Neutralization with Simultaneous Separation of Metallic Ions from Condensed Water Through Capillary Polypropylene and Cellulose Derivatives ^†

An interesting and unpredictable environmental issue raises condensing plants, with an average output of 20–100 Kw, producing thermal energy in individual homes, associations or small public buildings. Environmental problems arising from acidic waters containing metallic ions from condensing boilers can be adequately addressed using membrane processes [1,2,3].

This work deals with simultaneous neutralization and separation of aluminum and copper ion from acidic waters containing metallic ions traces through permeation through capillary composite membranes made of polypropylene with carboxymethyl cellulose (PP/CMC) inclusions.

The ionophore from the composite membrane, a cellulose derivative, carboxymethyl cellulose (CMC) (Figure 1), is one of the most performing ingredients.

The optimal operating parameters were determined—the flow rate, pH of the receiving phase and working time. Simultaneously with the quantitative removal of metallics trace ions, an almost neutral pH is obtained, which is compatible with the natural waters in which it can be dispersed. It is interesting to note that, after 4 h, the performance of the process—especially the neutralization—decreases, suggesting an osmotic or retro-dialysis process, generated by lowering the pH gradient.