Ceramic porous materials made of ZnO intended for eliminating particles imitating viruses from water
Milena Zalewska, Patrycja Kamińska, Mikołaj Szafran
Quarterly No. 1, 2013 pages 72-76
DOI:
keywords: zinc oxide, zinc acetate, filtration of particles imitating viruses, ceramic porous materials, polymer dispersion
abstract In water there are several pollutants having a significant impact on human health. The greatest difficulties are associated with the removal of viruses due to their small size (generally in the range of 20 to 400 nm). Currently, the most effective ways of removing of viruses from water are filters based on electrostatic adsorption. In this method, negatively charged viruses (in the pH of drinking water, pH 5÷9) are retained on an oppositely charged filter surface. These filters are characterized by large pores allowing a much more efficient flow of liquid through the filters and also eliminating the blockage of pores. In order to provide ceramic filters with a positive charge, their inner surface is modified. The purpose of this study was to obtain ceramic composite materials on the basis of zinc oxide with active layers from zinc oxide and simulate the filtration process using a polymer dispersion characterized by a similar size of particles to that of viruses and a negative charge in the pH of drinking water, as is in the case of viruses, was carried out. In order to obtain ceramic composite materials, two types of zinc oxide were used. The average grain sizes of the powders were different - an average particle size of about 200 nm for the powders which were purchased from NanoTek and about 7 μm for those which were purchased from POCH. Porous ceramic composite materials were formed by unilateral pressing. A 10 wt.% aqueous solution of poly(vinyl alcohol) with a molecular weight of 67 000 and degree of hydrolysis of 88% was used as the binder in the ceramic materials. Zinc acetate ((CH3COO)2Zn) was used to obtain the active layer of the ceramic composite materials while 0.01 wt.% solutions of polymer dispersion with a negative electrokinetic potential - Rokryl SW 4025 (Rokita S.A.) - was used to simulate the process of filtration. During the study, measurements characterizing the ceramic powders, measurements of the physical and mechanical properties of the samples were performed. The influence of the pressure (10 and 30 MPa) and additive of nano-ZnO (0 to 10 vol.%) on the tensile strength, open porosity and distribution of the pore size in the samples after sintering at 900 ºC were determined. Moreover, the effectiveness of the filtration process using the porous ceramic materials with an active layer of ZnO, which was formed by the impregnation of ceramic samples by zinc acetate and sintered at 430 ºC, were evaluated.