| A Comparative Study Between Surface and Physicochemical Properties of Materials Produced by Oxalic and Sulphuric Acid Activation on Different Smectite Samples Danai Tsakiri1; Iliana Douni1; Maria Taxiarchou1; 1NATIONAL TECHNICAL UNIVERSITY OF ATHENS, Athens, Greece; PAPER: 245/Mining/Regular (Oral) SCHEDULED: 14:25/Sat. 26 Oct. 2019/Zeus (55/Mezz. F) ABSTRACT: Acid activation of clays is a process in which sulphuric acid is usually used in order to obtain a material with enhanced surface properties. Several researchers have studied acid activation of aluminosilicates by using mineral acids. An alternative method to sufficiently producing acid activated minerals with eliminated environmental cost, however, could be achieved by using oxalic acid. Oxalate is a polyfunctional organic acid that forms strong complexes with aluminum and ferrous ions and enhances the dissolution rate of the minerals. It also has high acidity and preserves the clay structure during activation. Moreover, effluents resulting from oxalic acid activation are considered more environmentally friendly than those resulting from activation by inorganic acids. The main advantage of using oxalic acid is the formation, during activation, of soluble complexes which can be decomposed both microbiologically and under the action of daylight. The target of this work was to compare the surface and structural properties of the materials produced by oxalic acid activation of different smectite samples with the conventional inorganic acid activation. The physicochemical characteristics of raw materials and products were evaluated by various methods: X-Ray Fluorescence (XRF), Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and BET (Brunauer-Emmett-Teller) and BJH methods for specific surface area measurement and definition of pore size distribution of the samples. Results showed that acid activation led to new materials with higher specific surface areas and diverse porosity, compared to the raw materials. The organic and inorganic acid activation products presented structural differences which effluent their appropriateness to adsorb undesirable organic molecules. References: 1. Taxiarchou, M. & Douni, I. The effect of oxalic acid activation on the bleaching properties of a bentonite from Milos Island, Greece. Clay Miner. 49, 541-549 (2014). 2. Wang, X., Li, Q., Hu, H., Zhang, T. & Zhou, Y. Dissolution of kaolinite induced by citric, oxalic, and malic acids. J. Colloid Interface Sci. 290, 481-488 (2005). 3. Tarasova, I.I., Dudeney, A.W.L. and Pilurzu, S. Glass sand processing by oxalic acid leaching and photocatalytic effluent treatment, Minerals Engineering 14, 639-646 (2001). |
