Search

Nanoporous materials, such as metal-organic frameworks (MOFs), are renowned for their high selectivity as gas adsorbents due to their specific surface area, nanoporosity, and active surface chemistry. A significant challenge for their widespread application is reduced gas uptake in wet conditions, attributed to competitive adsorption between gas and water. Recent studies of gas adsorption in wet materials have typically used small amounts of powdered porous materials (in the milligram range) within very small reactors (1–5 mL). This leaves a gap in knowledge about gas adsorption behaviors in larger reactors and with increased MOF sample sizes (to the gram scale). Additionally, there has been a notable absence of experimental research on MOFs heavily saturated with water. In this study, we aimed to fill the gaps in our understanding of gas adsorption in wet conditions by measuring CH4 adsorption in MOFs. To do this, we used larger MOF samples (in grams) and a large-volume reactor. Our selection of commercially available MOFs, including HKUST-1, ZIF-8, MOF-303, and activated carbon, was based on their widespread application, available previous research, and differences in hydrophobicity. Using a volumetric approach, we measured high-pressure isotherms (at T = 274.15 K) to compare the moles of gas adsorbed under both dry and wet conditions across different MOFs and weights. The experimental results indicate that water decreases total CH4 adsorption in MOFs, with a more pronounced decrease in hydrophilic MOFs compared to hydrophobic ones at lower pressures. However, hydrophilic MOFs exhibited stepped isotherms at higher pressures, suggesting water converts to hydrate, positively impacting total gas uptake. In contrast, the hydrophobic ZIF-8 did not promote hydrate formation due to particle aggregation in the presence of water, leading to a loss of surface area and surface charge. This study highlights the additional challenges associated with hydrate-MOF synergy when experiments are scaled up and larger sample sizes are used. Future studies should consider using monolith or pellet forms of MOFs to address the limitations of powdered MOFs in scale-up studies. [ABSTRACT FROM AUTHOR]

The aim of the research was to investigate the resistance and efficacy of the fungi Aspergillus awamori in removing heavy metals. We conducted an analysis of the fungus's tolerance to several heavy metals by measuring the dry weight and using a plate method. The fungus exhibited growth in concentrations and lowest growth was observed in a concentration of 400 ppm of Cd. The heavy metals were successfully removed with the following orders: Zn> Co, > Ag, > Hg and Cu. The optimal parameters for the elimination of 100 mg/L of heavy metals were a temperature of 28°C, a pH range of 4.0 to 5.5, a heavy metal concentration of 100 ppm, and a biomass of fungi of 1 g. [ABSTRACT FROM AUTHOR]

The investigation concluded that the water quality of the Gomti river was found to be severely polluted. The Gomti River was determined to have a poor physicochemical condition, indicating significant hazards and rendering it unsuitable for any purpose. In the present investigation, the pH value measured at Daliganj was 7.33±0.29, which slightly exceeded the optimal range. Conversely, the lowest recorded pH level (pH 5±1) was found in close proximity to the riverbank. Biological oxygen demand (BOD) concentration serves as a dependable biomarker for water pollution. The existence of Dissolved Oxygen (DO) is vital for the survival of fish and other aquatic creatures, and its levels are directly influenced by water temperature. The water at Daliganj had the highest reported level of Biochemical Oxygen Demand (BOD), measuring 21.67 mg/l. However, the lowest recorded value was observed at the Lat riverbank, measuring 14.33 mg/l. The river is extensively polluted as a result of the release of home and industrial garbage through multiple drainage systems. The rise in total hardness value was attributed to household discharges. The water in the Shaheed Smarak locality has elevated levels of Chemical Oxygen Demand (COD). The water quality declined as a result of the drainage system throughout its vicinity. The main cause of pollution is the diverse range of industrial, agricultural and household waste, leading to an increase in the amount of garbage being dumped into the river. Consequently, there is an increase in the concentration of toxic heavy metals, resulting in the pollution of river water. The river's self-purification capacity has been impeded due to the accumulation of both organic and inorganic debris, leading to a rise in bacterial growth. Hence, it is imperative to eliminate the biological burden prior to its entry into the river, with the aim of safeguarding the well-being of both humans and aquatic organisms. The Gomati River is experiencing water contamination due to the presence of pollutants. [ABSTRACT FROM AUTHOR]

Supported metal single atom catalysis is a dynamic research area in catalysis science combining the advantages of homogeneous and heterogeneous catalysis. Understanding the interactions between metal single atoms and the support constitutes a challenge facing the development of such catalysts, since these interactions are essential in optimizing the catalytic performance. For conventional carbon supports, two types of surfaces can contribute to single atom stabilization: the basal planes and the prismatic surface; both of which can be decorated by defects and surface oxygen groups. To date, most studies on carbon‐supported single atom catalysts focused on nitrogen‐doped carbons, which, unlike classic carbon materials, have a fairly well‐defined chemical environment. Herein we report the synthesis, characterization and modeling of rhodium single atom catalysts supported on carbon materials presenting distinct concentrations of surface oxygen groups and basal/prismatic surface area. The influence of these parameters on the speciation of the Rh species, their coordination and ultimately on their catalytic performance in hydrogenation and hydroformylation reactions is analyzed. The results obtained show that catalysis itself is an interesting tool for the fine characterization of these materials, for which the detection of small quantities of metal clusters remains a challenge, even when combining several cutting‐edge analytical methods. [ABSTRACT FROM AUTHOR]