The Influence of Supersaturation and the Presence of Biuret on the Nucleation, Growth and Morphology of Urea Crystallised from Ethanolic Solutions

The influence of biuret, a degradation impurity, on the crystallisability, nucleation, growth and morphology urea, is examined as function supersaturation in ethanolic solutions, through combination polythermal turbidometry assessment optical microscopy measurements, complemented by molecular modelling. inclusion small amount impurity found to increase stability supersaturated solutions widening metastable zone width. Polythermal analysis crystallisation dissolution on-sets cooling heating rate, respectively, be concentration-dependent associated with both pure doped systems, nucleation mechanism changing from progressive instantaneous increasing solute concentration. addition biuret significantly increases rate when compared system, 9.2–20.5 9.3–67.7 nm−3 s−1, along decrease critical nucleus size, would consistent promoting i. e. resulting more nuclei smaller crystals. crystal habit urea dominated prismatic {110} faces, polar {111} capping faces. mean rates these faces are respect supersaturation, exhibiting greater level than {110}, stronger solvent binding which restricts face. have effect retarding compact equant morphology. These results rationalised computational visualisation modelling surface chemistry planes together energetics them.