Sinteza hidrotalcita

摘要

Proučavanjem sistema katjonskih glina i aditiva koji sadrže Mg i karbonatne anjone, uočeno je nastajanje nove faze - tipa anjonskih glina. Kako je identifikacija nove faze, u odnosu na dominantnu katjonsku glinu, dosta teška učinjen je pokušaj sinteze anjonske gline - hidrotalcita Mg_6Al_2(OH)_(16)(CO_3)4H_2O. Reaktanti su bili: magnezijum-hidroksi-karbonat - (MgCO_3)_4Mg(OH)_25H_2O (susendovan u vodi), i rastvori AlCl_3, Na_2CO_3 i NaOH. U radu su dati rezultati sinteze pri sobnim uslovima 18℃ i atmosferskom pritisku i pri pH vrednostima reakcionih smeša od pH=12 (sinteza Ⅰ) i pH=10,5 (sinteza Ⅱ). Produkti sinteze su kristalizovani i sušeni 24 časa na 60℃. Identifikacija sintetizovanog hidrotalcita obuhvatila je: hemijsku analizu, Rö, IR, DTA i TGA. Sintezom Ⅰ nastala je smeša minerala: hidrotalcita, manaseita, bajerita i brucita. Sintezom Ⅱ dobijen je hidrotalcit uz prisustvo neproreagovanog magnezijum baznog karbonata. Anjonske gline dobijaju sve veći značaj, zbog njihovog korišćenja u oblasti: katalizatora, anjonskih menjača, adsorbenata i u medicini Anjonske gline se primenjuju takođe i kao sredstvo za stabilizaciju disperznih sistema: keramičkih šlikera i isplaka u industriji nafte.%By examining the system of cationic clays and additives containing magnesium and carbonate anions, it has been observed that there is a new phase, i. e. type of anionic clay. Since the identification of the new phase in relation to the dominant cationic clay is rather difficult, it has been tried to synthetise the anionic clay - hydrotalcite Mg_6Al_2(OH)_(16)(CO_3)4H_2O. The reactants were basic magnesium carbonate -(MgCO_3)_4Mg(OH)_25H_2O (suspendedin water) andsolutions of AlCl_3, Na_2CO_3 and NaOH. In thispaper the results of the synthesis at room temperature of 18℃ and atmospheric pressure andpH values ofreactant mixtures of pH=12 (synthesis Ⅰ) and pH=10.5 (synthesis Ⅱ) are presented. The synthesis products have been crystalised and dried at 60℃ for 24 hours. The identification of the synthetised hydrotalcite included the chemical, X-ray, IR, TGA and DTA analyses. The product of the synthesis Ⅰ is the mixture of the following minerals: hydrotalcite, manasseite, bayerite and brucite. The product of synthesis Ⅱ is hydrotalcite, together with basic magnesium carbonate that failed to react Anionic clays are becoming more important for their application as catalysts, ion exchangers and adsorbents and medical applications as well. Anionic clays are also used as stabilisers of dispersive systems of ceramic suspensions and drilling fluids in the oil industry.