Showing papers by "King Saud University published in 2022"

Emerging contaminants of high concern for the environment: Current trends and future research

Abstract: Wastewater is contaminated water that must be treated before it may be transferred into other rivers and lakes in order to prevent further groundwater pollution. Over the last decade, research has been conducted on a wide variety of contaminants, but the emerging contaminants are those caused primarily by micropollutants, endocrine disruptors (EDs), pesticides, pharmaceuticals, hormones, and toxins, as well as industrially-related synthetic dyes and dye-containing hazardous pollutants. Most emerging pollutants did not have established guidelines, but even at low concentrations they could have harmful effects on humans and aquatic organisms. In order to combat the above ecological threats, huge efforts have been done with a view to boosting the effectiveness of remediation procedures or developing new techniques for the detection, quantification and efficiency of the samples. The increase of interest in biotechnology and environmental engineering gives an opportunity for the development of more innovative ways to water treatment remediation. The purpose of this article is to provide an overview of emerging sources of contaminants, detection technologies, and treatment strategies. The goal of this review is to evaluate adsorption as a method for treating emerging pollutants, as well as sophisticated and cost-effective approaches for treating emerging contaminants.

A comprehensive survey on ‘circular polarized antennas’ for existing and emerging wireless communication technologies

Abstract: Circular polarized (CP) antennas are well suited for long-distance transmission attainment. In order to be adaptable for beyond 5G communication, a detailed and systematic investigation of their important conventional features is required for expected enhancements. The existing designs employing millimeter wave, microwave, and ultra-wideband frequencies form the elementary platform for future studies. The 3.4 to 3.8 GHz frequency band has been identified as a worthy candidate for 5G communications because of spectrum availability. This band comes under ultra-wideband frequencies (3.1 to 10.6 GHz). In this survey, a review of CP antennas in the selected areas to improve the understanding of early-stage researchers specially experienced antenna designers has presented for the first time as best of our knowledge. Design implementations involving size, axial ratio, efficiency, and gain improvements are covered in detail. Besides that, various design approaches to realize CP antennas including (i) printed CP antennas based on parasitic or slotted elements, (ii) dielectric resonator CP antennas, (iii) reconfigurable CP antennas, (iv) substrate integrated waveguide (SIW) CP antennas, (v) fractal CP antennas, (vi) hybrid techniques CP antennas, and (vii) 3-D printing CP antennas with single and multiple feeding structures have investigated and analyzed. The aim of this work is to provide necessary guidance for the selection of CP antenna geometries in terms of the required dimensions, available bandwidth, gain, and useful materials for the integration and realization in future communication systems.

Facile synthesis and characterization of ZnO nanoparticles for studying their biological activities and photocatalytic degradation properties toward methylene blue dye

Abstract: Lately, attention to combustion synthesis has been encouraged owing to being cost-effective, rapid, and produces samples with low crystallite sizes and/or different morphology. So, in this paper, for the first time, ZnO nanoparticles were facilely fabricated utilizing the combustion procedure using L-arginine, L-valine, and L-alanine as organic fuels. Besides, the fabricated ZnO samples were recognized using different tools such as FT-IR, XRD, FE-SEM, HR-TEM, and UV–Vis. The XRD patterns show that the mean crystallite size of ZnO samples, which were fabricated operating L-arginine, L-valine, and L-alanine fuels, is 25.24, 31.11, and 35.65 nm, respectively. The HR-TEM images approved that the ZnO samples, which were fabricated operating L-arginine, L-valine, and L-alanine fuels, are composed of irregular, hexagonal, and sphere shapes with an average diameter of 22.46, 34.57, and 40.29 nm, respectively. The EDX patterns display peaks at 1.0 and 8.6 KeV for Zn. Also, there are peaks at 0.6 KeV for O. The values of the energy gap for the ZnO samples, which were fabricated operating L-arginine, L-valine, and L-alanine fuels, are 3.30, 2.88, and 2.63 eV, respectively. The photocatalytic degradation process is an important water treatment method due to its effectiveness in producing hydroxyl free radicals which able to degrade numerous dyes. So, the fabricated ZnO samples were examined for the photocatalytic degradation of methylene blue dye along with biological activity against some strains of bacteria. Furthermore, the maximum percent of degradation of 50 mL of 10 mg/L methylene blue dye under UV irradiations is 54.69, 41.34, and 30.76% after 90 min exploiting the ZnO samples which were fabricated operating L-arginine, L-valine, and L-alanine fuels, respectively. Also, % degradation of methylene blue dye under UV irradiations in the presence of hydrogen peroxide is 100% after 70 min using the ZnO sample which was fabricated operating L-arginine fuel. Moreover, the fabricated ZnO products show high bactericidal activity against Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. Additionally, the fabricated ZnO products show moderate bactericidal activity against Bacillus cereus and Salmonella typhimurium.