Quantifying the spreading factor to compare the wetting properties of minerals at molecular level – case study: sphalerite surface
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Tarbiat Modares University, Faculty of Engineering & Technology, Department of Mining Engineering, Tehran, Iran
Tarbiat Modares University, Faculty of Engineering & Technology, Department of Materials Engineering, Tehran, Iran
Mahmoud Abdollahy   

Tarbiat Modares University, Jalal Ale Ahmad, Tehran, Iran, 11114115 Tehran, Iran
Physicochem. Probl. Miner. Process. 2018;54(3):646–656
Spreading of water droplet on sphalerite surface was quantified at molecular level and was utilized for comparison of the wetting properties of sphalerite protonated and hydroxylated surfaces. Molecular dynamic simulations were used to characterize the wetting of sphalerite (110) plane. Experimental contact angles of water droplet on sphalerite surfaces were measured and the results were compared with simulated contact angles to ensure that the simulations are accurate enough for calculation of spreading factors. Shape descriptors such as perimeter, area, Feret’s diameters and circularity were used to characterize the shape of droplet-sphalerite interface at molecular level. Using the shape descriptors, different spreading factors were defined and calculated spreading factors were correlated with simulated contact angle. It was shown that spreading factors which were defined as the volume of water droplet divided by the area and Feret’s diameters, with correlation coefficient of 0.98 and 0.97, can be used as accurate tools for wetting comparison of functionalized sphalerite surface at molecular scale. Proposed approach also can be used for investigations on the effect of surface chemical and physical anisotropies on preferred wetting in specific direction at molecular scales.