Morphology of barium sulfate synthesized with barium(II)–aminocarboxylate chelating precursors

Abstract

The morphology of barium sulfate (BaSO 4 ), synthesized using the hydrothermal reaction of Ba II ± aminocarboxylate chelating precursors, was investigated. The precursors ethylenediaminetetraacetic acid (EDTA), bis(2-aminoethyl)ethyleneglycoltetraacetic acid (EGTA) and nitrilotriacetic acid (NTA) were dissolved by heating, resulting in the formation of BaSO 4 with rod-like, rhombohedral and spindle-shaped morphologies, respectively. Changing the chelating reagent resulted in the formation of BaSO 4 with differing morphologies. There was a correlation between the morphology of BaSO 4 and the dissociation constant of the Ba II ± aminocarboxylic acid complexes. When the dissociation constant was small, BaSO 4 formed rhombohedral morphologies, when it was large, spindle-shaped morphologies were formed. N 1s XPS measurements indicated that the aminocarboxylic acid was adsorbed on the surface of the precipitated particles. Comparison of the peak intensity X-ray diffraction patterns of EDTA and EGTA showed growth of the {101} face when EDTA was used.

Rod-shaped barium sulfate particles from a completely inorganic system

“…This suggests an alternative explanation for some previous work where the organic additive was seen as causing this particular morphology to form [32,33]. The concentration of sodium ions from the EDTA alone in these earlier reports is approximately 0.05 M while in this work we used $0.08 M at the highest concentration.…”

“…The concentration of sodium ions from the EDTA alone in these earlier reports is approximately 0.05 M while in this work we used $0.08 M at the highest concentration. Given that crystallization was also carried out at elevated temperatures (90-150 1C [32,33] versus 75 1C in this work) it is possible that the rod-shaped particles reported are due to the sodium ions alone.…”

“…Rod-shaped barite is not a common morphology unless the crystals are formed in the presence of emulsions [30,31] (although those particles formed in emulsions are not straight but curved, filamentous mesocrystals) or organic additives [32,33]. It is clear that in the rod-shaped particles produced in this work, the c-axis is much longer than expected for the equivalent S value (the c-axis is specified on some particles by the double headed arrow) and therefore the (0 0 1) face is obviously a fast growing face relative to the other faces.…”

The interaction of EDTA with barium sulfate

“…In the current study, we have purposely avoided high pHs in order to avoid such ambiguities. The only other literature to mention barite and EDTA is that of Uchida et al [13,14] where, once again, EDTA is used for its complexing ability (at high pH) and is shown to affect the morphology of barite. The role of EDTA as a complexing agent necessitates that sufficient EDTA be present to complex enough cations in solution to appreciably affect the supersaturation.…”

Formation and Application of High Reflectivity Controllable Barium Sulfate Microspheres

“…(3) Liu et al [15] prepared barium sulfate particles by complexation. Uchida et al [16,17] prepared needle-like barium sulfate nanoparticles by complexation. It has been widely used as an important complexing agent [18][19][20][21][22].…”