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Study of effective parameters on generating submicron (nano)-bubbles using the hydrodynamic cavitation

Nazari Sabereh, Shafaei Sied Ziaedin, Hassanzadeh Ahmad, Azizi Asghar, Gharabaghi Mahdi, Ahmadi Rahman, Shahbazi Behzad

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 5

884--904

Although submicron (nano)-bubbles (NBs) have been broadly used in the laboratory flotation processes, the role of critical factors in their generation is not adequately explored in the literature. The present study investigates the effect of six key factors on generating submicron-sized bubbles and its application to coarse-sized quartz flotation. Interaction of influential factors is highlighted, which was generally overlooked in previous studies. These parameters i.e. frother type (MIBC and A65), frother dosage (50-130 mg/L), air flow rate (0.1-0.4 L/min), pressure in Venturi tube (250-400 kPa), liquid temperature (22-42 °C) and pH (6-10) were evaluated through software based statistical fractional factorial design. The size distribution of NBs produced by the principle of hydrodynamic cavitation was measured using a laser particle size analyzer (LPSA), and Sauter mean bubble diameter (d32) was considered as the response of experimental design. Batch flotation experiments were performed with and without the A65 and MIBC-NBs. The results of experimental design showed that relative intensity of the main factors followed the order of air flow rate>temperature>frother type as the most effective parameters on the bubble size. It was revealed that the lowest air flow rate (0.1 L/min) produced the smallest bubbles. Meanwhile, the d32 decreased as the liquid temperature increased, and the bubble size strongly was related to the frother type and its concentration. Indeed, with changing frother from MIBC to A65, the reduction in mean bubble size was two-fold. Interaction of frother type with its dosage, air flow rate and pressure were statistically recognized significant on the mean bubble size, which was confirmed by p-values. Finally, flotation recovery of quartz particles improved ca. 22% in the presence of NBs compared to the conventional flotation.

Preliminary optimization of direct amination of 1-(2,6-dimethylphenoxy)-2-propanol. synthesis of 1-(2,6-dimethylphenoxy)-2-aminopropane

Leś A., Kajl M., Szelejewski W.

Polish Journal of Applied Chemistry

2005

Vol. 49, nr 3

195-203

Preliminary steps were reported of optimization of catalytic amination of 1-(2,6-dimethylophenoxy)-2-propanol in our new synthesis of 1-(2,6-dimethylphenoxy)-2-aminopropane (mexiletine). In our search for optimal conditions a series of experiments were performed based on the concept of fractional factorial design. A detailed statistical analysis of reaction responses indicated necessary modifications of the synthesis. Elevated temperatures and the use of a more efficient catalyst were found necessary in order to use direct amination in industrial synthesis of pharmaceutically important amine from commercially available alcohol.