Effect of sodium oleate on the agglomeration of calcium carbonate

The effect of Na‐Oleate on the agglomeration of calcium carbonate was investigated. Oleate is determined by Infrared spectroscopy. In order to detect the amount of Oleate adsorbed on the calcium carbonate crystals, the differential thermal analysis method was used. The agglomerate size and zeta potential were investigated as a function of Na‐Oleate concentration and pH value. It was found that the amount of Na‐Oleate adsorbed on the calcium carbonate is not only depending on the concentration but also on the pH value and zeta potential. The results also show that the critical Na‐Oleate concentration, where the maximum Na‐Oleate adsorption was reached, was found approximately 300 ppm under the selected experimental condition. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of trace metals on reactive crystallization of gypsum

The effect of Fe²⁺, Fe³⁺, and Cr³⁺ ions on crystallization of calcium sulfate dihydrate (gypsum) produced by the reaction between calcium hydroxide suspension and sulphuric acid solution was investigated at 3.5 pH and 65°C in the absence and presence of 2500 ppm citric acid concentration. Crystal size distributions, filtration rates, and morphology of gypsum were determined and discussed as a function of ion concentration. Average particle size of gypsum was not affected significantly by the presence of Fe²⁺, Fe³⁺, and Cr³⁺ ions individually. Variation of gypsum morphology depending on ion concentration affected the filtration characteristics. The presence of Fe³⁺ or Cr³⁺ ions besides 2500 ppm citric acid influenced both average particle size and filtration characteristics. The effect of citric acid on gypsum morphology was suppressed at high Fe³⁺ and Cr³⁺ ion concentrations. The change of morphology is related to the complex formation between Fe³⁺ or Cr³⁺ ions and citric acid at high ion concentrations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stochastic P-bifurcation in a nonlinear impact oscillator with soft barrier under Ornstein–Uhlenbeck process

Nonlinear Dynamics - This study investigates the effect of randomness in the forcing on a harmonically excited bilinear impact oscillator with a soft barrier. The system parameter range considered...     

Polynomial central set theorem near zero

Semigroup Forum - Hindman and Leader introduced the set $$0^{+}$$ of ultrafilters on $$\left( 0,1\right) $$ , characterized the smallest ideal of $$\left( 0^{+},+\right) $$ and proved the Central...     

Photocatalytic Conversion of Benzyl Alcohols/Methyl Arenes to Aryl Nitriles via H-Abstraction by Azide Radical

This report presents the visible-light-assisted synthesis of aryl nitriles from easily accessible alcohols or methyl arenes in the presence of O₂. Organic photoredox catalyst, 4CzIPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene), induces single electron transfer (SET) from azide N₃⁻ and generates azide radical N₃⋅.The photogenerated N₃⋅ abstracts H atom from α-C−H bond of benzylic system, which provides aldehyde and hydrazoic acid (HN₃) in situ. This reaction subsequently forms azido alcohol intermediate that transforms into nitrile with the assistance of triflic acid (Brønsted acid). A range of alcohols and methyl arenes successfully underwent cyanation at room temperature with good to excellent yields and showed good functional group tolerance.     

A facile green synthesis of silver nanoparticle-decorated hydroxyapatite for efficient catalytic activity towards 4-nitrophenol reduction

Research on Chemical Intermediates - Silver nanoparticles (AgNPs) were gradually grown on a hydroxyapatite surface via a green self-reducing approach. Hydroxyapatite (HAP) was functionalized by...     

Effect of Various Impurities on the Hardness of NaCl Crystals

The hardness of NaCl crystal in the presence of mono, divalent and polyvalent ions were measured. Measurements were made in the indentation load range from 5 x 10^‐3 to 20 x 10^‐3 N. The measured data showed that there is an indentation size effect. Classical Meyer's law was used for the characterization of crystal hardness f NaCl. The Meyer index was found to be smaller than 2 indicating brittle material characteristic. The PRS model was also used for the determination of the load‐independent microhardness value. It was found that the crystal hardness of NaCl is chancing depending on the type of impurity and the concentration.