Abstract:

Desulfurization gypsum whiskers were prepared by hydrothermal method using purified flue gas desulfurization(FGD) gypsum as raw materials, CuCl₂, CuSO₄ or Cu(NO₃)₂ as additive. The crystal samples were characterized by FTIR, XPS, XRD, etc. to discuss the mechanism of Cu ²⁺ under different anions and these anions in crystal crystallization. The results show that the solubility characteristics of FGD gypsum and the crystal morphology of whiskers are affected by the anions under the effect of Cu ²⁺. The effect of anions is stronger than that of Cu ²⁺, and the adsorption state of Cu ²⁺ on whisker surfaces is affected by anions. The N {\mathrm{O}}_3^{-} promotes the dissolution of FGD gypsum, the Cl ^- takes the second place, and the S {\mathrm{O}}_4^{2-} hinders the dissolution of FGD gypsum. The whiskers with uniform diameter and large aspect ratio are prepared under the effect of Cl ^-, the whisker samples with high content of granular products can be prepared under the effect of S {\mathrm{O}}_4^{2-} , and the whisker samples are coarsened under the effect of N {\mathrm{O}}_3^{-} . The degree of chemical adsorption of Cu ²⁺ is different under the effect of different anions, which leads to the right drift and narrowing of the antisymmetric stretching vibration absorption peak of S {\mathrm{O}}_4^{2-} on the surface of the sample, and the differences of the decrease extent of electron binding energy of oxygen elements on whisker surface and the intensity of Cu—O binding energy. The intensity of Cu—O binding energy is the highest under the effect of N {\mathrm{O}}_3^{-} , the second under the effect of S {\mathrm{O}}_4^{2-} , and the weakest under the effect of Cl ^-.

Key words: Desulfurization gypsum, Whisker, Additive, Surface characteristics, Dissolution