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Salinity is an important parameter when it comes to seawater or estuaries where freshwater from rivers mix with salty ocean water. Aquatic organisms have varied abilities to survive and thrive at different salinity levels which is due to the fact that salinity impacts dissolved oxygen levels in water. The difference in salinity levels can be detected via viscosity which is why viscosity is a key parameter when it comes to such applications.
Taking a sample of Sea Salt ASTM D1141-98 artificial sea water (ASW), in this post, we explain how to properly measure with microVISC™, our portable viscometer. The sample was provided by Lake Products, LLC*.
The challenges with measuring the viscosity of sea salt dissolved in water in general is due to the fact that water has high surface tension and the addition of the sea salt impacts the overall stability of the mixture based on how well it is dissolved into the solution. The salts appear to take much time to dissolve in water so you may notice in-homogeneity. With alternative methods of measuring viscosity, air interface could impact the surface tension of water, you won't have direct control over shear rates hence impacting the behavior of the sample during measurements (it is advised to run at higher shear rates when working with water).
Using VROC® technology powered viscometers, however, you will be able to reduce the impact of surface tension in your measurements and also work with high shear rates to help reduce the surface tension characteristic of the solution. With our small sample, portable QC viscometer, microVISC, you can use the following protocol:
To prep the sample, 41.95 grams of ASTM D1141-98, produced by Lake Products Company and pH adjusted to 8.2 were used to make ASW at the concentration and pH as instructed by Lake Products Company. With precise sample prep and vigorous testing, we observed the following:
To summarize, the ASW we used is a solution composed of 10 salts dissolved in DI water at a pH of 8.2. Viscosity is a direct reflection of molecular interactions and with the components as varied and as many, an ASW solution will have many levels and degrees of interaction between the individual molecules leading to a complex rheological profile. If you would like to see the excel sheet in which we exported for this experiment, you can download it below!
Questions? Want to access more information on the data? Contact us!
Written by: Rick Paulino, RhoeSense Regional Sales Manager
Our portable, small sample viscometer is intuitively designed so that users can start operating within one minute!
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