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Iron determines the abundance and diversity of life and controls primary production in numerous aqueous environments. Over the past decades, the availability of this metal in natural waters has decreased. Iron deficiency can apply a selective pressure on microbial aquatic communities. Each aquatic organism has their individual requirements for iron and pathways for metal acquisition, despite all having access to the common pool of iron. Cyanobacteria, a photosynthesizing bacterium that can accumulate and form so-called ‘algal blooms’, have evolved strategies to thrive in such iron-deficient aqueous environments where they can outcompete other organisms in iron acquisition in diverse microbial communities. Metabolic pathways for iron acquisition employed by cyanobacteria allow it to compete successfully for this essential nutrient. By competing more effectively for requisite iron, cyanobacteria can displace other species and grow to dominate the microbial population in a bloom. Aquatic resources are damaged by a diverse number of environmental pollutants that can further decrease metal availability and result in a functional deficiency of available iron. Pollutants can also increase iron demand. A pollutant-exposed microbe is compelled to acquire further metal critical to its survival. Even in pollutant-impacted waters, cyanobacteria enjoy a competitive advantage and cyanobacterial dominance can be the result. We propose that cyanobacteria have a distinct competitive advantage over many other aquatic microbes in polluted, iron-poor environments.

Biochar was prepared by anaerobic heating coffee ground at 800 o C for 3 hours. The prepared sample was used to adsorb crystal violet dye in an aqueous environment. The result showed that the biochar sample had good adsorption capacity for crystal violet dye, with the maximum adsorption capacity of 128.87 (mg/g). Thus, low-cost biochar prepared from coffee grounds has great potential to be used as an adsorbent material to remove crystal violet dye in an aqueous environment.

Aloe Vera (AV) gel is commonly used as a natural, inexpensive, edible coating that can improve the quality and shelf life of fruits. The objective of this study was to evaluate how two methods of applying AV, i.e. as an edible coating (dry environment) and as a gel solution (aqueous environment: a new method), prevent browning and maintain quality characteristics of fresh kernels of Persian walnut for 60 days during cold storage. Distilled water was used as a control group for both environments. In general, AV caused a reduction in the peroxide value (POV) of kernels, while preserving Total Phenolic Compound and Total Antioxidant Activity (TAA). The AV treatment slowed down the process of color change and maintained sensory properties during storage, compared to the control groups of both methods. The AV gel solution performed better than the AV edible coating in terms of POV, color (L* and h°) and microbial growth. In contrast, the AV edible coating was more effective in preserving TPC and TAA. Also, TAA was found to have a significant, positive correlation with L* and, simultaneously, a negative correlation with POV. As far as we know, this is the first instance that the AV gel was used as a formulated solution and as an edible coating on fresh fruits. This innovative method can be used in commercial practice, while being ecofriendly and non-chemical as a treatment for the maintenance of postharvest quality in fruits.

In this study, zeta potentials of graphitic carbon nitride (g-C3N4) nanoparticles were detailedly investigated under various electrolytes, solution pH, and humic acid (HA) concentration conditions. The hydrodynamic radius of g-C3N4 nanoparticles was measured to be 388.9 ± 24 nm, and the specific surface area of the g-C3N4 nanoparticles was measured to be 46.2 m2 g−1. The absolute values of g-C3N4 zeta potentials significantly decreased with the increasing ionic strength (IS) due to the charge screening. Compared to the monovalent cation, the zeta potentials of g-C3N4 were less negative with the presence of divalent cations. In addition, K+ was more effective than Na+ in decreasing the absolute values of g-C3N4 zeta potentials, and Ca2+ was more effective than Mg2+ in decreasing the absolute values of g-C3N4 zeta potentials. When NaCl and CaCl2 were used as the electrolytes, the zeta potentials of g-C3N4 became less negative with the decreasing pH conditions. When FeCl3 and AlCl3 were used as the electrolytes, the zeta potentials of g-C3N4 became more positive with increasing solution pH due to the changing species of Fe3+ and Al3+. The zeta potentials of g-C3N4 were significantly more negative with the presence of HA. The results from this work indicated electrolytes, solution pH, and HA concentration conditions play a complex role in zeta potentials of g-C3N4 nanoparticles in aqueous environment.

This study investigates the potential of using spent coffee grounds (SCG) as a sustainable biomass feedstock for the production of coffee ground activated carbon (CGAC) biochar via a hydrothermal method. The resulting biochar exhibited a highly porous, graphite-like structure with a specific surface area of 51.2 m 2 . g −1 , making it a promising material for environmental remediation. The adsorption capacity of CGAC for ciprofloxacin (CIP), a widely used antibiotic contaminant in aqueous environments, was systematically evaluated through static adsorption experiments. Factors such as equilibrium adsorption time, pH, and material-to-solution ratio were optimized, with the optimal pH for CIP removal determined to be 6.5 and the ideal material-to-solution ratio established at 1.5 g. L −1 . Adsorption isotherm analysis indicated that CIP adsorption followed multiple models, including Langmuir, Freundlich, and Redlich-Peterson, with a maximum adsorption capacity of 112 mg. g −1 according to the Langmuir model. The adsorption of CIP onto CGAC followed the pseudo-second-order (PSO) kinetic model, with an average reaction rate constant of 0.0167 L·mg⁻ 1 ·min⁻ 1 . The values for the free energy change (∆G°) ranged from -3.85 to -0.685 kJ·mol⁻ 1 as the temperature increased from 303 to 323 K, indicating that the CIP adsorption process on CGAC was spontaneous. The negative value of ∆H° (-51.58 kJ·mol⁻ 1 ) indicates that the adsorption process of CIP onto CGAC was exothermic. The results highlight the feasibility of utilizing CGAC biochar, derived from low-cost and abundant biomass waste (SCG), as an effective, eco-friendly adsorbent for antibiotic removal. This study not only demonstrates the potential of SCG as a valuable resource in the biorefinery process but also contributes to advancing sustainable methods for wastewater treatment and environmental protection.

Purpose Pollution of the environment with all kinds of plastics has become a growing problem. The problem of microplastics is mainly due to the absorption of stable organic pollutants and metals into them, and as a result, their environmental toxicity increases. The main purpose of this study is to investigate the appropriate and efficient methods of removing microplastics from aqueous environments through a systematic review. Methods Present study designed according to PRISMA guidelines. Two independent researchers followed all process from search to final analysis, for the relevant studies using international databases of PubMed, Scopus and ISI/WOS (Web of Science), without time limit. The search strategy developed based on the main axis of “microplastics”, “aqueous environments” and “removal”. This research was carried out from 2017 until the March of 2022. All relevant observational, analytical studies, review articles, and a meta-analysis were included. Results Through a comprehensive systematic search we found 2974 papers, after running the proses of refining, 80 eligible papers included to the study. According to the results of the review, the methods of removing microplastics from aquatic environments were divided to physical (12), chemical (18), physicochemical (27), biological (12) and integrated (11) methods. In different removal methods, the most dominant group of studied microplastics belonged to the four groups of polyethylene (PE), polystyrene (PS), polypropylene (PP) and polyethylene tetra phthalate (PET). Average removal efficiency of microplastics in different processes in each method was as: physical method (73.76%), chemical method (74.38%), physicochemical method (80.44%), biological method (75.23%) and integrated method (88.63%). The highest removal efficiency occurred in the processes based on the integrated method and the lowest efficiency occurred in the physical method. In total, 80% of the studies were conducted on a laboratory scale, 18.75% on a full scale and 1.25% on a pilot scale. Conclusion According to the findings; different processes based on physical, chemical, physicochemical, biological and integrated methods are able to remove microplastics with high efficiency from aqueous environments and in order to reduce their hazardous effects on health and environment, these processes can be easily used.

This study presents a novel capillary microgripper for manipulating micrometer-sized objects directly within aqueous environments. The system features dynamic, vision-based feedback control of a non-volatile silicone oil droplet volume, enabling precise adjustment of the capillary bridge force for the adaptable capture of varying object sizes. This approach ensures extended working time and stable operation in water, mitigating the issues associated with evaporation common in other systems. COMSOL Multiphysics simulations analyzed capillary bridge formation. Experimental validation demonstrated successful different object shapes and sizes capture in an aqueous environment and further explored active release strategies necessary due to the non-volatile fluid, confirming the system potential for robust underwater micromanipulation.

Fourier transform infrared (FTIR) spectroscopy has proven to be a non-invasive tool to analyse cells without the hurdle of employing exogenous dyes or probes. Nevertheless, the study of single live bacteria in their aqueous environment has long remained a big challenge, due to the strong infrared absorption of water and the small size of bacteria compared to the micron-range infrared wavelengths of the probing photons. To record infrared spectra of bacteria in an aqueous environment, at different spatial resolutions, two setups were developed. A custom-built attenuated total reflection inverted microscope was coupled to a synchrotron-based FTIR spectrometer, using a germanium hemisphere. With such a setup, a projected spot size of 1 × 1 μm2 was achieved, which allowed spectral acquisition at the single-cell level in the 1800–1300 cm−1 region. The second setup used a demountable liquid micro-chamber with a thermal source-powered FTIR microscope, in transmission geometry, for probing clusters of a few thousands of live cells in the mid-IR region (4000–975 cm−1). Both setups were applied for studying two strains of a model lactic acid bacterium exhibiting different cryo-resistances. The two approaches allowed the discrimination of both strains and revealed population heterogeneity among bacteria at different spatial resolutions. The multivariate analysis of spectra indicated that the cryo-sensitive cells presented the highest cell heterogeneity and the highest content of proteins with the α-helix structure. Furthermore, the results from clusters of bacterial cells evidenced phosphate and peptidoglycan vibrational bands associated with the cell envelope, as potential markers of resistance to environmental conditions.

Cerium atoms on the surfaces of nanoceria (i.e., cerium oxide in the form of nanoparticles) can store or release oxygen, cycling between Ce 3+ and Ce 4+ ; therefore, they can cause or relieve oxidative stress within living systems. Nanoceria dissolution occurs in acidic environments. Nanoceria stabilization is a known problem even during its synthesis; in fact, a carboxylic acid, namely citric acid, is used in many synthesis protocols. Citric acid adsorbs onto nanoceria surfaces, limiting particle formation and creating stable dispersions with extended shelf life. To better understand factors influencing the fate of nanoceria, its dissolution and stabilization have been previously studied in vitro using acidic aqueous environments. Nanoceria agglomerated in the presence of some carboxylic acids over 30 weeks, and degraded in others, at pH 4.5 (i.e., the pH value in phagolysosomes). Plants release carboxylic acids, and cerium carboxylates are found in underground and aerial plant parts. To further test nanoceria stability, suspensions were exposed to light and dark conditions, simulating plant environments and biological systems. Light induced nanoceria agglomeration in the presence of some carboxylic acids. Nanoceria agglomeration did not occur in the dark in the presence of most carboxylic acids. Light initiates free radicals generated by ceria nanoparticles. Nanoceria completely dissolved in the presence of citric, malic, and isocitric acid when exposed to light, attributed to nanoceria dissolution, release of Ce 3+ ions, and formation of cerium coordination complexes on the ceria nanoparticle surface that inhibit agglomeration. Key functional groups of carboxylic acids that prevented nanoceria agglomeration were identified. A long carbon chain backbone containing a carboxylic acid group geminal to a hydroxy group in addition to a second carboxylic acid group may optimally complex with nanoceria. The results provide mechanistic insight into the role of carboxylic acids in nanoceria dissolution and its fate in soils, plants, and biological systems.

Plastics are used across the world. Microplastics of size less than 5 mm and nanoplastics of size less than 0.1 μm are the result of huge plastic waste fragmentation or straight environmental emissions. Microplastics are present into personal hygiene items like facial makeup and cleansers and nanoplastics are present in paints, adhesives, electronics, and 3D printing. Microplastics are produced from various industries such as the flocking, plastics, and textile industries. Micro and nano plastics (MNPs) have a poor rate of degradation, great affinity for other pollutants, and high toxicity in water. MNPs pollution is a global problem that poses risks to human health and the environment including plants and animals. It also disturbs the operation of water and wastewater treatment plants. For the removal of MNPs from aqueous solution, the development of nanotechnology and the incorporation of nanomaterials in adsorption, photocatalysis and the membrane filtration realizes a conceptual technique to exceed the limitations of the conventional methods. Adsorbents based on nanomaterials, like layered double hydroxides, bio and carbon-based, metal-organic frameworks, are utilized for the removal of MNPs from water. The magnetic nano-Fe 3 O 4 can efficiently remove microplastics from water via surface absorption. The electrospun nanofiber membranes can remove MNPs from wastewater with 90% of removal efficiency. Recently, bionanomaterials are prevalent for the green remediation of microplastics because of their biocompatibility, biodegradability, non-toxicity, and minimal environmental impact. Microplastics are removed from water via bionanomaterials like chitosan-coated magnetic nanoparticles, silk, and lignin. This review is focused on various nanotechnologies especially bionanomaterials used for the removal of MNPs from aqueous environment. Further research is required in the direction of removal of nanoplastics through different bionanomaterials because of their mobility, small size, toxicity, and accumulation tendency.