First-ever study on the use of nutraceutical industrial turmeric root spent (NITRS) as biosorbent for the removal of Crystal violet (CV) from aqueous media was tried. The effects of initial dye concentration, adsorbent dosage, contact time between adsorbent and adsorbate, speed of agitation and pH on adsorption were studied. The experimental equilibrium data were analyzed by using isotherm models of Langmuir, Freundlich and Tempkin. The pseudo-first order and pseudo-second order models were applied for adsorption kinetic studies. Kinetic data fitted well to pseudo-second order model. Thermodynamic analysis showed that adsorption is favorable (negative values for ΔGᴼ) and endothermic (ΔHᴼ= 12-20 kJ mol-1) at the initial dye concentrations of 50, 100 and 150 ppm. The low ΔHᴼ value is the indication for the physical process of adsorption involving weak chemical interactions like hydrogen bonds and Van der Waals interactions. SEM images of NITRS show highly fibrous matrix with hierarchical porous structure. FTIR analysis of the spent confirmed the presence of cellulosic and ligno-cellulosic materials imparting hydrophilic and hydrophobic properties. The investigation proved that NITRS is a cost-effective and efficient biosorbent for the remediation of toxic CV dye.
