SORPTION OF TEXTILE DYES ON SORBENT MADE FROM COTTON TEXTILE WASTE - EQUILIBRIUM ADSORPTION

Abstract

The article analyzes the equilibrium adsorption and thermodynamics of the process of removing a disperse dye from water using a sorbent based on cotton textiles waste. Sorbent is made from cotton knitted fabric waste after cutting, during the procedure of clothes production. The loss after washing of raw cotton waste, before transformation into adsorbent, is about 9%. The yield of sorbent made from washed raw cotton waste is just under 40%. The characterization of the new sorbent showed that there is porosity in the structure of the particles and that the chemical composition is dominated by carbon. Equilibrium adsorption was verified by three models, Freundlich and Temkin. The Freundlich equilibrium isotherm showed the best result, i.e. the fitting curve is closest to the experimental points. Since the staining takes place according to the mechanism predicted by the Freundlich model, a monolayer of adsorbed dye molecules is formed in the initial phase of adsorption. At the same time, more layers of adsorbed dye molecules are formed at non-specific sites on the sorbent through self-association of adsorbed dye molecules. The newly-adsorbed dye molecules can bind to the previously adsorbed molecules within the sorbent. The heat of adsorption, determined from Temkin's model, has values that assume that an exothermic process takes place during the adsorption of the dye on the sorbent.

Keywords

• cotton knitted fabric
• cutting
• sorbent
• disperse dye
• equilibrium isotherms
• thermodynamics.