The texture of montmorillonites as influenced by the exchangeable inorganic cation and the drying method II: A comparative porosity study

The porosity of deferrated montmorillonites: ethanol and methylbromide sorption

“…For P/Po < 0.40, t becomes dependent on the adsorbate-adsorbent interaction which is best characterized by the CBE T value (Lecloux & Pirard, 1979). Some t curves are given in Stul & Van Leemput (1982c). If, however, the t values for CBE T ----1000 (Lecloux & Pirard, 1979) are used in cases where CBE T > 300 anomalous v-t plots are obtained, i.e.…”

“…a negative value of the adsorbed volume is found. For adsorption with 300 < CaE T < 500 a new t curve was derived by interpolation (Stul & Van Leemput, 1982c). Analysis of the V-t plot provides a porevolume distribution, a cumulative volume V~p, a cumulative surface area Sra p and, from the slope of the initial linear part of the plot, a measure of the total surface area S t = 15.47 V/t.…”

“…For the V-t plots the standard t curves were applied as reported elsewhere (Stul & Van Leemput, 1982c) according to the following CBE T values: (a) for 500 < CBE T < 2000, the untreated GY, GW and WB for which CBE T ----635, 734 and 768 respectively; (b) for 300 < CBE T < 500: deferrated MO, GY, GW, untreated MO; (c) for 100 < CBE T < 300, deferrated CB, MA, WB and untreated CB and MA.…”

“…This is the case for deferrated WB which can therefore not be treated with the techniques explained above. Disregarding the mesopores, the micropore volume can be determined with the DR method as outlined for the untreated clays (Stul & Van Leemput, 1982c). With the deferrated clays the DR method is no longer applicable.…”

“…As a consequence, an increase in porosity of the clay system should occur. Untreated montmorillonites present a mixed microporous-mesoporous system which is heterogeneous and essentially a mesoporous adsorbent (Stul & Van Leemput, 1982c). The effect of deferration on pore-size distribution and CEC of some Na-montmorfllonites is described here.…”