Removal of pigments from aqueous solution by a calcium alginate–grape marc biopolymer: A kinetic study

In this work, the potential use of a biopolymer based on grape marc entrapped in calcium alginate beads for the removal of pigments from an agro industrial effluent was evaluated. The parameters that affect the pigment adsorption such as pH (3.5–7.0), temperature (10–40 °C) and initial pigment concentration (6.9–55.1 mg/L) were studied by applying an incomplete factorial design. The dependent variables evaluated consisted of color effluent parameters from CIELAB and Tristimulus system, as well as the concentration of pigments in the wastewater after the adsorption treatment. The most significant independent variables tested were the pigments concentration followed by pH, whereas temperature had a negligible effect on the adsorption process. Moreover, at the optimal operational conditions (pH 3.5 and room temperature) kinetic studies were carried out by applying pseudo-first order, pseudo-second order, Chien–Clayton and intraparticle diffusion models, observing a good agreement between theoretical and experimental results.