Amount Of Tetramethylammonium Hydroxide Research Articles

Rationalized Fabrication of Structure-Tailored Multishelled Hollow Silica Spheres

This work demonstrates a simple approach to rational fabrication of multishelled hollow silica spheres via periodic injections of a given amount of tetramethylammonium hydroxide (TMAH) to catalyze ...

Effect of Tetramethyl Ammonium Hydroxide on Dispersion of the Silicon Carbide Submicron Powders

The distributed processing of β-SiC submicron powders were carried out by tetramethyl ammonium hydroxide (TMAH). The effects of dispersant on the dispersion stability of the β-SiC powders were investigated by the particle size, flow characteristics, morphology and other physical properties of the powder before and after dispersed treatment. The results show that the best dispersing state of SiC is obtained by using the ultrasonic 7mins. In these conditions, the suspension solid content of β-SiC is 8%, and the dosage of TMAH is 8wt.%. An optimum amount of TMAH is proved as 8wt.% when the solid content is kept as 8wt.%. The powder particle size has been reduced from 0.73μm to 0.45μm, and its flowability has improved significantly after low temperature drying. The dispersed powder has small particle size, uniform distribution and excellent dispersion stability.

One-step conversion of dipicolinic acid to its dimethyl ester using monomethyl sulfate salts for GC-MS detection of bacterial endospores

Methyl sulfate (MeSO4-) salts were explored as thermochemolysis-methylation (TCM) reagents for gas chromatographic (GC) analysis of dipicolinic acid (DPA) as its dimethyl ester (Me2DPA) from bacterial endospores. The reaction was carried out under non-pyrolytic conditions by inserting a small coiled wire filament coated with the sample and reagents directly inside a GC injection port at 290 °C. Above 10 : 1 methyl donor/DPA ratios, alkali metal salts of MeSO4- effected 80-90% conversion of DPA to Me2DPA, which was 10-20 times more active than the same amount of tetramethylammonium hydroxide (TMA-OH) at this temperature. A quaternary salt mixture consisting of 1 : 3 : 1 : 3 TMA+/Na+/OH-/MeSO4- methylated spore DPA with an average conversion of 86% (mean conversion by TMA-OH under the same conditions was 4%). Therefore, the sensitivity for detection of bacterial endospores was increased over 20-fold compared to that observed with the more commonly employed TMA-OH methylating reagent. The limit of detection by this method was 9 × 104 total spores. Mechanisms describing the observed behavior are proposed and discussed. This is the first use of MeSO4- as a TCM reagent for GC.

Characteristics of SiC/nano-TiN Aqueous Mixed Slurry and Its Spray Drying Behavior

The aqueous slurries were prepared using tetramethyl ammonium hydroxide(TMAH)as dispersant,nano-TiN and submicron SiC powders as starting materials.The dispersion,stabilization mechanism and spray drying behaviors of SiC/nano-TiN aqueous mixed slurry were analyzed.The results show that TMAH can be absorbed on the surface of nano-TiN and SiC particles,and the dispersibility of particles is cooperatively improved by electrostatic and steric effects.The mixed slurry possesses better dispersion and stabilization when pH value is 8 and the amount of TMAH is 0.75wt%, and the SiC/nano-TiN composite powders prepared by spray drying distribute uniformly with good fluidity.