Precipitation of Calcium Carbonate (CaCO₃) in Water–Monoethylene Glycol Solutions

Abstract

The influence of monoethylene glycol (MEG) on the precipitation process of calcium carbonate at constant supersaturation, 25 °C, and pH 8.5 was investigated. MEG aqueous solutions supersaturated with respect to all calcium carbonate polymorphs were used since they are often encountered in oil production processes where they are used as a hydrate inhibitor. Both seeded and unseeded experiments were done in aqueous supersaturated calcium carbonate solutions containing MEG over the concentration range 0–80% v/v. The presence of MEG affected the induction times and the subsequent rates of precipitation in unseeded, spontaneous precipitation of calcium carbonate. At low values of the supersaturation ratio (SRcalcite = 77.62–15 135.61 or σcalcite = 7.81–122) and for MEG concentrations in the range 30–80% v/v, the solutions were stable for 4 days. At lower than 30% v/v MEG concentrations, calcium carbonate precipitation took place past induction periods between 160 and 500 min. The morphological examination of the precipitates showed that in the presence of low MEG concentrations (10–20% v/v) the precursor vaterite was stabilized. The homogeneous nucleation and growth of calcium carbonate in the absence and in the presence of MEG was also investigated by the inoculation of stable supersaturated solutions with quartz and calcite seed crystals. In both cases nucleation and growth of calcium carbonate was significantly reduced with increasing MEG concentration in the solutions.

Characterization of Scale Deposits in a Drinking Water Network in a Semi-Arid Region

“…It can be said that they have crystallized in a polyform way, and it is common to present this type of crystallization since the changes in both temperature and pressure are factors that influence crystallization. The crystals do not particularly belong to this mineral type due to its crystallized form having more than one type of structure [ 52 ].…”

Effect of Operating Parameters and Foreign Ions on the Crystal Growth of Calcium Carbonate during Scale Formation: An Overview

“…The presence of additives, such as monoethylene glycol (MEG), prevents the vaterite to calcite transformation and stabilizes the formation of the relatively unstable vaterite polymorph. For example, Natsi et al [87] showed that, in the presence of low concentrations of MEG of (10À20% v/v), vaterite was stabilized. At stable supersaturated solutions, seeded with quartz and calcite crystals, the growth of CaCO 3 was significantly reduced with the increase of MEG concentrations.…”

Mineral Scaling in the Presence of Oil–Water Interfaces Combined with the Substrate’s Wettability Effect: From Batch to Microfluidic Experiments

“…More specifically, the precipitation of calcium carbonate in batch reactors made of Pyrex glass at a constant SR value and for different V Ro/a values, was performed in solutions supersaturated with respect to calcium carbonate. The calcium carbonate precipitation kinetics was measured under conditions of constant supersaturation . The effect of hydrodynamics was investigated using solutions of varying SR values under slow (100 rpm) and rapid (200 rpm) stirring conditions in the absence and in the presence of n -dodecane, at constant V Ro/a .…”

“…The calcium carbonate precipitation kinetics was measured under conditions of constant supersaturation. 29 The effect of hydrodynamics was investigated using solutions of varying SR values under slow (100 rpm) and rapid (200 rpm) stirring conditions in the absence and in the presence of n-dodecane, at constant V Ro/a . The precipitation rate of calcium carbonate in the supersaturated solutions and the induction time (t ind ) preceding crystal nucleation were measured.…”