Comparative performance of in-line rotor-stators for deagglomeration processes

Comparative performance of in-line rotor-stators for deagglomeration processe

Breakup of nanoparticle clusters using microfluidizerM110-P

A commercial design, bench scale microfluidic processor, Microfluidics M110-P, was used to study the deagglomeration of clusters of nanosized silica particles. Breakup kinetics, mechanisms and the smallest attainable size were determined over a range of particle concentrations of up to 17% wt. in water and liquid viscosities of up to 0.09 Pa s at 1% wt. particle concentration. The device was found to be effective in achieving complete breakup of agglomerates into submicron size aggregates of around 150 nm over the range covered. A single pass was sufficient to achieve this at a low particle concentration and liquid viscosity. As the particle concentration or continuous phase viscosity was increased, either a higher number of passes or a higher power input (for the same number of passes) was required to obtain a dispersion with a size distribution in the submicron range. Breakup took place through erosion resulting in a dispersion of a given mean diameter range regardless of the operating condition. This is in line with results obtained using rotor-stators. Breakup kinetics compared on the basis of energy density indicated that whilst Microfluidizer M110-P and an in-line rotor-stator equipped with the emulsor screen are of similar performance at a viscosity of 0.01 Pa s, fines volume fraction achieved with the Microfluidizer was much higher at a viscosity of 0.09 Pa s

A New Look at the Reactivity of TEMPO toward Diethylzinc

Reactions of diethylzinc with TEMPO were investigated. Dropwise addition of 1 equiv of TEMPO to Et₂Zn at −10 °C leads to the nitroxide complex EtZn­(TEMPO) in high yield, whereas upon addition of 2 equiv of TEMPO the corresponding homoleptic nitroxide compound Zn­(TEMPO)₂ is formed. Diffusion ordered NMR spectroscopy experiments revealed that both zinc nitroxide compounds exist in monomeric forms in solution, while single-crystal X-ray diffraction confirmed their dimeric structure in the solid state