Competitive adsorption of ternary dye mixture using pine cone powder modified with β-cyclodextrin

The adsorption characteristics for the uptake of a ternary dye mixture safranine O, brilliant green and methylene blue (SO, BG and MB) by pine cone modified with β-cyclodextrin (CD) were investigated. The adsorption process primarily followed a pseudo - second order model and the rate of adsorption was inversely proportional to the initial dye concentration. The adsorption was also a multi-stage process which was limited by intraparticle diffusion. The adsorption predominately followed the Langmuir isotherm and was controlled by physisorption and electrostatic interactions. The adsorption was spontaneous and endothermic in nature. The order of performance of adsorption of the dyes was BG > SO > MB at all temperatures studied. The adsorption of BG was therefore highly favoured at all temperatures.