Nanoscopic NaCl crystals as water-soluble porogens for polymer membranes

Range, Sven; Epple, Matthias

doi:10.1039/c2ra01237e

Cited by 7 publications

(8 citation statements)

References 15 publications

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“…As can be observed, the hydrolysis of the nanometric iron allows forming continuous pores through the thickness of the membrane, indicating better fluxes as a function of etching time and the almost constant rejection of the salt, as expected, because no bigger holes are induced. It is important to address that the idea of pore sizes via the use of different sizes of salts is reaching an admirable stage [ 41 , 44 , 45 , 52 , 53 ]; however, the use of a magnetic iron entity will allow us, in the future, to control not just the size of the pore but the position of the pore in the membrane and the total geometrical distribution of the pores on the membrane.…”

Section: Resultsmentioning

confidence: 99%

“…As a proof of principle, a crude array of polysulfone pillars was formed to investigate the adaptability of the membrane process to other templates [ 40 ]. Additionally, the utilization of various nanoparticles such as NaCl [ 41 ], NaHCO 3 [ 42 ], limestone [ 43 ], SrCO 3 [ 44 ], and CaCO 3 [ 44 , 45 , 46 ] as direct but random templates is also reported to be applicable in polysulfone or cellulose acetate. After the polymer matrix was stabilized, the removal of the solid salt particles by immersion in water or dilute acid generally led to the formation of closely controlled and interconnected pores.…”

Section: Introductionmentioning

confidence: 99%

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New Preparation Methods for Pore Formation on Polysulfone Membranes

Vainrot

Isloor

et al. 2021

Membranes

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This work described the preparation of membranes based on aromatic polysulfones through the phase-inversion method induced by a nonsolvent, generating the phase separation (NIPS) process. Three new techniques, including the nano iron acid etching method, base hydrolysis method of crosslinked polymers, and base hydrolysis method of a reactive component in a binary polymer blend, were developed for pore creation on membranes. The modified polymers and obtained membranes were carefully characterized. The uniform pores were successfully created by base hydrolysis of the crosslinked polymers and obtained at the size of the crosslinker. Moreover, homogeneous pores were created after base hydrolysis of the membranes prepared from binary polymer blends due to the internal changes in the polymer structure. The separation performance of membranes was tested with different inorganic salt solutions and compared with commercially known membranes. These new membranes exhibited high water flux (up to 3000 L/m−2·h−1 at 10 bar and at 25 °C) and reasonable rejections for monovalent (21–44%) and multivalent ions (18–60%), depending on the different etching of the hydrolysis times. The comparison of these membranes with commercial ones confirmed their good separation performance and high potential application for water treatment applications.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New Preparation Methods for Pore Formation on Polysulfone Membranes

Vainrot

Isloor

et al. 2021

Membranes

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“…30,31 The crystals, which were easily dispersible in organic solvents, were colloidally stabilized by a thin surface layer of the organic product resulting from the reaction, i.e., the malonic ester condensation product. By using a modified version of the original synthesis, it was possible in this work to obtain well-formed crystals that are essentially free of organic material.…”

Section: ■ Introductionmentioning

confidence: 99%

“…A facile organic synthesis of well-formed 100–300 nm NaCl nanocrystals was recently developed, based on the reaction of sodium diethylmalonate with phenacyl chloride or acetyl chloride. , The crystals, which were easily dispersible in organic solvents, were colloidally stabilized by a thin surface layer of the organic product resulting from the reaction, i.e., the malonic ester condensation product. By using a modified version of the original synthesis, it was possible in this work to obtain well-formed crystals that are essentially free of organic material.…”

Section: Introductionmentioning

confidence: 99%

Size Matters: An Experimental and Computational Study of the Influence of Particle Size on the Lattice Energy of NaCl

et al. 2015

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One of the most interesting features of nanomaterials is the change in properties that normally accompanies a decrease in particle size. Enthalpy of solution measurements in water, at 298 K, carried out with sodium chloride samples spanning a 500-fold particle size range (120 nm to 60 μm) evidenced the effect of the increase in surface area to volume ratio in the enthalpy of solution and cohesive energy of NaCl. The nanoscopic samples were prepared by a new malonic ester synthesis, which allowed the production of well-formed and approximately cubic crystals. It was found that a very small change in lattice energy (∼0.01%) can be translated into a comparatively much larger change in enthalpy of solution (∼4%) and that the largest changes in properties are expected to occur for particle sizes below ∼100 nm where a steep decrease in lattice energy (spanning a ∼230 kJ·mol −1 range) down to the limit of monomeric NaCl is expected to occur. The experimental findings were corroborated by the results of atom−atom pair potential calculations, which further suggested that the lattice energy within each crystal layer varies from site to site, with the energy differences between adjacent sites decreasing on moving from the periphery to the center of the crystal. The atoms at the outmost surface layer exhibit the lowest lattice energies. Finally the most stable atoms in terms of lattice energy are located in the second layer possibly because repulsive interactions with ions of similar type beyond the crystal surface are absent.

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“…[163,164] An approach for flat sheet membranes by precipitated sodium chloride (NaCl) nanoparticles of about 100 nm size was shown by Range and Epple. [165] The salt was precipitated by organic chemistry, washed and dispersed in polylactide and polysulfone at loadings from 20 to 100 wt% regarding the polymer. The membranes were produced by dip coating a silicon waver in the polymer dispersion.…”

Section: Direct Templatesmentioning

confidence: 99%

Porous Polymer Membranes by Hard Templating – A Review

2017

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Membranes are designed to bridge a precise separation process at the nanoscale with industrial applications running at cubic meters per hour. This review outlines materials applied in membrane production with a particular focus on polymers. Membrane performance and created value are directly linked to controlled pore formation. Their economic relevance has created a number of large companies and associated academic research at top institutions. The authors review, therefore, starts from well-established techniques applied in products and then moves on to evolving concepts from academia. Pore formation through hard templating is a versatile field for separation processes. A more detailed view is given on the two known concepts for nanopore formation, namely colloidal templates and random hard salt templating. A comparison between these two concepts underlines their relevance to combine a process specific separation with large scale manufacturing requirements (i.e., upscale possibility, flexible process control and environmental impact).

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Nanoscopic NaCl crystals as water-soluble porogens for polymer membranes

Cited by 7 publications

References 15 publications

New Preparation Methods for Pore Formation on Polysulfone Membranes

New Preparation Methods for Pore Formation on Polysulfone Membranes

Size Matters: An Experimental and Computational Study of the Influence of Particle Size on the Lattice Energy of NaCl

Porous Polymer Membranes by Hard Templating – A Review

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