Utilization efficiency of lime consumption during magnesium sulfate precipitation

Ineich, Théodore; Degreve, Christopher; Karamoutsos, Spyridon; Plessis, Chris A. du

doi:10.1016/j.hydromet.2017.09.001

Cited by 8 publications

(4 citation statements)

References 11 publications

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“…Different from calcium carbonate, pH adjustment is not effective for the control of gypsum (CaSO 4 ·2H 2 O) scaling because speciation of the sulfate ion barely changes with respect to solution pH. Instead, the feedwater pH influences the structure of gypsum, specifically the length to width aspect ratio, by altering the crystalline growth rate. , Magnesium sulfate precipitation occurs at a solution pH between 9 and 10.5, higher than calcite precipitation pH ranges, because MgSO 4 is more soluble than CaCO 3 . , Barium sulfate is the least soluble in water among the three sulfate species, and its structure also changes with pH. , …”

Section: Inorganic Scaling In Membrane Desalination Systemsmentioning

confidence: 99%

“…185,186 Magnesium sulfate precipitation occurs at a solution pH between 9 and 10.5, higher than calcite precipitation pH ranges, because MgSO 4 is more soluble than CaCO 3 . 187,188 Barium sulfate is the least soluble in water among the three sulfate species, and its structure also changes with pH. 189,190 Silicic acid or silicate (H 4 SiO 4 ) is a weak acid, and its speciation with respect to solution pH is described by 191…”

Section: Inorganic Scaling In Membrane Desalination Systemsmentioning

confidence: 99%

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Inorganic Scaling in Membrane Desalination: Models, Mechanisms, and Characterization Methods

Rolf

Cao

Huang

et al. 2022

Environ. Sci. Technol.

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Inorganic scaling caused by precipitation of sparingly soluble salts at supersaturation is a common but critical issue, limiting the efficiency of membrane-based desalination and brine management technologies as well as other engineered systems. A wide range of minerals including calcium carbonate, calcium sulfate, and silica precipitate during membrane-based desalination, limiting water recovery and reducing process efficiency. The economic impact of scaling on desalination processes requires understanding of its sources, causes, effects, and control methods. In this Critical Review, we first describe nucleation mechanisms and crystal growth theories, which are fundamental to understanding inorganic scale formation during membrane desalination. We, then, discuss the key mechanisms and factors that govern membrane scaling, including membrane properties, such as surface roughness, charge, and functionality, as well as feedwater characteristics, such as pH, temperature, and ionic strength. We follow with a critical review of current characterization techniques for both homogeneous and heterogeneous nucleation, focusing on the strengths and limitations of each technique to elucidate scale-inducing mechanisms, observe actual crystal growth, and analyze the outcome of scaling behaviors of desalination membranes. We conclude with an outlook on research needs and future research directions to provide guidelines for scale mitigation in water treatment and desalination.

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Section: Inorganic Scaling In Membrane Desalination Systemsmentioning

confidence: 99%

Section: Inorganic Scaling In Membrane Desalination Systemsmentioning

confidence: 99%

Inorganic Scaling in Membrane Desalination: Models, Mechanisms, and Characterization Methods

Rolf

Cao

Huang

et al. 2022

Environ. Sci. Technol.

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“…In this work, an attempt is made to improve the latter method further by separating the precipitation of magnesium hydroxide and gypsum in solution by using additives. This has the potential of enhancing the economic and environmental viability of the process, and the results can be extended to separate gypsum precipitation in time from rapidly precipitating solids other than Mg(OH) 2 .…”

Section: Introductionmentioning

confidence: 99%

Differential Precipitation of Mg(OH)2 from CaSO4·2H2O Using Citrate as Inhibitor—A Promising Concept for Reagent Recovery from MgSO4 Waste Streams

et al. 2020

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In hydrometallurgical processing and acidic wastewater treatment, one of the neutralizing agents employed is MgO or Mg(OH)2. At the end of this process, the resulting solution, which is rich in SO42− and Mg2+ is treated with lime to remove (or minimize the amount) of these ions via the precipitation of Mg(OH)2 and CaSO4·2H2O (gypsum). In our work, an attempt was made to separate the two solids by increasing the induction time of the gypsum precipitation, thus regenerating relatively pure Mg(OH)2 which could be reused in wastewater treatments or hydrometallurgical processing circuits, and in this way, significantly enhancing the economic viability of the process. During our experiments, the reaction of an MgSO4 solution with milk of lime prepared from quicklime was studied. The effects of a range of organic additives, which can slow down the precipitation of gypsum have been assessed. The process was optimized for the most promising inhibiting agent—that is, the citrate ion. The reactions were continuously monitored in situ by conductometric measurements with parallel monitoring of solution pH and temperature. ICP-OES measurements were also carried out on samples taken from the reaction slurry. The composition of the precipitating solids at different reaction times was established by powder XRD and their morphology by SEM. Finally, experiments were carried out to locate the additive after the completion of the precipitation reaction to get information about its potential reuse.

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“…The precipitation of the metal hydroxides can be separated if the neutralization is carried out in two steps using magnesium oxide or hydroxide in the first, instead of lime [121][122][123].…”

Section: Differential Precipitation Of Mg(oh)2 From Gypsummentioning

confidence: 99%

The kinetics of gypsum precipitation, the inhibiting effect of citric acid and its use in the differential precipitation of Mg(OH)₂ from CaSO₄·2H₂O

Ziegenheim

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The crystallization of solids from supersaturated solutions is a source of numerous complications during a range of industrial processes: undesirable precipitates may clog pipelines, foul membranes, contaminate the target compounds of a process, lower the effectiveness of heat-exchange via scale formation, etc. Calcium sulfate dihydrate (CaSO4·2H2O or gypsum) is one of the most common of such solids, therefore during the last decades, numerous studies were dedicated to the investigation of the precipitation kinetics and method development potentially suitable for precipitation control and inhibition. In the experimental work leading to this dissertation, the kinetics of gypsum precipitation was studied in the entire experimentally available concentration range. The impact of citric acid (or citrate ion) on the reaction was investigated in detail including some experiments in unconventional media. The acquired experience was used to optimize the differential precipitation of magnesium hydroxide from gypsum, which provides a promising method to improve the treatments of acidic wastewaters economically and in environmentally friendly way, and could also be useful in desalination processes.

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Utilization efficiency of lime consumption during magnesium sulfate precipitation

Cited by 8 publications

References 11 publications

Inorganic Scaling in Membrane Desalination: Models, Mechanisms, and Characterization Methods

Inorganic Scaling in Membrane Desalination: Models, Mechanisms, and Characterization Methods

Differential Precipitation of Mg(OH)2 from CaSO4·2H2O Using Citrate as Inhibitor—A Promising Concept for Reagent Recovery from MgSO4 Waste Streams

The kinetics of gypsum precipitation, the inhibiting effect of citric acid and its use in the differential precipitation of Mg(OH)₂ from CaSO₄·2H₂O

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Utilization efficiency of lime consumption during magnesium sulfate precipitation

Cited by 8 publications

References 11 publications

Inorganic Scaling in Membrane Desalination: Models, Mechanisms, and Characterization Methods

Inorganic Scaling in Membrane Desalination: Models, Mechanisms, and Characterization Methods

Differential Precipitation of Mg(OH)2 from CaSO4·2H2O Using Citrate as Inhibitor—A Promising Concept for Reagent Recovery from MgSO4 Waste Streams

The kinetics of gypsum precipitation, the inhibiting effect of citric acid and its use in the differential precipitation of Mg(OH)2 from CaSO4·2H2O

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The kinetics of gypsum precipitation, the inhibiting effect of citric acid and its use in the differential precipitation of Mg(OH)₂ from CaSO₄·2H₂O