Preparation of cordierite-based adsorbents for water purification

Abstract

In this study, porous cordierite-based ceramics was synthesized. In the first step, MgO, Al2O3, and SiO2 (all Aldrich, p.a.) were used. MgO and Al2O3 powders were calcined at 1000 oC for 2 h, in order to avoid hydroxides. They were mixed in 2:2:5 molar ratio, in order to form cordierite, Mg2Al4Si5O18. Ethanol was added to the mixture, and then milled in a Fritsch Pulverisette planetary mill, with 300 rpm, in air atmosfere. Times of activation were 0, 10, 40, and 80 min, while balls and vessels were made from ZrO2, and powder to balls mass ratio was 40:1. After milling, powders were dried, and then pressed under 3 t/cm2. Pallets with 8 mm radius were sintered in air at 1350 oC, for 2 h, heating rate was 20 oC/min. Sintered samples were crashed and sieved. In the secons step, the as-prepared cordierite was mixed with 20 wt.% yeast (0.1 g yeast + 0.4 g cordierite per sample). The other mixture was with 20 wt.% nanocellulose (0.1 g NC + 0.4 g cordierite per sample). Both mixtures were pressed into pallets under 5 t/cm2 and sintered at 700 oC, with 5 oC/min heating rate, in air atmosfere. During the second sintering regime, porous cordierite-based ceramics was obtained. The phase composition of the sintered samples as well as microstructures was analyzed by the means of X-ray diffraction method and SEM. Cordierite was the most abundant phase in all sintered samples. It was observed that addition of different pore-forming agent resulted in significantly different microstructures.