Abstract
The proposed plan for the 'Red Sea – Dead Sea project' has raised concerns that the surface water of the Dead Sea would turn white due to gypsum precipitation. The occurrence of such an event would depend on the precipitation kinetics and the morphology of the precipitating crystals. Batch experiments were conducted to study the effect of a phosphonate-based antiscalant on the precipitation kinetics and morphology of gypsum under the conditions of this project. Addition of the antiscalant was found to increase the induction time by a factor of 1.2-5 over the entire range of Dead Sea – Seawater mixtures investigated, depending on brine composition. Once nucleation occurred, the antiscalant also slowed the crystal growth by a factor of 1.2-3. However, when the solutions were seeded with gypsum, the rate of crystal growth with and without antiscalant were similar, within uncertainty. More crystals precipitated from unseeded solutions with no antiscalant and the crystals were smaller and less tabular than those precipitated from unseeded solutions with antiscalant.
Highlights
The proposed plan for the 'Red Sea – Dead Sea project' has raised concerns that the surface water of the Dead Sea would turn white due to gypsum precipitation
Experimental work and thermodynamic calculations have shown that mixing between the calcium rich-Dead Sea (DS) and sulfate rich-SW or reject brine (RB) would lead to an increase in Ωgypsum and gypsum precipitation potential, resulting in an increase in the precipitation rate of gypsum [2,3,4]
The present study focuses on the effect that a phosphonate-based antiscalant (Osmotech 1070), similar to the one that is expected to be used during the Red Sea – Dead Sea project' (RSDSP), has on gypsum precipitation kinetics and morphology in DS–SW and DS-DRB mixtures
Summary
Water demand is a limiting factor for the development, or even for life, in arid regions. It is expected that due to the RSDSP, gypsum precipitation in the lake would become much more significant. Whether whitening of the surface water will take place depends much on the ratio of the rates of nucleation to crystal growth, which would determine the number and size of gypsum crystals, and on the morphology of the precipitated crystals. The antiscalants which would be introduced to the DS during the RSDSP are likely to affect both the kinetics of gypsum precipitation and the morphology of the crystals. The present study focuses on the effect that a phosphonate-based antiscalant (Osmotech 1070), similar to the one that is expected to be used during the RSDSP, has on gypsum precipitation kinetics and morphology in DS–SW and DS-DRB mixtures
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