Preparation of high alkalinity polymer ferric sulfate flocculant by new bipolar membrane electrodialysis reactor.

The flocculating ability of the flocculant directly affects the quality of the treated water. Poly-ferric sulfate flocculant (PFS) is a commonly used flocculant. The purpose of this study is to use the electrodialysis process to concentrate the solution and the bipolar membrane electrodialysis to dissociate water to produce acid and alkali to achieve the preparation of poly-ferric sulfate flocculant. The effects of current density, feed flow rate, and sulfuric acid addition on the quality of PFS were tested. Experiments have proved that the increase of current density is beneficial to the increase of PFS alkalinity and turbidity removal rate, and at the same time energy consumption will be reduced. When the current density is 30 mA/cm2, the alkalinity reaches a maximum of 21.04% and the energy consumption is 1.52 kW·h (kg H2SO4). When the current density is 20 mA/cm2, the turbidity removal rate reaches a maximum of 94.23% and the energy consumption is 2.46 kW·h (kg H2SO4). In addition, the solid PFS was subjected to scanning electron microscopy, X-ray diffraction and Fourier-transform infrared spectroscopy tests after vacuum drying to further confirm the structure of the PFS. [ABSTRACT FROM AUTHOR]