Hybrid Materials Based on Bentonite Functionalized with Amine Groups via the Hydrolytic Sol-Gel Method

Abstract

Bentonite is a natural clay that presents characteristics such as good capacity to exchange cations, large specific surface area, large porosity, and possibility to undergo intercalation and/or functionalization. This work reports on bentonite functionalization with organomodified alkoxides. Functionalization afforded hybrid materials displaying desirable properties for adsorption of chromium trivalent ions. Infrared absorption spectroscopy, X-ray powder diffraction, thermal analysis, specific surface area analysis, and adsorption experiments with methylene blue helped to characterize the materials and evaluate their cationic exchange capability. These techniques evidenced functionalization of the Brazilian bentonite. Kinetic and equilibrium experiments on the adsorption of chromium trivalent ions aided determination of the equilibrium time of kinetic adsorption isotherms and revealed whether the functionalized matrices adsorbed chromium trivalent ions. Chromium displayed S1 type adsorption isotherms, which confirmed that adsorption capacity originated from cooperative forces between the adsorbate and the hybrid adsorbents.

Effect of covalently functionalized Indian bentonite clay on thermal, mechanical strength and morphology structure of extrusion/injection‐molded nylon 6 composites

“…Another adsorption peak at 1467 and 1475 cm −1 corresponds to the OCH 3 and CO stretching vibrations, respectively. The IR spectrum of organically modified clay shows that a silane compound has been grafted with the clay minerals 34–36 …”

“…The amine‐functionalized clay was produced by grafting DAMPS and 3‐aminopropyl tri‐methoxy silane with Indian bentonite (BMT), as previously reported 34–36 . A 5 g of Indian bentonite was added to two separate 250 mL round bottom flasks containing 200 mL of a methanol‐to‐water mixture in a 2:1 ratio.…”

“…The amine-functionalized clay was produced by grafting DAMPS and 3-aminopropyl tri-methoxy silane with Indian bentonite (BMT), as previously reported. [34][35][36] A 5 g of Indian bentonite was added to two separate 250 mL round bottom flasks containing 200 mL of a methanol-to-water mixture in a 2:1 ratio. The cation exchange capacity of Indian bentonite was determined to be 85 meq/100 g. Subsequently, 3-aminopropyltrimethoxysilane (APTMS) and DAMPS, both possessing twice the cation exchange capacity of clay minerals, were introduced into the clay suspension.…”

“…Furthermore, weight loss in the temperature range of 350-700 C is observed for AMSB and DAMSB, whereas there is no significant weight loss for BMT. 35,36 This notable weight loss between 350 and 600 C corresponds to the decomposition of silane molecules chemically grafted to the clay mineral interlayer.…”