Organo-kenyaites were prepared from a cetyltrimethylammonium hydroxide (C16TMAOH) solution and solid sodium kenyaite (Na2Si22O45.10H2O) mixture. The effect of the initial cetyltrimethylammonium solution on the structure of the intercalated materials was investigated by CHN analyses, X-ray diffraction (XRD), thermogravimetric analysis, SEM, and 29Si and 13C solid NMR techniques. For C16TMAOH concentration 0.25 mM, the Na+ cations were fully exchanged. Initial C16TMAOH concentrations higher than 0.25 mM had little effect on the intercalated amount of C16TMA+ cations. The organic cations content reached a plateau of 0.66 mmol/g. The arrangement model of C16TMA+ cations corresponded to a tilt of the organic cations to the silicate layers with an angle of 42° as deduced by XRD studies. The C16TMA+ cations exhibited mainly trans-configuration of the methyl chains, as was shown by solid 13C NMR. The thermal stability of the organo-silicates was studied using in situ FTIR and in situ XRD in the range 25–450°C. The C16TMA-kenyaites were stable at temperatures below 200°C. They collapsed at higher temperatures due to the decomposition of the intercalated surfactants. These organo-kenyaites were used to remove the acidic dye molecule, eosin. The removal tests were performed at varying conditions of initial dye concentrations, organic content in the organo-kenyaites and heating temperatures. In general, the organic modification improved the removal capacity of the Na-kenyaite from 2 mg of eosin/g to 60 mg of eosin/g, and this capacity was related to the organic contents and the calcination temperatures of the organo-kenyaites.

The organo-clays (OCs) were prepared by a cation exchange reaction between surfactant (cetyltrimethylammonium, C16TMA) from different counterions (Bromide, Chloride, and Hydroxide). The effect of the counterions was investigated on the physico-chemical properties of the prepared organo-clays. The highest uptake of organic cations (1.60 mmol/g) was achieved using cetyl trimethylammonium bromide solution and the lowest value (0.93 mmol/g) was obtained after modification with cetyl trimethylammonium hydroxide solution starting from the same initial ratio of mmol/g of clay greater than 2.40. The arrangement of C16TMA cations within the interlayer space was assumed to be perpendicular with a tilt angle of 32° to the plane of clay sheets instead of being parallel to the clay surface using C16TMAOH solution at the same ratio. Different techniques were used to characterize these materials. The thermal stability of these organ-clays was investigated using an in-situ X-ray diffraction (XRD) technique. The decomposition of the surfactant moiety occurred at temperatures higher than 215 °C and was accompanied with a shrinkage of the basal spacing value to 1.42 nm. These materials were applied in the removal of an acid dye “eosin.” The removed amount of eosin depended on the initial concentrations and the content of surfactants in the organo-clays. The removal of eosin was found to be an endothermic process. The maximum amount of 90 mg/g was achieved. The preheated treatment temperature of two selected OCs did affect the removal properties of eosin. A progressive reduction was observed at temperatures higher than 200 °C. The regeneration of spent OCs was studied and acceptable removal efficiency was maintained after 4 to 6 cycles depending on the used initial concentrations.

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Na-magadiite exchanged with cetyl-trimethylammonium cations provided organophilic silicate materials that allowed for the effective removal of the acidic dye “eosin”. The organic cations were intercalated into the interlayer spacing of the layered silicate via an exchange reaction between the organic cations from their bromide salt and the solid Na-magadiite at room temperature. Different techniques were used to characterize the effect of the initial concentration of the surfactant on the structure of the organo-magadiites. The C, H, and N analysis indicated that a maximum of organic cations of 0.97 mmol/g was achieved and was accompanied by an expansion of the basal spacing of 3.08 nm, with a tilted angle of 59° to the silicate layers. The conformation of the organic surfactants was probed using solid-state 13C, finding mainly the trans conformation similar to that of the starting cetyl trimethylammonium bromide salt (C16TMABr). Thermal gravimetric analysis was carried out to study the thermal stability of the resulting organo-magadiites. The intercalated surfactants started to decompose at 200 °C, with a mass loss percentage of 8% to 25%, depending on the initial loading of the surfactant, and was accompanied by a decrease of the basal spacing from 3.16 nm to 2.51 nm, as deduced from the in situ X-ray diffraction studies. At temperatures below 220 °C, an expansion of the basal spacing from 3.15 to 3.34 nm occurred. These materials were used as a removal agent for the anionic dye eosin. The maximum amount of the dye removed was related to the organic cation content and to the initial concentration of eosin, with an improvement from 2.5 mg/g to 80.65 mg/g. This value decreased when the organo-magadiite was preheated at temperatures above 200 °C. The regeneration tests indicated that an 85% removal efficiency was maintained after six cycles of use for the organo-magadiite using Ci of 200 mg/L.

Local clay from Al-Madinah Al-Munawwarah was modified by a solution of cetyltrimethylammonium bromide (C16TMABr) at different initial concentrations. The organoclays were characterized by PXRD, TGA, FTIR and N 2 adsorption isotherms. The ability of these samples to remove the dye eosin is evaluated. The removal properties of organoclays were dependent on the content of C16TMA cations, the initial concentrations of eosin, temperature of the removal process, the mass of the used organoclays. These organoclays exhibited removal percentages in the range of 80 ~100% and removed amounts of 50 ~ 68 mg of eosin/ g. The isotherms were fitted well in Langmuir model.