Hydration of Carboxyl Fiber Sorbent in Different Ionic Forms

Abstract—Characteristics of the hydration of carboxyl fiber materials in metal forms are calculated. The characteristics obtained are compared with the selectivity of VION KN-1 fiber to metal cations. The Cu²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Mg²⁺, and Ca²⁺ ion exchange is shown to be accompanied by a rearrangement in the second hydration shell of ion exchangers, which is characterized by a decrease in the amount of water. The dehydration enthalpy and the total amount of water diminish when passing from the sodium form to ionic forms of the fiber sorbent. On the basis of results of thermal analysis, the temperature ranges and the amount of removed water are found for each dehydration step of fiber ionic forms. For the Cu²⁺-, Ni²⁺-, Zn²⁺-, and Pb²⁺- forms of the fiber sorbent, the largest differences in the amount of released water are observed at different dеhydration steps as compared to the other forms. It is found that, when passing from the working to the exchangeable form of the sorbent, a change in the amount of moderate hydration water coincides with the most probable order of selectivity of the cations studied to VION KN-1 fiber.