Adsorption Mechanisms of Phenol and Methylphenols on Organoclays

Abstract

Eight clay-organic complexes were synthesized by placing quaternary ammonium cations (QUATs) on to bentonite (B) and kaolinite (K) by cation exchange. The organic cations used were hexadecyltrimethylammonium (H DTMA), dodecyltrimethylammonium (DDTMA), trimethylphenylammonium (TMPA) and tetramethylammonium (TMA). These organoclays were characterized via their organic carbon contents with the aid of XRD and Ff-IR spectroscopic analyses. The organoclays were examined for their ability to adsorb phenol (P) and several of its methyl congeners [2,4-dimethylphenol (2,4-DMP) and 2,4,6trimethylphenol (2,4,6-TMP)]. It was shown that inorganoclays (Na-clays) and organokaolinites were incapable of adsorbing any of these organic pollutants. It was also determined that the adsorption of phenol compounds from water decreased in the order: 2,4,6-TMP> 2,4-DMP > P for HDTMA-B and DDTMA-B, 2,4-DMP> P > 2,4,6-TMP for TMPA-B and P > 2,4-DMP > 2,4,6-TMP for TMA-B. With n-hexane as a solvent a different adsorption trend was found, which depended on the type and degree of solvent interaction with the organic compounds and the organoclays. It was observed that the degree of adsorption of phenols on to organoclays was dependent on the relative adsorbent-adsorbate energies and adsorbate-solvent interactions. The adsorption isotherms of phenols on to organophilic clays were evaluated according to the Giles classification.

Adsorption of Acid Blue 193 from aqueous solutions onto Na–bentonite and DTMA–bentonite

“…DTMA-bentonite was prepared by adding the respective quantities of dodecyltrimethylammonium bromide, which was used as a surfactant, equal to twice the cation exchange capacity of the bentonite [29]. The prepared DTMA-bentonite was then washed with distilled water until it was free of salts and a negative bromide test had been obtained with 0.1 M AgNO 3 .…”

Comportamiento De Un Fertilizante De Liberación Lenta a Base De Organobentonita-Fosfato en Plantas De Lechuga

“…La viabilidad de utilizar organoarcillas como fertilizantes de liberación lenta de nutrientes ha sido investigada por diversos autores (Berber et al, 2014;Bhardwaj et al, 2012;Malekian et al, 2011;Romero-Mendez et al, 2019). Dentro de las organoarcillas se destacan las organobentonitas (OB) por sus altas propiedades de adsorción y capacidad de intercambio iónico (Pandey y Ramontja, 2016) y han sido propuestas como fertilizantes de liberación lenta (Yuan, 2014); éstas son sintetizadas por sorción de un tensioactivo catiónico sobre una bentonita, que carga de negativa a positiva la superficie externa y el espacio de las capas intermedias (Ceyhan et al, 1999), lo que hace posible la adsorción de formas aniónicas como el fosfato; sin embargo, a pesar de estos resultados promisorios, el efecto de la liberación de fósforo con estos materiales no ha sido estudiado, tampoco su efecto en el crecimiento de las plantas.…”

Removal of Toxic Pollutants from Aqueous Solutions by Adsorption onto Organo-kaolin

“…Such modification is frequently achieved by sorbing a cationic surfactant onto the external surface and into the interlayer spacing of the clays [1][2][3]. The clay surface changes from hydrophilic to hydrophobic and from negatively to positively charge.…”

“…In several works, hexa-decyltrimethylammonium bromide (HDTMA) has been used as surfactant for modifying the surface of natural clays and zeolites [1,2,6].…”

“…Other authors [1,2,[11][12][13][14] have investigated the adsorption of organic compounds such as penta-chlorophenol, phenol, chlorobenzene and acid dyes onto montmorillonite and bentonite clays modified with cationic surfactants. They showed that modification of the clay increased the adsorption capacity.…”