A realistic approach for determining the pore size distribution of nanofiltration membranes

Sutariya, Bhaumik; Karan, Santanu

doi:10.1016/j.seppur.2022.121096

Cited by 34 publications

(8 citation statements)

References 103 publications

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“…Subsequently, we compared our numerical parameters to prior empirical membrane characterizations. The pore radius of NF 270 has been reported to be between 0.43 and 0.54 nm, ,− and the pore size distribution has been estimated to be approximately 0.3 ± 0.1 nm, based on MWCO experiments . In comparison, DSPM-DE suggested pore radii of 0.416 and 0.461 nm, at pH 7 and 2, which were within the error of the reported estimates.…”

Section: Resultssupporting

confidence: 60%

Lithium Concentration from Salt-Lake Brine by Donnan-Enhanced Nanofiltration

Foo

Rehman

Bouma

et al. 2023

Environ. Sci. Technol.

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Membranes offer a scalable and cost-effective approach to ion separations for lithium recovery. In the case of salt-lake brines, however, the high feed salinity and low pH of the post-treated feed have an uncertain impact on nanofiltration's selectivity. Here, we adopt experimental and computational approaches to analyze the effect of pH and feed salinity and elucidate key selectivity mechanisms. Our data set comprises over 750 original ion rejection measurements, spanning five salinities and two pH levels, collected using brine solutions that model three saltlake compositions. Our results demonstrate that the Li + /Mg 2+ selectivity of polyamide membranes can be enhanced by 13 times with acid-pretreated feed solutions. This selectivity enhancement is attributed to the amplified Donnan potential from the ionization of carboxyl and amino moieties under low solution pH. As feed salinities increase from 10 to 250 g L −1 , the Li + /Mg 2+ selectivity decreases by ∼43%, a consequence of weakening exclusion mechanisms. Further, our analysis accentuates the importance of measuring separation factors using representative solution compositions to replicate the ion-transport behaviors with salt-lake brine. Consequently, our results reveal that predictions of ion rejection and Li + /Mg 2+ separation factors can be improved by up to 80% when feed solutions with the appropriate Cl − /SO 4 2− molar ratios are used.

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Section: Resultssupporting

confidence: 60%

Lithium Concentration from Salt-Lake Brine by Donnan-Enhanced Nanofiltration

Foo

Rehman

Bouma

et al. 2023

Environ. Sci. Technol.

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“…The oxidative debris and metal throughput for a 14 kDa membrane are higher, with the main 1 μm fraction remaining in the solution. Although some approaches have been developed to determine the pore size distribution of nanofiltration membranes [ 81 ] for graphene oxide, such techniques have not yet been validated.…”

Section: Discussionmentioning

confidence: 99%

High-Throughput Preparation of Uncontaminated Graphene-Oxide Aqueous Dispersions with Antioxidant Properties by Semi-Automated Diffusion Dialysis

et al. 2022

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A semi-automated diffusion-dialysis purification procedure is proposed for the preparation of uncontaminated graphene oxide (GO) aqueous dispersions. The purification process is integrated with analytical-signal processing to control the purification degree online by several channels: oxidation-reduction potential, conductivity, and absorbance. This approach reduces the amounts of reagents for chemical treatment during dialysis. The total transition metal (Mn and Ti) content was reduced to a sub-ppb level (assessed by slurry nebulization in inductively coupled plasma optical atomic emission spectroscopy). Purified aqueous GO samples possess good stability for about a year with a zeta-potential of ca. −40 mV and a lateral size of ca. sub-µm. Purified GO samples showed increased antioxidant properties (up to five times compared to initial samples according to chemiluminometry by superoxide-radical (O2−) generated in situ from xanthine and xanthine oxidase with the lucigenin probe) and significantly decreased peroxidase-like activity (assessed by the H2O2–L-012 system).

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“…When the effect of steric and hydrodynamic hindrances is taken into account, the rejection of a solute with diameter D s by a membrane with uniform pore size D p depends upon the factor λ (= D s / D p ) in the following manner: 49–51 R = 1 − (1 − ( λ ( λ − 2)) 2 )exp(−0.7146 λ 2 )for, R = 0.5, λ = 0.416.…”

Section: Methodsmentioning

confidence: 99%