逐级化学分离法对水体沉积物各组分吸附作用模式的研究

天然水体中悬浮物和沉积物的主要活性组分,通常是粘土矿物,铁、锰、铝水合氧化物,有机物和碳酸盐。本文研究它们在重金属吸附中各自所起的作用。提出了一种逐级化学分离程序和多组分吸附剂的吸附模式及计算方法。应用于湘江上、中、下游三种底质样品,进行了所有分级样品的镉吸附实验。吸附模式计算得到若干有益的结果。 不论颗粒物整体,或是其各种组分,在广泛的重金属浓度范围内,都得到Langmuir型吸附等温式,并由它们共同组成Langmuir型吸附模式。电子显微镜研究表明,粘土矿物表面只有局部被其他组分复盖。模式计算表明,在湘江沉积物样品总吸附量中,粘土矿物的吸附、贡献仍占主要地位(60—70%)。金属水合氧化物(15—25%)和有机物(11—22%)大致在同一水平而前者略高,碳酸盐的作用(0.1—5%)则较微小。各种组分在吸附中所起的作用评价应该同它们的相对含量联系起来,综合加以考虑。

STUDY ON MULTI-COMPONENT ADSORPTION MODELOF AQUATIC SEDIMENTS WITH A SEQUENTIALCHEMICAL SEPARATION PROCEDURE

The major active components of natural aquat-' c suspended particulates and sediments are usually clay minerals, hydrous oxide of iron, manganese and aluminum, organic matter and carbonates. Their relative contributions in heavy metal adsorption were studied. With sequential chemical separation procedure, an adsorption model of multi-component adsorbent and the calculation method were proposed in this paper, which have been applied to three samples of sediments from the upper, middle and lower reaches of Xiangjiang River. The cadmium adsorption experiments at all levels of graded samples were conducted. Some useful results were obtained from adsorption model calculations.Whole participate or its components in a broad range of heavy metal concentration, showed the adsorption isotherms as of Langmuir type, and the isotherms, when put together, formed an adsorption model of Langmuir type, too. The electron microscope study showed that the covered part on the clay mineral surface by other components was limited. The model calculation indicated that of the total adsorption of particulate of Xiangjiang sediment samples, the relative contribution of clay minerals was dominant (60-70%). Those of hydroxides (15-25%) and of organic matter (11-22%) were of the similar level, with former a little higher. Carbonates(0.1-5%) played a little role. So in evaluation of the adsorption contributions of the components in sediments, their relative contents must be known beforehand.