Search results for "hydroxide"

A Bis‐Acridinium Macrocycle as Multi‐Responsive Receptor and Selective Phase‐Transfer Agent of Perylene

2020

A bis‐acridinium cyclophane incorporating switchable acridinium moieties linked by a 3,5‐dipyridylanisole spacer was studied as a multi‐responsive host for polycyclic aromatic hydrocarbon guests. Complexation of perylene was proven to be the most effective and was characterized in particular by a charge transfer band as signal output. Effective catch and release of the guest was triggered by both chemical (proton/hydroxide) and redox stimuli. Moreover, the dicationic host was also easily switched between organic and perfluorocarbon phases for application related to the enrichment of perylene from a mixture of polycyclic aromatic hydrocarbons. peerReviewed

Illustrating the processability of magnetic layered double hydroxides: layer-by-layer assembly of magnetic ultrathin films.

2013

We report the preparation of single-layer layered double hydroxide (LDH) two-dimensional (2D) nanosheets by exfoliation of highly crystalline NiAl-NO3 LDH. Next, these unilamellar moieties have been incorporated layer-by-layer (LbL) into a poly(sodium 4-styrenesulfonate)/LDH nanosheet multilayer ultrathin film (UTF). Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible light (UV-vis), and X-ray diffraction (XRD) profiles have been used to follow the uniform growth of the UTF. The use of a magnetic LDH as the cationic component of the multilayered architecture enables study of the resulting magnetic properties of the UTFs. Our magnetic data show the appearance of spontaneous …

Management of tannery wastewaters: treatment of spent chrome tanning bath and vegetable tanning effluents

2013

Abstract In this work, a chain of treatment processes was proposed and described in order to reach better management of mineral and vegetable tannery wastewaters. First, chromium was precipitated from the spent chrome tanning bath by sodium hydroxide (NaOH) and then reformulated to form a complex of basic chromium sulfate which was tested successfully in mineral tanning process. On the other hand, the supernatant recovered after precipitation of chromium with NaOH was used to dilute vegetable tanning wastewaters characterized by a high concentration of polyphenols (about 2,574 mg/L). Diluted effluent was then treated by liming and tangential microfiltration using a ceramic membrane based on…

Porous Anodic Alumina as template for the cathodic electrodeposition of oxide and hydroxide nanostructures

2009

Review of gas diffusion cathodes for alkaline fuel cells

2009

Abstract This paper gives a technical background to alkaline fuel cells (AFCs), introducing the advantages and drawbacks of the technology. AFCs offer the potential for low cost, mass producible fuel cells, without the dependency on platinum based catalysts and (currently) expensive membrane electrolytes. The AFC uses relatively low cost electrolytes based on aqueous bases such as potassium hydroxide. The inherent CO 2 sensitivity of the electrolyte can be addressed by filtering out the CO 2 from the air intake using a simple scrubber and periodically replacing the liquid electrolyte. A review of the state-of-the-art in gas diffusion cathode development is given. The overall cell performanc…

Clean-up and confirmation procedures for gas chromatographic determination of pesticide residues in contaminated waters. Part I

1993

The effects of sulphuric acid, potassium hydroxide and chromic acid on eleven organochlorine and ten organophosphorus pesticides were investigated. The treatments destroy some pesticides totally or partially, leave others unaltered and have a clean-up effect. These reactions can be used to confirm the presence of an identified pesticide. The clean-up extracts in the environmental samples facilitate the identification of the organochlorine and organophosphorus pesticides and their quantitative analysis. The results obtained for contaminated surface waters show the usefulness of these methods for multi-residue capillary gas chromatography without the need for other additional separative chrom…

Electrodeposited nickel–zinc alloy nanostructured electrodes for alkaline electrolyzer

2022

Abstract Over the last decade, as a consequence of the global decarbonization process, the interest towards green hydrogen production has drastically increased. In particular a substantial research effort has focused on the efficient and affordable production of carbon-free hydrogen production processes. In this context, the development of more efficient electrolyzers with low-cost electrode/electrocatalyst materials can play a key role. This work, investigates the fabrication of electrodes of nickel-zinc alloys with nanowires morphology cathode for alkaline electrolyzers. Electrodes are obtained by the simple method of template electrosynthesis that is also inexpensive and easily scalable.…

Hydrothermal Synthesis of ZnO Crystals from Zn(OH)2 Metastable Phases at Room to Supercritical Conditions

2014

The originality of this work is to highlight the effect of temperature and pressure on the size and morphology of hydrothermal ZnO particles from ambient to supercritical conditions (T > 374 °C and P > 221 bar) using a unique continuous one-step process. Experiments were carried out from zinc nitrate (Zn(NO3)2) and potassium hydroxide (KOH) solutions in the ranges of 1–300 bar and 30–400 °C. The as-prepared particles of ZnO (flower, ellipsoid, and sphere) and e-Zn(OH)2 (polyhedral) sized from nano to micrometers were characterized by X-ray diffraction and electronic microscopy. The wulfingite phase (e-Zn(OH)2) was detected inside some powders especially at room temperature for higher pressu…

Elucidation of reaction process between solid tricalcium silicate and a lanthanum salt solution in connection with the precipitation pH. Extension to…

1993

Abstract Dissolution of tricalcium silicate is strongly accelerated in a La salt solution and releases the amounts of OH, Ca and silicate ions just required to precipitate all of lanthanum at pH 8. It remained to be proved that (1) La silicate hydrate could form at pH 8, and (2) Ca silicate hydrate could not precipitate simultaneously. The plot of silicate hydrate and hydroxide precipitation pH of La, Ca and other elements (Th, Zr) against the dropped volume of K2SiO3 and KOH solution and some physico-chemical characterization methods bring affirmative answers to these questions and allow the immobilization process of La and other elements in the presence of tricalcium silicate to be better…

Analysis of toxic elements in plastic components for toys. Multi-elemental determination by x-ray fluorescence

1993

Abstract An x-ray fluorescence method is proposed for the multi-elemental determination of toxic elements in plastic articles for children, viz., Sb(III), Ba, Cd, Cr(III), Hg, Pb and As(III). Mineralization is achieved by using molten sodium hydroxide to decompose the organic matrix, with sodium nitrate as auxiliary oxidant. Stable solutions containing the chemical species for analysis are obtained. The species are separated from the solution by (co)precipitation, in a medium of NH+4-NH3 buffer (pH 8.5) with sodium diethyldithiocarbamate, sodium rhodizonate and Fe3+, which acts as a carrier. The precipitates deposited on filter-paper are placed in the x-ray spectrometer in fine layer morpho…