碳酸镁与铅的吸附和沉淀作用研究

本文系统研究了铅离子在不同初始pH值(4和7)和初始浓度(0~3 mmol/L)条件下与碳酸镁的相互作用。研究结果表明,由于碳酸镁的溶解作用和中和作用,体系的最终pH值保持在10.5左右;随着铅初始浓度的增加,体系的平衡pH值有增加的趋势,在大于0.75 mmol/L后p H值的变化不大;铅的平衡浓度随着初始浓度的增加而增加,在大于0.75 mmol/L后基本稳定;碳酸镁对铅的吸附等温线为折线型,在低浓度时的反应主要为表面配位吸附,而在高浓度时则发生表面沉淀,有Pb_3(CO_3)_2(OH)_2生成。

Adsorption and Precipitation of Lead on Magnesium Carbonate

The interaction between lead and magnesium carbonate is studied on condition that initial pH =4 ,7 and initial lead concentration 0~3 mmol/L .The result shows that the equilibrium pH maintains 10 .5 or so because of magnesium car-bonate dissolution .The initial pH has an upward trend with the increase of the initial lead concentration and changes a little when the concentration is greater than 0 .75 mmol/L .Lead equilibrium concentration increases with the increase of initial concentration and it is basically stable when the concentration is greater than 0 .75 mmol/L .The adsorption isotherms are polylines ,at the low concentration surface complexion sorption is the main reaction ,but at high concentration the precipita-tion occurs and solid Pb3 (CO3 )2 (OH)2 generates .