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  1. Article ; Online: Study of Phenol Red Photocatalytic Decomposition on KBrO 3 -Supported TiO 2 Nanoparticles for Wastewater Treatment

    Najla Khaled Almulhem / Chawki Awada / Nagih M. Shaalan

    Separations, Vol 10, Iss 162, p

    2023  Volume 162

    Abstract: In this study, the enhanced photodegradation of a high-concentration phenol red (PR) using very fine TiO 2 nanocrystals by adding a KBrO 3 electron acceptor was reported for the first time. The structural study on TiO 2 nanocrystals using HRTEM, XRD, ... ...

    Abstract In this study, the enhanced photodegradation of a high-concentration phenol red (PR) using very fine TiO 2 nanocrystals by adding a KBrO 3 electron acceptor was reported for the first time. The structural study on TiO 2 nanocrystals using HRTEM, XRD, Raman, and EDX was performed and it confirmed the anatase phase of TiO 2 nanocrystals. UV–Vis absorbance of 20 mg.L −1 PR was measured and the photodegradation was extracted. The KBrO 3 concentration effects exhibited an important enhancement in the degradation of PR dye. The efficiency of PR was increased during 110 min from 75% of pure TiO 2 to 92% and 98% of TiO 2 with 1 mg and 5 mg KBrO 3 , respectively. For different samples, a first-order kinetic of dye degradation is confirmed. The instantaneous amount of degraded dye increased from 150 to 180 and 197 mg/g TiO 2 with 1 mg and 5 mg KBrO 3 , respectively. The mechanism of the photodegradation reaction confirms the effect of OH - radicals on increasing the photocatalytic activities. The addition of electron acceptors KBrO 3 improved the photocatalysis rate, where it prevented e-h recombination through conduction band electron capture, which increases the concentration of hydroxyl radicals. The proposed mechanism and results were supported by photocurrent measurements and a Raman spectra analysis of the final photodegraded products. The photocurrent of TiO 2 was observed at 1.2 µA, which was significantly improved up to 13.2, and 21.3 µA with the addition of 1 mg and 5 mg of KBrO 3 . The Raman spectra of the final products confirmed that <semantics> SO 4 2 − </semantics> and carbons are byproducts of PR degradation.
    Keywords nanoparticles ; electron acceptor ; phenol red photodegradation ; photocurrent ; photodegradation mechanism ; Physics ; QC1-999 ; Chemistry ; QD1-999
    Subject code 290
    Language English
    Publishing date 2023-02-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Synergistic Effect of NiO-Ga 2 O 2 -Graphene Heterostructures on Congo Red Photodegradation in Water

    Nagih M. Shaalan / Mohamed Rashad / Chawki Awada

    Separations, Vol 9, Iss 8, p

    2022  Volume 201

    Abstract: We studied the effect of the mixed phase of nickel oxide–gallium oxide–graphene (NiO-Ga 2 O 2 /G) heterostructure nanocomposite on the photocatalytic degradation of Congo red dye. The effect was investigated based on NiO-Ga 2 O 2 junction, NiO-graphene, ... ...

    Abstract We studied the effect of the mixed phase of nickel oxide–gallium oxide–graphene (NiO-Ga 2 O 2 /G) heterostructure nanocomposite on the photocatalytic degradation of Congo red dye. The effect was investigated based on NiO-Ga 2 O 2 junction, NiO-graphene, and Ga 2 O 2 -graphene contacts. The laser-induced graphene was embedded into NiO and NiO-Ga 2 O 2 . Raman spectra confirmed the fabrication of disordered graphene and the mixed phase between the oxides and graphene. HRTEM showed that very fine nanoparticles for both NiO and Ga 2 O 2 with a size of ~7–10 nm were synthesized. Elemental compositional expressed the formation mixed phase. The effect of graphene content was investigated at 2 and 10% wt with NiO and the heterojunction of NiO-Ga 2 O 2 . The photocurrent studies was measured of these nanocomposite film deposited on two interdigitated gold electrodes, biased by 5.0 V and irradiated by the UV source. The results of photocatalysis measurements indicated an improvement occurred upon the heterojunction between Ga 2 O 2 and NiO, however, a dramatic improvement was observed with the addition of graphene of 10%. The results expressed that the ternary phase of p-NiO/n-Ga 2 O 2 /graphene is promising in the photocatalytic application toward Congo red decomposition.
    Keywords NiO-Ga 2 O 2 heterojunction ; ternary nanocomposite ; graphene ; Congo red ; photocatalytic ; Physics ; QC1-999 ; Chemistry ; QD1-999
    Subject code 290
    Language English
    Publishing date 2022-08-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Toward the Development of Ultrasensitive Detectors for Environmental Applications

    Hassan Traboulsi / Chawki Awada

    ACS Omega, Vol 5, Iss 48, Pp 31352-

    A Kinetic Study of Cr(III) Monitoring in Water Using EDTA and SERS Techniques

    2020  Volume 31361

    Keywords Chemistry ; QD1-999
    Language English
    Publishing date 2020-11-01T00:00:00Z
    Publisher American Chemical Society
    Document type Article ; Online
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  4. Article ; Online: Ultrafast Detection of SARS-CoV-2 Spike Protein (S) and Receptor-Binding Domain (RBD) in Saliva Using Surface-Enhanced Raman Spectroscopy

    Mohammed Ba Abdullah / Chahinez Dab / Mohammed Almalki / Abdullah Alnaim / Alaaedeen Abuzir / Chawki Awada

    Applied Sciences, Vol 12, Iss 5039, p

    2022  Volume 5039

    Abstract: Controlling contagious diseases necessitates using diagnostic techniques that can detect infection in the early stages. Although different diagnostic tools exist, there are still challenges related to accuracy, rapidity, cost-effectiveness, and ease of ... ...

    Abstract Controlling contagious diseases necessitates using diagnostic techniques that can detect infection in the early stages. Although different diagnostic tools exist, there are still challenges related to accuracy, rapidity, cost-effectiveness, and ease of use. Surface-enhanced Raman spectroscopy (SERS) is a rapid, simple, less expensive, and accurate method. We continue our previous work published on SERS detection of the SARS-CoV-2 receptor-binding domain (RBD) in water. In this work, we replace water with saliva to detect SARS-CoV-2 proteins at very low concentrations and during a very short time. We prepared a very low concentration of 10 −9 M SARS-CoV-2 spike protein (S) and SARS-CoV-2 receptor-binding domain (RBD) in saliva to mimic a real case scenario. Then, we drop them on a SERS substrate. Using modified SERS measurements on the control and the sample containing the biomolecules, confirmed the sensitivity of the target identification. This technique provides different diagnostic solutions that are fast, simple, non-destructive and ultrasensitive. Simulation of the real-world of silicon wire covered with silver and gold, were performed using an effective and accurate tool, COMSOL Multiphysics software, for the enhancement properties study.
    Keywords SARS-CoV-2 spike protein (S) ; receptor binding domain (RBD) ; Raman ; SERS ; Technology ; T ; Engineering (General). Civil engineering (General) ; TA1-2040 ; Biology (General) ; QH301-705.5 ; Physics ; QC1-999 ; Chemistry ; QD1-999
    Subject code 612
    Language English
    Publishing date 2022-05-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: A Comprehensive Photocatalysis Study of Promising Zirconia/Laser-Induced Graphene Nanocomposite for Wastewater Treatment-Based Methylene Blue Pollution

    Nagih M. Shaalan / Mohamed Rashad / Osama Saber / Adil Alshoaibi / Chawki Awada

    Separations, Vol 9, Iss 8, p

    2022  Volume 185

    Abstract: In this paper, the photocatalytic effect of zirconia/laser-induced graphene on the degradation of methylene blue was comprehensively studied. The average particle size measured by HRTEM is 6 nm for both ZrO 2 and ZrO 2 /G10 samples, which explains the ... ...

    Abstract In this paper, the photocatalytic effect of zirconia/laser-induced graphene on the degradation of methylene blue was comprehensively studied. The average particle size measured by HRTEM is 6 nm for both ZrO 2 and ZrO 2 /G10 samples, which explains the high-quality TEM imaging of isolated squared sections of cubic particles. The weight percentages of Zr, O, and C elements using EDX were 72.16, 18.56, and 9.28, respectively. These results confirm the formation of binary composites. Moreover, Raman scattering exhibited that the spectrum of pure ZrO 2 was difficult to be detected due to the high luminescence. However, ZrO 2 vibration modes were detected for ZrO 2 -graphene nanocomposites at 1012, 615, 246, and 150 cm −1 . A shift of the D- and G-bands of graphene were observed, where D-peak and G-peak were observed at 1370 and 1575 cm −1 for ZrO 2 /5G and, 1361 and 1565 cm −1 for ZrO 2 /10G, respectively. The shift is ascribed to the incorporation of graphene into the surface of the oxide material. Compared to ZrO 2 , the newly fabricated ZrO 2 -graphene nanocomposites have the advantage of increased photocatalytic effects. An adsorbent concentration of 5 and 10 mg·L −1 at room temperature over 240 min was observed to be suitable experimental conditions. The kinetic results indicate that the practical results obtained are well expressed by the first-order kinetic model at different concentrations. In addition, the results showed that the addition of graphene led to a significant degradation process increase. The results also showed the significant effect of the investigated ZrO 2 -graphene nanocomposites on the decomposition of methylene blue cation. The decomposition of cationic pollutants showed a synergistic effect of the ZrO 2 -graphene nanocomposites on wastewater treatment.
    Keywords ZrO 2 -graphene ; laser-induced graphene ; methylene blue ; photocatalysis studies ; Physics ; QC1-999 ; Chemistry ; QD1-999
    Subject code 290
    Language English
    Publishing date 2022-07-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Flower-Like ZnO Nanorods Synthesized by Microwave-Assisted One-Pot Method for Detecting Reducing Gases

    Abdullah Aljaafari / Faheem Ahmed / Chawki Awada / Nagih M. Shaalan

    Frontiers in Chemistry, Vol

    Structural Properties and Sensing Reversibility

    2020  Volume 8

    Abstract: In this work, flower-like ZnO nanorods (NRs) were successfully prepared using microwave-assisted techniques at a low temperature. The synthesized NRs exhibited a smooth surface and good crystal structure phase of ZnO. The sharp peak of the XRD and Raman ... ...

    Abstract In this work, flower-like ZnO nanorods (NRs) were successfully prepared using microwave-assisted techniques at a low temperature. The synthesized NRs exhibited a smooth surface and good crystal structure phase of ZnO. The sharp peak of the XRD and Raman spectrum confirmed the high crystallinity of these ZnO NRs with a pure wurtzite structure. The nanorods were ~2 μm in length and ~150 nm in diameter, respectively. The electron diffraction pattern confirmed that the single crystal ZnO nanorods aligned along the [001] plane. The NRs were applied to fabricate a gas sensor for reducing gases such as CH4, CO, and H2. The sensor showed a good performance and sensitivity toward the target gases. However, its response toward CH4 and CO was higher compared to H2 gas. Although the operating temperature was varied from room temperature (RT) up to 350°C, the sensor did not show a response toward any of the target gases in the range of RT-150°C, but dramatic enhancement of the sensor response was observed at 200°C, and up to higher temperatures. This behavior was ascribed to the activity of the smooth surface and the reactivity of surface oxygen species with the targeted gases. The sensor response was measured at various gas concentrations, where the calibration curve was shown. The gas sensing mechanism was described in terms of the reaction of the gases with the transformed oxygen species on the surface of the oxides.
    Keywords nanoflowers ; ZnO nanorods ; gas sensor ; methane ; carbon monoxide ; hydrogen ; Chemistry ; QD1-999
    Subject code 621
    Language English
    Publishing date 2020-07-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Correction to ‘Photocatalytic inactivation of Escherichia coli under UV light irradiation using large surface area anatase TiO2 quantum dots’

    Faheem Ahmed / Chawki Awada / Sajid Ali Ansari / Abdullah Aljaafari / Adil Alshoaibi

    Royal Society Open Science, Vol 7, Iss

    2020  Volume 1

    Keywords Science ; Q
    Language English
    Publishing date 2020-01-01T00:00:00Z
    Publisher The Royal Society
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Photocatalytic inactivation of Escherichia coli under UV light irradiation using large surface area anatase TiO2 quantum dots

    Faheem Ahmed / Chawki Awada / Sajid Ali Ansari / Abdullah Aljaafari / Adil Alshoaibi

    Royal Society Open Science, Vol 6, Iss

    2019  Volume 12

    Abstract: In this study, high specific surface areas (SSAs) of anatase titanium dioxide (TiO2) quantum dots (QDs) were successfully synthesized through a novel one-step microwave–hydrothermal method in rapid synthesis time (20 min) without further heat treatment. ... ...

    Abstract In this study, high specific surface areas (SSAs) of anatase titanium dioxide (TiO2) quantum dots (QDs) were successfully synthesized through a novel one-step microwave–hydrothermal method in rapid synthesis time (20 min) without further heat treatment. XRD analysis and HR-TEM images showed that the as-prepared TiO2 QDs of approximately 2 nm size have high crystallinity with anatase phase. Optical properties showed that the energy band gap (Eg) of as-prepared TiO2 QDs was 3.60 eV, which is higher than the standard TiO2 band gap, which might be due to the quantum size effect. Raman studies showed shifting and broadening of the peaks of TiO2 QDs due to the reduction of the crystallite size. The obtained Brunauer–Emmett–Teller specific surface area (381 m2 g−1) of TiO2 QDs is greater than the surface area (181 m2 g−1) of commercial TiO2 nanoparticles. The photocatalytic activities of TiO2 QDs were conducted by the inactivation of Escherichia coli under ultraviolet light irradiation and compared with commercially available anatase TiO2 nanoparticles. The photocatalytic inactivation ability of E. coli was estimated to be 91% at 60 µg ml−1 for TiO2 QDs, which is superior to the commercial TiO2 nanoparticles. Hence, the present study provides new insight into the rapid synthesis of TiO2 QDs without any annealing treatment to increase the absorbance of ultraviolet light for superior photocatalytic inactivation ability of E. coli.
    Keywords tio2 ; quantum dots ; microwave–hydrothermal ; x-ray diffraction ; photocatalysis ; Science ; Q
    Subject code 530 ; 620
    Language English
    Publishing date 2019-12-01T00:00:00Z
    Publisher The Royal Society
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Synthesis and Studies of Electro-Deposited Yttrium Arsenic Selenide Nanofilms for Opto-Electronic Applications

    Chawki Awada / Goodfriend M. Whyte / Peter O. Offor / Favour G. Whyte / Mohammed Benali Kanoun / Souraya Goumri-Said / Adil Alshoaibi / Azubice B. C. Ekwealor / Malik Maaza / Fabian I. Ezema

    Nanomaterials, Vol 10, Iss 1557, p

    2020  Volume 1557

    Abstract: Nanocomposite films grown by incorporating varying concentrations of Yttrium, a d-block rare-earth ion, into the binary chalcogenide Arsenic selenide host matrix is here presented. Films were grown via the wet-chemical electro-deposition technique and ... ...

    Abstract Nanocomposite films grown by incorporating varying concentrations of Yttrium, a d-block rare-earth ion, into the binary chalcogenide Arsenic selenide host matrix is here presented. Films were grown via the wet-chemical electro-deposition technique and characterized for structural, optical, surface morphology, and photoluminescence (PL) properties. The X-ray Diffraction (XRD) result of the host matrix (pristine film) showed films of monoclinic structure with an average grain size of 36.2 nm. The composite films, on the other hand, had both cubic YAs and tetragonal YSe structures with average size within 36.5–46.8 nm. The fairly homogeneous nano-sized films are shown by the Scanning Electron Microscopy (SEM) micrographs while the two phases of the composite films present in the XRD patterns were confirmed by the Raman shifts due to the cleavage of the As-Se host matrix and formation of new structural units. The refractive index peaked at 2.63 within 350–600 nm. The bandgap energy lies in the range of 3.84–3.95 eV with a slight decrease with increasing Y addition; while the PL spectra depict emission bands across the Vis-NIR spectral regions. Theoretically, the density functional theory (DFT) simulations provided insight into the changes induced in the structure, bonding, and electronic properties. Besides reducing the bandgap of the As 2 Se 3 , the yttrium addition has induced a lone pair p -states of Se contributing nearby to Fermi energy level. The optical constants, and structural and electronic features of the films obtained present suitable features of film for IR applications as well as in optoelectronics.
    Keywords nanocomposite ; rare-earth ion ; binary chalcogenide ; electro-deposition ; density functional theory ; Chemistry ; QD1-999
    Subject code 620
    Language English
    Publishing date 2020-08-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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