Kinetics of sorption and desorption of HCl and low molecular weight organic acids by styrene and acrylic weak base resins

Several important parameters for the operation of ion exchange resins in water treatment, such as breakthrough capacity, maximum flow rate, efficiency and reversibility of organic matter sorption and desorption, exhibit a close connection with the ion exchange rate. Therefore this value, expressed as the exchange half-time(l_0,5) can be used as a criterion for a proper resin type choice and can also help to judge its use for obtaining treated water of required composition.The sorption and desorption rates of HCl, caproic acid and sulfosalicylic acid by styrene and acrylic weak base resins were estimated and the results obtained with particular resins were compared. Attention has been paid to the effect of gelular and macroporous matrix and solution concentration. Acrylic resins are preferable for sorption and desorption of HCl at low concentrations, at higher concentrations macroporous-styrene resins are better. Sorption of low-molecular organic acids is primarily controlled by selectivity and proceeds faster on acrylic resins at all concentrations. Desorption is governed by the concentration of the elution solution, rather than by selectivity and occurs faster on macroporous styrene resins. The macroporous matrix generally has a substantially smaller kinetic advantage for acrylic than for styrene weak base resins.