The solubility of calcium sulphate as a factor in the extraction of magnesia from sea water

1946 ◽  
Vol 65 (4) ◽  
pp. 111-113
Author(s):  
F. C. Gilbert ◽  
W. C. Gilpin
Keyword(s):  
Sea Water ◽  
Calcium Sulphate

scholarly journals Spring and surface water quality of the Cyprus ophiolites

2002 ◽  
Vol 6 (5) ◽  
pp. 797-817 ◽  
Author(s):  
C. Neal ◽  
P. Shand
Keyword(s):  
Water Quality ◽  
Sea Water ◽  
Stream Water ◽  
Chemical Reactivity ◽  
Surface Water Quality ◽  
Calcium Sulphate ◽  
Stream Water Quality ◽  
Troodos Ophiolite ◽  
High Calcium ◽  
Hydrolysis Of

Abstract. A survey of surface, spring and borehole waters associated with the ophiolite rocks of Cyprus shows five broad water types (1) Mg-HCO3, (2) Na-SO4-Cl-HCO3, (3) Na-Ca-Cl-SO4-OH-CO3, (4) Na-Cl-SO4 and (5) Ca-SO4. The waters represent a progression in chemical reactivity from surface waters that evolve within a groundwater setting due to hydrolysis of the basic/ultrabasic rock as modified by CO2-weathering. An increase in salinity is also observed which is due to mixing with a saline end-member (modified sea-water) and dissolution of gypsum/anhydrite. In some cases, the waters have pH values greater than 11. Such high values are associated with low temperature serpentinisation reactions. The system is a net sink for CO2. This feature is related not only to the hydrolysis of the primary minerals in the rock, but also to CaCO3 or Ca-Mg-CO3 solubility controls. Under hyperalkaline conditions, virtually all the carbon dioxide is lost from the water due to the sufficiently high calcium levels and carbonate buffering is then insignificant. Calcium sulphate solubility controls may also be operative when calcium and sulphate concentrations are particularly high. Keywords: Cyprus, Troodos, ophiolite, serpentinisation, spring, stream, water quality, bromide, iodine, boron, trace elements, hyperalkaline.

scholarly journals Transformation Kinetics of Burnt Lime in Freshwater and Sea Water

2020 ◽  
Author(s):  
Harald Justnes ◽  
Carlos Escudero-Oñate ◽  
Øyvind Aaberg Garmo ◽  
Martin Mengede
Keyword(s):  
Calcium Hydroxide ◽  
Magnesium Hydroxide ◽  
Open System ◽  
Sea Water ◽  
Particle Surface ◽  
Calcium Sulphate ◽  
Burnt Lime ◽  
Common Ion ◽  
The Common ◽  
Kinetics Of

The reaction kinetics of burnt lime (CaO) in contact with sea water has been elucidated and compared to its behaviour in fresh water. In the first minutes of contact between burnt lime and water, it "slaked" as CaO reacted with water to yield calcium hydroxide (Ca(OH)2). Subsequently, calcium hydroxide reacted with magnesium, sulphate and carbonate from the sea water to yield magnesium hydroxide (Mg(OH)2), calcium sulphate dihydrate (gypsum, CaSO4·2H2O) and calcium carbonate (CaCO3), respectively. In a closed system of 1% CaO in natural sea water (where the supply of sulphate, magnesium and carbonate is limited), more than 90% reacted within the first 5 hours. It is foreseen that in an open system, like a marine fjord, it will react even faster. The pH 8 of sea water close to the CaO particle surface will immediately increase to a theoretical value of about 12.5 but will, in an open system with large excess of sea water, rapidly fall back to pH 10.5 being equilibrium pH of magnesium hydroxide. This is further reduced to < 9 due to the common ion effect of dissolved magnesium in sea water and then be diluted to the sea water background pH, about 8. Field test dosing CaO particles to sea water showed that the pH of water between the particles stayed around 8.

Calcium sulphate scale deposition in sea water evaporators

Desalination ◽  
1967 ◽  
Vol 2 (3) ◽  
pp. 308-324 ◽  
Author(s):  
H.C. Simpson ◽  
M. Hutchinson
Keyword(s):  
Sea Water ◽  
Calcium Sulphate ◽  
Scale Deposition

On The Transition of Calcium Sulphate in Water and in Concentrated Sea Water

1934 ◽  
Vol 55 (10) ◽  
pp. 1051-1059
Author(s):  
Tatsurô TORIUMI ◽  
Ryôsaburô HARA
Keyword(s):  
Sea Water ◽  
Calcium Sulphate

scholarly journals Bioprecipitation of Calcium Carbonate Crystals by Bacteria Isolated from Saline Environments Grown in Culture Media Amended with Seawater and Real Brine

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
G. A. Silva-Castro ◽  
I. Uad ◽  
A. Gonzalez-Martinez ◽  
A. Rivadeneyra ◽  
J. Gonzalez-Lopez ◽  
...  
Keyword(s):  
Organic Matter ◽  
Calcium Carbonate ◽  
Sea Water ◽  
Culture Media ◽  
Calcium Sulphate ◽  
Carbonic Anhydrase Activity ◽  
Rrna Gene ◽  
Crystal Formation ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation

The precipitation of calcium carbonate and calcium sulphate by isolated bacteria from seawater and real brine obtained in a desalination plant growth in culture media containing seawater and brine as mineral sources has been studied. However, only bioprecipitation was detected when the bacteria were grown in media with added organic matter. Biomineralization process started rapidly, crystal formation taking place in the beginning a few days after inoculation of media; roughly 90% of total cultivated bacteria showed. Six major colonies with carbonate precipitation capacity dominated bacterial community structure cultivated in heterotrophic platable bacteria medium. Taxonomic identification of these six strains through partial 16S rRNA gene sequences showed their affiliation with Gram-positiveBacillusandVirgibacillusgenera. These strains were able to form calcium carbonate minerals, which precipitated as calcite and aragonite crystals and showed bacterial fingerprints or bacteria calcification. Also, carbonic anhydrase activity was observed in three of these isolated bacteria. The results of this research suggest that microbiota isolated from sea water and brine is capable of precipitation of carbonate biominerals, which can occurin situwith mediation of organic matter concentrations. Moreover, calcium carbonate precipitation ability of this microbiota could be of importance in bioremediation of CO2and calcium in certain environments.

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