Highly porous clay and oxide ceramic | Augsti poraina mālu un oksīdu keramika

English. Obtaining of new porous ceramic materials with new or improved properties was the goal of these studies. The raw materials were quaternary and Devonian clays of Latvia, as well as such phyllosilicate as kaolin and talc. These materials were designed for the use in environmental technologies such as wastewater purification in the sorption processes or filtration together with sorption. Two different methods for the formation of ceramic body were used. Ceramic pellets from plastic mass with additive of organic substances 3 % of sawdust or glycerol (by-product in biodiesel technology) were formed. Ceramic for filtration purpose by casting of concentrated suspension of raw materials was obtained. Porosity, pore structure in the micrometer and nanometer range, specific surface area, sorption ability and phase composition were determined for materials obtained. Suitability of clay ceramic pellets as matrix for the obtaining of photocatalytic coatings was investigated. The chemical and mineralogical composition of used clays as well the grain size distribution in these clays as well as firing temperature of materials were the determining factors for the structure and sorption properties of obtained ceramic materials. The results of our studies domonstrate that ceramic obtained from Latvia clays by addition of sawdust or glycerol (by-product in biodiesel technology) in amount of 3 mass % was useful for the purification of wastewater. The sorption ability of materials was selective because the pellets of Quaternary and Devonian clays changed pH of water medium. PH is one of the main determinants of sorption processes. The clay ceramic pellets were also useful as matrixes for the nanosize particles coating of ZnO that were obtained by thermal decomposition of zinc acetate. The photocatalytic activity of such coating was 128.9 mg/g ZnO of acetic acid during 1 h by irradiation with light 460 nm.

Latvian. Pētījuma mērķis ir iegūt jaunus porainus keramikas materiālus ar jaunām vai uzlabotām īpašībām. Pētījuma uzdevums ir iegūt šādus materiālus no plastiskām masām vai suspensijas, un pēc apdedzināšanas noteikt to īpašības, kas saistītas ar šo materiālu praktisko pielietojumu: porainību, poru struktūru mikronu un nanometru diapazonos, īpatnējo virsmu, sorbcijas spēju, matricu fotokatalizatoru uznešanai. Darba rezultātā noteikta Latvijas mālu keramikas selektīva noderība dažāda veida ūdens piesārņojuma novēršanai, tai skaitā organisku (etiķskābe, organiskās krāsvielas) un molekulāru neorganisku savienojumu (jods) adsorbcijai. Iegūti fotokatalītiski pārklājumi uz keramikas granulu virsmas ar lielu fotokatalītisko aktivitāti. Iegūti augsti poraini mālu un oksīdu keramikas filtri, kuri vienlaicīgi ar suspendēto daļiņu atdalīšanu no ūdens saista arī ūdenī izšķīdušos jonus, par ko liecina ūdens elektrovadāmības samazināšanās. Programmas noslēgumā, izmantojot iepriekšējos pētījumos iegūtos rezultātus un praktisko pieredzi, iegūts jauna veida kompozīta materiāla sorbents, kurā apvienotas divas komponentes ar atšķirīgi darbojošamies sorbcijas mehānismiem. Saņemts pozitīvs lēmums par pieteikto patentu.