Spatially resolved micro-Raman observation on the phase separation of effloresced sea salt droplets.
We report on the investigation of the phase separation of individual seawater droplets in the efflorescence processes with the spatially resolved Raman system. Upon decreasing the relative humidity (RH), CaSO4.0.5H2O separated out foremost fromthe droplet atan unexpectedly high RH of approcimately 90%. Occasionally, CaSO4.2H2O substituted for CaSO4.O.5H2O crystallizing first at approximately 78% RH. Relatively large NaCI solids followed to crystallize at approximately 55% RH and led to the great loss of the solution. Then, the KMgCl3.6H2O crystallites separated out from the residual solutions, adjacentto NaCl at approximately 44% RH. Moreover, a shell structure of dried sea salt particle was found to form at low RHs, with the NaCl crystals in the core and minor supersaturated solutions covered with MgSO4 gel coating on the surface. Ultimately, the shielded solution partly effloresced into MgSO4 hydrates at very dry state (<5% RH).
Xiao
Han-Shuang
HS
The Institute of Chemical Physics, Beijing Institute of Technology, Beijing, China.
Dong
Jin-Ling
JL
Wang
Liang-Yu
LY
Zhao
Li-Jun
LJ
Wang
Feng
F
Zhang
Yun-Hong
YH
D000336:Aerosols; D002133:Calcium Sulfate / Q000737:chemistry; D011232:Chemical Precipitation; D003460:Crystallization; D006813:Humidity; D044367:Phase Transition; D012623:Seawater / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry*; D012996:Solutions; D013059:Spectrum Analysis, Raman
D000336:Aerosols; D012996:Solutions; D012965:Sodium Chloride; D002133:Calcium Sulfate