Person: El-Khawaga, Ahmed Mohamed
El-Khawaga, Ahmed Mohamed
Email Address
Birth Date
ORCID
SCOPUS
6505972311
Research Projects
Organizational Units
Name
Ahmed M. El-Khawaga
Last Name
El-Khawaga
First Name
Ahmed Mohamed
Main Affiliation
Galala University
Job Title
Senior laboratory specialist, School of medicine
Search Results
Now showing 1 - 9 of 9
- PublicationMetadata onlyPreparation methods of different nanomaterials for various potential applications: A review(Elsevier, 2023) Zidan, Alaa; El-Khawaga, Ahmed Mohamed; Abd El-Mageed, Ahmed I. A.Nanomaterials are an interesting class of materials that include a wide variety of samples with at least one dimension between 1 and 100 nm. Nanomaterials are cornerstones of nanoscience and nanotechnology. Controlling the size, shape, and composition of the nanomaterials is an uphill task and have a profound impact on their performance. Along with potential health and safety risks, producing large quantities of high-quality nanomaterials are challenging and expensive. The synthesis and growth process of nanostructures and nanomaterials is one of the key elements in the utilization of nanomaterials and their applications in several sectors. The morphology and structure of nanomaterials depend also on the method used for synthesis and growth. This review discusses the various nanomaterial synthesis methods which are categorized into two main types bottom-up methods and top-down approaches depending on starting precursors of nanoparticle generation. Both approaches are critically discussed, in addition, the advantages and disadvantages of each technique have been reported. The aforementioned approaches can have a potential technological applications, such as nano-molecular electronics, optoelectronics, sensors, energy storage materials, composite materials, nano-biotechnology, nano-medicine, etc.
- PublicationOpen AccessCocatalyst loaded Al-SrTiO3 cubes for Congo red dye photo-degradation under wide range of light(Springer Nature, 2023-04-18) Abd Elkodous, M.; Abouelela, Marwa Mohamed; Abdel Maksoud, M. I. A.; El-Khawaga, Ahmed MohamedThe continued pollution, waste, and unequal distribution of the limited amount of fresh water on earth are pushing the world into water scarcity crisis. Consequently, development of revolutionary, cost-effective, and efficient techniques for water purification is essential. Herein, molten flux method was used for the preparation of micro-sized Al-doped SrTiO3 photocatalyst loaded with RhCr2O3 and CoOOH cocatalysts via simple impregnation method for the photo-assisted degradation of Congo red dye under UV and visible irradiation compared with P25 standard photocatalyst. In addition, photoelectrochemical analysis was conducted to reveal the separation and transfer efficiency of the photogenerated e−/h+ pairs playing the key role in photocatalysis. SEM and TEM analyses revealed that both P25 and the pristine SrTiO3 have spherical shapes, while Al-doped SrTiO3 and the sample loaded with cocatalysts have cubic shapes with a relatively higher particle size reaching 145 nm. In addition, the lowest bandgap is due to Al+3 ion doping and excessive surface oxygen vacancies, as confirmed by both UV–Vis diffuse-reflectance and XPS analyses. The loading of the cocatalysts resulted in a change in the bandgap from n-type (pristine SrTiO3 and Al-SrTiO3) into p-type (cocatalyst loaded sample) as exhibited by Mott–Schottky plots. Besides, the cocatalyst-loaded sample exhibited good performance stability after 5 cycles of the photocatalytic removal of Congo red dye. OH· radical was the primary species responsible for CR degradation as confirmed by experiments with radical scavengers. The observed performance of the prepared samples under both UV and visible light could foster the ongoing efforts towards more efficient photocatalysts for water purification.
- PublicationMetadata onlyAntimicrobial synergism and antibiofilm activity of amoxicillin loaded citric acid-magnesium ferrite nanocomposite: Effect of UV-illumination, and membrane leakage reaction mechanism(Elsevier, 2022-02-07) El-Batal, Ahmed I.; Al-Hazmi, Nawal E.; Farrag, Ayman A.; Elsayed, Mohamed A.; Elshamy, Aliaa A.; El-Khawaga, Ahmed Mohamed; El-Sayyad, Gharieb SaiedMagnesium ferrite nanoparticles (Mg Fe2O4 NPs) was synthesized by a chemical co-precipitation method and characterized via structural and optical properties. The surface of Mg Fe2O4 NPs was stabilized with citric acid (CA) by a direct addition method (CA-Mg Fe2O4 NPs), then Amoxicillin (AX) was loaded with CA-Mg Fe2O4 nanocomposites. Furthermore, their antimicrobial, and antibiofilm activities, growth curve, and effect of UV-illumination methods were examined against different pathogenic microbes. Based on XRD, HRTEM and SEM analyses, it is found that Mg Fe2O4 NPs are located at the core, while the CA and AX are coated this core. In-vitro zone of inhibition (ZOI) and minimum inhibitory concentration (MIC) results verified that AX-loaded CA-Mg Fe2O4 nanocomposites exhibited its encouraged antimicrobial activity against S. aureus, E. coli, and C. albicans (32.2, 22.0, and 19.0 mm ZOI, respectively) & (0.312, 0.625, and 1.25 μg/ml MIC, respectively). AX-CA-Mg Fe2O4 nanocomposites are showed antibiofilm percentage against S. aureus (95.34%), E. coli (93.93%), and C. albicans (76.23%). AX-CA-MgFe2O4 nanocomposites are an excellent disinfectant agents once they are excited by UV light. Membrane leakage assay explains the formation of holes on the surface of bacteria, and confirms SEM reaction mechanism. AX-loaded CA-Mg Fe2O4 NPs are promising for potential applications in biomedical uses.
- PublicationOpen AccessPromising photocatalytic and antimicrobial activity of novel capsaicin coated cobalt ferrite nanocatalyst(Springer Nature, 2023-04-01) Elsayed, Mohamed A.; Fahim, Yosri A.; Shalaby, Rasha E.; El-Khawaga, Ahmed MohamedIn this study, CoFe2O4 nanoparticles were prepared by the co-precipitation method then surface modified with Capsaicin (Capsicum annuum ssp.). The virgin CoFe2O4 NPs and Capsaicin-coated CoFe2O4 NPs (CPCF NPs) were characterized by XRD, FTIR, SEM, and TEM. The antimicrobial potential and photocatalytic degradation efficiencies of the prepared samples via Fuchsine basic (FB) were investigated. The results revealed that CoFe2O4 NPs have spherical shapes and their diameter varied from 18.0 to 30.0 nm with an average particle size of 25.0 nm. Antimicrobial activity was tested on Gram-positive (S. aureusATCC 52923) and Gram-negative (E. coli ATCC 52922) by disk diffusion and broth dilution methods to determine the zone of inhibition (ZOI) and minimum inhibitory concentration (MIC), respectively. UV-assisted photocatalytic degradation of FB was examined. Various parameters affecting the photocatalytic efficiency such as pH, initial concentration of FB, and dose of nanocatalyst were studied. The in-vitro ZOI and MIC results verified that CPCF NPs were more active upon Gram-Positive S. aureus ATCC 52923 (23.0 mm ZOI and 0.625 μg/ml MIC) than Gram-Negative E. coli ATCC 52922 (17.0 mm ZOI and 1.250 μg/ml MIC). Results obtained from the photocatalytic activity indicated that the maximum FB removal achieving 94.6% in equilibrium was observed using 20.0 mg of CPCF NPS at pH 9.0. The synthesized CPCF NPs were effective in the removal of FB and also as potent antimicrobial agent against both Gram-positive and Gram-negative bacteria with potential medical and environmental applications.
- PublicationOpen AccessCocatalyst loaded Al-SrTiO3 cubes for Congo red dye photo-degradation under wide range of light(Springer Nature, 2023-04-18) Abd Elkodous, M. ; Abouelela, Marwa Mohamed; Abdel Maksoud, M. I. A. ; El-Khawaga, Ahmed MohamedThe continued pollution, waste, and unequal distribution of the limited amount of fresh water on earth are pushing the world into water scarcity crisis. Consequently, development of revolutionary, cost-effective, and efficient techniques for water purification is essential. Herein, molten flux method was used for the preparation of micro-sized Al-doped SrTiO3 photocatalyst loaded with RhCr2O3 and CoOOH cocatalysts via simple impregnation method for the photo-assisted degradation of Congo red dye under UV and visible irradiation compared with P25 standard photocatalyst. In addition, photoelectrochemical analysis was conducted to reveal the separation and transfer efficiency of the photogenerated e−/h+ pairs playing the key role in photocatalysis. SEM and TEM analyses revealed that both P25 and the pristine SrTiO3 have spherical shapes, while Al-doped SrTiO3 and the sample loaded with cocatalysts have cubic shapes with a relatively higher particle size reaching 145 nm. In addition, the lowest bandgap is due to Al+3 ion doping and excessive surface oxygen vacancies, as confirmed by both UV–Vis diffuse-reflectance and XPS analyses. The loading of the cocatalysts resulted in a change in the bandgap from n-type (pristine SrTiO3 and Al-SrTiO3) into p-type (cocatalyst loaded sample) as exhibited by Mott–Schottky plots. Besides, the cocatalyst-loaded sample exhibited good performance stability after 5 cycles of the photocatalytic removal of Congo red dye. OH· radical was the primary species responsible for CR degradation as confirmed by experiments with radical scavengers. The observed performance of the prepared samples under both UV and visible light could foster the ongoing efforts towards more efficient photocatalysts for water purification.
- PublicationOpen AccessSynthesis and applicability of reduced graphene oxide/porphyrin nanocomposite as photocatalyst for waste water treatment and medical applications(Springer Nature, 2022-10-12) Tantawy, Hesham; Elsayed, Mohamed A.; Abd El-Mageed, Ahmed I. A.; El-Khawaga, Ahmed MohamedThis study presents the synthesis and doping of reduced graphene oxide (rGO) with synthesized porphyrin (5,15-bisdodecyl porphyrin, C12P) nanoparticles to fabricate reduced graphene oxide-porphyrin (rGO-P) nanocomposite as well as demonstrates their outstanding removal activity of azo dye and antimicrobial potential. The synthesized porphyrin, rGO, and rGO-P nanocomposites were characterised using SEM, HRTEM, Raman spectroscopy, XRD, 1H-NMR, mass spectrometry, and UV–Visible spectroscopy. The ability of the synthesized rGO-P nanocomposite was then investigated (as catalyst and/or adsorbent) to impact its removal efficacy against Congo red (CR) as a well-known toxic, mutagenic and carcinogenic synthetic dye. The findings indicated that 0.01 g of rGO-P nanocomposite achieved 78.0% removal of CR at pH 3.0. Besides, the removal efficacy was evaluated while studying many aspects i.e. pH, CR initial concentration, and rGO-P nanocomposite amount. Moreover, the minimum inhibitory concentration (MIC) and zone of inhibition (ZOI) of antimicrobial activity against pathogenic bacteria and yeast were evaluated. The antimicrobial results showed that rGO-P nanocomposite revealed the greatest antimicrobial activity against Candida albicans, Enterococcus faecalis, and Staphylococcus aureus with ZOI values of 24.3, 21.8, and 22.1 mm, respectively. Consequently, it demonstrates the substantial potential of rGO-P nanocomposite in the effective removal of pollutant dyes as well as significant antibacterial and antifungal properties.
- PublicationMetadata onlyEnhanced photocatalytic and antimicrobial performance of a multifunctional Cu-loaded nanocomposite under UV light: theoretical and experimental study(Royal Society of Chemistry, 2022-05-18) Abd Elkodous, M. ; Abdel Maksoud, M. I. A. ; Alias, Nurhaswani; Abdelsalam, Hazem; Ibrahim, Medhat A.; Elsayed, Mohamed A.; Kawamura, Go; Lockman, Zainovia; Tan, Wai Kian; Matsuda, Atsunori; El-Khawaga, Ahmed Mohamed; El-Sayyad, Gharieb SaiedDue to modern industrialization and population growth, access to clean water has become a global challenge. In this study, a metal–semiconductor heterojunction was constructed between Cu NPs and the Co0.5Ni0.5Fe2O4/SiO2/TiO2 composite matrix for the photodegradation of potassium permanganate, hexavalent chromium Cr(VI) and p-nitroaniline (pNA) under UV light. In addition, the electronic and adsorption properties after Cu loading were evaluated using density functional theory (DFT) calculations. Moreover, the antimicrobial properties of the prepared samples toward pathogenic bacteria and unicellular fungi were investigated. Photocatalytic measurements show the outstanding efficiency of the Cu-loaded nanocomposite compared to that of bare Cu NPs and the composite matrix. Degradation efficiencies of 44% after 80 min, 100% after 60 min, and 65% after 90 min were obtained against potassium permanganate, Cr(VI), and pNA, respectively. Similarly, the antimicrobial evaluation showed high ZOI, lower MIC, higher protein leakage amount, and cell lysis of nearly all microbes treated with the Cu-loaded nanocomposite.
- PublicationMetadata onlyPreparation methods of different nanomaterials for various potential applications: A review(Elsevier, 2023-02-12) Zidan, Alaa; Abd El-Mageed, Ahmed I. A.; El-Khawaga, Ahmed MohamedNanomaterials are an interesting class of materials that include a wide variety of samples with at least one dimension between 1 and 100 nm. Nanomaterials are cornerstones of nanoscience and nanotechnology. Controlling the size, shape, and composition of the nanomaterials is an uphill task and have a profound impact on their performance. Along with potential health and safety risks, producing large quantities of high-quality nanomaterials are challenging and expensive. The synthesis and growth process of nanostructures and nanomaterials is one of the key elements in the utilization of nanomaterials and their applications in several sectors. The morphology and structure of nanomaterials depend also on the method used for synthesis and growth. This review discusses the various nanomaterial synthesis methods which are categorized into two main types bottom-up methods and top-down approaches depending on starting precursors of nanoparticle generation. Both approaches are critically discussed, in addition, the advantages and disadvantages of each technique have been reported. The aforementioned approaches can have a potential technological applications, such as nano-molecular electronics, optoelectronics, sensors, energy storage materials, composite materials, nano-biotechnology, nano-medicine, etc.
- PublicationOpen AccessCarbon-dot-loaded CoxNi1−xFe2O4; x = 0.9/SiO2/TiO2 nanocomposite with enhanced photocatalytic and antimicrobial potential: An engineered nanocomposite for wastewater treatment(Springer Nature, 2020-07-13) Abd Elkodous, M. ; Youssry, Sally M. ; Nada, Hanady G. ; Gobara, Mohamed ; Elsayed, Mohamed A. ; Kawamura, Go ; Kian Tan, Wai ; El-Batal, Ahmed I. ; Matsuda, Atsunori ; El-Khawaga, Ahmed Mohamed; El-Sayyad, Gharieb SaiedWater scarcity is now a serious global issue resulting from population growth, water decrease, and pollution. Traditional wastewater treatment plants are insufficient and cannot meet the basic standards of water quality at reasonable cost or processing time. In this paper we report the preparation, characterization and multiple applications of an efficient photocatalytic nanocomposite (CoxNi1−xFe2O4; x = 0.9/SiO2/TiO2/C-dots) synthesized by a layer-by-layer method. Then, the photocatalytic capabilities of the synthesized nanocomposite were extensively-studied against aqueous solutions of chloramine-T trihydrate. In addition, reaction kinetics, degradation mechanism and various parameters affecting the photocatalytic efficiency (nanocomposite dose, chloramine-T initial concentration, and reaction pH) were analyzed in detail. Further, the antimicrobial activities of the prepared nanocomposite were tested and the effect of UV-activation on the antimicrobial abilities of the prepared nanocomposite was analyzed. Finally, a comparison between the antimicrobial abilities of the current nanocomposite and our previously-reported nanocomposite (CoxNi1−xFe2O4; x = 0.9/SiO2/TiO2) had been carried out. Our results revealed that the prepared nanocomposite possessed a high degree of crystallinity, confirmed by XRD, while UV–Vis. recorded an absorption peak at 299 nm. In addition, the prepared nanocomposite possessed BET-surface area of (28.29 ± 0.19 m2/g) with narrow pore size distribution. Moreover, it had semi-spherical morphology, high-purity and an average particle size of (19.0 nm). The photocatalytic degradation efficiency was inversely-proportional to chloramine-T initial concentration and directly proportional to the photocatalyst dose. In addition, basic medium (pH 9) was the best suited for chloramine-T degradation. Moreover, UV-irradiation improved the antimicrobial abilities of the prepared nanocomposite against E. coli, B. cereus, and C. tropicalis after 60 min. The observed antimicrobial abilities (high ZOI, low MIC and more efficient antibiofilm capabilities) were unique compared to our previously-reported nanocomposite. Our work offers significant insights into more efficient water treatment and fosters the ongoing efforts looking at how pollutants degrade the water supply and the disinfection of water-borne pathogenic microorganisms.