Source Clay Minerals Repository

Source Clay Mineral Repository, Universitv of Missouri, Rolla, Mo. 

Periodically, these mixtures were centrifuged and an aliquot of the clay-free supemate taken for counting analysis. Two naturally-occurring clays were selected for the experiments one was labeled kaolin (for the mineral kaolinite) while the second was referred to as attapulgite (or polygorshite). Both were obtained from the Source Clay Mineral Repository (3) as standard clays representative of each class of clay and were used as received. Stable, colloidal suspensions of each were prepared by ultrasonically dispersing weighed quantities of each clay in triple-distilled water. 

Sepiolite (SepSp-1) was obtained from the Source Clay Mineral Repository (University of Missouri) and was used without additional purification. Thermal treatment was carried out for 19-20 hours under air in a baffle furnace, using 0. l-0.2g sepiolite that had been gently ground in a mortar and passed through a 100-mesh sieve. The vials containing dried sepiolite were transferred into capped bottles containing a few milliliters of acetone (acetone-d6 for the broad line 2H NMR experiments) and then remained in contact with the acetone vapor at room temperature for 4 days. 

Source Clay Minerals Repository, Dept, of Geology, University of Missouri Columbia, Missouri 65201 USA. 

Figure 6. Observed relationship between specific surface area (Sm) and Fe2 content of a chemically reduced series of ferruginous smectite (sample SWa-1 from the Source Clay Minerals Repository of The Clay Minerals Society). (Reproduced with permission from Lear,...

Figure 15 Layer charge of ferruginous smectite (sample SWa-1 from the Source Clay Minerals Repository of The Clay Minerals Society).

Same samples as used by Stuck et al. (29) and Lear and Stucki (32). UPMsUpton (API 25) montmorilIonite CZMsCzechoslovakia 630 montmorillonite NZM New Zealand montmorilIonite GAN Garfield (API H-33a) nontronite SWa-lsferruginous smectite (Source Clay Minerals Repository, The Clay Minerals Society). 

As an example of thin-foil analysis in the SEM, samples of the mineral standard kaolinite (<2 pm fraction, KGa-2, Source Clay Minerals Repository) were dispersed on TEM grids and analyzed using a JEOL JSM 6400 SEM under the control of an automated Noran Voyager EDS system equipped with a thin-window EDS detector.93 For comparison, EDS spectra were also collected using the same instrument for the kaolinite size fractions deposited on polycarbonate filters, fixed to SEM... 

AR grade acetic anhydride, dodecatugstophasphoric acid-a heteropolyacid (HPA), zirconium oxychloride, anhydrous aluminium chloride, sodium carbonate and ammonium sulphate were obtained from s.d.Fine Chem. Ltd, Mumbai. 2-MON (yarayara) was obtained from Aerofine Industries Ltd, Mumbai. Amberlyst-15 was procured from Rohm and Huss, USA., and Indion-130 from Ion Exchange (India) Ltd. These catalysts were used as such. Zeolites ZSM-5, Y and Mordenite were obtained from M/s Associated Cement Company (ACC), India. Commercially available acid treated KIO montmorillonite clay was obtained from Fluka. SWy-2 (Wyoming Na -montmorillonite) was obtained from Clay Minerals Society, Source Clay Minerals Repository, Missouri University, Columbia, USA. 

In polarized experiments performed on self-supporting films of the SHCa-1 hectorite from the Source Clay Minerals Repository of the Clay Minerals Society ([MnO] = 0.008 wt. %), we observed that Mn(II) present in trace amounts (0.03 weight %) was oxidized to Mn(III) when measurements were carried out on the undulator beamline ID26 of the ESRF (photon density 108 ph s-1 pm-2), and remained in reduced form when... 

Starting clay a saponite from Ballarat (USA) described by Post (9) and supplied by Source Clay Minerals Repository (University of Missouri) has been us. ... 

The formation of the M-PILCs involved the use of a suspension of <2pm STx-1 montmorillonite (Source Clay Minerals Repository, University of Missouri), which had been acid washed (2M HCl), neutralized and exchanged three times with 4M NaCl. This clay mineral has a cation exchange capacity of approximately 84 meq/l(X)g, and a surface area of about 83.3 m2/g (Van Olphen and Fripiat 1979). The hydrolyzed metal solutions were added dropwise to vigorously stirred suspensions (ca. 1% w/w) of the Na-STx-1 (or vice versa), to solution loadings of ca. 10 meq metal/g STx-1. The suspensions were then washed with distilled water by centrifugation until testing with silver nitrate revealed the supernatant fluid to be negative for chloride ions. 

Materials. Naturally occurring sodium hectorite from Hector, California, with a particle < 2 Xm was obtained from the source clay mineral repository. University of Missouri, Columbia. The cation exchange capacity, as determined by the displacement of ammonia from an ammonium saturated sample using NaOH and an ammonia specific electrode, was 73 meq per 100 grams of air-dried clay. All reagents and solvents used in this work were obtained from Chemical Dynamics Corporation and Aldrich Chemical Company and were used without further purification. 

---