph/mass spectrometer (GC/MS). ZnO nanorods with significant amount of electronic defect states, due to the fast crystallization of the nanorods under microwave irradiation, exhibited efficient degradation of BTEX under visible light, degrading more than 80% of the individual BTEX components in 180 minutes. Effect of initial concentration of BTEX as individual components is also probed and the photocatalytic activity of the ZnO nanorods in different conditions is explored. Formation of intermediate byproducts such as phenol, benzyl alcohol, benzaldehyde and benzoic acid were confirmed by our HPLC analysis which could be due to the photocatalytic degradation of BTEX. Carbon dioxide was evaluated and showed an increasing pattern over time indicating the mineralization process confirming the conversion of toxic organic compounds into benign products.
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| 9. |
- Al-Sabahi, J., et al.
(författare)
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Visible light photocatalytic degradation of HPAM polymer in oil produced water using supported zinc oxide nanorods
- 2018
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Ingår i: Chemical Engineering Journal. - : Elsevier B.V.. - 1385-8947 .- 1873-3212. ; 351, s. 56-64
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Tidskriftsartikel (refereegranskat)abstract
- Polymer flooding displacement ability during petroleum extraction from the earth's crust plays an important role in enhanced oil recovery processes. Produced water, as a byproduct, still contain high concentrations of petroleum hydrocarbons and partially hydrolyzed polyacrylamide (HPAM) which is a serious environmental concern. Remediating produced water economically is a big challenge for meeting the permissible discharge limits leading to failure in the effectiveness of the conventional water treatment technologies. Advanced oxidation processes (AOPs) are playing increasing role in the treatment of polluted water and is receiving much attention in recent times as a green and safer water treatment technology. Here we report a new approach to use vertically aligned zinc oxide nanorods (ZnO NRs) supported on substrates engineered for improving their visible light harvesting capacity for effective solar photocatalytic degradation of HPAM. The viscosity of collected oilfield produced water containing HPAM were found to be reduced dramatically when the samples are photocatalytically degraded using ZnO nanorod catalysts irradiated with simulated solar light showing a reduction of 51% within 6 h. With high pressure liquid chromatography 68, 62, 56 and 45% removal of 25, 50, 100 and 150 ppm HPAM, respectively, was demonstrated. The pH of the solution was observed to move to acidic region due to acetamide, nitrate, propionamide and acetic acid which are the intermediate byproducts formed during degradation as determined by mass spectrometry. Zinc oxide nanorod coatings showed about 74% removal efficiency over 5 cycles with less than 1.2% removal of zinc ions after 6 h of light irradiation.
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| 10. |
- Al-Soubaihi, Rola, et al.
(författare)
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Comparative investigation of structure and operating parameters on the performance and reaction dynamic of CO conversion on silica aerogel and fumed-silica-supported Pd catalysts
- 2022
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Ingår i: SURFACES AND INTERFACES. - : Elsevier BV. - 2468-0230. ; 29, s. 101776-
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Tidskriftsartikel (refereegranskat)abstract
- The catalyst morphology, metal-support interaction, and reaction conditions greatly influence the catalytic performance and reaction dynamics. Similarly, the dispersion of the metal within the support plays a crucial in the thermal stability and sintering of the catalyst. Furthermore, temperature-dependent conversion hysteresis is well-known to occur during ignition and extinction of exothermic CO oxidation over supported Pd catalysts due to the variation of CO adsorption on the surface or bulk oxidation of Pd and the ability of the catalyst regenerate the active sites. Herein, the catalytic performance and the hysteresis behavior of mesoporous silica aerogel supported Pd (Pd/a-SiO2), and commercial fumed silica-supported Pd (Pd/f-SiO2) were investigated compared using CO oxidation as a probe reaction under different reaction conditions and operating parameters (i.e., catalyst weight, ramp rate, and flow rate). Surface and morphologic examination using XPS, FTIR, and of Pd/a-SiO2 and Pd/f-SiO2 reveal a strong correlation between the catalyst surface and structure and its catalytic performance and stability under different reaction parameters. Moreover, this study presents the effect of surface area, particle size, and size distribution on diffusion and mass transport of reactants (CO, O-2) and products (CO2) and active sites accessibility. This study showed that Pd/f-SiO2 had better efficiency under high (turbulence) flow. Moreover, intrinsic apparent activation energy (E-a) and the number of active sites were calculated from the Kinetics of CO oxidation fitted using Arrhenius plots indicate that the ramp rate has less effect on Pd/f-SiO2 catalytic behavior. though, Pd/f-SiO2 had higher relative active sites than Pd/a-SiO2, (E-a) was lower. Cyclic stability and long-term stabilities showed that both catalysts are stable and can regenerate the active sites. The current study contributes to understanding the catalysts' surface, structural and morphological properties on the catalysts' performance toward CO oxidation and other reactions under dynamic conditions.
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