• Journal of Korean Society on Water Environment
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• v.36 no.1
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• pp.48-54
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• 2020

This paper presents a screening protocol for the selection of solvents available for the solvent extraction desalination process. The desalination solvents hypothetically and theoretically require the capability of (1) Forming hydrogen bonds with water, (2) Absorbing some water molecules into its non-polar solvent layer, (3) Changing solubility for water-solvent separation, and (4) Rejecting salt ions during absorption. Similar to carboxylic acids, amine solvents are solvent chemicals applicable for desalination. The key parameter for selecting the potential solvent was the octanol-water partitioning coefficient (Kow) of which preferable value for desalination was in the range of 1-3. Six of the 30 amine solvents can absorb water and have a variable, i.e., temperature swing solubility with water molecule for water-solvent separation. Also, the hydrogen bonding interaction between solvent and water must be stronger than the ion-dipole interaction between water and salt, which means that the salt ions must be broken from the water and only water molecules absorbed for the desalination. In the final step, three solvents were selected as desalination solvents to remove salt ions and recover water. The water recovery of these three solvents were 15.4 %, 2.8 %, 10.5 %, and salt rejection were 76 %, 98 %, 95 %, respectively. This study suggests a new screening protocol comprising the theoretical and experimental approaches for the selection of solvents for the desalination method which is a new and challenges the desalination process in the future.

• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.53-57
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• 2013

For the purpose of development of the extraction process of lithium ion from concentrated water eliminated from desalination process, an experimental research on the solvent extraction of lithium ion from aqueous solutions was performed. The effects of operating parameters, such as concentration of extractant, ratio of extracting solution/aqueous solution, pH of aqueous solution, were examined. The effect of sodium chloride, the major component of sea water, was also examined. Lithium ion in aqueous solutions of pH=10.2~10.6 adjusted by ammonia solution was most effectively extracted by extracting solution composed of 0.02 M TTA and 0.04 M TOPO in kerosine. The addition of sodium chloride in lithium aqueous solution significantly interfered the extraction of lithium ion.

• Membrane and Water Treatment
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• v.10 no.3
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• pp.207-212
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• 2019

Non-aqueous solvents (NASs) are generally known to be barely miscible, and reactive with polar compounds, such as water. However, water can interact with some NASs, which can be used as a new means for water recovery from saline water. This study explored the fate of water and salt in NAS, when saline water is mixed with NAS. Three amine solvents were selected as NAS. They had the same molecular formula, but were differentiated by their molecular structures, as follows: 1) NAS 'A' having the hydrophilic group ($NH_2$) at the end of the straight carbon chain, 2) NAS 'B' with symmetrical structure and having the hydrophilic group (NH) at the middle of the straight carbon chain, 3) NAS 'C' having the hydrophilic group ($NH_2$) at the end of the straight carbon chain but possessing a hydrophobic ethyl branch in the middle of the structure. In batch experiments, 0.5 M NaCl water was blended with NASs, and then water and salt content in the NAS were individually measured. Water absorption efficiencies by NAS 'B' and 'C' were 3.8 and 10.7%, respectively. However, salt rejection efficiency was 98.9% and 58.2%, respectively. NAS 'A' exhibited a higher water absorption efficiency of 35.6%, despite a worse salt rejection efficiency of 24.7%. Molecular dynamic (MD) simulation showed the different interactions of water and salts with each NAS. NAS 'A' formed lattice structured clusters, with the hydrophilic group located outside, and captured a large numbers of water molecules, together with salt ions, inside the cluster pockets. NAS 'B' formed a planar-shaped cluster, where only some water molecules, but no salt ions, migrated to the NAS cluster. NAS 'C', with an ethyl group branch, formed a cluster shaped similarly to that of 'B'; however, the boundary surface of the cluster looked higher than that of 'C', due to the branch structure in solvent. The MD simulation was helpful for understanding the experimental results for water absorption and salt rejection, by demonstrating the various interactions between water molecules and the salts, with the different NAS types.

• Journal of Conservation Science
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• v.31 no.2
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• pp.95-104
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• 2015

Excavated archaeological cast iron objects in improper storage are quickly corroded and disintegrated into block and powder finally. Hence desalination treatment which is a way of removing internal corrosive factors, especially chloride ion, is an important process. But desalination is often omitted or objects are dehydrated by alcohol because the destruction of objects could occur during desalting. Although current desalting methods mostly use an aqueous alkali solution, $OH^-$ ions of water could accelerate corrosion and broaden internal cracks cause of high surface tension. Therefore this study experimented desalting using ethyl alcohol, which is low surface tension, to investigate an effect of desalination. As a result, desalting using ethyl alcohol showed the similar or more effective results of desalting using water. In addition, as aspects of desalting safety, ethyl alcohol desalting method was smaller destruction of objects and extraction of Fe from the objects than the aqueous alkali solution. However, this study explored the possibility of desalting methods using organic solvent in fieldwork, so the results would provide basic date for making the safe and effective desalting method for archaeological cast iron objects through further experiments.

• Resources Recycling
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• v.25 no.4
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• pp.3-10
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• 2016

A lot of researches have been carried out on the recovery of resources from the seawater all over the world. The boron concentration in seawater is low about at 4.5ppm, but considering the volume of seawater, the total weight of dissolved boron amounts to about 5.4 trillion tons. The boron is an essential resource in about 300 kinds of industries. Korea has imported all of the boron and spent more than 700 billion won each year. In this article, we introduce the domestic and international research trends and technologies for removing or recovering the boron from wastewater and seawater. Most of the researches have been conducted to remove the boron from the desalination process, and to recover the boron mainly from wastewater and brine. The technique for the recovery of the dissolved boron includes the ion exchange, which is the most representative, the adsorption membrane filtration (AMF), solvent extraction, and so on.