The simulation of photocatalytic reactor is conducted using computational fluid dynamics. Turbulence is described by using the RNG k-ε turbulence model. The DO radiation model is used to simulate the irradiance distribution in the photocatalytic reactor. The effects of operating parameters on the performance of photocatalytic reactor are considered. Results show that the degradation rate of oxalic acid decreases with the increase of inlet flow. The degradation efficiency decreases from 50% to 40% when the flow rate changes from 2.5 m3 h−1 to 10 m3 h−1. The degradation rate of oxalic acid can be improved by increasing the irradiance of the lamp. The degradation efficiency of oxalic acid in the photocatalytic reactor first reaches a maximum degradation efficiency with the increase of titanium dioxide concentration, and then decreases with the increase of titanium dioxide concentration. An optimal concentration of catalysts exists. The maximum degradation efficiency is 27% for the catalyst concentration of 20 µgL−1.

Coronavirus (COVID-19) pandemic ushered in a new era that led to the adjustments of diverse ecosystems. The pandemic restructured the global socio-economic events which prompted several adaptation measures as a response mechanism to cushion the negative impact of the disease pandemic. Critical health safety actions were imperative to curtail the spread of the disease such as wearing personal protective equipment (PPEs), masks, goggles, and using sanitizers for disinfection purposes. The daily demands for the products by individuals and medical personnel heightened their production and consumption, leading to a corresponding increase of COVID-19 wastes in the environment following indiscriminate waste disposal and poor waste management. The persistent occurrence of COVID-19 wastes aggravated microplastics (MPs) contamination in the aquatic ecosystem following the breakdown of PPEs-based plastics via oxidation, fragmentation, and photo-degradation actions. These MPs are transported in the aquatic environment via surface runoff and wind action, apart from discrete sources. MPs' presence in the aquatic systems is not without repercussions. Ingestion of MPs by aquatic organisms can cause several diseases (e.g., poor growth, oxidative distress, neurotoxicity, developmental toxicity, reproductive toxicity, immunotoxicity, and organ toxicity). Humans are at high risk of MPs uptake. Apart from aerial and soil contamination sources, consumption of aquatic food products is a critical pathway of MPs into the human body. MP toxicities in humans include liver disorder, respiratory failure, infertility, hormonal imbalance, diarrhea, developmental disorder, and mortality. Measures to alleviate the effect of COVID-19 waste litters include effective waste management plans and the adoption of technologies to extract cum degrade MPs from the aquatic and terrestrial environment.

Benin’s waterways are affected by several forms of pollution that are linked in particular to anthropic activities. This study aims to detect the presence of antibiotic residues, the frequency of antibiotic resistant bacteria and the levels of heavy metals in Benin’s waterways. 160 surface water samples from streams in Benin were collected. They were filtered by the membrane filtration method, then incubated on different media. The isolated bacterial species were identified by API 20E gallery and specific biochemical tests. After detection of the resistance profile of the latter, the antibiotic residues were quantified in the samples by the ELISA technique on plate and the physicochemical analyses were performed by Multi 3630 IDS SET KS2 multimeter. Finally, heavy metal levels were detected by the MERCK test kit method specific to each metal. The bacterial species mostly identified were Klebsiella pneumoniae (56.59%), Klebsiella spp. (18.68%), Enterobacter spp. (12.63%). The most abundant resistance of bacterial strains was to amoxicillin + clavulanic acid (92%), followed by metronidazole (86%). Metronidazole was the antibiotic with the highest residue concentration in the samples (6.578 to 6.829 µg/L), followed by ciprofloxacin (2.142 to 9.299 µg/L). Benin streams contain heavy metals such as mercury (0.454±0.129 µg/L), lead (0.040±0.50 mg/L), zinc (6.120±16.017 mg/L), nickel (0.155±0.233 mg/L) and cadmium (0.154±0.132 mg/L). The analysis of the physico-chemical parameters showed that, apart from electrical conductivity, all parameters comply with Beninese and World Health Organization standards. Actions must be taken to clean up these rivers to preserve the integrity of aquatic ecosystems in Benin.

Gas storage is an important branch of technology that has many economic and environmental aspects. This technique could save gas to the need time and contribute to solving the CO2 and global warming problems. In this work, the structure and physicochemical properties of the prepared palladium complex were characterized in the solid and solution states using spectroscopic techniques. These examination methods include ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR), metal and elemental analyses, and measurements of magnetic susceptibility and conductivity at room temperature. Also, findings on the surface morphology and surface area were provided via Field emission scanning electron microscopy (FESEM) and Brunauer–Emmett–Teller (BET) techniques, respectively. High-pressure adsorption measurements were investigated by storing carbon dioxide, and the results proved that such materials own remarkable gas adsorption properties that make them a good option for gas separation and storage. Gases uptake at 323 K for the complexes leads to the highest CO2 uptake. The prepared material could pave the road for further exploitation of similar materials.

Nickel nitrate is a heavy metal known as an environmental contaminant due to its toxicity, long environmental half-lives, and capacity for bioaccumulation.  This study aims to determine chromosomal aberration, nuclear alteration, and cell death in Allium cepa var. aggregatum L. root caused by different nickel concentrations.  Roots of Allium cepa var. aggregatum were induced by soaking bulbs in water, then transferred to a solution containing nickel (Ni) at a concentration of 20 ppm, 30 ppm, and 40 ppm for 72 hours.  Root tip mitotic chromosome preparations were done by the squash method.  The chromosome was stained with aceto-orcein and chromosomal damages were observed under a microscope.  The results showed that the mitotic index decreased from 5.025% at control to 3.144%, 2.467%, and 2.181% at immersion with 20 ppm, 30 ppm 40 ppm nickel nitrate, respectively.  Anaphase and telophase indexes in roots with Ni treatments were lower than in control, suggesting that nickel inhibits cell division.  Nickel nitrate induced chromosomal damages and nuclear abnormalities, such as sticky chromosome, fragmented chromosome, chromosome bridge and chromosome laggard, micronuclei, binucleate and nuclear budding.  The percentage of chromosomal damage increases with a higher concentration of Ni.  In situ cell visualization showed that the higher the nickel concentration, the more coloured the root tips indicating high levels of cell death.

Using ethanol in gasoline is considered one of the most significant goals in the 2030 agenda, which has been set a 15-year plan in order to achieve it since 2015. Appropriately, this project was planned for predicting the value of the most important engine parameters such as the equivalence air-fuel ratio (φ), fuel consumption (ṁf), and brake thermal efficiency nb. th, and brake-specific fuel consumption (BSFC) by regression models. According to the protocol of this project, first, the determined percentages of ethanol were added (0, 20, 40, 60, and 80%) to gasoline at different engine speeds (850, 1000, 2000, 3000, and 4000 rpm and the New European Driving Cycle test). After testing, calculating, mathematical programming, and fitting the regression models for the two SI-engine (TU5 and EF7) with different properties of engine design,12 regression equations have been determined for each of the ‘ (positive linear model), (ṁf) (negative linear model), nb.th (negative second-order polynomial model), and BSFC (positive second-order polynomial model), respectively. Clearly, these 48 regression equations with different line slopes will be able to predict the exact value of the ‘, (ṁf), nb.th, and BSFC for each concentration of ethanol at different engine speeds in order to help automotive industries for trend predicting them in other similar engines.

In this work, single layered Ti3C2(OH)2 MXene nanosheets have been successfully prepared through a facile approach by etching Ti3AlC2 with alkaline solution treatment (KOH with minimum amounts of water). The structure and morphology of the produced nanosheets were evaluated through X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis and the chemical composition was determined using an energy dispersion X-ray (EDX) spectrometer. Methylene Blue (MB) as a target pollutant adsorption and photocatalytic degradation tests were subsequently performed to assess the functionalities of hydroxyl-terminated MXene. MB removal using Ti3C2(OH)2 MXene in the dark in 20 minutes achieved an absorption-desorption balance of 51.2%, and then MB was degraded within 80 minutes under UV light irradiation with great efficiency. Our results presented that the powder of as produced exhibited good photocatalytic activity for three cycles photodegradation. The first-order rate constant (k) was calculated to be 0.0372 1/min. About 97% degradation of Methylene Blue dye in the solution was confirmed within 80 min of exposure to ultraviolet light.

Persistent pollution of surface waters by hydrocarbon compounds is one of the foremost threats to limited global freshwater resources. This study analyzed the abundance, diversity and degradative capacities of hydrocarbon-utilizing bacteria in chronically polluted Kono River in the Nigerian Niger Delta in order to establish the bacterial drivers of ecological regeneration of the river after an oil spill. The study further aimed to develop a specialized bacterial consortium for application in bioremediation interventions. Bacillus, Pseudomonas and Enterobacter spp. were predominant out of the 82 isolates obtained. Klebsiella pneumoniae and two species of Enterobacter cloacae were identified as the most efficient hydrocarbon utilizers. The isolates were also confirmed as biosurfactant producers and possessed the alkB1 and nahAc genes for degradation of aliphatics and aromatics. E. cloacae-K11, K. pneumoniae-K05, E. cloacae-K12 and their consortium were able to degrade the total petroleum hydrocarbons and polycyclic aromatic hydrocarbons in batch systems by 59.37% – 96.06% and 68.40% – 92.46% respectively. K. pneumoniae-K05 showed the greatest petroleum degradation capacity of the three isolates but hydrocarbon degradation was most efficient with the bacterial consortium. The results obtained showed no significant differences at p≤0.05 between the degradation capacities of K. pneumoniae-K05 and the consortium for PAHs but a significant difference (p≤0.05) was seen with TPH degradation. A viable hydrocarbon degrading bacterial consortium was developed at the end of the study and it was concluded that the polluted river water displayed inherent potential for effective natural attenuation.

The aim of this research was to use a variety of leaching methods to see how different parameters affected the amount of lead leaching from tailings. Synthetic precipitation leaching procedure, toxicity characteristic leaching procedure, leachate extraction procedure, and field leach test protocols were utilized to assess the toxicity of the tailings. The impact of the liquid-solid ratio, particle size, contact time, and pH on lead release from tailings was also investigated. According to the findings, pH entirely effects on the release of lead from the tailings, and amphoteric leaching behavior was observed. The tailings were classified as hazardous material as a result of the TCLP leaching protocol's findings. S1 and S2 samples had lead mobility indexes of 51% and 5.6%, respectively. The solubility process influenced the discharge of lead from the tailings. In the particle size ranges of 0.3-0.5 mm and 0.6-1.0 mm, respectively, the maximum amount of lead was released from S1 and S2 samples. Various experiments have shown that the interaction between different factors will have complex and strong effects on the leaching process. To that end, managing of tailings and preventing lead emission into the environment necessitates a unique technique. Leachability is affected by a number of factors and often multiple factors can produce synergistically different releases than would be predicted by each factor alone. However, validation of the leaching approaches to field-collected and monitored cases indicates that combined effects are either captured by the test data or can be considered through fate and transport modeling.

In the eastern region of the Algerian Northern Sahara, the groundwater is the only resource for drinking water supply and irrigation. This study aimed to assess the physical-chemical quality of groundwater with exposition of the fluoride distribution in the eastern region of Algeria taking as case study Ouargla area. The sampling campaign was carried out in such a way to cover the exploited aquifers (Miopliocene and Senonian).  Water temperature, pH, conductivity, hardness, alkalinity, principal ions (Sodium, Potassium Calcium, Magnesium, Bicarbonates, Nitrates, Sulfates, and Chlorides) and the fluoride content in the groundwater were measured and determined. Examination and validation of obtained results were by the use ionic balance method and the hydrochemical analysis by Piper, Stabler and Richards diagrams. The obtained results of our study show that the groundwater of the Ouargla area presents a chlorinated sodium and potassium facies. Moreover, the groundwater quality in the study area is of poor quality; it is hard and characterized by very high mineralization, The Richards' diagram indicates that the groundwater of the study area are unsuitable for irrigation. The spatial distribution of fluoride ions in groundwater of the terminal complex shows that fluoride levels in Ouargla exceed the World Health Organization standard.