温度对硼在三种矿物上吸附—解吸特性的影响

EFFECTS OF TEMPERATURE ON CHARACTERISTICS OF BORON ADSORPTION-DESORPTION BY MINERALS

在实验室对天然Ca 蒙脱进行了纯化 ,并在一定条件下人工合成了针铁矿、水锰矿 ,以此作为实验材料 ,用吸附—解吸平衡法和反应动力学方法研究了温度对硼在Ca 蒙脱 ,针铁矿 ,水锰矿上的吸附、解吸特性的影响。结果表明 :随温度升高 ,Ca 蒙脱对硼的吸附量升高 ,其对硼的解吸滞后性下降 ,水锰矿和针铁矿对硼的吸附量下降 ,其对硼的解吸滞后性加强。计算表明 ,在常温下 ,硼在Ca 蒙脱上的吸附热为 63.0 8kJmol- 1 ,在针铁矿和水锰矿上分别为 - 1 2 2 .45和 - 93 .91kJmol- 1 ,硼在Ca 蒙脱、针铁矿和水锰矿上的解吸热分别为- 31 .0 2 ,53 .95和 46 .30kJmol- 1 。上述结果说明 ,硼在Ca 蒙脱上的吸附为吸热过程 ,解吸为放热过程 ;硼在针铁矿、水锰矿上的吸附为放热过程 ,解吸为吸热过程。随着温度的升高 ,硼与矿物的初始反应速率明显加快 ,而整体反应速率略有下降。

Effects of temperature on characteristics of boron adsorption desorption by Ca montmorillonite, goethite and manganite were studied. The results showed that boron adsorption by Ca montmorillonite increased with increasing temperature, whereas boron adsorption by goethite and manganite decreased as temperature rose. Boron adsorption desorption by Ca montmorillonite was less hysteretic as compared to goethite and manganite in terms of boron desorption rates at different temperatures. At constant temperature, boron adsorption heat for Ca montmorillonite, goethite and manganite were 63.08, -122.45 and -93.91 kJ mol -1 , respective desorption heat were -31.02, 53.95 and 46.30 kJ mol -1 . The process of boron adsorption by Ca montmorillonite was endothermic. By contrast, the process for goethite and manganite were exothermic. As temperature rose, boron reacted faster with minerals initially. However, the reaction rate as a whole slightly decreased.