Application of Organo-Magadiites for the Removal of Eosin Dye from Aqueous Solutions: Thermal Treatment and Regeneration

• Published in: Molecules (Basel, Switzerland) Vol. 23; no. 9; p. 2280
• Main Authors: Kooli, Fethi, Liu, Yan, Abboudi, Mostafa, Rakass, Souad, Hassani, Hicham Oudghiri, Ibrahim, Sheikh Muhammad, Al-Faze, Rawan
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 06.09.2018; MDPI
• Subjects: Adsorption; Aluminum Silicates; Ammonium; Aqueous solutions; Bromine; Cation exchange; Cation exchanging; Clay; Coloring Agents - chemistry; Coloring Agents - toxicity; Dyeing; Dyes; eosin; Eosine Yellowish-(YS) - chemistry; Fluorescence; Heat treatment; Humans; Layered materials; Leather; magadiite; Nitrogen; Organic Chemicals - chemistry; Organic Chemicals - toxicity; Organic chemistry; organo-layered silicate; Organosilicon Compounds - chemistry; Pigments; regeneration; removal; Silica; Silica fume; Silicates - chemistry; Studies; Surface-Active Agents - chemistry; Surfactants; Temperature; thermal stability; Water - chemistry; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - toxicity; Water pollution; Water Purification; X-Ray Diffraction; United States > US; magadiite; removal; thermal stability; regeneration; eosin; organo-layered silicate
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules23092280

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 C, finding mainly the 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 C of 200 mg/L.