Processes for deionization and demineralization of a fluid containing ions comprising:(a) Loading an amine or ammonia buffer onto a first weakly acidic cation exchange resin to occupy cation exchange sites and to form a first bed comprising a first amine-buffered resin;(b) Passing said fluid containing ions through said first bed comprising said first amine-buffered resin and exchanging cations of said fluid for amine cations of said first amine-buffered resin to form a first effluent comprising an anion-buffer salt complex;(c) Passing said anion-buffer salt complex through a first weakly basic anion exchange resin where an anion portion of said anion-buffer salt complex is split from said anion-buffer salt complex by adsorption of said anion portion onto said weakly basic anion exchange resin to form a second effluent comprising buffer in free hydrated base form;(d) Passing said buffer in free hydrated base form to a second weakly acidic cation exchange resin where said buffer loads onto said second weakly acidic cation exchange resin as in step (a) and repeating the process of steps (b)-(d); and(e) Regenerating said first weakly acidic cation exchange resin with an organic acid.