Three natural adsorbents were used in this study to determine the absorption rate of diazinon pollution from water environments: date kernel powder, powdered pine cone, and powdered natural biochar from Kuhbanan mining. The tests were conducted using a batch-series test. To model the diazinon pollutant, various concentrations of each adsorbent were investigated as the primary research parameter. The Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and methylene blue test were used to examine the characteristics of the natural absorbent particles employed in this investigation. The findings demonstrate that each adsorbent has a large specific surface area that is ideal for pollutant absorption, a high porosity and roughness, and a multitude of functional groups on its surface.

Analyzing diazinon pollutant absorption by adsorbents quantitatively involves examining Langmuir and Freundlich isotherms. The outcomes of the batch tests demonstrated that 5 grams of natural biochar powder, with an absorption percentage of 1.65%, and 1 gram of natural biochar powder, with an absorption percentage of 0.1, respectively, had the highest and lowest rates of diazinon pollutant absorption. With an RMSE of 0.04 and an R² of 0.96, the Freundlich isotherm model fits the date kernel powder absorbent data the best out of all the fitted models. In conclusion, the data obtained indicate that natural biochar powder exhibits the highest absorption rate and the highest effectiveness when it comes to eliminating diazinon from water.

The ocean holds about 97% of the water on the Earth's surface; the remaining 3% is found in glaciers, ice, and groundwater like rivers and lakes. The total water supply to the world is about 332 million cubic miles of water, which plays an important role in agricultural fields, as well as industrial and domestic purposes. In Pakistan, as per the International Monetary Fund, the per capita annual water availability has reduced from 1500m³ in 2009 to 1017m³ in 2021. In Pakistan’s different regions like Thar, Sukkur, Hyderabad, and Karachi, mostly in their rural and marginalized urban areas, the water is highly contaminated. Water quality is deteriorating daily due to the rapid increase in population, industrialization, poor agricultural sector management, inefficient infrastructures, and the sewerage system. In Pakistan, 20% of the population has access to pure water, while the remaining 80% is forced to use unsafe drinking water. Therefore, the aim of this study is to provide safe drinking water sources to the remaining population. There is a need to install water disinfectants, filters, and treatment plants for the monitoring of water quality parameters in marginalized urban areas and rural areas. Applying different methods for the filtration of water will make water drinkable. The technique of boiling water is also helpful in rural areas. Pipelines could be designed from a nearby water source to a community that lacks a drinking water supply. Due to the implementation of these methods, the 33% death rate in Pakistan may decrease; this rate is caused by anthropogenic activities, of which the major cause (80%) is waterborne disease. We need to spread awareness by starting a Public Awareness Campaign among the people of Pakistan to use pure water for health and safety.

This study delves into the degradation of various dyes using a visible light-driven heterogeneous semiconductor photocatalyst, with a particular focus on a Bi2WO6/ZnO binary composite material synthesized via a hydrothermal method. The composite's enhanced photosensitivity to visible light, attributed to a reduced band gap, was revealed through thorough characterization using various analytical techniques. The photocatalytic efficiency of the Bi2WO6/ZnO composite was rigorously evaluated by subjecting cationic and anionic dyes to visible light exposure for a duration of 90 minutes.

The kinetic studies conducted demonstrated exceptionally high degradation efficiencies for cationic dyes. Notably, the composite achieved impressive degradation rates, including 99.94% degradation of RhB, 96% degradation of MB, 88% degradation of CV, and a substantial 66% degradation of MG within just 30 minutes. While anionic dyes exhibited slightly lower degradation percentages, the overall efficacy of the Bi2WO6/ZnO composite remained commendable.

Beyond its prowess in dye degradation, the Bi2WO6/ZnO composite exhibited intriguing antimicrobial activity against a spectrum of microorganisms. This included notable inhibition of Escherichia coli, Staphylococcus aureus, and Candida albicans, suggesting its potential application in addressing challenges associated with microbial contamination in addition to its role in environmental remediation.

This research underscores the multifaceted functionality of Bi2WO6/ZnO composites and their promising potential for various applications. By harnessing the power of visible light and innovative semiconductor materials, this study not only contributes to the development of sustainable water treatment strategies but also offers insights into broader environmental remediation efforts. The findings pave the way for the advancement of cleaner and safer environments, marking a significant step forward in the quest for effective solutions to contemporary environmental challenges.

Antibiotics have attracted increasing attention as an emerging class of environmental pollutants in recent years, mainly due to their usage for preventing infection, as well as their inevitable leakage into various environmental media. Although the reported concentration levels are commonly low, the persistence and long-term exposure of these antibiotics may induce the development of antibiotic-resistant bacteria/genes, subsequently threatening the ecological environment and human health.

Chemical oxidation using permanganate has been extensively applied in water and wastewater treatment processes for controlling taste, odor, and algae growth. Recently, permanganate as a powerful oxidant has shown great potential in the degradation of multiple micropollutants including antibiotics. However, the acid/base catalytic mechanism of permanganate remains unclear, although it is very important to effectively control the antibiotic pollutants in aqueous solutions.

From the kinetic and mechanistic points of view, the acid catalysis of permanganate towards sulfamethoxazole could be attributed to the formation of neutral HMnO₄, which showed a four orders of magnitude higher reactivity than anionic MnO₄^-. The rate-limiting step was determined to be simple N-H bond oxidation, which was also studied computationally using DFT calculations. It is the first time that the Brønsted acid catalysis of permanganate could not only produce the stronger electrophile HMnO₄, but also change the reaction mode by avoiding bond cleavage in the electron transfer process.

Although base catalysis was also considered to, similarly, add a hydroxyl ion to permanganate, the kinetic salt effect and DFT analysis indicated that the hydroxyl ion could attract the proton of tetracycline toward itself to form a complex-like structure with a highly reactive phenolate-type moiety. The base-catalyzed effect was finally explained by the HOMO orbital and electrostatic potential, whereby the hydroxyl ion could make the phenolic group a more electron-rich moiety for electrophilic attack.

Background: The synthesis temperature and duration were shown to impact the physicochemical properties and photocatalytic performance of the g-C₃N₄/ZnO (g-CN/ZnO) nanocomposites. Higher temperatures (≈400°C) and longer reaction times (≈ 2-4 hours) generally led to better crystallinity, surface area, and visible light absorption of the nanocomposites, resulting in improved photocatalytic degradation of MB dye compared to pure ZnO or pure g-CN.

Objective: The primary object of the present work is to synthesise g-CN/ZnO at different temperatures with different time intervals and then assess its photocatalytic activity against methylene blue dyes.

Methods: g-C₃N₄/ZnO nanocomposites will be synthesised with a certain weight of urea and zinc acetate through the thermolysis method by varying the temperature: 400⁰C for 1 hour (S1), t400⁰C for 2 hours (S2), 500⁰C for 3 hours (S3), and 550⁰C for 4 hours (S4). Properties like functional groups; particle size, shape, surface morphology, and surface area; porosity of the composite; phase purity; crystalline nature; and band gap were analysed using FTIR, SEM, TEM, BET, XRD, UV-visible, and DRS techniques. For Photocatalytic activity tests, 0.001 gram g-CN/ZnO was immersed in 100 mL of the MB solution, and then the solution was continuously stirred in the dark for 20 min to reach the equilibrium state of adsorption, followed by placing it in sunlight.

Results and Conclusion:

Fabricated nanocomposites have an appearance of light yellow (S1 and S2), whereas S3 and S4 have a creamy colour. The percentage yields of S1, S2, S3, and S4 are 26.1%, 25.39%, 12.12%, and 3.2%, respectively. The photocatalytic performance of MB dyes in sunlight is S1<S2<S3, and the results indicate that the temperature and duration of the g-CN/ZnO nanocomposites' synthesis play a key role in determining their structural, optical, and photocatalytic properties for the degradation of methylene blue dye under visible-light irradiation.

It is important to find new materials for water treatment. The interplay of the physical properties of materials leads to new results [1-3]. Combining several methods for the investigation of materials allows the full range of information on the modified physical properties to be deduced. Manganese fluoride (MnF₂)-filled single-walled carbon nanotubes (SWCNTs) show great potential in water treatment. This salt is inert with a very high melting point, and it was introduced into SWCNTs for the first time. Here, we studied the modified electronic structure of the filled SWCNTs with several methods, such as transmission electron microscopy (TEM) and Raman spectroscopy. The TEM method showed the filling of metallic and semiconducting carbon nanotubes with high filling degrees and high purity. The TEM method, along with Raman spectroscopy, is capable of revealing the electronic structure of the filled SWCNTs. These methods are fundamental for finding the Fermi level shifts in the filled SWCNTs. P-doping in the filled SWCNTs was proven by shifts in the RBM and G-band Raman peaks. The obtained information shows the potential of the new compound, MnF₂, for water treatment applications.

[1] Kharlamova M. V. et al. Eur. Phys. J. B 2012, 85, 34.

[2] Kharlamova M. V. et al. Carbon 2018, 133, 283−292.

[3] Kharlamova M. V. et al. Appl. Phys. A 2015, 118(1), 27−35.

The foundations of the electronic structures of single-walled carbon nanotubes (SWCNTs) are studied for applications in water treatment. The SWCNTs have metallic and semiconducting physical properties. To improve the functionality of the SWCNTs, they are filled [1-4]. The methods of improving the functionality of the SWCNTs include surface functionalization and filling. In this contribution, the semiconducting SWCNTs were filled with silver chloride (AgCl). Silver chloride is an electron acceptor. The filling of AgCl in the SWCNTs causes strong Fermi level variations. Raman spectroscopy proved the doping-mediated differences in the electronic structures of the pristine and the filled SWCNTs. The physical properties of the different-diameter SWCNTs were modulated in a different manner with the filling. This was demonstrated with the radial breathing band, and the G-band of Raman spectra. The observed differences were the different locations of the peaks, the variations in the intensities, and the disappearance of the peaks. The detected modulations of the electronic structure of the SWCNTs are useful in the water treatment.

[1] Kharlamova M.V. et al. Nanotechnologies Russ. 2009, 4, 634 – 646.

[2] Kharlamova M.V. et al. JETP Lett. 2010, 91, 196 – 200.

[3] Kharlamova M.V. et al. J. Spectrosc. 2018, 2018, 5987428.

[4] Kharlamova M.V. et al. J. Mater. Sci. 2018, 53, 13018 – 13029.

Droughts and floods are common in the Baro basin, and climate change may exacerbate them. This study aimed to investigate the hydrological response to the impact of climate change on the Baro basin. From four climate models, namely the Hadley Centre Global Environmental Model, version 2 (HadGEM2-ES); Myocardial perfusion imaging, low resolution (MPI-ESM-LR); Coupled Model Version 5, Medium Resolution (CM5A-MR); and the European Community Earth System Model (EC-Earth), dynamically downscaled outputs were obtained from an African coordinated regional downscaling experiment programme. Changes in the hydrological response to climate change were compared to the baseline scenario (1971 to 2000) under the Representative Concentration Pathway Scenarios for the medium term (2041 to 2070). The climate data were heavily skewed before being used in the impact analysis and needed correction. In terms of bias, HadGEM2-ES performed the worst, while EC-Earth performed the best. MPI-ESM-LR was the worst performer in terms of RMSE, and CM5A-MR was the best. The GCM predictions for the RCP 4.5 scenarios suggested that, in the medium period (2041 to 2070), the maximum temperature in the Baro River basin will probably rise by 2.1 °C for MPI-ESM-LR and 2.49 °C for CM5A-MR, while the minimum temperature will likely climb by 1.7 °C for EC-Earth and 2.8 °C for HadGEM2-ES. Annual rainfall is expected to fall by 7.02% for CM5A-MR and 17.01% for HadGEM2-ES, while annual evapotranspiration potential is likely to rise. Except for Belg (from March to May), CM5A-MR consistently generated the greatest streamflow change, while MPI-ESM-LR consistently generated the highest magnitude of streamflow change. Generally, climate change is predicted to significantly impact the hydrological response in the Baro River basin under the RCP 4.5 scenario.

Surface and groundwater variations are difficult to assess due to complexity and the lack of spatiotemporal observation. The increasing population of Ethiopia is coupled with growth in infrastructure, agriculture, and industries, which are the largest water consumers, leading to the depletion of water resources, including groundwater. From the review of past studies, it is clear that no attempts have been made to study the spatiotemporal variability of groundwater at the country level using GRACE and GLDAS datasets. Nowadays, different parts of Ethiopia face a severe water crisis due to the overexploitation of surface water resources, which adds extra pressure on groundwater. In this study, groundwater storage was estimated using the three products of gravity recovery and climate experimentation from the global land data assimilation system in Ethiopia. The estimated monthly groundwater storage ranged from 1948.69 to 28111.07 mm and yearly groundwater storage ranged from 263879.1 to 311505.5 mm for the study period. The monthly, seasonal, and annual variations in groundwater storage were evaluated. This research found that groundwater storage exhibits interannual fluctuation following the seasonal pattern of the study area. The variation in groundwater storage may be occurring as a result of complex activities with natural and anthropogenic impacts. We found that GRACE and GLDAS datasets can be combined effectively to evaluate the long-term GWS in large-scale basins with limited hydrological data.

Himalayan high-altitude catchments are crucial sources of freshwater, supporting essential activities both upstream and downstream. However, the warming climate is causing the cryospheric cover to diminish, affecting freshwater availability throughout the Himalayan catchments. Therefore, understanding the hydrological processes shaping the regional water cycle is vital for effective water resource management policies. The dataset reveals significant spatial and temporal variability in meltwater without clear isotopic signatures of different river flow sources. Nevertheless, distinctive signatures of river/stream flow sources emerge at the sub-basin or catchment scale due to changing physiographical, meteorological, and local climatic conditions. Microclimatic factors like altitude variation and aspect slope further influence the spatio-temporal variability in water sources and streamflow, resulting in different lapse rates at the sub-basin/catchment level. This study highlights that the contribution of snowmelt and glacier melt to river flow varies across space and time, with snowmelt dominating in the Indus while glacier melt dominates in the Suru catchment. The rugged topography and microclimate of the Upper Indus River Basin (UIRB) primarily govern the diverse contributions from various river flow sources. With a warming climate leading to reduced solid precipitation, continuous glacier mass loss, and early snow cover melting, the perennial flow of rivers is expected to be impacted inconsistently. This has the potential to disrupt the economic and political stability of the region.