Synergistic inhibition effect and mechanism of polycation and polyanion on colloidal silica

The silica inhibition of Reverse osmosis (RO) membrane can be treated by adding scale inhibitor. The polycation adipic acid/amine-terminated polyethers D230/diethylenetriamine copolymer (AA/AT/DE) was found to be an effective silica scale inhibitor. The drawback of this scale inhibitor is that small amounts of SiO2 -AA/AT/DE white insoluble floc appear in the solution during the inhibition process. In this study, polyepoxysuccinic acid (PESA) was added to solve this problem. The scale inhibition efficiency of different combinations was tested by static screening tests. The content of silicon dioxide was determined by silicomolybdate spectrophotometric method. In a certain dose range (< 50 ppm), the introduction of PESA can improve the inhibition performance of AA/AT/DE, while, it will have a negative impact when the concentration of PESA was increased to 50 ppm. Based on zeta potential and atomic force microscopy (AFM) topographical analyses, the effect of polycation on the formation of silica particles and the mechanism of the synergistic effect of AA/AT/DE and PESA were placed attention on.