以白云岩为原料制备Mg-Al-CO_(3)类水滑石/方解石复合粉体及机理

Green Synthesis and Mechanism of Mg-Al-CO_(3) Layered Double Hydroxides/Calcite Composite Powders from Dolomite

以白云岩为原料,通过酸溶和共沉淀工艺合成了Mg-Al-CO_(3)类水滑石/方解石复合粉体.利用白云岩的镁、钙和二氧化碳,无CO_(2)温室气体排放,属绿色合成工艺.确定了优化的工艺条件:酸溶温度为60℃,OH-/(Mg^(2+)+Al^(3+))摩尔比为3.5:1.0,Mg^(2+)/Al^(3+)摩尔比为3:1,结晶温度和时间分别为120℃和18 h.结果表明:复合粉体中Mg-Al-CO_(3)类水滑石和方解石的质量分数分别为39.5%和60.5%;方解石粒度在0.6~1.8μm,形态为规则粒状;类水滑石呈规则六边形片状,片径在100~200 nm.对酸溶与共沉淀过程及其Mg-Al-CO_(3)类水滑石和方解石的结晶过程及其机理进行了讨论.

Green synthesis of Mg-Al-CO_(3) layered double hydroxides/calcite composite powders(LDH/Cal)via the acid dissolution and co-precipitation process was investigated in this paper.This method uses dolomite as a source of magnesium,calcium,and carbon dioxide with no CO2 release in the process of preparation.LDH/Cal prepared under optimized conditions(acid dissolution temperature was 60℃,OH-^(-)/[Mg^(2+)+Al^(3+)]mole ratio was 3.5:1.0,Mg^(2+)/Al^(3+)mole ratio was 3:1,temperature and time of crystallization were 120°C and 18 h,respectively)was characterized.LDH/Cal consists of LDH(39.5%)and calcite(60.5%).The calcite was regular and granular with a diameter of about 0.6 to 1.8μm,and LDH contained well-defined plate-like particles with regular hexagonal shape,and sizes between 100 and 200 nm.The acid dissolution process of dolomite and the compound mechanism of LDH and calcite were discussed.