Hello Jean-Marc, I believe your best shot here is to work on assuring the dispersability of your particles. If they fall too easily as you say, you may try a denser solvent, let's say DMF, DMSO or eventually even some oil. Sonication will help to get your particles dispersed and break aggregates which in turn will make separation easier. If you succeed to that, then indeed optimizing either settling or slow centrifuging should allow you to recover one or another size population.
Otherwise, I wouldn't discard sieving so quickly. In the lab we use these syringe filters which are quite accurate in the pore size ( https://www.sigmaaldrich.com/FR/en/product/sigma/wha10462260?context=product). I would make a good dispersion as said before and try to pass it through this filter with a syringe, if it seems to work, do it repeatedly until you recover only one population. Hope it helps! Sincerely, *Fernando Igoa* PhD student Laboratoire Chimie de la Matière Condensée de Paris Sorbonne Université 4 place Jussieu 75005 PARIS ORC*ID*: orcid.org/0000-0002-3960-4720 ResearchGate: researchgate.net/profile/Fernando_Igoa <https://www.researchgate.net/profile/Fernando_Igoa> : twitter.com/figoa96 El jue, 1 de jul. de 2021 a la(s) 11:21, Jean-Marc Joubert ( joub...@icmpe.cnrs.fr) escribió: > Dear all, > I have another question more or less related to the topic of clay sample > preparation. > I would like to separate the coarse from the fine grains in a powder > obtained by crushing. > This is in order to get the finest (1 to 5 µm) grains without having to > introduce too much strain by a too energetic crushing. > From the SEM analysis this fine particles are indeed present in the powder > but mixed with larger particles (~30 µm). > Sieving in this size range is probably not very efficient. > I considered using settling in alcohol or acetone but the density of the > materials is very large (~7, it is an intermetallic compound) so that all > the particles fall very fast to the bottom. > I wonder if somebody has any advice. > Thanks in advance. > /Jean-Marc > > > > > > > Le 01/07/2021 à 09:30, Kemp, Simon J. a écrit : > > Hi Matthew, > > > > Welcome to the wonderful world of clay mineralogy ! > > > > Separating the clay (typically <2 um) by gravity settling is actually > preferable to centrifuging, as you can more easily check for flocculation. > [If this is a problem add some drops of sodium hexametaphosphate (‘Calgon’) > solution.] At BGS, we dry our isolated <2 um fractions right down in a > moisture extraction oven (set at 55degC), homogenise and then resuspend a > known amount (¬80 mg) to produce a consistently thick oriented mount. > > > > If you are not aware of it – Moore & Reynolds (1997) is the bible for clay > preparation and analysis – very easy to follow. > > > > Moore, D.M. and Reynolds, R.C. 1997*. X-Ray Diffraction and the > Identification and Analysis of Clay Minerals, Second Edition.* Oxford > University Press, New York. > > > > Best regards, Simon > > > > *Simon Kemp* > > Senior Mineralogist > > > > *p *+44 (0)115 936 3448 > > *e *s...@bgs.ac.uk > *w *www.bgs.ac.uk > > > > British Geological Survey | Nicker Hill | Keyworth | Nottingham NG12 5GG | > UK > > > > > > Profile <http://www.bgs.ac.uk/staff/profiles/0778.html> | *Twitter > <https://twitter.com/SimonKempBGS>* | Research Gate > <https://www.researchgate.net/profile/Simon_Kemp2> | Google Scholar > <https://scholar.google.co.uk/citations?user=UcipPfUAAAAJ&hl=en> > > > > > > *From:* rietveld_l-requ...@ill.fr <rietveld_l-requ...@ill.fr> > <rietveld_l-requ...@ill.fr> *On Behalf Of *Matthew Rowles > *Sent:* 01 July 2021 05:26 > *To:* RIETVELD_L Distribution List <email@example.com> <firstname.lastname@example.org> > *Subject:* Clay sample preparation > > > > Hi all > > I’m gingerly venturing into clay analysis. > > I’ve done previous analyses on pre-separated clay fractions by > resuspending the clay in a little ethanol and dripping onto a Si wafter to > make an oriented mount (which is then also successively glycolated and heat > treated). > > I have some upcoming work which will necessitate creating the clay > fraction. > > I don’t have a centrifuge, so I have to separate the clay fraction by > settling. The USGS methodology looks like a good method to follow: > https://pubs.usgs.gov/of/2001/of01-041/htmldocs/methods/decant.htm > > > After I’ve suctioned off the clay suspension, what is the best way to get > at the clay? Leave it settle more? Evaporate the water? > > (I’m also in the middle of commissioning a spray-drier, so that will help > with the random mounts.) > > Thanks > > Matthew Rowles > This email and any attachments are intended solely for the use of the > named recipients. If you are not the intended recipient you must not use, > disclose, copy or distribute this email or any of its attachments and > should notify the sender immediately and delete this email from your > system. UK Research and Innovation (UKRI) has taken every reasonable > precaution to minimise risk of this email or any attachments containing > viruses or malware but the recipient should carry out its own virus and > malware checks before opening the attachments. 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Opinions, conclusions or other information in this > message and attachments that are not related directly to UKRI business are > solely those of the author and do not represent the views of UKRI. > > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > Please do NOT attach files to the whole list <alan.he...@neutronoptics.com> > <alan.he...@neutronoptics.com> > Send commands to <lists...@ill.fr> <lists...@ill.fr> eg: HELP as the subject > with no body text > The Rietveld_L list archive is on > http://email@example.com/ > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > > > -- > Jean-Marc Joubert > Institut de Chimie et des Matériaux Paris-Est > UMR 7182 CNRS-Université Paris-Est Créteil > 2-8 rue Henri Dunant, 94320 Thiais, France > Lab: https://www.icmpe.cnrs.fr/ > phone/fax: 33 1 49 78 13 44/12 03 > Researcher ID: A-1259-2013, ORCID: 0000-0001-7266-1850 > email : joub...@icmpe.cnrs.fr > personal page: https://www.icmpe.cnrs.fr/annuaire/joubert-jean-marc/ > > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > Please do NOT attach files to the whole list <alan.he...@neutronoptics.com > > > Send commands to <lists...@ill.fr> eg: HELP as the subject with no body > text > The Rietveld_L list archive is on > http://firstname.lastname@example.org/ > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > >
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