Effect of iron (III) on the swelling pressure of dioctahedral smectites: A molecular dynamics study

Smectites in bentonites contain variable amounts of iron substituting aluminum and silicon in the crystal structure. The swelling pressure of smectite models with varying Fe3+ content, layer charge and charge location were studied using molecular dynamics method. Swelling pressures decrease with increasing iron content at high-dry densities, this is more pronounced in montmorillonites than beidellites with same layer charge. This swelling pressure decrease is slightly faster for smectites with lower layer charge. Results obtained from the study is useful in the screening process of iron-containing bentonites intended for use as sealants in High Level Radioactive Waste (HLRW) repositories.