Continuous flow krypton adsorption for low surface area measurements

1973 ◽  
Vol 45 (8) ◽  
pp. 1576-1577 ◽  
Author(s):  
Seymour. Lowell
Keyword(s):  
Surface Area ◽  
Continuous Flow ◽  
Krypton Adsorption

Efficient (Tube) Settling Tanks

1991 ◽  
Vol 24 (7) ◽  
pp. 223-228 ◽  
Author(s):  
Lazar Ignjatović
Keyword(s):  
Surface Area ◽  
Continuous Flow ◽  
Settling Tank ◽  
Design Flow ◽  
Flowing Water ◽  
Vertical Flow ◽  
Settling Basin ◽  
New Type ◽  
Theoretical Results ◽  
Maximum Design

This paper discusses design principles and theoretical results for a new type of settling tank. Within the settling zone of the tank, sedimentation takes place in tube, as in a quiescent container of equal (3-5 cm) depth. The inlet, sludge and outlet zone are arranged for a continuous-flow rectangular (or circular) basin. A particle that enters the sludge zone is and stays removed, and the sludge can be removed by gravity or pumped from the sludge zone. Hydraulically, the process can be formulated in terms of horizontal-vertical-flow without short-circuiting. Tank loadings are 0.5 L/s per m2 to 1.5 L/s per m2 of tank surface area. The detention period of 15-20 minutes offers the same overall removal efficiency as 4-5 hours for classical one. Variations in flow are of little concern, provided that the maximum design flow is not exceeded. Scum is removed without difficulty from the tank as well as the sludge, and the sludge removal device will also act as a flocculator. This type of settling basin is suitable where sludge volumes are large or where putrefaction of sludge in contact with the flowing water is to be avoided.

A method of surface analysis and its application to reduced nickel powder

1957 ◽  
Vol 242 (1231) ◽  
pp. 534-543 ◽  
Keyword(s):  
Surface Area ◽  
Surface Analysis ◽  
Nickel Powder ◽  
Surface Adsorption ◽  
Metal Powders ◽  
Complex Surfaces ◽  
Stable Layer ◽  
Adsorptive Properties ◽  
Krypton Adsorption ◽  
Hydroxyl Formation

The possibility of analyzing the complex surfaces of reduced metals by comparing their adsorptive properties with the known behaviour of evaporated films has been explored by experiments on nickel powder. Nickel prepared by reduction of the oxide in hydrogen at 450°C for periods up to 12h has been shown by measurement of hydrogen and krypton adsorption at -183°C to have a surface containing up to 37% of clean nickel atoms. Traces of silica introduced during the preparation of the powder possibly account for the rest of the surface. Adsorption of hydrogen at -183°C is effectively complete within ½ min at about 10 -5 mm, and all gas is desorbed by evacuation at 450°C. Oxide is probably not a significant impurity, because the powder does not exhibit the slow adsorption at 20°C and above which is characteristic of incompletely reduced nickel. Such activated adsorption can be restored by the addition of oxygen and eliminated again by further reduction; its stoichiometry suggests that the process consists of hydroxyl formation. Reduction of the sulphide gives nickel of appreciable surface area but completely inert to hydrogen; presumably a stable layer of sulphide is retained. Some thermodynamic and kinetic problems involved in the preparation of metal powders with surfaces of known purity are briefly discussed in the light of these results.

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