ЕMISSION REDUCTION OF COLORED WASTE WATER AFTER CONTACT WITH A NATURAL SORBENT WITH A SPECIAL FOCUS ON THE THERMODYNAMICS OF ADSORPTION

Abstract

The possibilities of using an inexpensive sorbent for dyes removal from waste waters after textile dyeing were investigated in this work. Ashes from city heating plant that arise as a by-product in the burning process during the city central heating operated were sorbent. After chemical modification of the ashes it were transformed to the efficient sorbent. Based on the results from this paper, it can be said that the sorbent produced from ashes has potential for the textile dyes removal from aqueous solutions and emission reduction of toxic dyes. A metal complex textile dye was used and the adsorption thermodynamics were studied. On the basis of obtained results, it can be concluded that the natural sorbent is an efficient sorbent for metal complex removal dye from aqueous solution and has a potential for use on an industrial scale. Characterization of other similar, solid waste materials can help explain adsorbate–sorbent interactions in order to optimize and increase efficiency of adsorption process as an environmentally acceptable process. Negative values of free energy change indicate a spontaneous nature of adsorption, negative values of free enthalpy change indicate an exothermic adsorption process and negative values of free entropy change indicate a decrease of disordered system at solid – liquid interface during adsorption. Based on adsorption, kinetic and thermodynamic parameters it can be concluded that chemisorption of the dye on the sorbent is also present together with physical adsorption.

Keywords

• ashes
• dyeing
• metal complex dye
• enthalpy
• entropy
• free energy