Investigating the zeolite and bentonite adsorbent effect on the static, dynamic, and environmental parameters of soil

Contamination of soils and groundwater resources has become one of the most serious global environmental problems in recent years. The use of natural and inexpensive adsorbents such as zeolite is one of the appropriate methods to prevent the spread of contaminants and increase the adsorption capacity of the soil. Therefore, in the present study, zeolite is used as an option to improve the soil environmental condition. In this research, the behavior of the mixture of sand with 15% kaolinite clay is investigated at first, in both conditions of non-contaminated and contaminated with lead nitrate. Due to the limited adsorption capacity of the sand containing kaolinite, different percentages of zeolite adsorbent (as 5, 10, and 15 percent of soil weight) were added to this mixture to investigate the adsorption capacity and changes in strength parameters of the soil and adsorbent mixture. These parameters were also compared between zeolite and bentonite adsorbents. According to the results of the atomic adsorption test, zeolite has a favorable effect on increasing the adsorption capacity of heavy metals in soils such that by adding 5% zeolite, the amount of lead adsorption capacity increases by about 70%. Followed by investigating the static behavior and adsorption capacity of different compounds of soil containing adsorbent and without adsorbent, the dynamic behavior of these compounds in both conditions of non-contaminated and contaminated with lead nitrate was studied. The results show that in both contaminated and uncontaminated conditions, the initial shear modulus decreases with increasing zeolite content adsorbent. Also, dynamic behavior shows that in the combination of soil with both types of adsorbents, by increasing the concentration of heavy metal, the cycles corresponding to Ru decreases.