The work is devoted to the study of dynamic, kinetic, and thermodynamic features of chromium(VI) sorptive extraction in the form of its complex compounds (CC) with 1,5-diphenylcarbazide (DPC) and carmoazine (CAN) on strong ion-exchangers, i.e. KU-2-8 and AV-17-8, respectively, and to subsequent development of quantitative solid-phase spectrophotometric (SPS) and semi-quantitative visual colorimetric (VC) determination of chromium(VI) when its concentrations in waters are equal or above the maximum permissible concentration. The conditions of complexation reaction of chromium(VI) with CAN accompanied with their redox interaction have been optimized. Analytic-chemical charac-teristics of the interaction product, Cr(III):CAOH = 1:3 (CAON - carmoazone), namely, the charge of the complex ion, and a value of the stability constant have been determined. The influence of some reaction hindering ions was studied. The formation of adsorption layers on ionite surface in the course of sorption in dynamic regime for systems: I - the solution of chromium(III) diphenylcarbazonate complexes - CU-2-8 and II - the solution of chromium(III) diphenylcarbazonate complexes - AV-17-8 occurs with the predominance of chemisorptive interaction, has been confirmed by the thermo-dynamic experiments. The influence of macrokinetic and dynamic factors (the initial CC concentration, cin; the sorbent mass, ms; the ionite grain diameter, dg; the column diameter, dc; the solution volume rate - Vvol) on the sorption processes was studied in systems I and II. Those are the volume rate, with the help of mathematical modeling (MM) the mass-exchange coefficient, and the dynamic equilibration time for the systems under study. The data obtained correlate with the experimental ones confirming the adequacy of the MM. Based on the principles of both colorimetry and computer modeling, colorimetric scales for semi-quantitative VC chromium(VI) determination using systems I and II in the form of their IP (an indicator pipe - IP) versions and also for the quantitative SPS method, namely, for diffuse reflectance spec-troscopy, have been developed. For the latter, the chromium(VI) detection limit is: system I - 0.02 g/ml (natural waters), system II - 0.43 g/ml (waste waters). As shown, the total pres-ence of salt ions in systems does not affect the quantitative performance for chromium detec-tion. Keywords: chromium(VI), determination, 1,5-diphenylcarbazide, carmoazine, sorption, dynamic regime, indicator pipe, solid-phase spectrophotometry.
