A Comparative Study of Phosphonate and Phosphorus-Free antiscalantEfficiency by Static and Dynamic Methods. Do we have Reliable Tools for an Adequate Reagent Selection?

Abstract

A relative ability of four industrial samples of phosphorus-free polymers (polyaspartate, PASP; polyepoxysuccinate, PESA; polyacrylic acid sodium salt, PAAS; copolymer of maleic and acrylic acid, MA-AA) and of two phosphonates (aminotris(methylenephosphonic acid), ATMP; 1-hydroxyethane-1,1-bis(phosphonic acid), HEDP) to inhibit calcium carbonate precipitation at a dosage 10 mg•dm -3 is tested in static experiments following the NACE Standard TM0374-2007 and in a dynamic modeоfevaporation plant for Caspian Sea water imitate. The reagent efficiency ranking following NACE Standard gives evidently a preference to phosphonates over polymers: ATMP~HEDP>PESA (400-1,500 Da) ~PASP (1,000-5,000 Da)>PAAS (3,000-5,000 Da) ~MA-AA. At the same time the kinetic tests exhibit the better efficiency of PESA and MA-AA: PESA>MA-AA>PAAS~HEDP>ATMP~PASP. Therefore, a lot of work is still needed to elaborate a system of laboratory tests for antiscalants in order to provide reliable assessment and selection on their way from laboratory to industry.

Fluorescent-Tagged Antiscalants—The New Materials for Scale Inhibition Mechanism Studies, Antiscalant Traceability and Antiscaling Efficacy Optimization during CaCO3 and CaSO4·2H2O Scale Formation

“…Nevertheless, there is a qualitative correlation in the order of reagent effectiveness between continuous saturation (present work) and supersaturation provided “all at once” (NACE test) for both calcium carbonate and gypsum deposits: PAA-F1 > ADMP-F > HEDP-F. Notably, there was a lack of correlation between the NACE results and the estimates previously obtained on the basis of induction time measurements [ 47 ].…”

Enhanced hydraulic cleanability of biofilms developed under a low phosphorus concentration in reverse osmosis membrane systems

“…Our study recommends a low-cost optimization strategy for reverse osmosis desalination plants by lowering or avoiding the increase of the phosphorus concentration in the feed water by adding different chemicals (antiscalants, acids, biocides) to develop a biofilm with enhanced hydraulic cleanability. The phosphates added to the antiscalants get concentrated in the brine and act as a nutrient for algae promoting eutrophication when brine is discharged into the sea generating environmental problems ( El Din et al., 1994 ; Popov et al., 2017 ). Besides the environmental advantages of dosing phosphorus-free antiscalants, if phosphorus limitation is combined with carbon restriction after feed water pretreatment, the approach could delay biofilm formation prolonging the system performance ( Javier et al., 2020 ).…”