Kaolinite:NaCl intercalates with basal layer dimensions of 0.95 and 1.25 nm have been prepared by direct reaction of saturated aqueous NaCl solution with well-crystallized source clay KGa-1. The intercalates and their thermal decomposition products have been studied by XRD, solid-state 23Na, 27Al, and 29Si MAS NMR, and FTIR. Intercalate yield is enhanced by dry grinding of kaolinite with NaCl prior to intercalation. The layered structure survives dehydroxylation of the kaolinite at 500°–600°C and persists to above 800°C with a resultant tetrahedral aluminosilicate framework. Excess NaCl can be readily removed by rinsing with water, producing an XRD “amorphous” material. Upon heating at 900°C this material converts to a well-crystallized framework aluminosilicate closely related to low-carnegieite, NaAlSiO4, some 350°C below its stability field. Reaction mechanisms are discussed and structural models proposed for each of these novel materials.

The sedimentation characteristics of two commercial bentonites, Tixoton (organically treated) and Montigel-F (untreated), were investigated using a 3% w/v clay suspension at different concentrations (1, 3.5 and 10%) of NaCl and pH values (2, 7 and 12). Settling rates, floc diameters and sediment volumes were derived from changes in light transmittance using a Turbiscan Ma 2000 instrument.

Both bentonite suspensions were unstable (flocculated) in NaCl solutions. The settling rate increased with increasing concentration of NaCl and was directly related to floc diameter. The sediment volume reduced with increasing NaCl concentrations, a result of greater double layer compression caused by increased ionic strength. At comparable salt concentrations, the organically-treated bentonite (Tixoton) settled at a much slower rate and had a greater sedimentation volume. The suspensions of both organically-treated and untreated bentonites were stable (dispersed) above pH 7 and unstable in acidic conditions. The settling rate for Tixoton under acid conditions was much smaller than that for the Montigel-F. Differences in sedimentation characteristics between the two bentonite samples are probably due to the presence of an anionic polymer (carboxymethyl cellulose: CMC) in Tixoton.

The viscosity of the bentonite suspensions was also studied. The viscosity of the clay suspension is closely related to clay dispersivity in solution. The CMC was highly effective in increasing the viscosity of the bentonite suspensions, but only under neutral and alkaline conditions.

Intense fibrosity develops in wet porous NaCl crystal aggregates (grain size 250–500 µm) held in a temperature (T) gradient field (0.5–4°C/mm) at temperatures between 20 and 50–60°C. In situ microscopic observation of the process shows that fibre growth is associated with T-gradient driven motion of tiny gas (air, water vapour) bubbles present in the saturated intercrystalline aqueous NaCl solution. Gas bubbles move through the intercrystalline pore fluid into the cold direction. They only move if they are next to an NaCl crystal; bubbles that are ‘free’ do not move. Each bubble is ‘pushed’ into the cold direction by a growing crystal fibre of the same diameter as the bubble itself. Fibres apparently grow due to oversaturation of the NaCl solution at the hot side of the gas bubble. Crystals dissolve at the cold side of the gas bubbles, apparently by undersaturation of the NaCl solution there. Thus, bubbles dissolve their way through NaCl-crystals and aggregates. Intense fibrosity develops within weeks.

Concentration, conductivity, temperature, and flow logs from sixteen brine-filled shafts in northern Germany have shown that the brines in all former potash salt mines exhibit a very sharp stratification into lower Mg-rich brine, an upper layer of Na-rich brine, and groundwater at the top. Laboratory experiments have shown that, at the MgCl2-brine/NaCl-brine boundary, both solutions become oversaturated with regard to NaCl, due to diffusion processes. NaCl therefore crystallizes from the solutions and forms a salt plug in the boundary region, which considerably reduces further diffusion. It is concluded that the observed effects would also take place in shafts. The backfilling material helps to nucleate the halite crystals and provides a structure on which they might be supported. The results of these experiments show that the density boundaries in the brine bodies act as barriers against transport of matter while the formation of a halite plug growing independently at the MgCl2/NaCl-brine interface acts as an additional barrier.

Kikuyugrass was analyzed for nitrate (expressed as KNO3) and soluble oxalate concentration after it was grown for 8 wk in nutrient solution supplemented with KCl, NaCl, or NH4NO3; fertilized in the greenhouse with urea and KNO3 at 112 kg N ha-1; and fertilized in the field in Hawaii and Panama with urea at 56 and 112 kg N ha-1. Both treated and untreated kikuyugrass grown in nutrient solution contained toxic levels of nitrates and soluble oxalates. Plants treated with urea in the greenhouse contained 0.4% nitrate (nontoxic) 72 h after treatment whereas those treated with KNO3 contained 2.36% nitrate (highly toxic). Fertilization of kikuyugrass with urea in Panama and Hawaii did not significantly affect soluble oxalate concentration, but nitrate concentration increased to potentially lethal levels (over 1.5% as KNO3, dry wt) in plants from Hawaii.

The aim of the study was to investigate how the use of fresh cheese brines compared with used brines and various combinations of pH and NaCl concentrations affected the survival of Listeria monocytogenes. Cheese brines from five Norwegian small scale cheese producers were analysed and showed great variations in pH (4·54–6·01) and NaCl concentrations (14·1–26·9 %). The survival of five strains of List. monocytogenes (two clinical isolates, two food isolates and one animal isolate) in four different cheese brines (three used and one fresh) was investigated. Results showed significant differences in survival both depending on the strains and the brines. Strains of human outbreak listeriosis cases showed greater ability to survive in the brines compared with food isolates and a List. monocytogenes reference strain (1–2 log10 difference after 200 d). All strains showed highest survival in the freshly prepared brine compared with the used brines. Molecular typing by multiple locus variable number tandem repeats analysis (MLVA) showed that there were no detectable alterations in the examined variable number tandem repeats of the genome in five strains after 200 d storage in any of the salt brines. Combined effects of pH (4·5, 5·25 and 6·0) and NaCl (15, 20 and 25 %) in fresh, filter sterilised brines on the survival of List. monocytogenes were examined and results showed that pathogen populations decreased over time in all brines. Death rates at any given NaCl concentration were highest at low pH (4·5) and death rates at any given pH were highest at low NaCl concentrations (15 %). In conclusion, the use of used brines reduced the survival of List. monocytogenes and a combination of low pH (4·5) and low salt concentrations (15 %) decreased the risk of List. monocytogenes survival compared with higher pH (5·25 or 6·0) and higher NaCl concentrations (20 or 25 %).

Precipitation of calcium phosphates occurs in dairy products and depending on pH and ionic environment, several salts with different crystallinity can form. The present study aimed to investigate the effects of NaCl and citrate on the characteristics of precipitates obtained from model solutions of calcium phosphate at pH 6·70 maintained constant or left to drift. The ion speciation calculations showed that all the starting solutions were supersaturated with respect to dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP) and hydroxyapatite (HAP) in the order HAP>OCP>DCPD. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses of the precipitates showed that DCPD was formed at drifting pH (acidic final pH) whereas poor crystallised calcium deficient apatite was mainly formed at constant pH (6·70). Laser light scattering measurements and electron microscopy observations showed that citrate had a pronounced inhibitory effect on the crystallisation of calcium phosphates both at drifting and constant pH. This resulted in the decrease of the particle sizes and the modification of the morphology and the microstructure of the precipitates. The inhibitory effect of citrate mainly acted by the adsorption of the citrate molecules onto the surfaces of newly formed nuclei of calcium phosphate, thereby changing the morphology of the growing particles. These findings are relevant for the understanding of calcium phosphate precipitation from dairy byproducts that contain large amounts of NaCl and citrate.

Seed salinity tolerance and dormancy play important roles in germination behaviour. The effects of NaCl concentration and different dormancy-breaking treatments on germination were determined for six species growing on the coasts of the Baltic Sea or the Gulf of Riga: Juncus balticus, Triglochin maritima, Triglochin palustre, Anthyllis maritima, Linaria vulgaris and Linaria loeselii. Germination percentages were significantly reduced at NaCl concentrations >100 mM. Germination of J. balticus, T. maritima and T. palustre, but not that of A. maritima and L. vulgaris, recovered after seeds were rinsed with distilled water. Seeds of J. balticus were non-dormant; those of A. maritima had physical dormancy; and those of T. palustre, T. maritima, L. loeselii and L. vulgaris had non-deep to intermediate physiological dormancy, which was broken by cold stratification or gibberellic acid. The seeds of plants growing in habitats periodically exposed to sea water (coastal meadows) were characterized by greater salinity tolerance than seeds of plants growing in habitats less exposed to sea water (dunes).

Electron beam damage is a significant limitation for transmission electron microscopy (TEM) studies of beam-sensitive samples. An approach for studying surface reactions on alkali halide crystals using 200 kV TEM is presented. Experiments were designed to monitor the reaction of NaCl crystals with HNO3 gas followed by water vapor to form solid NaNO3. During beam damage experiments, TEM micrographs record structural changes to both NaCl and NaNO3, including dislocation loops, void formation, and decomposition. Sample decomposition can be successfully minimized by a combination of commonly used techniques: (1) focusing the beam adjacent to the area of interest, (2) lowering the electron density, (3) choosing to image larger (micrometer- versus submicrometer-sized) alkali halide crystals, and (4) lowering temperature by the use of a liquid nitrogen cooling stage. From these results, additional studies were designed that monitored sequential experiments. Sensitive micrometer-sized sodium chloride single crystals before and after exposure to nitric acid vapor and water vapor and the subsequent growth of submicrometer-sized sodium nitrate single crystals could then be successfully imaged using TEM.