Application of Zeolite in Soil Improvement and Remediation

With the rapid development of industrial civilization and the irrational use of land at home and abroad, the nutrients in the soil become depleted, and loss problems such as volatilization and leaching phenomena occur after fertilizers are applied to the soil. 

As a new environmentally friendly material, zeolite has high ion exchange and small pore adsorption properties, so in recent years zeolite has been widely studied and used as a remediation material that can mitigate and improve soil. Application of zeolite in soil can improve the adsorption capacity of NH4, PO34- and K, and improve the utilization of soil nutrients, which is beneficial to the uptake and utilization of nutrients by plants.

Since zeolite has a porous structure and a high affinity for water, it can absorb water and gas components, increase the water content of the soil, and improve the permeability of the soil. It has been demonstrated by Jiang Chun et al. that zeolite can increase the water holding capacity of soil, and in arid areas, the water holding capacity of soil treated with zeolite usually increases by 5% to 15%, up to 27.9%, which is very beneficial for seeding in arid areas. 

It is also known through practice that zeolite is more effective than conventional polyacrylic acid water retention agents with a reticulated structure. Foreign mixing of 5% zeolite material with soil can increase the water retention rate of soil by 7 to 8 times.

In addition, during the rapid development of industry and agriculture, a large number of pollutants have accumulated in the soil because effective control measures were not taken in time. 

These harmful substances are absorbed by plants and can affect human health when ingested by human food. Since zeolite has good adsorption and ion exchange properties, it has been widely used in soil remediation in recent years as a way to immobilize harmful substances in the soil and reduce their uptake by plants.

Gworek added synthetic zeolites to Cd-contaminated soils, which significantly reduced Cd concentrations in rhizomes of lettuce, oats and ryegrass. When the zeolite rate was 1% of the soil weight, the Cd concentration in the leaves of potted lettuce was reduced by 86% compared to the control group. 

Two types of synthetic zeolites were used in this experiment: type 13X (pore size 0.9 nm) and type 4A (pore size 0.42 nm), where type 13X bound Cd more efficiently than type 4A due to the former having a larger crystal pore size than the latter. In addition, zeolite can be widely used to control radioactive materials in soil.