This article investigates the relationship between additive induced creeping and anticaking activity in sodium chloride. Through a series of creeping experiments and powder flow analysis, we establish a clear correlation between the amount of creeping and the anticaking effect of an additive. Habit modification is found not to be a sufficient condition for an anticaking agent. The correlation is explained by the fact that both creeping and anticaking require blocking of crystal growth.Creeping pattern of saturated brine with 1% (w/w) nitrilotriacetamide (NTAA). AbstractThis article investigates the relationship between additive induced creeping and anticaking activity in sodium chloride. Through a series of creeping experiments and powder flow analysis, we establish a clear correlation between the amount of creeping and the anticaking effect of an additive. Habit modification is found not to be a sufficient condition for an anticaking agent. The correlation is explained by the fact that both creeping and anticaking require blocking of crystal growth.

The interfacial structure of muscovite in contact with aqueous CsI solutions was measured using surface X-ray diffraction for several CsI concentrations (2–1000 mM). At CsI concentrations up to 200 mM, Cs+ adsorption is likely hindered by H3O+, as both cations compete for the adsorption site above the muscovite hexagonal cavity. Above this concentration, more Cs+ adsorbs than is required to compensate the negatively charged muscovite surface, which means that coadsorption of an anion takes place. The I– anion does not coadsorb in an ordered manner. Moreover, the hydration ring and water layers do not change significantly as a function of the CsI concentration.

The surface potassium ions of muscovite mica were exchanged for several different metal ions from aqueous solution (Ag, Ca, V, Mn, Fe, Ni, Cu, Zn, Co, and Cd). The surfaces were rinsed in water, dried under nitrogen atmosphere, and subsequently analysed using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and, for half the systems, surface X-ray diffraction (SXRD). XPS and SXRD confirmed the presence of the different metal ions at the muscovite mica surface, with a partial monolayer of the monovalent and divalent ions present on the surface. No counter ions from the used salts were detected. AFM revealed that Ni-, and Fe-terminated muscovite mica surfaces were partially covered by nanoparticles, most likely consisting of metal (hydr)oxide. The exchanged ions remained on the surface after rinsing with ultra pure water three times. SXRD showed that Cd and Ag have a lower affinity for the muscovite mica surface than Cu, Ca, and Mn.

A multitude of ultrathin crystal needles are formed during the evaporation of saturated aqueous NaCl solution droplets in the presence of amide containing additives. The needles are as small as 300 nm wide and 100–1000 μm in length. Heating experiments, X-ray diffraction, and energy dispersive X-ray spectroscopy showed that the needles are cubic sodium chloride crystals with the needle length direction pointing toward [100]. This shape, not expected for the 43̅m point group symmetry of NaCl, has been explained using a model, based on tip formation by initial morphological instability followed by time dependent adsorption of additive molecules blocking the growth of the needle side faces. The latter also suppresses side branch formation, which normally occurs for dendrite growth.

We have investigated the use of polymers and monomers as habit modifiers and anticaking agents for sodium chloride. We show that amide functional groups cause the {111} faces to propagate on sodium chloride crystals and that polymer amides give a 1−2 orders of magnitude greater effect than the corresponding monomers on the habit modification of sodium chloride. We have also shown that the alcohol functional group does not have an effect on the surface or habit modification but that, when in a polymer form, leads to macrostep formation and acts as a nucleation inhibitor. The latter also holds true for other polymers that we have also tested. We have also found that there is no evidence of these polymers having anticaking abilities. Finally, we found that no amino acids, apart from glycine, have an effect on the morphology of NaCl crystals.