Application of fluorescent-tagged antiscalants for mitigation of membrane scaling by calcium carbonate and calcium phosphate in electrodialysis stack

• V. Gil¹, M. Porozhnyy¹, M. Oshchepkov², V. Ruleva¹, A. Ryabova³, M. Trukhina⁴, S. Tkachenko², N. Pismenskaya¹ and K. Popov⁴

¹ Kuban State University, 149 Stavropolskaya Str., 350040 Krasnodar, Russian Federation 2Mendeleev University of Chemical Technology of Russia, Miusskaya Sq. 9, 125047 Moscow, Russian Federation
² Mendeleev University of Chemical Technology of Russia, Miusskaya Sq. 9, 125047 Moscow, Russian Federation
³ Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov Str., 38, 119991 Moscow, Russian Federation
⁴ JSC “Fine Chemicals R&D Centre”, Krasnobogatyrskaya, Str. 42, b1, 107258 Moscow, Russian Federation

Abstract: Wide application of electrodialysis, which is proven to be highly effective in waste waters treatment and in a broad spectrum of other technologies, is restrained by membrane fouling. The present study is dedicated to the application of fluorescent-tagged antiscalants (ASs) for mitigation of membrane scaling by calcium carbonate and calcium phosphate in the electrodialysis stack within a set of model experiments. Hydroxyethylidenebis(phosphonic acid), conjugated with naphthalimide (HEDP-F), and two fluoresceine-tagged polyacrylates (PAA-F2 and PAA-F2S) are tested. It is demonstrated that all three ASs are highly efficient in CaCO₃ scaling retardation: PAA-F2S>PAA-F2>HEDP-F. The similar efficiency is found for the case of CaHPO₄·2H₂O: PAA-F2S>PAA-F2>>HEDP-F. At the same time, PAA-F2S and PAA-F2 affect the crystal habit of both CaCO₃ and CaHPO₄·2H₂O, while HEDP-F does not. However, due to the visualization of antiscalants it is found that there is no direct relevance between scale inhibition efficacy and an ability of ASs to affect the CaCO₃ crystal growth kinetics and the crystal form of a deposit. The major scaling inhibition effect is detected at the nucleation step: an increase of induction time. However, no definite decrease of the crystal growth rate at the stages following nucleation is registered relative to the blank run. Meanwhile, most of AS molecules are found to stay in aqueous phase till the end of scale formation and only then do they begin to get adsorbed by the deposit. Notably, in the case of CaCO₃, PAA-F2S and PAA-F2 reveal selective sorption on vaterite, a bit less intensive sorption on flake-like modification of calcite and the least sorption on rhomboherdal modification of calcite surfaces. In the same way, PAA-F2S and PAA-F2 demonstrate location on plate-like modifications of CaHPO₄·2H₂O, but reveal no presence on the pellet-like modifications of this mineral. It is shown that there is no direct correlation between location of ASs and crystal growth rate. The observed effects are interpreted in terms of AS interactions with natural nanoimpurities acting as crystallization centers at the nucleation step.

Keywords: electrodialysis, scaling, scale inhibition, fluorescent-tagged antiscalants, antiscalant visualization, chronopotentiometry, fluorescence microscopy, calcium carbonate, calcium phosphate, polyacrylate, bisphosphonate

Int. J. Corros. Scale Inhib., 2024, 13, no. 1, 475-507
doi: 10.17675/2305-6894-2024-13-1-24

Download PDF (Total downloads: 133)

Back to this issue content: 2024, Vol. 13, Issue 1 (pp. 1-629)