Novel eco-friendly antiscalant for major inorganic scaling control: laboratory tests and scale-up in a pilot RO unit

Abstract

Eco-friendly antiscalants have garnered considerable interest, particularly regarding their structural development and performance assessment. In this study, polyaspartic acid (PASP) and a novel derivative, polyaspartic acid-2 amino ethane sulfonic acid (PASP-SEA), were synthesized. For comparative analysis, two additional green antiscalants were utilized: sodium carboxymethylcellulose (CMC) and a citric acid-sodium citrate mixture (CA-SC). The inhibition efficiency (IE. %) of PASP, PASP-SEA, CMC, and CA-SC was evaluated through static tests. The saline solution was derived from a brine RO unit. The optimal doses determined at pH = 8.2 and LSI = 2.9 were 1, 0.25, 0.5, and 5 ppm, respectively. At an antiscalant concentration of 1 ppm and pH = 7.07, the IE. ranked PASP-SEA > PASP > CMC > CA-SC with values of 94%, 100%, 38%, and 29%, respectively. All antiscalants exhibited improved performance with increasing ionic strength (I). Dynamic tests were performed on the antiscalants using pilot RO unit, revealing a significantly lowest scaling rate for PASP-SEA. UV/Vis, FTIR, and GP/SEC spectra clearly verified PASP-SEA synthesis. While PASP-SEA was slightly less biodegradable than PASP, it had superior thermal stability, and XRD/SEM revealed optimal performance with the highest crystalline deformation. Furthermore, an economic assessment of each antiscalant was conducted.