Controlled-pore ceramics

The controlled-pore ceramics and the fritted glasses employed in these studies were manufactured by Corning Glass Works. The borosilicate glass is a product of Corning Glass Works. 

The adsorbent should have a high affinity and capacity for the enzyme and it should not absorb the reaction product or enzyme inhibitors. Among the materials used the more popular are cation and anion exchange resins, activated charcoal, silica gel, alumina, control pore glasses and ceramics. 

Baumgartner, C.E. Controlled-pore-size composite nickel oxide structures for carbonate fuel cell cathodes. J. Am. Ceram. Soc. 1990, 73 (3), 516-520. 

Entrapment provides an alternative to covalent immobilization. IVpically, cells are entrapped in a porous matrix and the cells grow throughout the pores/media to result in high cell densities. Cells may be added to the matrix at the time it is formed, or may be added after matrix formation. Many matrices have been used for entrapment including agarose beads, ceramics and silica, collagen microspheres, polyacrylamide, controlled pore glass, and various membranes [68, 69]. Membrane retention of cells, which has been used for biosensors (table 8.7) is, per se, not an immobilized system since the cells are... 

Glass ceramics Sealing glasses Cafalysf supports Fiber-optic preforms Controlled pore glasses... 

Porous ceramic A very large developing topic, e.g, bioceramics, where we want controlled pore size for tissue ingrowth... 

Several methods have been used to produce porous HA ceramics. Remember that historically much of ceramic processing was concerned with trying to produce components that were fully dense. So to produce porous components, particularly where we need to control pore size, often requires ingenuity and a rethink. We discussed porous ceramics in Section 23.15, so will just point out special features for producing porous HA ceramics. 

Class Ceramics Sealing Glasses Catalyst Supports Fiber Optic Preforms Controlled Pore Glasses j... 

Ordered stmctures can also play a key role in the manufacture of membranes with controlled pore size distributions. Ramakrishnan et al. (2003) synthesized membranes by depositing monodisperse latex particles onto a base substrate to form an ordered stmcture. The voids between the particles serve as narrowly distributed pores and the size of the pores is controlled by the size of the particles used in deposition. Monodispersity plays a key role in achieving pores of uniform size and in the processing step, which involves the sintering of the formed stmcture to achieve stability. As with the processing of ceramic suspensions. 

The fluidized bed described by Gemmer is still standard. For PVC powders, dry air is satisfactory (the moisture content of the compound should be held below 0.5 percent). The plenum chamber into which compressed air enters is designed for streamline flow. The porous plate through which it passes to fluidize the bed may be of sintered stainless steel or ceramic composition, with controlled pore size typically one-tenth that of the powder compound. In some cases, the fluidized bed is equipped with a mechanical vibrator to assist in fluidization. In many operations, provision is also made for the part to move up and down or from side to side in the bed. This is often important in obtaining a uniform coating at intersections, edges and comers. 

Although it is safe to say that NF nowadays can be implemented without problems in many known applications, it is expected that the evolution in NF wUl continue. Some of the expected progresses include modeling of rejection in aqueous solutions, understanding of the performance in organic solvents, prediction and control of fouling, membranes with controlled pore size, possibly in hoUow-fiber configmation, development of hydrophobic ceramic NF membranes, and the optimization of hybrid processes with NF. 

Tang, F.Q., Fudouzi, H., Uchikoshi, T, and Sakka, Y. (2004). Preparation of porous materials with controlled pore size and porosity. J. Euro. Ceram. Soc. 24 (2), 341-344. 

A typical ozone system consists of 100 g/hr at a concentration of 1.0 percent to 1.5 percent in air fed to the bottom of bleach collection tanks through ceramic spargers (pore size of approximately 100 t). The system contains air compression and drying equipment, automatic control features, and a flat-plate, air-cooled ozone generator. Regeneration of bleach wastes totaling about 10,000 gallons a year, and recovery of other chemicals can also be cost effective. 

---