Increasing solubility of metal silicates by mixed polymeric antiscalants

Abstract

The increase of silicate solubility is a big challenge for both hot and cold water because it reduces the deposition of metal silicates frequently observed in such systems and causes operational obstacles. The deposition of silicate coats the inner surface of the pipelines in an uncontrolled manner and reduces the harvesting of energy from brines. In this work, the solubility performance of two commercial water-soluble polymeric agents (poly(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA)) of various molecular weights employing dosage from 25 to 100 mg/L was examined. Along with dispersant-type antiscalant, poly(acrylamide) (PAM), poly(vinylsulfonic acid, sodium salt) (PVSA), and poly(vinylphosphonic acid) (PVPA) having chelating acidic groups were employed. Metal silicate deposits were obtained artificially in the lab-scale pressurized reactor. The experimental conditions employed were quite similar to a model power plant located in Çanakkale, Turkey. The concentration of dissolved silica was increased from 130 to 420 mg/L when 100 mg/L PEG 1500 and 25 mg/L PVSA were employed as a mixture. For the atomic-level understanding of the interaction of chelating groups with metal cations, DFT calculations were performed too.

An efficient silica scale inhibiting strategy for geothermal systems: Combination of cationic and anionic polymers

“…The silica scale inhibition efficiencies of six scale inhibitors (PEIE, PEG4000, PEOx, PVP, AA/AMPS, and TA) were tested at 136.7°C with salt. According to the literature, 25 the characterization of test solutions was shown in Table 2. To prepare the solutions, FeCl 2 ·4H 2 O (0.329 g), MgCl 2 ·6H 2 O (0.343 g), CaCl 2 (0.369 g), NaCl (0.359 g), and Na 2 SiO 3 ·9H 2 O (1.183 g) were dissolved by distilled water in 500 mL beakers, and the pH was adjusted to 7.0 ± 0.1 by HCl and NaOH.…”

“…40 However, the combination of PEIE + AA/AMPS showed more resistance to Ca 2+ and Mg 2+ , possibly because AA/AMPS is rich in carboxyl groups, which can chelate some metal ions. 25 The silica scale inhibition efficiencies of PEIE, PEIE + AA/AMPS, and PEG4000 were greatly influenced by temperature (Figure 6c). When temperature increases, the solubility of silica increases, but the intense movement of silicic acid molecules in solution leads to faster self-polymerization, resulting in a decrease in scale inhibition efficiency.…”

“…The silica scale inhibition efficiencies of six scale inhibitors (PEIE, PEG4000, PEOx, PVP, AA/AMPS, and TA) were tested at 136.7 C with salt. According to the literature, 25 automatic control of experimental temperature and sampling with pressure. The above 400 mL solutions ware placed in the reactor.…”

Process design of coal seam gas associated water treatment plants to facilitate beneficial reuse

“…A silica anti-scalant was simulated using a dosage of 100 mg/L, which was a value promoted as the upper limit when minimizing scale formation in the pipework of a power plant [37].…”

The injection of CO2 to hypersaline geothermal brine: A case study for Tuzla region

“…For the former method, organic molecules are commonly employed to eliminate the scaling using either chelating or dispersion mechanisms. In general, these compounds include protonated primary, secondary or tertiary amines (Danilovtseva et al, 2011;Demadis et al, 2008;Spinde et al, 2011), amide moieties (Demadis and Neofotistou, 2007), phosphonate (Spinthaki et al, 2018), ether (Preari et al, 2014), or alcohol functional groups (Topcu et al, 2019). For the latter, the brine is regulated using weak organic acids to reduce pH and increase the solubility.…”