Organically Modified Saponites: SAXS Study of Swelling and Application in Caffeine Removal

Abstract

This study aimed to assess the capacity of saponite modified with n-hexadecyltrimethylammonium bromide (CTAB) and/or 3-aminopropyltriethoxysilane (APTS) to adsorb and remove caffeine from aqueous solutions. Powder X-ray diffraction (PXRD) revealed increased basal spacing in the modified saponites. Small-angle X-ray scattering (SAXS) confirmed the PXRD results; it also showed how the different clay layers were stacked and provided information on the swelling of natural saponite and of the saponites functionalized with CTAB and/or APTS. Thermal analyses, infrared spectroscopy, scanning electron microscopy, element chemical analysis, and textural analyses confirmed functionalization of the natural saponite. The maximum adsorption capacity at equilibrium was 80.54 mg/g, indicating that the saponite modified with 3-aminopropyltriethoxysilane constitutes an efficient and suitable caffeine adsorbent.

Kaolinite/TiO2/cobalt(II) Tetracarboxymetallophthalocyanine Nanocomposites as Heterogeneous Photocatalysts for Decomposition of Organic Pollutants Trimethoprim, Caffeine and Prometryn

“…Caffeine features characteristic stimulant, psychoactive properties, acting on the central nervous system of humans, promoting changes in sleep and agility. 11,12 Large amounts of caffeine occur in the seeds, leaves, and fruits of some plants, the microorganisms existing in the environment cannot metabolize this compound satisfactorily.…”

“…3,24,25 This problem can be mitigated with some procedures, such as the dispersion on inorganic matrices, 17,26,27 such as clay minerals. Clay minerals are attractive materials for many significant applications, due to their physical and chemical properties, including catalysis/photocatalysis and adsorption, 12,28,29 especially kaolinite, whose layered structure provides the possibility of retention of a great variety of compounds to reduce the energy required for the activation of the semiconductor. Catalyst improvement via immobilization might also be due to the force field between the support and the TiO 2 particles that inhibits the recombination of electron-hole pairs.…”

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

“…Therefore, the presence of alkoxides in BEN reduced the cation exchange capacity of the clay, probably because the silanes molecules on the edge of the clay blocked access to the interlayer space and reduced the cation exchange capacity, as observed by us in another work. 13 The Brazilian bentonite clay from Paraíba State, Brazil has CEC of about 87.53 meq per 100 g of clay as estimated by ammonium cation exchange. 43 Another work has reported CEC of 74 meq per 100 g of clay for bentonite on the basis of flame emission spectrophotometry.…”

“…Nucleophilic attack from the interlayer siloxane hydroxyls or from water in hydrated cations can induce hydrolysis, and silanol and Mg-OH present in lateral edge sites or in clay surface defects can favor condensation. [13][14][15] Clay functionalization with organic compounds can add new properties to hybrid materials and increase chemical affinity between adsorbent and adsorbate, consolidating their use for environmental purposes. 16 Study of natural clay adsorption capacity and comparison of this capacity with the adsorption capacity of hybrid clay materials can contribute to entrapping contaminants in the physical environment of the clay, thereby enabling treatment of industrial effluents with modified clays.…”

One‐pot Synthesis of Novel Composite@Composite‐Typed Core@Shell Nanostructures and the Adsorption Property for Dye Wastewater

“…To date, various biotechnology, physical and chemical methods have been used to reduce the pollution and hazard of dyes, e. g., adsorption, chemical oxidation, photo‐oxidation and biodegradation . Among these methods, adsorption is one of the most economical and effective technologies to separate dyes from wastewater . Up to now, various absorbents, including biochar, activated carbon, graphene, metal‐organic frameworks and metal oxides, have been employed to adsorb pollutants in wastewaters.…”