China 
Africa 
Explore chapters and articles related to this topic
Dynamic Systems for Producing Gas Mixtures
Published in O. Nelson Gary, Gas Mixtures, 2018
The classical types of evaporation units are shown in Figure 5.23. Usually a two-piece vessel with a capacity of 100 mL to 2 L connected by a ground-glass joint is chosen. The gas normally enters through a centrally located gas dispersion tube and is dispersed into minute bubbles, the size of which depend on the tube porosity. Dispersion tubes, shown in Figure 5.24, are available in the arbitrary porosity designations of extra fine, fine, medium coarse, and extra course. The finer the porosity, the greater the pressure required to force the gas through the tube, and the better the efficiency of evaporation. Small-volume bubblers with replaceable dispersion tubes (lower right in Figure 5.23) have also been specially designed.226 The amount of liquid evaporated will depend on the bubble size, the rate of ascent, the temperature of the liquid, and the height of the liquid column, as well as its boiling point, vapor pressure, and viscosity. It should also be noted that the carrier or diluent gas should be purified and free from dust, oil mists, water, and other organic materials. Accumulations of such materials will alter the evaporation characteristics of vapor generation systems.
Introduction
Published in Jamie Bartram, Richard Ballance, Water Quality Monitoring, 1996
Jamie Bartram, Richard Ballance
✓ A reflux apparatus consisting of a 250-ml Erlenmeyer flask ( 500ml if large samples are used) with ground-glass neck, and a 300-mm double surface condenser (Liebig, Friedrichs, West or equivalent) with a ground-glass joint. Since absolute cleanliness is essential, flasks and condensers should be protected from dust by inverted cups when not in use. The glassware must be used exclusively for COD determinations. ✓ A heating mantle or hotplate.
Preparation of CTAB-functionalized aqai stalk and its efficient application as adsorbent for the removal of Direct Blue 15 and Direct Red 23 dyes from aqueous media
Published in Chemical Engineering Communications, 2018
Fernando M. Kasperiski, Eder C. Lima, Glaydson S. dos Reis, Janaina B. da Costa, Guilherme L. Dotto, Silvio L. P. Dias, Mariene R. Cunha, Flavio A. Pavan, Carine S. Correa
For vapor adsorption experiments, about 300 mg of powdered adsorbent material was dried in 10 mL beakers at 105°C for 24 h. The samples were cooled in a desiccator before determining their accurate weight (about 300.0 mg). Storage in an atmosphere of saturated solvent vapor was performed in Erlenmeyer flasks capped with glass caps (45/50 ground glass joint), using 60 mL of solvent (water or n-heptane) (dos Reis et al., 2016a; Leite el., 2017a). The dried powder samples inside the beakers were placed in such a way that they were not in contact with the wall of the Erlenmeyer flasks and kept at 25°C under static conditions. The beakers containing the solid samples were removed from the Erlenmeyer flasks after 24 h and dried carefully from the outside with laboratory tissues. The vapor amount adsorbed on the samples was obtained by the difference between the final and initial weights of the solid sample and expressed in mg g−1. The hydrophobic–hydrophilic ratio (HI) was calculated by the ratio of adsorbed amount of n-heptane vapor (mg g−1) divided by the adsorbed amount of water vapor (mg g−1) (dos Reis et al., 2016a; Leite et al., 2017a).
Homogeneous precipitation at solid/solution interface as a novel chemical route for synthesis of nanoparticles: application to Cd(II) and Pb(II) sulfides
Published in Journal of Experimental Nanoscience, 2018
Adel F. Shoukry, Nadia M. Shuaib, Abdulhakeem A. Ajadi
A preparation cell consisting of two concentric glass tubes fit together at the neck through a ground glass joint was used (Figure 1). The outer tube is closed and has a flat bottom, with an inner diameter of 4.0 cm, and a capacity of about 150 mL, while the inner tube is open at the bottom and has an inner diameter of 1.8 cm. In the outer tube, 1.5 g of thioacetamide and 5.0 g of CTAB have been dissolved in 50 mL of bi-distilled water. With this solution, 30 mL of n-heptane, as organic phase, and 20 mL of n-butanol, as co-surfactants, have been added and the mixture was thoroughly mixed for 5 min. The water-insoluble metal salt, CdCO3, CdC2O4, CdS, PbCl2, PbCO3, or PbS was contained in a filter paper and introduced into the lower end of the inner tube, and then the tube was fixed as appropriate (Figure 1). The cell has been heated gently, and the solution was stirred vigorously for 2 h. The yellow, cadmium sulphide (Figure 1(a), inset), or the reddish-black PbS formed in the outer tube (Figure 1(b), inset) was separated by centrifugation, washed with water, followed by ethanol, and then dried at 120 °C for one hour. It is also an advantage of the method that the formation process can be halted at any time by just removing the internal tube and vice versa.
A greener tetraphenylporphyrin synthesis and metallation: an undergraduate teaching experiment
Published in Green Chemistry Letters and Reviews, 2023
Matthew A. Nitka, Katarina E. Zerbee, Julianne M. Dee, Matthew A. Cranswick, Edward P. Zovinka, John R. De Backere
Working inside a fume hood, a small Erlenmeyer flask with a ground glass joint and stir bar was charged with 15 mg of H2TPP and ten molar equivalents of the corresponding metal(II) acetate hydrate salt (Zn, 0.054 g; Cu, 0.049 g). Next 10 mL of EtOH:EtOAc solvent mixture (1:1 v/v) was added before attaching a reflux condenser (with a small amount of silicon grease and connected to circulating water). The solution was heated to a gentle reflux for at least 30 min before allowing the reaction mixture to cool to room temperature. The UV-vis spectrum was obtained using a few drops of the reaction mixture which was further diluted with EtOAc.