Batch adsorption studies were carried out to investigate the adsorption behaviour of textile dye- Reactive red 2 (RR2) from aqueous
solution onto montmorillonite (Mt) clay and organophilic Mt clays. The monovalent organic cations- cetyltrimethylammonium (CTA+
) and
cetylpyridinium (CP+
) were exchanged for the metal cations in montmorillonite clay to prepare the organophilic Mt clays- CTA–Mt and
CP-Mt. The synthesis of these organophilic clays was confirmed by X-Ray diffraction (XRD), Fourier Transformed Infra Red (FTIR),
specific surface area (BET ) and zeta potential techniques. The adsorption affinity of Mt, CTA-Mt and CP-Mt for RR2 was investigated as a
function of pH of the aqueous dye solution, contact time, initial dye concentration and adsorbent dosage. The adsorption data obtained was
fitted to the Langmuir, Freundlich and Temkin adsorption models and it was found that Langmuir adsorption isotherm yielded the most
favourable representation of the adsorption behaviour of RR2. The adsorption kinetics of RR2 has been studied in terms of pseudo-firstorder, pseudo-second-order and intraparticle diffusion processes. It was found that the pseudo-second-order mechanism is predominant in
the present adsorption system suggesting chemisorption of the dye.
Key words: adsorption; adsorption kinetics; cation exchange; montmorillonite; organophilic clays; zeta potential
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