WO2014188450A1 - Improved process to retain nutritious constituents in potable water obtained through desalination - Google Patents

Improved process to retain nutritious constituents in potable water obtained through desalination Download PDF

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WO2014188450A1
WO2014188450A1 PCT/IN2014/000348 IN2014000348W WO2014188450A1 WO 2014188450 A1 WO2014188450 A1 WO 2014188450A1 IN 2014000348 W IN2014000348 W IN 2014000348W WO 2014188450 A1 WO2014188450 A1 WO 2014188450A1
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ppm
water
pani
desalination
ion
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PCT/IN2014/000348
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French (fr)
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Pushpito Kumar Ghosh
Vinod Kumar Shahi
Amit Kumar THAKUR
Niharika SRIVASTAVA
Tina CHAKRABARTY
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Council Of Scientific & Industrial Research
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D61/00Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis, ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42Electrodialysis; Electro-osmosis Electro-ultrafiltration
    • B01D61/44Ion-selective electrodialysis
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D67/00Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081After-treatment of organic or inorganic membranes
    • B01D67/0093Chemical modification
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/58Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/60Polyamines
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/76Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74
    • B01D71/82Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74 characterised by the presence of specified groups, e.g. introduced by chemical after-treatment
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/46Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/4604Treatment of water, waste water, or sewage by electrochemical methods for desalination of seawater or brackish water
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/46Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4693Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/08Seawater, e.g. for desalination
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124Water desalination

Abstract

The present invention describes a selective electrodialysis process for the retention of useful mineral ions in potable water obtained from desalination process. More particularly, the invention relates to selective electrodialysis of brackish and seawater to obtain potable water rich in useful constituents such as Ca2+, Mg2+, SO4 2-, and HCO3 -, while discarding much of the NaCI present in the feed water. Polyaniline (PANI)-modified ion exchange membranes are used for carrying out the claimed process.

Description

IMPROVED PROCESS TO RETAIN NUTRITIOUS CONSTITUENTS IN POTABLE WATER OBTAINED THROUGH DESALINATION
Field of invention
The present invention relates to an improved electrodialytic process of brackish water desalination to obtain potable water rich in nutritious constituents Ca2+, Mg2+, S04 2", and HC03 ". Particularly, the present invention relates to retention of useful mineral ions in potable water obtained from desalination process. More particularly, the invention relates to selective electrodialysis of brackish and seawater to obtain potable water rich in useful constituents such as Ca2+, Mg2+, S04 2", and HC03 ", while discarding much of the NaCl present in the feed water.
Background of invention
Reference may be made to the article by Srivastava et al. (J. Ind. Water Works Asso. 2010, January-March, 50) and references therein which indicate the mineral constituents desirable in potable water and their amounts. It will be evident from these articles that divalent constituents such as Ca2+, Mg2+, S04 2" are required in larger amounts than Na+ and CI".
Reference may be made to numerous articles in the prior art which emphasis the importance of desalination to make saline waters potable.
It is also well known in the prior art that brackish and seawater can be made potable by removing excess salts by any of different methods such as thermal distillation, reverse osmosis, electrodialysis, etc.
It is well known in the, prior art that thermal desalination of saline waters yields distillate water with virtually no salt, be it NaCl or essential mineral constituents. Such waters ideally require remineralisation to make them fit for consumption.
Reference is made to the article by U. Yermiyahu et al. (Science 318 (2007) 920) wherein it is stated that desalination by reverse osmosis not only separates the undesirable salts from the water, but also removes basic nutrient ions like Ca2+, Mg2+, S04 2" etc. It is well known in the prior art that electrodialysis is useful for desalination applications but no report exists of its utility for production of potable water which is healthier by virtue of greater retention of nutritious constituents during desalination. Reference may be made to the articles by Onoue et al. (Denki Kagaku 1961, 29, 544), Soga (Bull. Soc. Sea Water Sci. Jpn. (Nippon En Gakkai-Shi) 1962, 16, 24), Sata et al. (J Polym. Sci., Polym. Chem. Ed. 1979, 17, 2071 ; J. Membr. Sci. 2002, 206, 31) wherein modification of ion-exchange membranes are reported which improve the selectivity of separations of similarly charged ions. However, none of these papers discuss the utility of such selectivity in desalination processes for production of healthier drinking water.
Reference may also be made to the article by Sata et al. (J Phys. Chem. 1995, 99, 12875) wherein surface modification of ion-exchange membranes with polyaniline is reported and it is further demonstrated that these membranes have superior selectivity towards differentiation between monovalent and bivalent ions of similar charge. However, there is no mention of its application in electrodialysis-based desalination for the production of healthier drinking water.
Objects of the invention
The main object of the present invention is to provide an improved electrodialytic process of brackish water desalination to obtain potable water rich in nutritious constituents Ca2+, Mg2+, S04 2", and HC03 ".
Another object of the present invention is to retain basic inorganic nutrient ions in treated water obtained in the course of desalination of saline waters. Another object is to obtain product water with desired concentration levels of such inorganic nutrient ions so as to make the water healthiest for consumption.
Another object is to provide such healthier water through the process of electrodialysis (ED). Another object is to modify conventional ion exchange membranes with weakly basic conducting polymers such as polyaniline and polypyrrole as disclosed in the prior art to enhance the selectivity of electrodialytic removal of NaCl while retaining the more desired constituents such as Ca2+, Mg2+, S04 2", and HC03 '.
Another object is to extend the benefit of such selective removal of NaCl to obtain irrigation water enriched in Ca , Mg , S04 and HC03 " in cost-effective manner from brackish and seawater. Summary of the invention
Accordingly, the present invention provides an improved electrodialytic process of brackish water desalination to obtain potable water rich in Ca2+, Mg2+, S04 2", and HCO3' while discarding NaCl present in the feed water, wherein the improvement consists of using polyaniline (PANI)-modified ion exchange interpolymer membranes, the said process comprises passing feed water in an electrodialysis unit containing 10-12 cell pairs of polyaniline (PANI)-modified ion exchange interpolymer membranes between an anode and a cathode at 1.5 to 2.0 V/cell pair to obtain potable water rich in Ca2+, Mg2+, S04 2", and HC03 ".
In an embodiment of the present invention aniline concentration used in polyaniline (PANI)-modified ion exchange interpolymer membranes is in the range of 5-20% (v/v) in 0.1-1.0 M HC1.
In one embodiment of the present invention effective area per membrane is in the range of 80 -82 cm2.
In another embodiment of the present invention the feed water used had total dissolved solids (TDS) in the range of 3000-4000 ppm, 917 to 1255 ppm Na+, 1468- 1937 ppm CI", 40-60 ppm K+, 100-150 ppm Mg2+, 30-60 ppm Ca2+, 230-270 ppm S04 2\ and 20-30 ppm total alkalinity (as CaC03)
In another embodiment of the present invention the potable water had overall TDS in the range of 440 to 450 ppm , 100-1 10 ppm Na+, 3-5 ppm K+, 20-30 ppm Mg2+, 10-20 ppm Ca2+, 140-170 ppm CI", 75-100 ppm S04 2', and 50-100 ppm total alkalinity (as CaC03). Still in another embodiment of the present invention the current efficiency is in the range of 85 to 90%.
Still in another embodiment of the present invention PANI modification on the both surfaces of the ion-exchange membrane was achieved by the polymerization of aniline) in the presence of oxidant ((NH4)2S208) in aqueous solution.
Still in another embodiment of the present invention oxidant concentration may be varied between 0.1-3.0M, for achieving desired loading of the PANI in the ion- exchange membrane.
Still in another embodiment of the present invention the desired loading of PANI in the ion-exchange membrane may be obtained by varying the concentration of (NH4)2S208, anilne and equilibration time.
Still in another embodiment of the present invention PANI modification of ion- exchange membrane controls the electro-transport of different mono-valent and bi- valent ions across the membrane under electrodialytic conditions.
Still in another embodiment of the present invention, PANI modification was carried out with CEM containing acidic functional groups and AEM containing basic functional groups.
Still in another embodiment of the present invention the membrane is conditioned prior to evaluation of membrane properties and membrane performance.
Still in another embodiment of the present invention electrodialysis process with PANI modified ion-exchange membranes exhibits relatively high energy consumption and low current efficiency in compare with unmodified ion-exchange membranes under similar experimental conditions.
Still in another embodiment of the present invention PANI modified ion exchange membrane is found suitable for electrodialytic desalination and is used for all applications where such ion exchange membranes are used.
Brief description of the drawing
Fig 1 : Schematic drawing electrodialysis unit. Detailed description of the Invention
Brackish water desalination through distillation produces essentially distilled water devoid of all minerals. In reverse osmosis (RO) all dissolved minerals get depleted but depletion of useful minerals (Mg2+, Ca2+, S04 2" and C03 27HC03 ") are even greater extent than Na+ and CI". Conventional electrodialysis (EDconv) too fails to meet the desired objective, all constituents being depleted in similar proportions with respect to feed. Consequently, re-mineralisation is necessary but in many cases not implemented. We report selective electrodialysis (EDsei), for production of desalinated water containing relatively higher proportions of desirable minerals. Commercial cation- and anion exchange membranes (CEMCNS and AEMCNS) were coated with polyaniline (PANI), and the resultant membranes (PANI-CEMCNS, PANI- AEMCNS) were characterised by physico-chemical and electrochemical techniques. Due to sieving and hydrophobic effects, the PANI coating was demonstrated to improve the retention of Mg2+, Ca2+ and S04 2" during desalination. Retention of mineral constituents was further enhanced with PANI modified styrene-co- divinylbenzene-polyethylene-based interpolymer cation- and anion-exchange membranes (CEMn> and AEMiP). The total alkalinity of the treated stream increased during EDsei, presumably due to concentration polarization accompanied by preferential transport of H+ over OH". The process efficiency was only marginally lower (5%) for EDsei, suggesting that this approach to desalination may be of practical importance.
The present invention provides a process for the desalination of brackish and sea water for producing mineral en-reached drinking and irrigation water. The said process comprises the following steps:
a) Poly(aniline) (PANI) modification of ion-exchange membranes (cation- and anion-exchange membranes),
b) For PANI modification of cation-exchange membrane (CEM), first step consisted of exchanging the H+ initially present in CEM with anilinium species using a 10% (v/v) aniline in 1 M HC1 solution added to the reagent compartment while stirring for 1-3 hours at room temperature. The cell was then rinsed with distilled water. Polymerization was induced in the second step by adding the 1 M (NH4)2S208 aqueous solution under stirring for various time intervals at room temperature.
c) The same procedure was adopted for the preparation of PANI modified anion- exchange membranes, except that both steps were reversed; i.e., step two was performed first, and then step one, in order to exchange S208 with OH . d) Before use, PANI modified ion-exchange membranes were conditioned in 1 M HC1 solution for 24 hour to ensure complete protonation of PANI. The present invention relates to the actual production of desalinated water with better retention of nutritious constituents (Mg2+, Ca2+, S04 2" and C03 27HC03 ") by EDse using PANI modified ion-exchange membranes. Experiments were conducted with 3000 ppm and 4000 ppm diluted sea water. Ion chromatographic analysis data also confirmed absence of N03 ", P04 " and Br" in the feed water. EDconv and EDsei were comparatively assessed for desalination to similar extent (350-460 ppm product water). In the case of the former, the ratios of mineral ion concentrations in product water remained the same as those in feed water. Although EDsei experiments using commercial CEMCNS/AEMCNS produced desalinated water with relatively higher nutritious mineral content, the overall improvement was modest and the performance of the PANI modified CEM was particularly poor. PANI-CEM1P/PANI-AEMiP cell pair fared better in contrast. Obtained data confirmed relatively higher concentrations of not only S04 2" and HC03 ' but of Mg2+ and Ca + also in desalinated product water.
The study set out to realize a better potential from desalination through electrodialysis by enhancing the relative retention of bivalent ions which are nutritious for the body. The strategy involved PANI modification known to impart such selectivity through a combination of sieving and hydrophobic effects. Judicious selection of the ion-exchange membranes appeared to be of critical importance, however, to realize the desired results through PANI modification. Of the two sets of membrane pairs studied, modification of the interpolymer membranes was found to be more effective for retention of the majority of nutritious mineral ions higher proportions in the desalinated water compared to the feed water. Expectedly, K+ behaved like Na+ and its retention could not be enhanced. Not only did EDsei with interpolymer membrane produce a superior effect, it did so with better process efficiency. The observation of an increase in pH during EDsei was an advantage in as much as bicarbonate loss through ED was compensated by re-absorption of C02 from the atmosphere. However, too high a pH of TS may not be acceptable and the process parameters will need to be fine-tuned accordingly. Further improvements in the relative rejection of NaCl will also be necessary to comply with the desired specifications of nutritious potable water. Method of selective desalination by EDsei eliminates the need for re-mineralization in the desalinated drinking water. ED additionally offers the advantages of higher recovery, less problem of membrane fouling, absence of moving parts, avoidance of hazards of high pressure operation, and easy interfacing to solar energy due to DC operation.
Novel features of the Invention: Recognizing the need for a more attractive solution than re-mineralisation to overcome the problem of depletion of useful minerals in desalinated waters.
Identifying electrodialytic desalination as a potential opportunity for such an alternative solution.
Capitalizing on the known prior art of permselective ion-exchange membranes to induce selective removal of NaCl from saline waters while retaining the healthier constituents such as Ca2+, Mg2+, S04 2', HC03 " which are required to be present in similar or relatively higher amounts than Na+ and CI".
Recognising further that this approach may be beneficial for desalination of seawater besides brackish water.
Recognising further that such desalination of seawater with selective removal of NaCl may be used for the production of irrigation water which would be more beneficial to plants than conventional desalinated water. Recognising further that such selective electrodialytic desalination may, if anything, be more cost-effective than conventional ED desalination.
Recognising further that there may be advantages in combining the present ED process with conventional ED process to derive benefits no achievable by either alone.
EXAMPLES
Following are the examples given to further illustrate the invention and should not be construed to limit the scope of the present invention.
Example 1
This example pertains to controlled modification of interpolymer CEM and AEM with PANI. Styrene-codivinylbenzene polyethylene-based interpolymer CEM and AEM were sourced from the Electromembrane Processes Division. This was achieved in three steps, i. Surface activation of CEM by exchange of H+ with anilinium species (10.0% (v/v) aniline solution in 0.5 M HC1) for 3 hours at room temperature. Washing of the interpolymer CEMs was carried out with deionized water. Polymerization was induced in the second step by adding the 1 M (NH4)2S208 aqueous solution under stirring at room temperature, ii. Surface activation of AEM was carried out by exchange of OH" with S20g2" using 0.1 M aqueous solution (NH4)2S208. Washing of the interpolymer AEMs with deionized water Then Loading and in-sitii surface polymerization of anilinium species on interpolymer AEM surface in aniline solution (10.0% (v/v) in 0.5 M HC1). PANI modified interpolymer CEMs and AEMs were conditioned in HCl/NaOH solution (1.0 M) for 24 hours to ensure complete exchange of H+/OH\
Example 2
The experiment of Example- 1 was repeated for the preparation of PANI modified inter-polymer cation- and anion-exchange membrane (PANI-CEM1P and PANI- AEMIP, respectively). Similar procedure was also adopted for the modification of commercial cation- and anion-exchange membranes sourced from Hangzhou Iontech
Environmental Technology Co., Ltd., China (IONSEP™ low water permeation special separation membrane model CN standard (CNS)). PANI modified commercial cation- and anion-exchange membranes were named as PANI-CEMCNS
5 and PANI-AEMCNS, respectively.
Physicochemical and electrochemical properties of unmodified or PANI modified of ion-exchange membranes are included in Table 1.
Table 1. Physicochemical and electrochemical properties of without and with CEMCNS, PANI- CEMCNS, AEMCNS, PANI-AEMCNS, CEMIP, PANI-CEMIP, AEMIP, PANI-AEMIP membranes.
Properties Commercialized ion-exchange Interpolymer ion-exchange membranes membranes
CEMCN PANI- AEMCN PANI- CEMIP PANI AEMi PANI s CEMCN s . AEMCN P
s S ' CEMi AEMi
P P
Thickness (μιη) 483 564 509 553 140 142 152 155
Water content 54.2 43.2 63.0 53.6 27.1 25.2 22.3 20.4 (%)
Ion-exchange 1.68 1.39 1.05 0.74 1.78 1.47 1.48 1.51 capacity
(meq./gm)
Counter-ion 0.89 0.87 0.84 0.86 0.94 0.91 0.92 0.95 transport number
( )
Conductivity 4.7 4.3 6.0 6.4 10.3 9.7 8.4 8.8
(x lO^ S crn 1)
Contact angle - - - - 88.0 72.1 74.3 63.8
A laboratory-scale electrodialysis unit containing 10 cell pairs of IEMs (effective area per membrane: 80 cm2) was used to evaluate ED desalination performance. The
10 electrode housings were prepared from rigid PVC sheets . with built-in flow distributors and outlets. A stainless steel 316 sheet and platinum coated titanium netting were used as cathode and anode, respectively. A parallel-cum-series flow arrangement in three stages was used in the unit. Pumps were used to feed the different inputs of respective streams in continuous manner. There were three outlet streams: treated stream (TS), concentrated stream (CS) and electrode wash (EW). Both electrode chambers were interconnected and flushed with feed inlets. TDS and pH of TS and CS were recorded periodically. A predetermined DC electrical potential was applied between the electrodes by means of an AC-DC rectifier. Samples were withdrawn at different time intervals and analyzed. Electrodialysis experiments undertaken with unmodified membranes were designated as conventional ED (EDconv) while those carried out with the PANI-modified membranes were designated as selective ED (EDsel). Further, EDconv and EDsel experiments were carried out using CEMCNS/AEMCNS and CEMIP/AEMIP membrane cell pairs.
Example 3
A laboratory-scale electrodialysis unit containing 10 cell pairs of ion-exchange membranes (effective area per membrane: 80 cm2) was used to evaluate ED desalination performance at 2.0 V/Cell pair. Electrodialysis experiments were undertaken with unmodified interpolymer cation- and anion-exchange membrane (CEMff/AEM^) and designated as conventional ED (EDconv)- To investigate the nutritious mineral constituents in the desalinated water, concentration of different minerals (Mg2+, Ca2+, S04 2" and total alkalinity as CaC03) was monitored in feed and desalinated water. Diluted sea water with 4000 ppm TDS was taken as feed water. Mineral content in product water obtained through desalination by EDconv of a typical brackish feed, are included in Table 2. Electrodialytic performance may be assessed by energy consumption (EC) (0.53 kWh/kg of salt removed) and Current Efficiency (CE) (94.1%).
Table 2. Mineral analysis data for desalinated water produced from 4000 ppm feed water (through dilution of seawater) by EDconv using CEMJP/AEMJP cell pairs.
Figure imgf000013_0001
Example 4
A laboratory-scale electrodialysis unit containing 10 cell pairs of ion-exchange membranes (effective area per membrane: 80 cm2) was used to evaluate ED desalination performance at 2.0 V/Cell pair. Electrodialysis experiments were undertaken with unmodified interpolymer cation- and anion-exchange membrane (CEMip/AEMip) and designated as conventional ED (EDconv)- To investigate the nutritious mineral constituents in the desalinated water, concentration of different minerals (Mg2+, Ca2+, S04 2" and total alkalinity as CaC03) was monitored in feed and desalinated water. Diluted sea water with 3000 ppm TDS was taken as feed water. Mineral content in product water obtained through desalination by EDconv of a typical brackish feed, are included in Table 3. Electrodialytic performance may be assessed by energy consumption (EC) (0.68 kWh/kg of salt removed) and Current Efficiency (CE) (90.6%).
Table 3. Mineral analysis data for desalinated water produced from 3000 ppm feed water (through dilution of seawater) by EDconv using CEMIP/AEMIP cell pairs.
Figure imgf000014_0001
Example 5
A laboratory-scale electrodialysis unit containing 10 cell pairs of ion-exchange membranes (effective area per membrane: 80 cm ) was used to evaluate ED desalination performance at 2.0 V/Cell pair. Electrodialysis experiments were undertaken with PANI modified interpolymer cation- and anion-exchange membrane (PANI-CEMip/PANI-AEMip) and designated as selective ED (EDse|). To investigate the nutritious mineral constituents in the desalinated water, concentration of different minerals (Mg2+, Ca2+, S04 2" and total alkalinity as CaC03) was monitored in feed and desalinated water. Diluted sea water with 4000 ppm TDS was taken as feed water. Mineral content in product water obtained through desalination by EDsei of a typical brackish feed, are included in Table 4. Electrodialytic performance may be assessed by energy consumption (EC) (0.67 kWh/kg of salt removed) and Current Efficiency (CE) (88.3%).
Table 4. Mineral analysis data for desalinated water produced from 4000 ppm feed water (through dilution of seawater) by EDsei using PANI-CEMIP/PANI-AEMIP cell pairs.
Figure imgf000015_0001
Example 6
A laboratory-scale electrodialysis unit described in example 4, in which interpolymer ion-exchange membranes (CEMjp/AEMIP) were replaced with commercial ion- exchange membranes (CEMCNS/AEMCNS) was used to produce drinking water (TDS: ~ 500 ppm) by EDconv from diluted sea water with 3000 ppm TDS. Mineral content in product water obtained through desalination by EDconv of a typical brackish feed, are included in Table 5. Feed water composition was similar as example 4. Electrodialytic performance may be assessed by energy consumption (EC) (1.15 kWh/kg of salt removed) and Current Efficiency (CE) (60.8%).
Table 5. Mineral analysis data for desalinated water produced from 3000 ppm feed water (through dilution of seawater) by EDconv using CEMCNS/AEMCNS cell pairs.
Figure imgf000015_0002
Figure imgf000016_0001
Example 7
A laboratory-scale electrodialysis unit described in example 3, in which interpolymer ion-exchange membranes (CEMrp/AEMtp) were replaced with commercial ion- exchange membranes (CEMCNS/AEMCNS) was used to produce drinking water (TDS: - 500 ppm) by EDconv from diluted sea water with 4000 ppm TDS. Mineral content in product water obtained through desalination by EDconv of a typical brackish feed, are included in Table 6. Feed water composition was similar as example 3. Electrodialytic performance may be assessed by energy consumption (EC) (1.15 kWh/kg of salt removed) and Current Efficiency (CE) (60.8%).
Table 6. Mineral analysis data for desalinated water produced from 3000 ppm feed water (through dilution of seawater) by EDconv using CEMCNS/AEMCNS cell pairs.
Figure imgf000016_0002
Figure imgf000017_0001
Example 8
A laboratory-scale electrodialysis unit described in example 5, in which PANI modified interpolymer ion-exchange membranes (PANI-CEM1P/PANI-AEMIP) were replaced with. PANI modified commercial ion-exchange membranes (PANI- CEMCNS PANI-AEMCNS) was used to produce drinking water (TDS: ~ 500 ppm) by EDConv from diluted sea water with 4000 ppm TDS. Mineral content in product water obtained through desalination by EDsei of a typical brackish feed, are included in Table 7. Feed water composition was similar as example 5. Electrodialytic performance may be assessed by energy consumption (EC) (1.29 kWh/kg of salt removed) and Current Efficiency (CE) (61.7%).
Table 7. Mineral analysis data for desalinated water produced from 4000 ppm feed water (through dilution of seawater) by EDsei using PANI-CEMCNS/PANI-AEMCNS cell pairs.
Figure imgf000017_0002
Example 9
A laboratory-scale electrodialysis unit containing 10 cell pairs of ion-exchange membranes (effective area per membrane: 80 cm ) was used to evaluate ED desalination performance at 2.0 V/Cell pair. Electrodialysis experiments were undertaken with PANI modified interpolymer cation- and anion-exchange membrane (PANI-CEM!P/PANI-AEMIP) and designated as selective ED (EDsei). To investigate the nutritious mineral constituents in the desalinated water, concentration of different minerals (Mg , Ca , S04 " and total alkalinity as CaC03) was monitored in feed and desalinated water. Diluted sea water with 3000 ppm TDS was taken as feed water. Mineral content in product water obtained through desalination by EDsei of a typical brackish feed, are included in Table 8. Electrodialytic performance may be assessed by energy consumption (EC) (0.72 kWh/kg of salt removed) arid Current Efficiency (CE) (86.9%).
Table 8. Mineral analysis data for desalinated water produced from 3000 ppm feed water (through dilution of seawater) by EDsei using PANI-CEMip/PANI-AEMtp cell pairs.
Figure imgf000018_0001
Example 10
A laboratory-scale electrodialysis unit described in example 5, in which PANI modified interpolymer ion-exchange membranes (PANI-CEMIP/PANI-AEMJP) were replaced with PANI modified commercial ion-exchange membranes (PANI- CEMCNS/PANI-AEMCNS) was used to produce drinking water (TDS: ~ 500 ppm) by EDconv from diluted sea water with 3000 ppm TDS. Mineral content in product water obtained through desalination by EDsei of a typical brackish feed, are included in Table 8. Feed water composition was similar as example 4. Electrodialytic performance may be assessed by energy consumption (EC) (1.32 kWh/kg of salt removed) and Current Efficiency (CE) (58.6%).
Table 9. Mineral analysis data for desalinated water produced from 3000 ppm feed water (through dilution of seawater) by EDsei using PANI-CEMCNS/PANI-AEMCNS cell pairs.
Figure imgf000019_0001
ADVANTAGES OF THE INVENTION
1. The main advantage of the invention is that it provides a more attractive solution than re-mineralisation to overcome the problem of depletion of useful minerals in desalinated waters.
2. Another advantage is that it enables electrodialytic desalination as a potential opportunity for such an alternative solution.
3. Another advantage is to induce permselective ion-exchange membranes for selective removal of NaCl from saline waters while retaining the healthier constituents such as Ca2+, Mg2+, S04 2", HC03 ' which are required to be present in similar or relatively higher amounts than Na+ and CI".
4. Another advantage is that such desalination of seawater with selective removal of NaCl may be used for the production of irrigation water which would be more beneficial to plants than conventional desalinated water.
5. Another advantage is that process provides mineral-enriched drinking water by selective removal of NaCl.

Claims

An improved electrodialytic process of brackish water desalination to obtain potable water rich in Ca2+, Mg2+, S04 2", and HC03 " while discarding NaCl present in the feed water, wherein the improvement consists of using polyaniline (PANI)-modified ion exchange interpolymer membranes, the said process comprises passing feed water in an electrodialysis unit containing 10- 12 cell pairs of polyaniline (PANI)-modified ion exchange interpolymer membranes between an anode and a cathode at 1.5 to 2.0 V/cell pair to obtain potable water rich in Ca2+, Mg2+, S04 2", and HC03 ".
A process as claimed in claim 1 , wherein aniline concentration used in polyaniline (PANI)-modified ion exchange interpolymer membranes is in the range of 5-20% (v/v) in 0.1 - 1.0 M HC1.
A process as claimed in claim 1, wherein effective area per membrane is in the range of 80 -82 cm2.
A process as claimed in claim 1 , wherein the feed water used had total dissolved solids (TDS) in the range of 3000-4000 ppm, 917 to 1255 ppm Na+, 1468-1937 ppm CI', 40-60 ppm K+, 100-150 ppm Mg2+, 30-60 ppm Ca2+, 230- 270 ppm S04 2", and 20-30 ppm total alkalinity (as CaC03)
A process as claimed in claim 1, wherein the potable water had overall TDS in the range of 440 to 450 ppm , 100-1 10 ppm Na+, 3-5 ppm K+, 20-30 ppm Mg2+, 10-20 ppm Ca2+, 140-170 ppm CI", 75-100 ppm S04 2", and 50-100 ppm total alkalinity (as CaC03).
A process as claimed in claim 1 , wherein the current efficiency is in the range of 85 to 90%.
PCT/IN2014/000348 2013-05-23 2014-05-23 Improved process to retain nutritious constituents in potable water obtained through desalination WO2014188450A1 (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107930420A (en) * 2017-11-02 2018-04-20 昆明理工大学 A kind of acidproof high conductivity anion-exchange membrane of hydrophobicity and preparation method thereof
US9969638B2 (en) 2013-08-05 2018-05-15 Gradiant Corporation Water treatment systems and associated methods
US10167218B2 (en) 2015-02-11 2019-01-01 Gradiant Corporation Production of ultra-high-density brines
US10245555B2 (en) 2015-08-14 2019-04-02 Gradiant Corporation Production of multivalent ion-rich process streams using multi-stage osmotic separation
US10301198B2 (en) 2015-08-14 2019-05-28 Gradiant Corporation Selective retention of multivalent ions
US10308537B2 (en) 2013-09-23 2019-06-04 Gradiant Corporation Desalination systems and associated methods
US10308526B2 (en) 2015-02-11 2019-06-04 Gradiant Corporation Methods and systems for producing treated brines for desalination
CN110621391A (en) * 2017-05-08 2019-12-27 懿华水处理技术有限责任公司 Water treatment of sodium-containing, high salinity or high sodium water for agricultural applications
US10518221B2 (en) 2015-07-29 2019-12-31 Gradiant Corporation Osmotic desalination methods and associated systems
US10689264B2 (en) 2016-02-22 2020-06-23 Gradiant Corporation Hybrid desalination systems and associated methods

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001087762A (en) * 1999-09-27 2001-04-03 Nkk Corp Water based on sea deep water, its production and production device therefor
JP2002292371A (en) * 2001-01-23 2002-10-08 Goshu Yakuhin Kk Fresh water obtained from deep sea water, concentrated deep sea water, mineral concentrate, concentrated salt water, bittern, and specifyed salt
JP2003063969A (en) * 2001-08-24 2003-03-05 Goshu Yakuhin Kk Functional goods using concentrated mineral solution obtained from deep sea water by separation
KR20080108925A (en) * 2008-07-07 2008-12-16 김문수 Preparation method of natural mineral salt from deep ocean water

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001087762A (en) * 1999-09-27 2001-04-03 Nkk Corp Water based on sea deep water, its production and production device therefor
JP2002292371A (en) * 2001-01-23 2002-10-08 Goshu Yakuhin Kk Fresh water obtained from deep sea water, concentrated deep sea water, mineral concentrate, concentrated salt water, bittern, and specifyed salt
JP2003063969A (en) * 2001-08-24 2003-03-05 Goshu Yakuhin Kk Functional goods using concentrated mineral solution obtained from deep sea water by separation
KR20080108925A (en) * 2008-07-07 2008-12-16 김문수 Preparation method of natural mineral salt from deep ocean water

Non-Patent Citations (7)

* Cited by examiner, † Cited by third party
Title
J. MEMBR. SCI., vol. 206, 2002, pages 31
NAGARALE R ET AL: "Preparation and electrochemical characterization of cation- and anion-exchange/polyaniline composite membranes", JOURNAL OF COLLOID AND INTERFACE SCIENCE, ACADEMIC PRESS, NEW YORK, NY, US, vol. 277, no. 1, 1 September 2004 (2004-09-01), pages 162 - 171, XP027132417, ISSN: 0021-9797, [retrieved on 20040722] *
ONOUE ET AL., DENKI KAGAKU, vol. 29, 1961, pages 544
SATA ET AL., J POLYM. SCI., POLYM. CHEM. ED., vol. 17, 1979, pages 2071
SOGA, BULL. SOC. SEA WATER SCI. JPN. (NIPPON EN GAKKAI-SHI, vol. 16, 1962, pages 24
SRIVASTAVA ET AL., J IND. WATER WORKS ASSO., January 2010 (2010-01-01), pages 50
U. YERMIYAHU ET AL., SCIENCE, vol. 318, 2007, pages 920

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US10167218B2 (en) 2015-02-11 2019-01-01 Gradiant Corporation Production of ultra-high-density brines
US10518221B2 (en) 2015-07-29 2019-12-31 Gradiant Corporation Osmotic desalination methods and associated systems
US10245555B2 (en) 2015-08-14 2019-04-02 Gradiant Corporation Production of multivalent ion-rich process streams using multi-stage osmotic separation
US10301198B2 (en) 2015-08-14 2019-05-28 Gradiant Corporation Selective retention of multivalent ions
US10689264B2 (en) 2016-02-22 2020-06-23 Gradiant Corporation Hybrid desalination systems and associated methods
CN110621391A (en) * 2017-05-08 2019-12-27 懿华水处理技术有限责任公司 Water treatment of sodium-containing, high salinity or high sodium water for agricultural applications
EP3634608A4 (en) * 2017-05-08 2021-01-13 Evoqua Water Technologies LLC Water treatment of sodic, high salinity, or high sodium waters for agricultural applications
CN107930420A (en) * 2017-11-02 2018-04-20 昆明理工大学 A kind of acidproof high conductivity anion-exchange membrane of hydrophobicity and preparation method thereof
CN107930420B (en) * 2017-11-02 2020-10-27 昆明理工大学 Hydrophobic acid-resistant high-conductivity anion exchange membrane and preparation method thereof

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