Dielectric relaxation of dilute aqueous NaOH, NaAl(OH)(4), and NaB(OH)(4)

The complex dielectric permittivity of aqueous NaOH (c less than or equal t o 2 M) and of dilute (less than or equal to 0.6 M) NaAl(OH)(4) and NaB(OH)( 4) solutions in NaOH ([Na] = 1 M) at 25 degrees C has been determined in th e frequency range 0.2 less than or equal to v/GHz less than or equal to 20. All spectra could be represented by a single Cole-Cole relaxation time dis tribution attributed to the cooperative relaxation of the solvent. The conc entration dependence of the effective hydration number of OH- has been dete rmined. For aluminate and berate solutions the deduced parameters: effectiv e conductivity kappa(e), static permittivity epsilon, relaxation time tau, and distribution parameter or suggest a 1:1 replacement of hydroxide by alu minate and berate, accompanied by a release of bound water. The lack of an ion-pair relaxation process despite notable ion association suggests that r apid proton exchange is important not only for the dynamics of OH- but also for Al(OH)(4)(-) and B(OH)(4)(-).