ACADEMIA ROMÂNĂ Revue Roumaine de Chimie http://web.icf.ro/rrch/ Rev. Roum. Chim., 2019, 64(5), 403-407 Doi: 10.33224/rrch.2019.64.5.03 MATHEMATICAL MODELING FOR KINETICS OF Fe 3+ EXCHANGE ON PRETREATED ANALCIME ** Claudia COBZARU, Adriana MARINOIU, b Gabriela Antoaneta APOSTOLESCU, Ramona Elena TATARU-FARMUS and Corina CERNATESCU * a “Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, D. Mangeron, no. 73, 700050, Roumania b National R D Institute for Cryogenics and Isotopic Technologies- ICIT, 4 Uzinei St., Rm Valcea, Roumania. Received July 25, 2017 The kinetics of the ion-exchange process with iron on pretreated analcime has been investigated in different conditions of temperature, time and concentration of the exchange solution. The performances of the catalyst were analyzed using the Table Curve software. The mathematical model corresponding to the characteristic equation provides a good arrangement of the experimental points on the responding surface, simplicity of the characteristic equation and a good determination coefficient that is near unity. INTRODUCTION * There are many natural zeolites that can be used in different chemical processes, due to their properties. This category includes clinoptilolite, analcime, mordenite, ferrierite, heulandite, erionite, chabazite, faujasite, etc. Although it is part of the feldspar group, the analcime has all the structural and chemical characteristics of zeolites. This natural zeolite has a cubic structure, consisting of rings made from 4-6 and 8 tetrahedral cavities that form 16 larger interconnected cavities and a secondary series of 24 smaller cavities. Moreover, some of the sodium ions may be replaced by other ions such as potassium, lithium, cesium, etc. in the composition of the analcime. In Roumania, the analcime is found in an amount of 50-60% in the volcanic tuff. 1,2 The industrial wastewaters often contain significant amounts of heavy metal ions, which could be harmful to both the environment and to the people. Heavy metals, such as iron, have low atomic density and are usually associated with toxic materials. 3 Among the procedures applied for removing heavy metals, the ion-exchange on natural zeolites is the most advantageous from economical point of view, as showed in previous studies. 4-10 This method showed remarkable performances when used for removing undesirable ions from residual waters, the ion-exchange capacity being influenced both by chemical and structural properties of the zeolites (composition, porosity, pre-treating, etc.) and the exchange process parameters (ions concentration, temperature, time, etc.). Several studies dealing with the development of mathematic models that emphasize the performance * Corresponding author: ccernatescu@yahoo.com ** Supplimentary Information on http://web.icf.ro/rrch/ or http://revroum.lew.ro