Modified clay minerals for environmental applications

Sarkar, Binoy; Rusmin, Ruhaida; Ugochukwu, Uzochukwu C.; Mukhopadhyay, Raj; Manjaiah, K.M.

doi:10.1016/b978-0-12-814617-0.00003-7

Cited by 47 publications

(32 citation statements)

References 70 publications

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“…For comparison, the thermal stability of the C 16 Br salt used was investigated. Previous studies indicated that the solid C 16 Br exhibited a layered structure with a length of the C 16 chain about 2.6 nm, this value was close to that reported in the literature [24,116]. By heating the salt, the in-situ the PXRD study indicated that the layered structure expanded from 2.60 nm to 3.32 nm, in the temperature range of 25 °C to 210 °C, then it collapsed, due the melting of the solid salt [33,47] (Supplementary Material 3).…”

Section: Resultssupporting

confidence: 89%

“…Among the natural materials, clay minerals were proposed as good candidates due to their outstanding adsorption properties [21,22]. However, these clay minerals are typically subjected to many modifications prior their use, depending of the target pollutant and its charge [23,24]. The clay minerals are efficient at removing cationic metals and positively charged organic pollutants such as basis dyes [23], due to their negatively charged and hydrophilic surface, however, in case of nonpolar hydrophobic contaminants or negatively charged pollutants such as acid dyes or anions, clays are largely ineffective due to the electrostatic repulsion; and their hydrophilic character as mentioned above [25,26].…”

Section: Introductionmentioning

confidence: 99%

“…The most common modification consists of the use of cationic surfactant solutions that generate organoclay adsorbents that combine both the properties of the inorganic layered material and hydrophobic environment with the intercalation of the organic cations. Indeed, these materials adsorb a large range of pollutants, such as pesticides [27], phenolic compounds [28], various pharmaceutical products [29] and acidic dyes [23,24]. The removal efficiency of these organoclays mainly depends on both the chemical nature and the structural organization of the intercalated surfactants [30,31].…”

Section: Introductionmentioning

confidence: 99%

“…A maximum amount equivalent to 1 time the cation exchange capacity (CEC) of the clay mineral allows the creation of a hydrophobic environment without any strong steric effects that may restrict the removal of pollutants, while the uptake of surfactants at high concentration (i.e., > 1 CEC) creates a large hydrophobic network with an arrangement of the organic cations in the bilayer within the interlayer space that may enhance or reduce the removal properties [29]. The removal of acidic dyes was improved when the content of C 16 cations was increased and exceeded the CEC values, due to favourable interactions arising with the R groups of the quaternary ammonium ions [24,33], which made the acidic dyes more easily attracted into the expanded interlayer space of the clay [33].…”

Section: Introductionmentioning

confidence: 99%

“…However, in other cases, the origin of clay minerals and the type of C 16 salt used to modify the clay mineral was crucial and it has to be taken in consideration during the preparation of the organoclays [33,36,37]. The commonly used C 16 modifiers are prepared by dissolving their solid salt with bromide anion in water solutions [24,33]. Few studies using chloride or hydroxide C 16 TAM salts are reported [33,36,38,39,40,41,42].…”

Section: Introductionmentioning

confidence: 99%

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Eosin Removal by Cetyl Trimethylammonium-Cloisites: Influence of the Surfactant Solution Type and Regeneration Properties

et al. 2019

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The effect of the counteranion of hexadecyltrimethylammonium salts on the physico-chemical properties of organoclays was investigated, using a selected natural clay mineral with a cation exchange capacity of 95 meq/100 g. The uptake amount of C16 cations was dependent on the hexadecyltrimethylammonium (C16) salt solution used, the organoclay prepared from C16Br salt solution exhibited a value of 1. 05 mmole/g higher than those prepared from C16Cl and C16OH salt solutions. The basal spacing of these organoclays was in the range of 1.81 nm to 2.10 nm, indicating a similar orientation of the intercalated surfactants, and could indicated that the excess amount of surfactants, above the cation exchange capacity of 0.95 meq/g could be adsorbed on the external surface of the clay mineral sheets. These organoclays were found to be stable in neutral, acidic, and basic media. The thermal stability of these organoclays was carried out using thermogravimetric analysis and in-situ X-ray diffraction (XRD) techniques. The decomposition of the surfactant occurred at a maximum temperature of 240 °C, accompanied with a decrease of the basal spacing value close to 1.42 nm. The application of these organoclays was investigated to remove an acidic dye, eosin. The removal amount was related to the initial used concentrations, the amount of the surfactants contents, and to the preheated temperatures of the organoclays. The removal was found to be endothermic process with a maximum amount of 55 mg of eosin/g of organoclay. The value decreased to 25 mg/g, when the intercalated surfactants were decomposed. The reuse of these organoclays was limited to four regeneration recycles with a reduction of 20 to 30%. However, noticeable reduction between 35% to 50% of the initial efficiency, was achieved after the fifth cycle, depending of the used organoclays.

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