The regulating mechanism of MgCO3·3H2O whisker growth orientation with the presence of SDS

Abstract

Abstract CO2 mineralization is an effective route to reduce CO2 emission. But the commercialization of CO2 mineralization process is impeded by the poor or even negative profit. MgCO3·3H2O whisker was prepared by indirect CO2 mineralization of MgSO4-(NH4)2CO3 in the presence of Sodium Dodecyl Sulfate (SDS) to improve the profit. MgCO3·3H2O whisker with an average length of 40 μm, average diameter of 1 μm, and aspect ratio as big as 40 was successfully prepared with the presence of SDS. SEM, AFM, XRD and TGA were used to characterize the morphology and structure of MgCO3·3H2O whisker, and XPS was used to characterize the compositions of MgCO3·3H2O crystal planes. The regulating mechanism of MgCO3·3H2O whisker growth orientation was studied systematically. The SDS ionizes CH3(CH2)11-OSO3- in the solution, and then combines with the active site Mg2+ complex on the crystal plane in the [100] direction. The (CH3(CH2)11-OSO3)2Mg faces the liquid phase with the hydrophobic group CH3(CH2)11-, which separates the [100] direction from the liquid phase, hindering the growth of the [100] direction crystal plane. Therefore, MgCO3·3H2O whisker is oriented and grows easily on the [010] direction with high aspect ratio.