Optimization and Feasibility of Alizarin Red S Retention on Iron- Loaded Cellulose Nanocomposite Bead

Abstract

Iron(III) loaded cellulose nanocomposite bead, synthesized through sol-gel method, was characterized by Fourier transform infra-red spectroscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, tunneling electron microscopy, and tested for adsorptive removal of alizarin red S from aqueous solution. The influence of variables such as pH, contact time, initial dye concentration, adsorbent dose and temperature for dye retention were investigated in batch operation. The process was optimized by employing response surface methodology following full factorial and central composite design. The maximum adsorption of 97% was observed at an optimum condition of pH 3.0, dose of 2.0 gdm-3 and shaking time of 45 mins corresponding to the dye concentration of 100 mgdm-3 at 303 K. Correlation of cooperative influences of the significant variables and the extent of dye adsorption were represented by a second order polynomial equation. The mutual interactions of the significant variables were presented by 3D response surface and 2D contour plots in the design space. The adsorption was better described by Langmuir isotherm and pseudo second order kinetics. The process was spontaneous (-∆G°, 48.19 kJmol-1 ), feasible (∆S°, 0.284 Jmol -1 K-1 ) and endothermic (∆H°, 71.62 kJmol-1 ). The adsorbent can be regenerated with NaOH (10.0 × 10-2 M) and recycled for reuse, at least for five successive operations.