RESUMO
The aim of this paper is to study the adsorption of the acid dye Supranol Yellow 4 GL (S.Y. 4 GL) from aqueous solution on an inorgano-organo clay. Bentonite is naturally occurring clay with good exchanging ability. By exchanging its interlamellar cations with cetyltrimethylammonium bromide (CTAB) and hydroxyaluminic or chromium polycations, the properties of natural bentonite can be greatly improved. Batch adsorption tests of Supranol Yellow 4 GL were carried out at 20 degrees C and constant pH 6.5. To investigate the adsorption mechanisms, the simplified kinetic models, such as pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion are tested. The results show that adsorption follows second-order rate kinetic. The correlation coefficients obtained for second-order kinetics model are greater than 0.998 indicating a better fitting of this equation. The experimental data are analysed by Langmuir, Freundlich and Elovich isotherms. The equilibrium adsorption capacity of anionic dye is determined from the Langmuir equation and found to be 142, 85 and 128, 20mg/g (standard deviation; Deltaq (%)=3.52 and 18.51) for CTAB-Cr-B and CTAB-Al-B, respectively.
Assuntos
Alumínio/química , Bentonita/química , Cromo/química , Corantes de Rosanilina/química , Tensoativos/química , Adsorção , Algoritmos , Cetrimônio , Compostos de Cetrimônio , Difusão , Cinética , Modelos Lineares , Corantes de Rosanilina/isolamento & purificação , Soluções , Espectroscopia de Infravermelho com Transformada de Fourier , Água , Difração de Raios XRESUMO
Cr(III)-intercalated montmorillonite was utilized as an adsorbent for the removal of the organic pollutant, Supranol Yellow 4GL, a synthetic dye used for chemical fibres. The material was prepared by the reaction of Na montmorillonite with a base-hydrolyzed solution of Cr nitrate salt (OH(-)/Cr(3+) molar ratios of 2). XRD data showed that the interlayer spacing (d(001)) of montmorillonite was increased from 12.35 to 23.06 Angstroms. The kinetics and mechanism of the adsorption of the acid dye, Supranol Yellow 4GL, on Cr(III)-intercalated montmorillonite was investigated. The equilibrium time was reached within 30 min. The process follows pseudo-second-order rate kinetics. The Langmuir isotherm described the adsorption data over the concentration range (20-160 mg/l). The separator factor R(L) revealed the favourable nature of this adsorption process. Also, the thermodynamic parameters such as DeltaS degrees, DeltaH degrees, DeltaG degrees were determined.
