A weak cation exchanger by encapsulating silica with maleic anhydride-modified polyvinyl alcohol

A novel weak cation exchanger is described by encapsulating silica with a (or multiple) layer(s) of maleic anhydride-modified polyvinyl alcohol coating(s). The preparation method is facile and fast, which is simply performed by dipping silica particles into maleic anhydride-modified polyvinyl alcohol solution as-synthesized, then filtering and curing thermally, and finally generating a thin coating onto silica particles. Multiple layers of maleic anhydride-modified polyvinyl alcohol coatings can be generated by repeating above steps, offering an easy way to manipulate the capacity. The obtained weak cation exchanger demonstrated high separation efficiency and good selectivity toward common inorganic cations, for example, high plate count of 81 000 per meter was obtained for NH₄ ⁺ . Simultaneous separation of alkali and alkaline earth metals could be achieved within 14 min under isocratic conditions.