Chen Wang,Feng Wu,Yanfeng Sui,Guoxiong Wang,Tielin Wang,Jiayu Ma
The solubility of K2SiF6 in MgCl2 and FeCl3 solutions within a temperature range between 20 and 70 °C was experimentally determined by the static method under atmospheric pressure. The equilibrium solids obtained under various conditions were analyzed by XRD, SEM, and FTIR to confirm the stability of corresponding solid phases. The solubility of K2SiF6 in MgCl2 and FeCl3 solutions increased with increasing temperature and concentration, and K2SiF6 remained stable in MgCl2 and FeCl3 solutions. Moreover, the experimental data were successfully correlated with the Apelblat empirical equation. The thermodynamic properties of the solution process, including the Gibbs energy, enthalpy, and entropy, were calculated by the van’t Hoff analysis and the Gibbs equation. The dissolution process of K2SiF6 in the measured solutions was found to be endothermic and nonspontaneous. The findings above can provide fundamental data and theoretical support for optimizing the crystallization of K2SiF6 in acid leaching solution from phosphorus–potassium associated ore and preventing scale formation of K2SiF6 in wet-process phosphoric acid (WPA) vacuum filtration.
Double-network (DN) hydrogels consisting of noncovalent interacting networks are highly desired due to their well-controlled compositions and environmental friendliness, but the low water resistance always impairs their mechanical strength. Here, an anti-swelling hydrogel possessing the core/shell architecture through rational regulation of multiple weak noncovalent interactions is prepared. A composite hydrogel consists of chitosan (CS) and poly( N -acryloyl 2-glycine) (PACG), readily forming the shell-structured DN hydrogel after soaking in a FeCl 3 solution because of in situ formation of chain entanglements, hydrogen bonds, and ionic coordination. The produced DN hydrogels exhibit excellent anti-swelling behaviors and mechanical durability for over half a year, even in some strict situations. Taking the merits of noncovalent bonds in adjustability and reversibility, the swelling property of these hydrogels can be easily customized through control of the ion species and concentrations. A dynamically reversible transition from super-swelling to anti-swelling is realized by breaking up and rebuilding the metal-coordination complexes. This facile but efficient strategy of turning the noncovalent interactions and consequently the mechanics and anti-swelling properties is imperative to achieve the rational design of high-performance hydrogels with specific usage requirements and expand their applicability to a higher stage.
危险品化学品经营许可证（带存储）