In this study, lemon balm (Melissa officinalis L.) and dill (Anethum graveolens L.) essential oils (EOs) were encapsulated into collagen hydrolysates extracted from bovine tendons and rabbit skins, ...both mixed with chitosan (CS) by using the coaxial electrospinning technique for potential wound dressing applications. The morphology and chemical composition of the electrospun nanofibers were investigated using scanning electron microscopy (SEM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The antimicrobial activity of the dill EO and lemon EO, as well as the electrospun samples loaded with essential oils was determined by disk diffusion assay against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Enterococcus faecalis ATCC 29212, and Salmonella typhimurium ATCC 14028 bacterial strains; Candida albicans ATCC 10231 and Candida glabrata ATCC 90028 yeast strains; and Aspergillus brasiliensis ATCC 9642 fungal strain. In vivo biocompatibility testing of the collagen hydrolysate-chitosan/essential oil electrospun nanofibers was based on the determination of the hematological, biochemical, and immunological profile and the evaluation of the influence produced on the oxidative stress in white Swiss mice. The synergetic effect of dill and lemon balm EOs can improve the antimicrobial activity of collagen hydrolysate-chitosan nanofibers against the most important bacterial strains. The in vivo test results suggested a good biocompatibility of electrospun samples based on collagen hydrolysate extracted from bovine tendons or rabbit skin mixed with chitosan and containing dill and/or lemon balm essential oils as encapsulated bioactive compounds.
Anthropogenic microplastics (MPs) and nanoplastics (NPs) are ubiquitous pollutants found in aquatic, food, soil and air environments. Recently, drinking water for human consumption has been ...considered a significant pathway for ingestion of such plastic pollutants. Most of the analytical methods developed for detection and identification of MPs have been established for particles with sizes > 10 μm, but new analytical approaches are required to identify NPs below 1 μm. This review aims to evaluate the most recent information on the release of MPs and NPs in water sources intended for human consumption, specifically tap water and commercial bottled water. The potential effects on human health of dermal exposure, inhalation, and ingestion of these particles were examined. Emerging technologies used to remove MPs and/or NPs from drinking water sources and their advantages and limitations were also assessed. The main findings showed that the MPs with sizes > 10 μm were completely removed from drinking water treatment plants (DWTPs). The smallest NP identified using pyrolysis-gas chromatography-mass spectrometry (Pyr-GC/MS) had a diameter of 58 nm. Contamination with MPs/NPs can occur during the distribution of tap water to consumers, as well as when opening and closing screw caps of bottled water or when using recycled plastic or glass bottles for drinking water. In conclusion, this comprehensive study emphasizes the importance of a unified approach to detect MPs and NPs in drinking water, as well as raising the awareness of regulators, policymakers and the public about the impact of these pollutants, which pose a human health risk.
The goal of the present paper is to explore the properties of medium molecular-weight chitosan/polyvinyl alcohol blends mixed in volume ratios of 75:25, 50:50, and 25:75 obtained by solution casting. ...Cross-linked chitosan/poly(vinyl alcohol) nanostructures were obtained by treating these blends with 5% (v/v) glutaraldehyde. The prepared chitosan/polyvinyl alcohol films were characterized by attenuated total reflectance - Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering, and cytotoxicity, while the nanostructured materials were examined by scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction. Also, the removal of lead(II) ions from aqueous solution by adsorbents nanostructures was studied in the batch adsorption mode. The effects of adsorbent dosages, initial metal concentration, and contact time on the adsorption capacity were investigated. The FT-IR spectra indicated the interactions of polyvinyl alcohol with chitosan. DSC and TGA analyses revealed the loss of water up to 100 °C. The zeta potential and mobility of the prepared nanostructures were enhanced with the increasing ratio of the cationic polymer. The results showed that the 100% chitosan adsorbent provided the highest removal of Pb(II) during the first 15 min (̴94%). The chitosan100/polyvinyl alcohol0 and chitosan75/polyvinyl alcohol25 nanostructures fitted well with the Langmuir isotherm model. The maximum adsorption capacities for Pb(II) ions reached maxima of 7.36 and 7.67 mg/g, respectively. The Freundlich isotherm model best described the Pb(II) adsorption on the 50% chitosan/50% polyvinyl alcohol and 25% chitosan/75% polyvinyl alcohol adsorbents. Furthermore, (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay results demonstrated that chitosan/polyvinyl alcohol films are biocompatible with more than 90% cell viability.
Synthesis and characterization of iron oxide nanoparticles coated with a large molar weight dextran for environmental applications are reported. The first experiments involved the synthesis of iron ...oxide nanoparticles which were coated with dextran at different concentrations. The synthesis was performed by a co-precipitation technique, while the coating of iron oxide nanoparticles was carried out in solution. The obtained nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectrometry, Fourier transform infrared spectroscopy and superconducting quantum interference device magnetometry. The results demonstrated a successful coating of iron oxide nanoparticles with large molar weight dextran, of which agglomeration tendency depended on the amount of dextran in the coating solution. SEM and TEM observations have shown that the iron oxide nanoparticles are of about 7 nm in size.
Removing heavy metals from wastewaters is a challenging process that requires constant attention and monitoring, as heavy metals are major wastewater pollutants that are not biodegradable and thus ...accumulate in the ecosystem. In addition, the persistent nature, toxicity and accumulation of heavy metal ions in the human body have become the driving force for searching new and more efficient water treatment technologies to reduce the concentration of heavy metal in waters. Because the conventional techniques will not be able to keep up with the growing demand for lower heavy metals levels in drinking water and wastewaters, it is becoming increasingly challenging to implement technologically advanced alternative water treatments. Nanotechnology offers a number of advantages compared to other methods. Nanomaterials are more efficient in terms of cost and volume, and many process mechanisms are better and faster at nanoscale. Although nanomaterials have already proved themselves in water technology, there are specific challenges related to their stability, toxicity and recovery, which led to innovations to counteract them. Taking into account the multidisciplinary research of water treatment for the removal of heavy metals, the present review provides an updated report on the main technologies and materials used for the removal of heavy metals with an emphasis on nanoscale materials and processes involved in the heavy metals removal and detection.
Massive amounts of industrial and agricultural water around the world are polluted by various types of contaminants that harm the environment and affect human health. Alginic acid is a very versatile ...green polymer used for heavy metal adsorption due to its availability, biocompatibility, low cost, and non-toxic characteristics. The aim of this paper was to prepare new low-cost hybrid composite beads using sodium alginate with treated montmorillonite and kaolin for the adsorption of copper (Cu) cations. Modified and unmodified clays were investigated by studying their morphology and elemental composition, functional groups, and mean particle size and particle size distribution. The characterization of alginate/clay hybrid composite beads was carried out by evaluating surface morphology (by scanning electron microscopy, SEM), crystallinity (by X-ray diffraction, XRD), and point of zero charge (pH
)(Zeta Potential Analyzer). Batch adsorption experiments of alginate/clay hybrid composite beads investigated the effect of metal concentration in the range of 1-4 mg L
on Cu(II) removal, adsorption kinetic for maximum 240 min, and Langmuir and Freundlich adsorption isotherms by using atomic absorption spectrometry. The pseudo-second-order kinetic model best fitted the adsorption for alginate/montmorillonite beads (R
= 0.994), while the diffusion process was predominant for montmorillonite/kaolin beads (R
= 0.985). The alginate/clay hybrid materials best fitted the Langmuir isotherm model.
The paper addresses environmental protection by valorizing an important agri-food waste category, namely fruit and vegetables with focusing on the main characteristics regarding consumption, waste ...quantities, and ways for valorizing these materials. Thus, vast research was undertaken in order to emphasize the main commodities and their potential application as adsorbents for organic and inorganic pollutants. The main methods or treatment techniques applied for the valorization of eco-materials as adsorbents were presented and the principal efficiency results were indicated. The advantages and disadvantages of using these eco-materials as adsorbents in wastewater treatment were revealed and future recommendations were established. According to the international statistics, the most purchased and consumed five commodities were studied regarding waste generations as potential conversion into eco-materials with an adsorbent role for water pollutants. Thus, the performances for adsorbents based on fruit wastes (such as citrus, banana, apples, grapes, mango) and vegetable wastes (such as potatoes, tomatoes, cabbage, carrots, cauliflower, and/or broccoli) were studied and highlighted in this research.
Copper matrix nanocomposites reinforced with magnetite nanoparticles were developed using powder metallurgy. Various processing parameters were taken into consideration, such as magnetite content, ...compaction pressure, sintering time and temperature. The nanopowder blends were compacted using various uniaxial pressures and sintered at 650 and 800 °C in order to study the influence of processing parameters on morphology, structure, thermal, magnetic and mechanical properties. The structure and morphology of the nanocomposites analyzed by X-ray diffraction (XRD), bright field transmission electron microscopy (TEMBF) and scanning electron microscopy (SEM) showed that sintered composites retained the nanoscale characteristics of the initial Fe3O4 and Cu nanopowders. These nanocomposites have good cold-rolling deformability and Vickers micro-hardness. The Cu-xFe3O4 nanocomposites have thermal and magnetic properties that make them suitable for electronical applications.
The need to recycle and develop nanomaterials from waste, and use them in environmental applications has become increasingly imperative in recent decades. A new method to convert the mill scale, a ...waste of the steel industry that contains large quantity of iron and low impurities into a nanoadsorbent that has the necessary properties to be used for water purification is presented. The mill scale waste was used as raw material for iron oxide nanopowder. A thorough characterization was performed in each stage of the conversion process from the mill scale powder to magnetic nanopowder including XRD (X-ray diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), BET (Brunauer, Emmett and Teller) and magnetization properties. Iron oxide nanoparticles were approximately 5–6 nm with high specific surface area and good magnetic properties. These are the necessary properties that a magnetic nanopowder must have in order to be used as nanoadsorbents in the heavy metal removal from waters. The iron oxide nanoparticles were evaluated as adsorbents for the removal of Cu, Cd and Ni ions.
Due to its valuable compounds, food waste has been gaining attention in different applications, such as life quality and environment. Combined with circular economy requirements, a valorization ...method for waste, especially banana waste, was to convert them into adsorbents with advanced properties. The banana waste, after thermal treatment, was used with high removal performances (100%) for the removal of heavy metals, such as Cr, Cu, Pb, and Zn, but their small particle size makes them very hard to recover and reuse. For this reason, a biopolymeric matrix was used to incorporate the banana waste. The matrix was chosen for its remarkable properties, such as low cost, biodegradability, low carbon footprint, and reduced environmental impact. In this research, different types of materials (simple banana peel ash BPA and combined with biopolymeric matrix, ALG–BPA, CS–BPA) were prepared, characterized, and tested. The materials were characterized by means of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), optical microscopy (OM), scanning electron microscopy (SEM), and tested for the removal of metal ions from synthetic solutions using atomic absorption spectroscopy (AAS). The ALG–BPA material proved to be the most efficient in the removal of heavy metal ions from synthetic solution, reaching even 100% metal removal for Cr, Fe, Pb, and Zn, while the CS-based materials were the least efficient, presenting the best values for Cr and Fe ions with a removal efficiency of 34.14% and 28.38%, respectively. By adding BPA to CS, the adsorption properties of the material were slightly improved, but also only for Cr and Fe ions, to 37.09% and 57.78%.
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