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.