Kinetics and Mechanism of Metal Retention/Release in Geochemical Processes in Soil - Final Report

Taylor, Robert W.

doi:10.2172/775037

Cited by 2 publications

(1 citation statement)

References 25 publications

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“…surface complexation, and non specific adsorption such as ion exchange [1]. The chemistry of Pb in soils is affected by three main factors: specific adsorption to various solid phases, precipitation of sparingly soluble or highly stable compounds and formation of relatively stable complexes or chelates with soil components [2][3] [4] [5] investigated the retention of Pb 2+ ion by montmorillonites and found that cation exchange predominated in pH range 2 -4, precipitation was the main mechanism at pH > 6, and a combination of both took place at intermediate pH 4 -6. A strong dependence on ionic strength is typical for an outer-sphere complex, whereas insensibility of ionic strength is an indication for inner sphere surface complexation [6].…”

Section: Introductionmentioning

confidence: 99%

Batch Studies for the Investigation of the Mechanism of Pb Sorption in Selected Acid Soils of China

Nkwopara¹

2015

AFF

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The experiment focuses on mechanisms of Pb retention on acid soils. A batch experiment was conducted to investigate the effect of solution pH and ionic strength of electrolytes which will show the mechanisms of Pb retention on the soils. Result show that sorption of lead was affected strongly by solution pH and ionic strength of electrolytes. Retention of lead increased with increase in solution pH and decreased with increase in ionic strength of electrolytes. This suggests that surface complexation and ion exchange are the mechanisms of Pb retention on these acid soils. At pH above 6 there was precipitation of lead. SEM studies visualized the formation of white layers of Pb over the soil surface. Scanning electron microscopy (SEM) revealed that the adsorption of lead ions made the surface of the soil particles rougher than those without lead. This morphological change points to the formation of a surface coating on the soil particles.

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