The present study explores the potential use of plant waste i.e. spotted golden thistle (Scolymus maculatus L.) stalks, as an
inexpensive sorbent for the removal of methylene blue from synthetic aqueous solutions. Firstly, the waste material was
characterized using different analysis methods, then kinetics and equilibrium of dye sorption were investigated using a batch
sorption technique. The influence of contact time, initial dye concentration, sorbent dose, particle size and agitation speed on the
dye sorption kinetics has been studied. The amount of dye sorbed at equilibrium increased with initial dye concentration, and with
decreasing of particle size and sorbent dose. Agitation speed of 400 rpm afforded immersion of sorbent at earlier contact time and
enhanced sorbed dye equilibrium amount. The necessary time to achieve equilibrium was increasing in the range of 12-19 h with
initial dye concentration. Five models including first-order, pseudo second-order, Elovich, Avrami and Tobin ones were selected
to describe the dye sorption kinetics. The best fitting model was the Avrami one. A multiple-stage diffusion of methylene blue onto
thistle stalks particles was observed. Equilibrium data of methylene blue sorption by thistle stalks were fitted to six models namely
Freundlich, Langmuir, Temkin, Sips, Toth and Redlich-Peterson models; Sips model best fitted the data. Maximum monolayer
sorption capacity of sorbent was found to be 74 mg/g towards methylene blue. These first results obtained under the investigated
experimental conditions, show that this sorbent is promising material for methylene blue removal from aqueous solutions.