Trimellitated sugarcane bagasse : a versatile adsorbent for removal of cationic dyes from aqueous solution. Part I : batch adsorption in a monocomponent system.

Abstract

Trimellitated-sugarcane bagasse (STA) was used as an environmentally friendly adsorbent for removal of the basic dyes auramine-O (AO) and safranin-T (ST) from aqueous solutions at pH 4.5 and 7.0. Dye adsorption was evaluated as a function of STA dosage, agitation speed, solution pH, contact time, and initial dye concentration. Pseudo-first- and pseudo-second-order, Elovich, intraparticle diffusion, and Boyd models were used to model adsorption kinetics. Langmuir, Dubinin-Radushkevich, Redlich-Peterson, Sips, Hill-de Boer, and Fowler-Guggenheim models were used to model adsorption isotherms, while a Scatchard plot was used to evaluate the existence of different adsorption sites. Maximum adsorption capacities for removal of AO and ST were 1.005 and 0.638 mmol g 1 at pH 4.5, and 1.734 and 1.230 mmol g 1 at pH 7.0, respectively. Adsorption enthalpy changes obtained by isothermal titration energy and entropy of adsorption were calculated. These thermodynamic parameters were also used to evaluate the adsorption mechanism at both pH values.