| 摘要 |
Highly acidic cation-exchange synthetic resins, such as sulphonated styrene-divinyl benzene copolymers, are usually contaminated by acid formed during sulphonation. The production of waste acid as a by-product of maximum sulphuric acid concentration is achieved when the resin discharged from the sulphonating unit and contaminated with acid is washed with water in at least two washing units of which one is a multi-stage washer while the other is a countercurrent washing column, by taking care to keep the quantity of washing liquor at a minimal level and avoiding the osmotic and heat load on the resin caused by dilution of the acid. The concentration of the sulphuric acid is controlled such that the resin is buoyant in the multistage washing unit but causes the resin to settle out in the counter current column. Part of the heat formed by the dilution of the concentrated sulphuric acid with water is removed during the dilution of the resin-free solutions. <IMAGE> |
