Concentrate processing advantages/disadvantages

In the N method, NH4+ or N02 is added to a sample and then the appearance of N label in the N02 or NOa pools is measured over time (e.g., Olson, 1981). The advantage of this technique is that it is a direct, unambiguous measure of the process. One disadvantage is that the increase in NH4+ or N02 concentrations caused by the tracer addition can result in enhanced NH4+ or N02 oxidation rates (e.g., Helder and De Vries, 1983 Ward et ai, 1984). When small additions of N are used, the isotope dilution of the substrate pool must be monitored over time. 

In this work the state-of-the-art and perspectives of column characterization and compai ison have been presented and discussed. All information about physico-chemical properties of RP HPLC Cl8 and C8 columns as porosity, average surface area, free silanol concentration, binding ligand density and others, were summarized. The points of views about column classifications, its advantages and disadvantages were discussed. It was shown that Cl8 and C8 HPLC column classification processes do not allow selecting the column with the same or preai range selectivity. 

A semi-batch reactor has the same disadvantages as the batch reactor. However, it has the advantages of good temperature control and the capability of minimizing unwanted side reactions by maintaining a low concentration of one of the reactants. Semi-batch reactors are also of value when parallel reactions of different orders occur, where it may be more profitable to use semi-batch rather than batch operations. In many applications semi-batch reactors involve a substantial increase in the volume of reaction mixture during a processing cycle (i.e., emulsion polymerization). 

Toyopearl HW resins overcome several disadvantages of conventional gels, which do not function well at higher flow rates or pressures, are unstable to extremes of pH, salt, and organic solvent concentrations, and can leach saccharide derivatives into the process material. For process-scale SEC, Toyopearl HW resins provide the following advantages ... 

Electrodialysis has advantages and disadvantages. For instance, the process requires very little energy and can recover highly concentrated solutions. On the other hand, similarly to other membrane processes, electrodialysis membranes are susceptible to fouling and must be regularly replaced. 

---