2008 NSTI Nanotechnology Conference and Trade Show - Nanotech 2008 - 11th Annual

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TechConnect Summit
Clean Technology 2008

Preparation of nano aluminium trihydroxide by forced hydrolysis in presece of emulsifying agent

B.K. Padhi, B.W. Harry, B.N. Mohanty
Manager(R&D), IN

Keywords:
nanoparticle, aluminium trihydroxide, carbonation, emulsifying, forced hydrolysis

Abstract:
Ultra fine nano aluminium trihydroxide (ATH) with 100–200 nm in particle size have been synthesized by carbonation of sodium aluminate liquor or aluminium sulphate in a rotating packed bed reactor, followed by forced thermal hydrolysis using carbonating agents like urea, ammonium bicarbonate and ammonium carbonate in presence of emulsifying agents. Due to the intensified absorption of CO2 under hydrolysis situations, and thereby nano-scale particles of ATH were precipitated from the aluminium salt solution. This paper mainly discussed the factors of controlling carbonation process such as carbonation temperature, aluminium ion concentration, pH and emulsifying agents on the properties of precipitated ATH, which were characterized by SEM/TEM, XRD and BET. With carbonation temperature lowered ATH size sharply reduced to below 200 nm. Higher carbonating agents favor the absorption of CO2, resulting in higher supersaturation degree of precursor with the lower pH for nucleation stage. But only when pH values were kept steady in the nucleation stage, the formed particles had a minimum size. In order to achieve ATH crystal phase, the final pH should be above 12.0 in case of sodum aluminate, and pH 3.0 in case of aluminium sulphate. When sodium aluminate concentration rose to 2.0 mol/L, the productivity of ATH achieved 75% and in case of aluminium sulphate 95%.


Nanotech 2008 Conference Program Abstract