Beaker mixer

This section discusses subsequently the Stephan mixer, the rotor-stator mixer, the planetary mixer, the mortar with pestle, the beaker mixer/blender, the three roll mill, the coffee grinder, the Topitec mixer and Unguator mixers. 

For dispersion of agglomerates amid another substance usually a (non-rough) pestle and mortar, an three roll mill (ointment miU, see Sect. 28.6.6) or a rotor-stator mixer (see Sect. 28.6.2) are used as a tool. Sometimes a beaker mixer/ blender (Sect. 28.6.5) or the Stephan mixer (Sect. 28.6.1) is used). Trituration of an active substance with eye ointment base is done in a stone mortar with a stone pestle because a lot of force is needed. Sometimes it is possible to disperse agglomerates on an ointment tile with a spatula, but a drawback is that no great force can be exerted. For the dispersion of a sohd substance amid other solids, a plastic or metal mortar can be used. 

To an 8-L beaker a solution of 3.78 g (0.630 mol) of ethylene diamine and 0.126 mol of potassium hydroxide in 4.5 L of distilled water are added and stirred with a high-speed mixer. To this, 12.79 g (0.634 mol) of terephthaloyl chloride dissolved in 1 L of methylene chloride (a safer solvent is THF) is added and stirred for 10 min. The suspension is filtered and washed twice with methanol. After drying, the polymer has an of 1.0 as measured in 96% sulfuric acid (0.5% solution at 30°C). The melting temperature of the polymer is 455° C. 

For the preparation of the foam, a solution of 1 g technical sodium diisobutyl naphthalene sulfonate in 50 ml of 3% orthophosphoric acid is prepared. 20 ml of this solution are poured into a 11 beaker and air is stirred in with a fast running mixer until the cream-like dispersion has reached a volume of 300-400 ml.Then,20 ml of the prepared urea/formaldehyde resin are mixed in, whereby the resin must be evenly distributed. After 3-4 min the introduced resin gellifies into a molded article permeated with many water/air pores under the influence of the acidic catalyst. After 24 h,the crosslinking is completed. Drying for 12 h at 40 °C in a circulating air dryer yields a brittle thermoset foam.The foamed plastic obtained is hydrophobic and has a large internal surface. It can take up about 30 times its own weight of petroleum ether. 

This property can be used to separate highly volatile and low-viscous mineral oils from oil-water dispersions.To demonstrate this,a dispersion of 20 ml of ligroin or petroleum ether in 200 ml of water is prepared in a 400 ml beaker with a fast-running mixer.Then approx. 5 g of crushed urea/formaldehyde foam are added. After 5 min the solution is filtered through a folded filter.The aqueous filtrates are optically free from dispersed hydrocarbons. In the same way a crude oil/water dispersion can be separated. 

Preparation of Ammonium Iodide. Put 10 g of the sublimed iodine and pour 50 ml of water into a 250-ml beaker. Simultaneously pour a 20% ammonia solution (40 ml) and a concentrated solution (30 %) of hydrogen peroxide into the mixture from two dropping funnels. Stir the solutions with a mechanical mixer. Add the ammonia and hydrogen peroxide solutions until the colour vanishes completely the latter should not reappear when the mixture is left standing for 10-15 min. 

Pour 30 ml of a 35% sodium hydroxide solution into a 250-ml beaker provided with a mechanical mixer, a thermometer, and a dropping funnel reaching almost to the bottom of the beaker. Cool the beaker with a mixture of ice and sodium chloride, switch on the mixer, and introduce a catalyst—a solution of 0.3 g of manganese(II) sulphate pentahydrate or 0.1 g of manganese(II) chloride tetrahydrate in 1 ml of water. Cool the solution to 0 °C and introduce 7 g of urea into it. Lower the temperature to 5-7 °C below zero and gradually add 63 ml of the filtered sodium hypochlorite solution cooled to the same temperature from the dropping funnel. The temperature even at the end of the reaction must not rise above 10 °C. 

Preparation of Sodium Paratungstate, a. Pour 20 ml of a 50% sodium hydroxide solution into a 100-ml porcelain beaker provided with a mechanical mixer, put the beaker on a water bath, and introduce the calculated amount of a freshly precipitated wet suspension of tungstic acid in small portions while vigorously stirring. At the end of the reaction, the pH of the solution should be 6-6.5. Filter the solution, evaporate it a little, and let it stand for 24 hours. Separate the formed crystals by filtration and dry them in the air. 

Basic alumina (18 g) was added to a 2.72 g 2 (0.01 mol) dissolved in 3 mL aqueous ammonia at room temperature. In another beaker, 10 g basic alumina were added to a solution of 1 (0.01 mol) in acetone. The mixture was dried at room temperature, and the two reactants were thoroughly mixed using a mortar mixer and then placed in an alumina bath inside the microwave oven. Upon completion of the reaction (90-120 s) as monitored by HPLC examination, the mixture was cooled to room temperature, and the product was extracted into a mixture of water and acetic acid (1 4 4xl0mL). Removal of the solvent under reduced pressure afforded the product which was purified by crystallization from a mixture of acetone-acetic acid. 

Neutral alumina (35 g) is added to a solution of lc (0.760 g, 2 mmol) dissolved in a minimum amount of dichloromethane (5 mL) at room temperature and the reaction mixture is thoroughly mixed using a vortex mixer. The adsorbed material is dried in air (beaker) and placed in an alumina bath inside the microwave oven. Upon completion of the reaction as followed by TLC examination (10 min), the product is extracted into dichloromethane (4x15 mL). Removal of the solvent, under reduced pressure yielded the product which is purified by crystallization from methanol-dichloromethane. Alternatively, the adsorbed material is charged directly on a silica gel column to afford the pure product, 3-(4-hydroxy-phenyl)-l-propanol 2c in 78% yield, mp 53-55 °C, in ethyl acetate-methanol (4 1, v/v) as an eluent. 

The separation-layer micro mixer was mounted about 2 cm above a funnel-shaped glass element which was connected to a glass tubular reactor, not being cooled [53], The end of the tube was set about 2 cm above a glass beaker collecting the solutions. All experiments were made using the micro mixer and the mixer-tubular reactor set-up only. 

Layers of 4,4 -bipyridyl (0.3 mol T1 in dichloromethane) and ethyl bromoacetate (0.3 mol 1 1 in dichloromethane) and a separation layer of dichloromethane are fitted into each other by means of the concentric separation mixer [53]. The reaction temperature is 22 °C. The reaction solution is inserted as droplets or a continuous stream either directly or via the tubular reactor in the beaker. The precipitate solution yielded is passed through a frit and the remaining solid is washed with dichloromethane and dried at elevated temperature and weighed. The quatemized product is characterized by NMR spectroscopy. 

The propeller rotates clockwise in a down-pumping mode. The vessel (glass beaker) has a diameter of 7.2 cm and the fluid height is 6.5 cm corresponding to a stirred volume of 264 cm. The same fluid as the one considered in the coaxial mixer experiments was used. The rotating speed and the volume concentration of the particles were varied in order to investigate the... 

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