Seawater Desalination via Hydrogels: Practical Realisation and First Coarse Grained Simulations

Höpfner, Johannes; Richter, Tobias; Košovan, Peter; Holm, Christian; Wilhelm, Manfred

doi:10.1007/978-3-319-01683-2_19

Cited by 40 publications

(69 citation statements)

References 33 publications

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“…Repetition of the same experiment three times showed that the volume, pressure, and salt concentration data had qualitatively the same behavior with some quantitative differences. The uncertainty of the energy data for three experiments in previous work was found to be within 10%, while the uncertainty of the reusability test with 20 data points was 21.5%.…”

Section: Resultsmentioning

confidence: 72%

“…Desalination experiments were conducted using a self‐built press setup (see Figure ), whereby the construction and typical procedures to desalinate are described in detail in previous work …”

Section: Methodsmentioning

confidence: 99%

“…(3) Release of the desalinated water from inside the gel by an external pressure. Adapted from Höpfner et al…”

Section: Introductionmentioning

confidence: 99%

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Energy Consumption for the Desalination of Salt Water Using Polyelectrolyte Hydrogels as the Separation Agent

Arens

Albrecht

Höpfner

et al. 2017

Macro Chemistry & Physics

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The energy consumption for a novel desalination approach using charged hydrogels under externally applied pressure is experimentally measured and calculated. The salt separation is based on a partial rejection of mobile salt ions caused by the fixed charges inside the polyelectrolyte network. Self‐synthesized and commercial poly(acrylic acid) hydrogels are used to study the desalination performance in reference to sodium chloride solutions within the concentration range of 0.1–35 g L−1. The influence of various synthetic parameters, such as the degree of crosslinking (DC) and the size and shape of the particles, is investigated. Furthermore, the effect of process parameters including the amount of the feed solution, the applied pressure profile, and the swelling time of the hydrogel is discussed. The best energy estimation found so far, is 8.9 kWh m−3 fresh water if a poly(acrylic acid) with a DC of 5 mol% is used in an infinite large salt bath.

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Section: Resultsmentioning

confidence: 72%

Section: Methodsmentioning

confidence: 99%

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Energy Consumption for the Desalination of Salt Water Using Polyelectrolyte Hydrogels as the Separation Agent

Arens

Albrecht

Höpfner

et al. 2017

Macro Chemistry & Physics

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“…It is important to point out that one can also model Donnan equilibrium in ionic systems by performing semi-grand canonical simulations [33,[37][38][39]. The value of the chemical potential for these simulations was obtained from separate simulations of the particle insertion [33].…”

Section: Discussionmentioning

confidence: 99%

“…The value of the chemical potential for these simulations was obtained from separate simulations of the particle insertion [33]. This approach was successfully implemented to study hydrogels in equilibrium with salt solutions [37][38][39].…”

Section: Discussionmentioning

confidence: 99%

Salt Effect on Osmotic Pressure of Polyelectrolyte Solutions: Simulation Study

Carrillo

Dobrynin

2014

Polymers

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Abstract:We present results of the hybrid Monte Carlo/molecular dynamics simulations of the osmotic pressure of salt solutions of polyelectrolytes. In our simulations, we used a coarse-grained representation of polyelectrolyte chains, counterions and salt ions. During simulation runs, we alternate Monte Carlo and molecular dynamics simulation steps. Monte Carlo steps were used to perform small ion exchange between simulation box containing salt ions (salt reservoir) and simulation box with polyelectrolyte chains, counterions and salt ions (polyelectrolyte solution). This allowed us to model Donnan equilibrium and partitioning of salt and counterions across membrane impermeable to polyelectrolyte chains. Our simulations have shown that the main contribution to the system osmotic pressure is due to salt ions and osmotically active counterions. The fraction of the condensed (osmotically inactive) counterions first increases with decreases in the solution ionic strength then it saturates. The reduced value of the system osmotic coefficient is a universal function of the ratio of the concentration of osmotically active counterions and salt concentration in salt reservoir. Simulation results are in a very good agreement with osmotic pressure measurements in sodium polystyrene sulfonate, DNA, polyacrylic acid, sodium polyanetholesulfonic acid, polyvinylbenzoic acid, and polydiallyldimethylammonium chloride solutions.

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Osmotic Engine: Translating Osmotic Pressure into Macroscopic Mechanical Force via Poly(Acrylic Acid) Based Hydrogels

et al. 2017

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Poly(acrylic acid)‐based hydrogels can swell up to 100–1000 times their own weight in desalinated water due to osmotic forces. As the swelling is about a factor of 2–12 lower in seawater‐like saline solutions (4.3 wt% NaCl) than in deionized water, cyclic swelling, and shrinking can potentially be used to move a piston in an osmotic motor. Consequently, chemical energy is translated into mechanical energy. This conversion is driven by differences in chemical potential and by changes in entropy. This is special, as most thermodynamic engines rely instead on the conversion of heat into mechanical energy. To optimize the efficiency of this process, the degree of neutralization, the degree of crosslinking, and the particle size of the hydrogels are varied. Additionally, different osmotic engine prototypes are constructed. The maximum mean power of 0.23 W kg−1 dry hydrogel is found by using an external load of 6 kPa, a polymer with 1.7 mol% crosslinking, a degree of neutralization of 10 mol%, and a particle size of 370–670 µm. As this is achieved only in the first round of optimization, higher values of the maximum power average over one cycle seem realistic.

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Seawater Desalination via Hydrogels: Practical Realisation and First Coarse Grained Simulations

Cited by 40 publications

References 33 publications

Energy Consumption for the Desalination of Salt Water Using Polyelectrolyte Hydrogels as the Separation Agent

Energy Consumption for the Desalination of Salt Water Using Polyelectrolyte Hydrogels as the Separation Agent

Salt Effect on Osmotic Pressure of Polyelectrolyte Solutions: Simulation Study

Osmotic Engine: Translating Osmotic Pressure into Macroscopic Mechanical Force via Poly(Acrylic Acid) Based Hydrogels

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