English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The data by Q.Yang et al suggest absence of "ultrafast flow" of solventacross graphene oxide (GO) membranes. The "ultrafast flow" is result of usingunrealistic geometrical model with close packed hole-free micrometer sized GOflakes providing only 0.1 % of area in each layer available for permeation. Thedata by Q.Yang et all demonstrate that at least 3-5 % of total layer area areavailable for permeation in real GO membranes due to holes between irregularlyshaped flakes. At least 2-3 percent of area also needs to be added to thepermeation cross section due to holes and cracks in GO flakes, especiallyabundant due to prolonged sonication of dispersions. Permeation of solutionsmostly through pinholes penetrating tens of GO layers suggests that "graphenecapillaries" are not required to explain water flow across the membrane. Takinginto account realistic packing of GO flakes with holes between the flakes andacross the flakes, 2-3 orders of magnitude shorter permeation path should beformed. Considering shorter zigzag permeation path between GO sheets and 5-10 %of area in each layer available for permeation due to holes across and betweenGO flakes, permeation rates across GO membranes can be explained by trivialdiffusion. In absence of "graphene capillaries", the "ultra-precise sieving"related to "cutoff" value of 4.5 \AA{} (hydration diameter) provided by"graphene capillaries" has little meaning. As it is well known from earlierstudies and now demonstrated by Q.Yang et al using their own samples theswelling of GO membranes is different for different solutions, depends onconcentration of solutes and results in delamination in many solutions. Q.Yanget al provide controversial data for stability of their GO membranes in waterciting use of surfactant to prevent dissolving. Oxidation state of GO membranesremains to be unknown due to incorrect analysis of XPS spectra.

Graphene oxide membranes: on the absence of "graphene capillaries", "ultrafast flow" rate and "ultraprecise sieving"