The assembly of bio-based macromolecules of gum kondagogu/sodium alginate (KO/SA) was fabricated using glycerol as a plasticiser and their optimum blending ratio was identified based on their physical and chemical, structural, mechanical, barrier, and morphological properties. The attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) analysis show that both biomacromolecules are well organised due to the hydrogen bond interaction between molecular chains involving the hydroxyl, carbonyl, and acetyl groups. Structural identification was performed by recording X-ray diffraction (XRD) spectra. Field emission scanning electron microscopy (FESEM) was used to identify the distinction between the surface of the films of biopolymers, and their conjugates, where the addition of SA increased the surface homogeneity and smoothness. The water contact angle of the blend films reached up to 81°, although the value for pure biomacromolecule films was very low. The blend films also exhibited high tensile strength (up to 24 MPa) compared to the pure biopolymer films. Investigation of film-forming ability, mechanical strength, permeability, transparency, and biodegradability of the developed KO/SA bio-macromolecular association may be established as green and sustainable food packaging films.
- MeSH
- algináty chemie MeSH
- Bixaceae chemie MeSH
- membrány umělé * MeSH
- obaly potravin * MeSH
- rostlinné gumy chemie MeSH
- Publikační typ
- časopisecké články MeSH
This review summarizes and broadly classifies all of the major sustainable natural carbohydrate bio-macromolecular manifestations in nature - from botanical (cellulose, starch, and pectin), seaweed (alginate, carrageenan, and agar), microbial (bacterial cellulose, dextran, and pullulan), and animal (hyaluronan, heparin, chitin, and chitosan) sources - that have been contrived into electrospun fibers. Furthermore, a relative study of these biomaterials for the fabrication of nanofibers by electrospinning and their characteristics viz. solution behavior, blending nature, as well as rheological and fiber attributes are discussed. The potential multidimensional applications of nanofibers (filtration, antimicrobial, biosensor, gas sensor, energy storage, catalytic, and tissue engineering) originating from these polysaccharides and their major impacts on the properties, functionalities, and uses of these electrospun fibers are compared and critically examined.
- MeSH
- agar chemie MeSH
- algináty chemie MeSH
- biokompatibilní materiály chemie MeSH
- celulosa chemie MeSH
- chitin chemie MeSH
- chitosan chemie MeSH
- dextrany chemie MeSH
- elektrochemické techniky MeSH
- glukany chemie MeSH
- heparin chemie MeSH
- karagenan chemie MeSH
- kyselina hyaluronová chemie MeSH
- lidé MeSH
- nanotechnologie metody MeSH
- nanovlákna chemie ultrastruktura MeSH
- pektiny chemie MeSH
- škrob chemie MeSH
- tkáňové inženýrství metody MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Over the past two decades, the use of nanoscale zero-valent iron (nZVI) has emerged as a standard method of contaminated groundwater remediation. The effectiveness of this method depends on key intrinsic hydrogeological parameters, which can affect both reactivity of the nanoparticles and their migration in the aquifer. In the case of low hydraulic permeability, the migration of nanoparticles is limited, which negatively influences remediation. An application of nZVI reinforced with a DC electric field led to a significant increase in the efficiency of remediation, as demonstrated by long-term monitoring at a former industrial site in Horice (Czech Republic). For the method testing, a 12 × 9 m polygon was defined around well IS4, where the original contamination was predominantly composed of DCE (7300 μg/l), and with a total concentration of chlorinated ethenes of 8880 μg/l. During the first stage of the activities, 49 kg of nZVI was injected and monitored for two years. Subsequently, the electrodes were installed, and for three years, the synergistic action of nZVI within an applied DC field was monitored. Based on 32 monitoring campaigns performed over the six years, the combined method was compared with an application of the only nZVI in technical, environmental and economic terms. Technically, the method requires annual reinstallation of anodes as a result of their oxidative disintegration. Environmentally, the method provides significantly improved chlorinated ethane reduction, remediation of low permeable zones, and extended efficiency. Economically, the method is five times cheaper when compared to the nZVI used alone.
- MeSH
- chemické látky znečišťující vodu analýza chemie MeSH
- ethyleny analýza chemie MeSH
- halogenace MeSH
- kovové nanočástice chemie MeSH
- podzemní voda MeSH
- regenerace a remediace životního prostředí * MeSH
- železo MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
Non-spherical metal-based and carbon-based nanostructures have found applications in every facet of scientific endeavors, including engineering and biomedical fields. These nanostructures attract attention because of their biocompatibility and negligible cytotoxicity. Chemical and physical methods have been used for synthesizing earlier generations of metal-based and carbon-based nanostructures with variable architectures, including nanorods, nanowires, nanodots and nanosheets. However, these synthesis strategies utilize organic passivators which are toxic to the environment and the human body. Biogenic synthesis of nanoparticles is becoming increasing popular because of the necessity to develop eco-friendly and non-toxic strategies. Nanoparticles synthesized by natural compounds have immense potential in the biomedical arena. The present review focuses on plant-mediated synthesis of metal-based and carbon-based non-spherical nanoarchitectures and the role of green synthesis in improving their activities for biomedical applications.
- MeSH
- biokompatibilní materiály chemie metabolismus MeSH
- kovy chemie MeSH
- lidé MeSH
- nanostruktury chemie MeSH
- nanotechnologie metody MeSH
- uhlík chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Electrospinning has garnered significant attention in view of its many advantages such as feasibility for various polymers, scalability required for mass production, and ease of processing. Extensive studies have been devoted to the use of electrospinning to fabricate various electrospun nanofibers derived from carbohydrate gum polymers in combination with synthetic polymers and/or additives of inorganic or organic materials with gums. In view of the versatility and the widespread choice of precursors that can be deployed for electrospinning, various gums from both, the plants and microbial-based gum carbohydrates are holistically and/or partially included in the electrospinning solution for the preparation of functional composite nanofibers. Moreover, our strategy encompasses a combination of natural gums with other polymers/inorganic or nanoparticles to ensue distinct properties. This early established milestone in functional carbohydrate gum polymer-based composite nanofibers may be deployed by specialized researchers in the field of nanoscience and technology, and especially for exploiting electrospinning of natural gums composites for diverse applications.
Nanoscale zero-valent iron (nZVI) is recognized as a powerful tool for the remediation of groundwater contaminated by chlorinated ethenes (CEs). This long-term field study explored nZVI-driven degradation of CEs supported by electrokinetic (EK) treatment, which positively affects nZVI longevity and migration, and its impact on indigenous bacteria. In particular, the impact of combined nZVI-EK treatment on organohalide-respiring bacteria, ethenotrophs and methanotrophs (all capable of CE degradation) was assessed using molecular genetic markers detecting Dehalococcoides spp., Desulfitobacterium spp., the reductive dehalogenase genes vcrA and bvcA and ethenotroph and methanotroph functional genes. The remediation treatment resulted in a rapid decrease of the major pollutant cis-1,2-dichloroethene (cDCE) by 75% in the affected area, followed by an increase in CE degradation products methane, ethane and ethene. The newly established geochemical conditions in the treated aquifer not only promoted growth of organohalide-respiring bacteria but also allowed for the concurrent presence of vinyl chloride- and cDCE-oxidizing methanotrophs and (especially) ethenotrophs, which proliferated preferentially in the vicinity of an anode where low levels of oxygen were produced. The nZVI treatment resulted in a temporary negative impact on indigenous bacteria in the application well close to the cathode; but even there, the microbiome was restored within 15 days. The nZVI-EK treatment proved highly effective in reducing CE contamination and creating a suitable environment for subsequent biodegradation by changing groundwater conditions, promoting transport of nutrients and improving CE availability to soil and groundwater bacteria.
- MeSH
- biodegradace MeSH
- chemické látky znečišťující vodu * MeSH
- ethyleny MeSH
- podzemní voda * MeSH
- železo MeSH
- Publikační typ
- časopisecké články MeSH
Over the last few years, the electrospinning technique has attracted significant attention for the production of novel nanofibrous materials. At the same time, the use of graphene oxide and the natural products extracted from plants and/or trees have become very popular in various fields of science. In this work, a new method for the production of nanofibers based on a combination of Gum Arabic (GA), as a natural tree gum exudate, PVA, as an environmentally-friendly stabilizer, and graphene oxide (GO) has been developed and characterized. SEM analysis showed fundamental differences on the surface of bare nanofibers with and without GO, and also significantly smaller fiber diameters in the case of the presence of GO (fibers <100 nm present). Raman spectroscopy confirmed and TGA analysis approximated the content of GO in the nanofibers. Adsorption of methylene blue on the produced nanofibrous membrane was about 50% higher in the presence of GO, which opens the possibility to use GO/GA/PVA fibers in several applications, for example for the removal of dyes.
- MeSH
- adsorpce MeSH
- arabská guma chemie MeSH
- chemické látky znečišťující vodu izolace a purifikace MeSH
- elektrochemické techniky MeSH
- grafit chemie MeSH
- kinetika MeSH
- lidé MeSH
- methylenová modř izolace a purifikace MeSH
- nanovlákna chemie ultrastruktura MeSH
- polyvinyly chemie MeSH
- velikost částic MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
This study investigates an environmentally benign approach to generate platinum nanoparticles (Pt NP) supported on the reduced graphene oxide (RGO) by non-edible gum waste of gum kondagogu (GK). The reaction adheres to the green chemistry approach by using an aqueous medium and a nontoxic natural reductant-GK-whose abundant hydroxyl groups facilitate in the reduction process of platinum salt and helps as well in the homogenous distribution of ensued Pt NP on RGO sheets. Scanning Electron Microscopy (SEM) confirmed the formation of kondagogu gum/reduced graphene oxide framed spherical platinum nanoparticles (RGO-Pt) with an average particle size of 3.3 ± 0.6 nm, as affirmed by Transmission Electron Microscopy (TEM). X-ray Diffraction (XRD) results indicated that the Pt NPs formed are crystalline with a face-centered cubic structure, while morphological analysis by XRD and Raman spectroscopy revealed a simultaneous reduction of GO and Pt. The hydrogenation of 4-nitrophenol could be accomplished in the superior catalytic performance of RGO-Pt. The current strategy emphasizes a simple, fast and environmentally benign technique to generate low-cost gum waste supported nanoparticles with a commendable catalytic activity that can be exploited in environmental applications.
ISCO using activated sodium persulphate is a widely used technology for treating chlorinated solvent source zones. In sensitive areas, however, high groundwater sulphate concentrations following treatment may be a drawback. In situ biogeochemical transformation, a technology that degrades contaminants via reduced iron minerals formed by microbial activity, offers a potential solution for such sites, the bioreduction of sulphate and production of iron sulphides that abiotically degrade chlorinated ethenes acting as a secondary technology following ISCO. This study assesses this approach in the field using hydrochemical and molecular tools, solid phase analysis and geochemical modelling. Following a neutralisation and bioaugmentation, favourable conditions for iron- and sulphate-reducers were created, resulting in a remarkable increase in their relative abundance. The abundance of dechlorinating bacteria (Dehalococcoides mccartyi, Dehalobacter sp. and Desulfitobacterium spp.) remained low throughout this process. The activity of iron- and sulphate-reducers was further stimulated through application of magnetite plus starch and microiron plus starch, resulting in an increase in ferrous iron concentration (from
- MeSH
- chemické látky znečišťující vodu analýza metabolismus MeSH
- chlor metabolismus MeSH
- Chloroflexi metabolismus MeSH
- čištění vody metody MeSH
- Desulfitobacterium metabolismus MeSH
- ethyleny metabolismus MeSH
- halogenace MeSH
- oxidace-redukce MeSH
- Peptococcaceae metabolismus MeSH
- podzemní voda analýza chemie mikrobiologie MeSH
- regenerace a remediace životního prostředí metody MeSH
- rozpouštědla metabolismus MeSH
- sírany metabolismus MeSH
- sloučeniny sodíku MeSH
- tetrachlorethylen analýza metabolismus MeSH
- trichlorethylen analýza metabolismus MeSH
- železo metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
Lindane (γ-hexachlorocyclohexane) and its isomers (HCH) are some of the most common and most easily detected organochlorine pesticides in the environment. The widespread distribution of lindane is due to its use as an insecticide, accompanied by its persistence and bioaccumulation, whereas HCH were disposed of as waste in unmanaged landfills. Unfortunately, certain HCH (especially the most reactive ones: γ- and α-HCH) are harmful to the central nervous system and to reproductive and endocrine systems, therefore development of suitable remediation methods is needed to remove them from contaminated soil and water. This paper provides a short history of the use of lindane and a description of the properties of HCH, as well as their determination methods. The main focus of the paper, however, is a review of oxidative and reductive treatment methods. Although these methods of HCH remediation are popular, there are no review papers summarising their principles, history, advantages and disadvantages. Furthermore, recent advances in the chemical treatment of HCH are discussed and risks concerning these processes are given.
