Adsorptive removal of micropollutants by natural and faujasite zeolites: Structural effect of micropollutants on adsorption

Abstract

To effectively characterize natural zeolite powder (ZP) and faujasite zeolite (FAU) as adsorbents to remove a wide variety of organic micropollutants, quantitative structure-activity relationship (QSAR) models for the adsorption of zeolites were developed. For this purpose, batch isotherms were performed to measure the adsorption affinity (Kd) between zeolite and organic micropollutants, and the measured Kd values were used as a dependent variable in the QSAR modeling. In the modeling, the concept of a linear free energy relationship (LFER) was employed and used either empirically measured or in silico calculated descriptors. Modeling results based on empirical descriptors showed that log Kd values for ZP could be predicted with R2 = 0.949 and standard error (SE) = 0.137 log units, and for FAU, R2 = 0.895 and SE = 0.144 log units. A test set was used to validate the models developed by the training set. The predictabilities of the models for the test set were R2 = 0.907 and SE = 0.209 log units for ZP and R2 = 0.784 and SE = 0.236 log units for FAU, indicating that the models have reasonable robustness and predictability. Also, we showed that in silico-based descriptors could be applied to the prediction. These findings may help determine the general coverage of ZP and FAU zeolites and identify suitable applications.

Keywords

• Ionic micropollutant
• Removal
• Quantitative structure–adsorption relationship
• In silico