The 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... 

---