Sorption of direct dyes from aqueous solution onto a synthetic adsorbent. Kinetic study.

The aim of this work was to investigate the efficiency of copolymer microbeads (styrene-divinylbenzene functionalized with trimethylamonium groups) as adsorbents for removal of direct dyes (orange OD, and green GD) from aqueous solutions. The influence of initial concentration, and contact time on the adsorption have been investigated. With increasing of the initial dye concentration, the amount of dye adsorbed increased, while the percentage removal decreased, indicated that the dye removal is concentration dependent. The adsorption kinetics of the removal of studied dyes has been investigated. The kinetics of adsorption is described by the first-order Lagergren model, and pseudo second-order. The correlation coefficients (R²) were used to determine the best fitting kinetic model. The best fits were obtained with the second order kinetic model (higher values of R²), meaning that the adsorption process for OD and GD dyes removal, can be described by the pseudo-second order kinetic model.