Argilas bentoníticas da península de Santa Elena, Equador: pilarização, ativação ácida e seu uso como descolorante de óleo de soja

Abstract

pillared with Al 13 ions in the ratio of 10, 15 and 20 meq of Al g-1 of clay, calcinated at 573, 723 and 873 °K and acid activated with 4, 6 and 8 mol L-1 H 2 SO 4. Analyses by X-ray diffraction, X-ray fluorescence, differential and gravimetric thermal, density, surface area and porosity, were applied in order to study the modifications occurred in the crystalline structure of the montmorillonite. The 8 mol L-1 H 2 SO 4 acid-activated 15 meq of Al g-1 of clay at 573 °K Al-pillared samples indicated the best results in the bleaching of the soybean oil measured by UV-visible spectrophotometer.

Effects of acid treatment on the clay palygorskite: XRD, surface area, morphological and chemical composition

“…No significant difference was observed in morphological operating conditions used, even in the most severe cases of concentration and time. This result is in agreement with the results obtained in research that studied the effect of acid activation in palygorskite 14,21,24,25 .…”

“…The increased surface area to a maximum value and additional decrease were described in the literature for activation with acid on the palygorskite 21,22 and clays such as: halloysites 23 , and bentonites 24 . The surface area is one of the most important physicochemical properties of palygorskite, especially when it is used as an adsorbent to remove heavy metals and dyes ions.…”

Clarification of used lubricating oils by application of chemically-modified clays

“…3c). The bands at 3705 and 3618 cm -1 corresponded to the hydroxyl mixture of clay minerals (palygorskite and kaolinite) linked to metal (Me), where Me corresponds to the ions Al 3+ , Mg 2+ or Fe 3+ [30][31][32][33][34][35][36]. The bands in the range from 3406 to 3516 cm -1 were attributed to the elongation vibrational mode of water absorbed by clay [12].…”

“…The band at 1643 cm -1 represented the deformation of water molecules [19] and at 913 cm -1 of the octahedral leaf (Al-OH) [17]. The absorption at 1029 cm -1 referred to the stretching of Si-O groups from the tetrahedral sheet for kaolinite and palygorskite [34][35][36][37][38]. The band at 796 cm -1 was attributed to the quartz impurity crystalline phase [34].…”

“…The second event occurred between 151 and 292 °C with a loss of mass (PM2) of 0.72%. The third event with a less intense band than CNAT occurred in the range between 292 and 597 °C with loss of mass (PM3) of 2.03% and was related to water loss and loss of the hydroxyls of the silanol (Si-OH) and aluminol groups (Al-OH) [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Above 600 °C, no further loss of mass occurred in the clay and therefore, a total mass loss of 9.08% was observed.…”