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Topic Review
PEC Reactors for Water/Wastewater Treatment
Now and in the coming years, how we use and treat water, greywater and wastewater will become more important. A suitably designed photoelectrocatalytic (PEC) reactor is one potential solution. The photoexcitation of suitable semiconducting materials in aqueous environments can lead to the production of reactive oxygen species (ROS). ROS can inactivate microorganisms and degrade a range of chemical compounds. In the case of heterogeneous photocatalysis, semiconducting materials may suffer from fast recombination of electron–hole pairs and require post-treatment to separate the photocatalyst when a suspension system is used. To reduce recombination and improve the rate of degradation, an externally applied electrical bias can be used where the semiconducting material is immobilised onto an electrically conducive support and connected to a counter electrode. These electrochemically assisted photocatalytic systems have been termed “photoelectrocatalytic” (PEC). The term is stated in the IUPAC Recommendations 2011 as “electrochemically assisted photocatalysis. The role of the photocatalyst is played by a photoelectrode, often a semiconductor”. A short description of photocatalysis is included as it can be beneficial for those unfamiliar with the topic, before moving onto PEC. This entry is adapted from https://doi.org/10.3390/w13091198
  • 1.9K
  • 20 Oct 2021
Topic Review
Reversible Hydrogen Storage
In the field of energy storage, recently investigated nanocomposites show promise in terms of high hydrogen uptake and release with enhancement in the reaction kinetics. Among several, carbonaceous nanovariants like carbon nanotubes (CNTs), fullerenes, and graphitic nanofibers reveal reversible hydrogen sorption characteristics at 77 K, due to their van der Waals interaction. The spillover mechanism combining Pd nanoparticles on the host metal-organic framework (MOF) show at room temperature uptake of hydrogen. Metal or complex hydrides either in the nanocomposite form and its subset, nanocatalyst dispersed alloy phases illustrate the concept of nanoengineering and nanoconfinement of particles with tailor-made properties for reversible hydrogen storage. Another class of materials comprising polymeric nanostructures such as conducting polyaniline and their functionalized nanocomposites are versatile hydrogen storage materials because of their unique size, high specific surface-area, pore-volume, and bulk properties. The salient features of nanocomposite materials for reversible hydrogen storage are reviewed and discussed.
  • 1.9K
  • 22 Jul 2020
Topic Review
Prussian Blue
Efficient water remediation methods towards the extraction of 137Cs are being studied. Prussian blue (PB) and its analogs have shown very high efficiencies in the capture of 137Cs+ ions.
  • 1.9K
  • 07 Jun 2021
Topic Review
Zwitterionics Surfactants
Zwitterions are molecules that contain both a positive and negative charge within the same molecule. They are electrically neutral as a whole, but have distinct positive and negative regions within the molecule. The most common example of a zwitterion is the amino acid molecule, which contains both a carboxyl group (-COOH) and an amino group (-NH2) within the same molecule. The carboxyl group is negatively charged at physiological pH, while the amino group is positively charged, resulting in a net charge of zero for the molecule as a whole. Zwitterions have unique properties that make them useful in various applications. They are often used as buffer solutions in biochemistry and molecular biology, as they can maintain a stable pH even when small amounts of acid or base are added. Zwitterions are also used as surfactants, due to their amphipathic nature (i.e. they have both hydrophilic and hydrophobic regions). They are used in applications such as detergents and fabric softeners, where they can help to reduce surface tension and improve the wetting and dispersibility of the product. Zwitterionic surfactants have a unique structure that allows them to interact with a wide range of substances, making them useful in various applications. The unique combination of positive and negative charges in the same molecule provides a balance that enables them to interact with both hydrophilic and hydrophobic substances, allowing them to solubilize oils and greases, emulsify water-insoluble substances, and reduce surface tension.
  • 1.9K
  • 24 Mar 2023
Topic Review
Metal Nanoclusters
Metal nanoclusters (NCs), comprising only a few to roughly hundreds of metal atoms, have a metal core-protective agent shell structure. Owing to the size of metal NCs approaching the Fermi wavelength of electrons, the spatial confinement of free electrons in metal NCs generates discrete electronic transitions, thereby exhibiting intriguing molecular-like properties. Therefore, metal NCs are deemed to bridge the gap between molecules and nanoparticles.
  • 1.9K
  • 01 Dec 2020
Topic Review
Nanophotocatalysts
Biomedical waste management is getting significant consideration among treatment technologies, since insufficient management can cause danger to medicinal service specialists, patients, and their environmental conditions. The improvement of waste administration protocols, plans, and policies are surveyed, despite setting up training programs on legitimate waste administration for all healthcare service staff. Most biomedical waste substances do not degrade in the environment, and may also not be thoroughly removed through treatment processes. Therefore, the long-lasting persistence of biomedical waste can effectively have adverse impact on wildlife and human beings, as well. Hence, photocatalysis is gaining increasing attention for eradication of pollutants and for improving the safety and clearness of the environment due to its great potential as a green and eco-friendly process. In this regard, nanostructured photocatalysts, in contrast to their regular counterparts, exhibit significant attributes such as non-toxicity, low cost and higher absorption efficiency in a wider range of the solar spectrum, making them the best candidate to employ for photodegradation. Due to these unique properties of nanophotocatalysts for biomedical waste management, we aim to critically evaluate various aspects of these materials in the present review and highlight their importance in healthcare service settings.
  • 1.9K
  • 18 Aug 2020
Topic Review
Electron Paramagnetic Resonance
Electron Paramagnetic Resonance, EPR is resonance absorption of microwave quanta by electron spins placed in a swept external magnetic field B at a definite value of magnetic field. Other used names are Electron Magnetic Resonance, EMR and Electron Spin Resonance, ESR.
  • 1.9K
  • 24 May 2021
Topic Review
Principles of the Suzuki Coupling Reaction
The Suzuki coupling is a transition metal-catalyzed, cross-coupling carbon–carbon (C–C) bond forming reaction between organic boron compounds and organic halides. As an operationally simple and versatilely applicable procedure, the Suzuki coupling reaction has found immense applications in drug discovery and development in the pharmaceutical industry. 
  • 1.9K
  • 06 Jan 2023
Topic Review
N-Butanol
n-Butanol or n-butyl alcohol or normal butanol is a primary alcohol with a 4-carbon structure and the chemical formula C4H9OH. Its isomers include isobutanol, 2-butanol, and tert-butanol. Butanol is one of the group of "fusel alcohols" (from the German for "bad liquor"), which have more than two carbon atoms and have significant solubility in water. n-Butanol occurs naturally as a minor product of the fermentation of sugars and other carbohydrates, and is present in many foods and beverages. It is also a permitted artificial flavorant in the United States, used in butter, cream, fruit, rum, whiskey, ice cream and ices, candy, baked goods and cordials. It is also used in a wide range of consumer products. The largest use of n-butanol is as an industrial intermediate, particularly for the manufacture of butyl acetate (itself an artificial flavorant and industrial solvent). It is a petrochemical, manufactured from propylene and usually used close to the point of manufacture. Estimated production figures for 1997 are: United States 784,000 tonnes; Western Europe 575,000 tonnes; Japan 225,000 tonnes.
  • 1.9K
  • 26 Oct 2022
Topic Review
Supercapacitor
Supercapacitors are electrical devices for fast storage and release of electric energy utilizing charge accumulation in the electrochemical double layer. In terms of volumetric and gravimetric capacities they exceed conventional dielectric and electrolytic capacitors by several orders of magnitude. However, the low energy density of supercapacitors has seriously limited their wider application in many fields. Increase of energy density highly depends on development of a new generation of advanced electrode materials for supercapacitors.
  • 1.9K
  • 26 Oct 2020
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