PH swing process

All commercial activity is currently based on the phenolic-oximes. A convenient Mg-catalyzed process for the manufacture of parent salicylaldehydes has been developed.116 Extraction equilibria based on the pH-swing process... 

The pH-swing process, which was developed in Japan (and later also presented in a patent by Yogo et al. [60]) is another two-step aqueous carbonation process where at first the pH of the solution is lowered so as to enhance the extraction of divalent metal ions. In the second step, the pH is raised to enhance the precipitation of carbonates. A schematic representation of a process utilizing the pH-swing is shown in Figure 14.3 (taken from Ref. [61]), where the principal reactions... 

The term parametric pumping was coined by Wilhelm et al. [Wilhelm, Rice, and Bendelius, Ind. Eng. Chem. Fundam., 5,141-144 (1966)] to describe a liquid-phase adsorption process in which separation is achieved by periodically reversing not only flow but also an intensive thermodynamic property such as temperature, which influences adsorptivity. Moreover, they considered the concurrent cycling of pressure, pH, and electrical and magnetic fields. A lot of research and development has been conducted on thermal, pressure, and pH driven cycles, but to date only gas-phase pressure-swing parametric pumping has found much commercial acceptance. 

Several methods have been reported in the literature for preparing refiectoiy support materials with variable surface characteristics. Careful control of the specific gelation and ageing conditions of pseudo-boehmite has been found to have an effect on the surface properties of the final alumina support [4]. The control of pore structure in alumina supports has also been realised by rapidly swinging the solution pH during the gelation process [5]. 

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