The most dangerous chemical element is Pb, which enters the soil from landfills for storing municipal solid waste. The aim of the work is to study the absorption capacity of sandy soils with the addition of clay matter and starch in relation to Pb.
To study the absorption capacity, a model soil was created based on 100 g of fine quartz sand, 10 g of montmorillonite clay and 10 g of starch. The study was conducted by dynamic filtering. A solution of Pb(NO3)2 with a concentration of Pb 1.25 g/l was passed through the model soil.
Over time, the pH of the filtrate decreases from 7-8 to 5-6 units, which corresponds to the pH of the initial solution Pb(NO3)2, which indicates the completion of the Pb absorption process by the soil. There was no correlation between the Eh values of the filtrate and its selected amount.
The pHZPC value of the model soil was determined before and after absorption of Pb ions. The values of 8.5 before absorption and 6.25 units after absorption correspond to the general behavior of the soil during Pb absorption.
The measurement of soil CEC showed that the absorption of lead by the model soil does not depend on its CEC value (0.07 mg-eq/100 g for the entire model soil and model soil excluding starch), therefore, lead sorption does not occur in the exchange complex of the soil, but in more durable centers.
According to the results of measuring the concentration of Pb absorbed by the model soil, an absorption capacity value of 1.96 mg/g was obtained. The maximum amount of lead absorbed by clay and starch is 11.76 mg/g, which is much less than the values obtained by studying the absorption capacity of similar soils under static sorption conditions (on average 48.24 mg/g).