Flocs in the electrolyzer

The flocs in the electrolyzer are products of sodium polyacrylate after the anodic reaction. The mechanism of formation is as follows: When saltwater containing Ca2+ and Mg2+ is electrolyzed, sodium hydroxide or sodium carbonate is usually added to cause precipitation and removal of these ions; however, the settling speed is very slow. The use of coagulants such as starch also yields little effect. By using sodium polyacrylate instead, the settling speed can be increased. In the production of caustic soda by the diaphragm process, the alkali solution contains impurities such as 1%–2% sodium chloride and trivalent iron ions, which limit the range of applications for the product. By adding a small amount of sodium polyacrylate, these impurities can be aggregated at the surface or bottom of the alkali solution; after clarification or filtration, caustic soda with very high purity can be obtained. Therefore, sodium polyacrylate is generally used as the saline flocculant in processes that employ Doul barrels, sand filters, and diaphragms. Harm: 1. Adheres to asbestos membranes or ion exchange membranes, increasing cell voltage and power consumption. 2. Clogs the Teflon tube at the saltwater inlet of the ion exchange membrane