Adsorptive removal of a triphenylmethane dye from its aqueous solutions using a biosorbent

A hazardous triphenylmethane dye, Crystal Violet, was effectively removed from its aqueous solution using a waste material—Hen Feather—as biosorbent. The Crystal Violet-Hen Feather adsorption system gives promising results and has not been studied previously. By removing a highly toxic dye, using a ubiquitous biowaste material this research provides dual advantages. The influence of contact time, adsorbent dosage, dye concentration, and solution pH on the uptake of Crystal Violet by Hen Feathers was systematically investigated. Six adsorption isotherm models, namely the Freundlich, Langmuir, Temkin, Dubinin–Radushkevich, Halsey, and Jovanovic models, were studied for the adsorption of Crystal Violet over Hen Feather and various physicochemical parameters were derived. Langmuir isotherm data were exploited to obtain thermodynamic variables. Negative values for ΔH° were recorded as −15.15 to −17.01 kJ·mol⁻¹, and negative ΔG° values of −23.34 to 25.94 kJ·mol⁻¹ confirmed the adsorption process was exothermic and spontaneous. It was determined that a pseudo-second-order kinetic model is applicable to the present adsorption system at all three tested temperatures. It was established that Hen Feather possesses a very strong affinity for Crystal Violet and works as an excellent scavenger through physisorption.