PRECIPITATION OF SOLID PHASES IN REACTION ZONE BETWEEN ACID INDUSTRIAL WASTE AND NEUTRALISATION SOLUTIONS
František Eichler 1, Jirí Ditz 2
1 Jáchymovská 282, 460
10 Liberec 10, Czech Republic
2 VÚANCH, Výzkumný ústav
anorganické chemie a.s., Revoluení 84, 400 01 Ústí nad Labem,
Czech Republic
Keywords: acid industrial
waste, neutralisation process, pH indicators, precipitated and
coprecipitated solid phases, system solid phase-amourphous
phase-liquid phase
Interaction between acid industrial waste and
neutralisation solutions has been studied under light microscope
as a result of chemical staining techniques. Acid industrial
waste may be defined as the thermodynamic system (NH4)2SO4-Al2(SO4)3-H2SO4-H2O
and neutralusation solution by system Na2CO3-H2O.
Chemical process from pH< 1 in acid industrial waste to pH
> 7 in neutralisation solution, and some local changes in
chemical composition of liquid phase are stained by Bromocresol
Blue as pH indicator. A variety of precipitated and
coprecipitated solid phases dependent on pH of liquid phase as
Al(OH)3, Al2(SO4)3.17H2O
and (Na, NH4)Al(SO4)2.12H2O
were identified by XRD, FTIR, light microscopy, electron
microscopy and electron microanalysis. Crystal structure
parameters of selected well-crystallised phases are refined by
Rietveld method. It is shown that the relative disttribution of
Al between various complexes dictates dissolution and
precipitation of components from reaction zone in system solid
phase-amorphous phase-liquid phase. Time-dependent chemical
processes are documented as colour changes of Bromocresol Blue on
colour photos.