| 摘要 |
PURPOSE:To obtain extremely high-quality water from seawater by treating seawater with an acid such as sulfuric acid, then controlling the pH to a high value, drawing off the deposit and desalting the residual seawater. CONSTITUTION:Seawater is adjusted to low pH with a strong acid contg. sulfate ion and then to high pH with a strong alkali, the deposit generated is removed, and the seawater is distilled until its amt. is reduced to a specified value to produce distilled water. A several % dil. sulfuric acid is used as the strong acid contg. sulfate ion and used to control the seawater to low pH. Sodium hydroxide, potassium hydroxide, calcium oxide or their mixture are used as the strong alkali. The residual seawater is conventionally distilled in a well- known desalting plant or distilled under reduced pressure. The seawater is concentrated to 10-20%, the seawater concentrated to <=20% is cooled to deposit salt, and the salt and solid residue are utilized for respective purposes. |
