H2SO4-H2O中硝酸铜对脱硫石膏晶须生长的影响

以处理后的脱硫石膏为原料,在H₂SO₄-H₂O体系中以Cu(NO₃)₂为晶形控制剂采用水热法制备脱硫石膏晶须,探讨了Cu(NO₃)₂对脱硫石膏晶须生长的影响机理。结果表明:Cu(NO₃)₂对脱硫石膏有明显促溶作用,其中Cu²⁺可减小溶液中各离子的活度系数,使溶液中的Ca²⁺浓度增大。NO^-₃通过静电作用在Ca²⁺周围聚集并对SO^2-₄产生屏蔽作用,导致脱硫石膏继续溶解并使Ca²⁺和SO^2-₄的浓度处于相对稳定状态,有利于半水脱硫石膏晶体的形核与生长。此外,Cu²⁺还可在晶须的生长过程中选择性吸附在晶须表面,生成CuSO₄,促进了脱硫石膏的结晶生长,最终在Cu(NO₃)₂用量为2.0%(质量分数)时制备的脱硫石膏晶须长径比约为73。

Influence of Cu(NO3)2 in H2SO4-H2O on the Growth of Desulfurized Gypsum Whiskers

Desulfurized gypsum whiskers were prepared by hydrothermal method using treated desulfurized gypsum as raw materials, and Cu(NO₃)₂ was used as the crystal form control agent in the H₂SO₄-H₂O system. The influence mechanism of Cu(NO₃)₂ on the growth of desulfurized gypsum whiskers was discussed. The results show that Cu(NO₃)₂ has obvious dissolution-promoting effect on desulfurized gypsum, and Cu²⁺ could reduce the activity coefficient of each ion in the solution and increase the concentration of Ca²⁺ in the solution. Moreover, NO^-₃ accumulate around Ca²⁺ and shield SO^2-₄ through electrostatic action, which cause the desulfurized gypsum dissolve continuously and keep the concentration of Ca²⁺ and SO^2-₄ in a relatively stable state, and facilitate the nucleation and growth of hemihydrate desulfurized gypsum crystals. In addition, Cu²⁺ selectively adsorb on the surface of the whiskers to generate CuSO₄ during the growth of the whiskers, thereby improve the crystal growth of desulfurized gypsum whiskers. When the amount of Cu(NO₃)₂ is 2.0% (mass fraction), desulfurized gypsum whiskers with an aspect ratio of about 73 are prepared.