CADMIUM AND NICKEL REMOVAL FROM WASTEWATER USING MODIFIED FLY ASH: THERMODYNAMIC AND KINETIC STUDY
MARIA VISA 1, 2, ANCA DUTA 1* (1)TRANSILVANIA UNIVERSITY OF BRASOV, CENTRE PRODUCT DESIGN FOR SUSTAINABLE DEVELOPMENT, EROILOR 29, 500036 BRASOV, ROMANIA (2)COLLEGE FOR NATURAL SCIENCES âEMIL RACOVITAâ, ARMONIEI 13, BRASOV, ROMANIA *CORRESPONDING AUTHOR: A.DUTA@UNITBV.RO
The fly ash surface properties depend on many factors, including the coal composition, the burning process and the furnace characteristics. Developing an up-scalable process requires reproducible surface properties, less (or no) related to the above mentioned influences that can be obtained by tailoring the fly ash surface. The study presents the results obtained in Cd2+ and Ni2+ removal, using fly ash from CHP Brasov (Romania) with modified surface, prepared by long contact with alkaline solutions (NaOH 1N, 2N, 4N) and complexion agents (Complexone III, Pyrocatechol Violet). The immobilization efficiency is discussed in connection with contact time, wastewater volume: adsorbent mass ratio and ions concentration; Langmuir and Freundlich mechanisms were found to describe the adsorption processes. The process follows a pseudo-second order kinetic, for both metals, on the entire concentration range. Highly efficient adsorption, even at very low heavy metals concentrations (20 ppm), is registered for fly ash modified with NaOH.
