Scale evaluation and antiscalant testing based on fluorescent probe technology in RO process

Inventing the technology based on fluorescent probes to detect antiscalants in reverse osmosis (RO) concentrated water is of great significance for guiding the use of antiscalant and the control of scale. In this study, Amino trimethylene phosphonic acid (ATMP) was taken as the representative of the antiscalant, and a new fluorescent probe for ATMP detection was designed and synthesized. The new fluorescent probe showed high accuracy for ATMP detection (R2 > 0.94) and resistance to the interference of ions (change rate <3%). Further, the use of probe to detect the antiscalant in RO concentrate and realize the evaluation of the scaling phenomenon was carried out. The model of the relationship between the probe fluorescence intensity and the concentration of precipitated ions was established to analyze the scale evaluation mechanism of the probe. Meanwhile, Critical fluorescence intensity (CFI) was introduced for scale evaluation. The results showed that the new probe could accurately judge the formation of scale under the condition of different antiscalant concentrations, and 926 ± 20 a.u. was judged as CFI for scaling evaluation. Finally, results of the new probe detection in RO scale evaluation test were consistent with the membrane flux and SEM detection, indicating that the probe can accurately evaluate scale during the RO operation. This research can provide technical support for the precise application of antiscalants and scale inhibition.