Natural waters are prone to pollution with organic contaminants, waste pharmaceuticals being an example. Pharmaceutical compounds are widely detected in different surface waters, such as lakes and ...rivers. Removal of such contaminants from water is therefore imperative. Different strategies are commonly followed such as adsorption, chlorination, ozonation, peroxidation and others. Each method has its shortcomings. Photodegradation of water organic contaminants by semiconductors is a safe and non-costly method. In photodegradation, the organic contaminant is completely mineralized with radiation and oxygen using stable semiconductor nanoparticles as photocatalysts. ZnO nanopowder is widely described for photodegradation processes. Due to its wide band gap (~3.2 eV) ZnO excitation is limited to UV radiation. Moreover, the nano-particle nature for the ZnO catalyst makes it difficult to recover and re-use after process completion. Supporting the ZnO nanoparticles onto stable solid material surfaces is one possible way out, and is studied here. Raw clay (kaolin) is described to support ZnO particles in photodegradation of a widely encountered pharmaceutical contaminant, tetracycline (TC). The results show the possibility of annealed ZnO/Kaolin to remove TC from water, firstly by adsorbing the contaminant then by photodegrading it into mineral species. The study shows that TC molecules pre-adsorbed onto ZnO/Kaolin were mineralized during photodegradation experiments. Complete mineralization of reacted contaminant molecules was confirmed by spectrophotometry, high performance liquid chromatography (HPLC) and total organic carbon (TOC) study. Control experiments with a cut-off filter (400 nm and shorter) confirmed the ability of the catalyst to function in the visible region, where contaminant molecules behave as sensitizers in the photodegradation process. Optimizing the efficiency of the ZnO catalyst in TC photodegradation processes by studying the effect of pH using the point of zero charge (pHPZC) concepts is achieved. Collectively, the results show the possibility to prepare an efficient recoverable ZnO/Kaolin catalyst, which can be sensitized with TC molecules themselves with optimal working pH range 6–9.
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•Nano-size ZnO particles are supported onto raw clay particles.•Supported ZnO/Clay effectively catalyses aqueous tetracycline mineralization.•Tetracycline molecules self-sensitize ZnO/Clay catalyst in the visible light.•Photo-degraded tetracycline molecules are completely mineralized.•ZnO/Clay particles retain photo-catalytic efficiency on multi-recovery and reuse.
A coronavirus disease-19 (COVID-19) caused by a novel coronavirus has appeared in China by the end of 2019 and later recognized as a global pandemic. This pandemic has evolved as a global public ...health menace. It has affected every aspect of human life. In line with these concerns, governments and the scientific community react promptly to the outbreak of this pandemic. These efforts are devoted to develop vaccine and curative medicines. Further efforts are dedicated to assessing the impacts of the pandemic in relation to socioeconomic, psychological, and environmental dimensions. In this regard, it is important to follow up developments and research activities on this global issue. The present work intended to tracking the current hotspots and research trends on COVID-19 in environmental fields. Bibliometric analysis and visualization mapping were utilized with the objective of revealing and evaluating the developments in knowledge on COVID-2019 and its impacts based on a collection of environmental sources. A sum of 729 documents were collected from Scopus database limiting to environmental sources only. Of all these publications, 563 (77.2%) were articles, 56 (7.7%) were reviews, and 110 (15.0%) were others. China has the highest share of publications (163; 22.4%). It is followed by the USA (139; 19.15), and Italy (110; 15.1%). Most publications on COVID-19 were in prestigious journals. The most productive institution at global level was
Chinese Academy of Sciences
, China (24 documents; 3.3%). The most prevalent topics are in relation to impacts of the pandemic on air quality, mental health, psychological, and economic aspects. The development of these topics is based on cross-sectional studies, evidence-based tools, remote sensing, satellite mapping, geographic information systems, market analysis and sampling. The progress of environmental research on COVID-19 will guide the development of global environmental strategies to control future global environmental risks.
Water, sanitation, and hygiene (WASH) services play a crucial role in promoting public and environmental health as well as social and economic development. At the global level, particularly in the ...developing world, WASH issues continue to present significant challenges. These challenges have been further intensified by factors such as the COVID-19 pandemic, escalating conflicts, climate change, water scarcity, and rising inequality. The scientific community has actively engaged in constructive discussions on these issues, as evidenced by the notable research findings. Therefore, the aim of this study was to comprehensively examine and evaluate global knowledge on WASH. To search for relevant publications, the Scopus database was utilized using specific terms associated with WASH. VOSviewer 1.6.18 software was employed to generate network visualization maps, which assessed collaborative patterns and research trends in the field of WASH. The research output of countries was adjusted considering their gross domestic product (GDP) and population size. The total number of WASH-related publications, including all types of documents, was 1805. By narrowing the search to articles and reviews, the overall global productivity yielded 1589 documents: 1367 (86.0%) original articles and 222 (14.0%) review articles. The USA had the highest number of WASH publications (
n
= 668; 42.0%), followed by the UK (
n
= 396; 24.9%), Switzerland (
n
= 151; 9.5%), and Australia (
n
= 141; 8.9%). Ethiopia emerged as the leading country in terms of GDP per capita and the number of publications, followed by Uganda, Malawi, India, and Bangladesh. The USA, the UK, and Switzerland exhibited the most extensive collaboration among countries. The main research areas encompassed the role of WASH in sustainable development, the impacts of inadequate access to WASH services on gender equality, children, infants, and the outbreak of COVID-19 and other diseases, as well as the significance of hygiene practices and community and school-based WASH interventions in reducing infections. This study provides a novel analysis of global WASH-related research and highlights the distribution of outcomes across nations. Continued and increased collaboration between developed and developing nations will facilitate the sharing of responsibility for WASH research outcomes and the implementation of effective policies.
A novel insoluble Ca-Alginate created from soluble Na-Alginate was used as a support substrate for ZnO nanoparticles producing ZnO@Ca-Alginate composite photocatalyst. Fourier Transform Infrared ...(FT-IR), Ultraviolet-Visible (UV-Vis), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), and X-ray Diffraction (XRD) analysis techniques were used in the characterization of the prepared ZnO@Ca-Alginate. The ZnO@Ca-Alginate was tested for its potential use in the photodegradation of Methylene Blue (MB) from an aqueous solution under solar-simulated light. This composite photocatalyst efficiency in MB removal was compared with naked ZnO potential considering different conditions and parameters (e.g. pH, MB concentration, amount of photocatalyst, and irradiation time). The MB concentrations were identified using UV-vis spectrophotometric methods. While, high-performance liquid chromatography (HPLC), Total organic carbon (TOC) analysis, and other elemental analyses were used to confirm the MB complete mineralization. The MB photodegradation results were performed by using UV-vis analysis., the results showed that up to 95% of MB (40 mL, 40 ppm) was removed within 30 min of irradiation using either ZnO@Ca-Alginate or naked ZnO. The pH and the zero-charge point (Pzc) values play a main role in the adsorption and photodegradation results. The Pzc values for Ca-Alginate, ZnO, and Zn@Ca-Alginate were 6.5, 8.8, and 6.8 respectively. The prepared composite catalyst showed a maximum adsorption and photodegradation in a basic to slightly basic medium, the MB completely removed at pH of 7.7 within an hour of irradiation. The complete miniralzation of MB at the end of the photodegrdation process was confirmed. Here it is proved that the ZnO@Ca-Alginate photocatalyst can be recovered and reused without any significant decrease in its effectiveness.
Interests and concerns on environmental issues have attracted much attention over the past few decades. This is in harmony with the growing understanding of environmental impacts associated with ...human activities and their role in degrading ecosystems. In line with these concerns, considerable advances in science and technology to assess, mitigate, or lessen these adverse impacts have emerged (i.e., environmental impact assessment (EIA) methodologies). The involvement of EIA in sustainable development has become a prevalent topic in research in either developed and developing countries. The present work investigated the research status, development trends, and hotspots of EIA in a region with massive environmental challenges; the Arab world. Bibliometric analysis and visualization mapping were utilized with an objective of revealing and evaluating the developments in knowledge on EIA from the Arab world. A sum of 595 documents was the productivity of the Arab world on EIA (2.1% of total global productivity). Most of the studies were performed by scholars in Egypt (143 documents; 24.0%), followed by Saudi Arabia (96 documents; 16.1%), and Tunisia (68 documents; 11.4%). France, the USA, and the UK were, respectively, the most collaborated countries with the Arab world on EIA. Most of the publications on EIA were in prestigious journals in relation to environmental sciences.
King Abdulaziz University
, Saudi Arabia and
University of Kuwait
were the most productive institutions (24 documents/institution). Topics in relation to assessing different environmental impacts on the quality and quantity of water will continue to be vital themes of research. While, the utilization of remote sensing, geographic information systems, risk assessment, life cycle assessment, bioaccumulation, and biomarkers techniques in assessing environmental impacts will continue to be dominant as efficient tools in conducting EIA related research. The outcomes displayed, in general, a rapidly and steadily rising interests on EIA. However, the development of regional experience, increasing of funds and advancing of competencies will further promote research activities on EIA.
The numerical modeling of a copper zinc tin sulfide (CZTS)-based kesterite solar cell is described in detail in this article. To model FTO/ZnO/CdS/CZTS/MO structured solar cells, the Solar Cell ...Capacitance Simulator-one-dimension (SCAPS-1D) program was utilized. Numerical modeling was used to estimate and assess the parameters of various photovoltaic thin film solar cells. The impact of different parameters on solar cell performance and conversion efficiency were explored. Because the response of a solar cell is partly determined by its internal physical mechanism, J-V characteristic characteristics are insufficient to define a device’s behavior. Regardless of the conviction in solar cell modeling, variable attributes as well as many probable conditions must be handled for simulation. Promising optimized results were obtained with a conversion efficiency of (η% = 25.72%), a fill factor of (FF% = 83.75%), a short-circuit current of (JSC = 32.96436 mA/cm2), and an open-circuit voltage of (VOC = 0.64 V). The findings will aid in determining the feasibility of manufacturing high-efficiency CZTS-based solar cells. First, in the SCAPS-1D environment, the impacts of experimentally constructed CZTS solar cells were simulated. The experimental data was then compared to the simulated results from SCAPS-1D. After optimizing cell parameters, the conversion efficiency of the improved system was observed to rise. The influence of system factors, such as the thickness, acceptor, and donor carrier concentration densities of the absorber and electron transport layers, and the effect of temperature on the efficiency of CZTS-based photovoltaic cells, was explored using one-dimensional SCAPS-1D software. The suggested findings will be extremely useful to engineers and researchers in determining the best method for maximizing solar cell efficiency, as well as in the development of more efficient CZTS-based solar cells.
Cadmium telluride (CdTe), a metallic dichalcogenide material, was utilized as an absorber layer for thin film–based solar cells with appropriate configurations and the SCAPS–1D structures program was ...used to evaluate the results. In both known and developing thin film photovoltaic systems, a CdS thin–film buffer layer is frequently employed as a traditional n–type heterojunction partner. In this study, numerical simulation was used to determine a suitable non–toxic material for the buffer layer that can be used instead of CdS, among various types of buffer layers (ZnSe, ZnO, ZnS and In2S3) and carrier concentrations for the absorber layer (NA) and buffer layer (ND) were varied to determine the optimal simulation parameters. Carrier concentrations (NA from 2 × 1012 cm−3 to 2 × 1017 cm−3 and ND from 1 × 1016 cm−3 to 1 × 1022 cm−3) differed. The results showed that the use of CdS as a buffer–layer–based CdTe absorber layer for solar cell had the highest efficiency (%) of 17.43%. Furthermore, high conversion efficiencies of 17.42% and 16.27% were for the ZnSe and ZnO-based buffer layers, respectively. As a result, ZnO and ZnSe are potential candidates for replacing the CdS buffer layer in thin–film solar cells. Here, the absorber (CdTe) and buffer (ZnSe) layers were chosen to improve the efficiency by finding the optimal density of the carrier concentration (acceptor and donor). The simulation findings above provide helpful recommendations for fabricating high–efficiency metal oxide–based solar cells in the lab.
Saliva is a biofluid that can easily be obtained and used for biomonitoring lead levels in occupationally and environmentally exposed individuals. The aims of this study were to determine salivary ...lead levels among workers in different industrial areas in the West Bank of Palestine and investigate the association between sociodemographic and occupational characteristics of the workers and their salivary lead levels. Salivary samples were obtained from workers in different industrial areas in metal-free polyethylene tubes. The samples were analyzed for their lead contents using a pre-validated inductively coupled plasma-mass spectrometric method. A total of 97 salivary samples were analyzed. The median salivary lead level was 1.84 μg/dL an IQR of 5.04 μg/dL. Salivary lead levels were significantly higher in workers who were 40 years and older (
p
value = 0.031), had 3 children or more (
p
value = 0.048), worked in repair workshops (
p
value = 0.012), worked in industrial areas for 20 years or more (
p
value = 0.048), did not consume fruits on regular basis (
p
value = 0.031), and smoked for 30 years or more (
p
value = 0.013). Multiple linear regression showed that smoking of 30 years old or more was a significant (
p
value < 0.001) predictor of higher salivary lead levels. Salivary lead levels among workers from different industrial areas of the West Bank were comparable to those occupationally exposed to lead in more industrialized and urbanized areas of the world. Smoking was a predictor of higher salivary lead levels.
Mineralization of phenazopyridine, 1, in water, under solar-simulator radiation was efficiently achieved using nanoparticle CdS-sensitized rutile TiO(2), TiO(2)/CdS, 2, as photo-catalysts. Despite ...that, 2 showed two main drawbacks. Firstly, the system was difficult to recover by simple filtration, and demanded centrifugation. Secondly, the sensitizer CdS showed relatively high tendency to leach out hazardous Cd(2+) ions under photo-degradation reaction conditions. In an attempt to solve out such difficulties, 2 was supported onto sand surface. The sand/TiO(2)/CdS system, 3, was easier to recover but showed slightly lower catalytic activity compared to 2. On the other hand, the support failed to prevent leaching of Cd(2+). This indicates limited future applicability of CdS-sensitized TiO(2) photo-catalyst systems, in solar-based water purification strategies, unless leaching out tendency is completely prevented.
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