Predicting adsorption isotherms of organic micropollutants by high-silica zeolite mixtures

One framework type of high-silica zeolite only can effectively remove a limited range of organic micropollutants (OMPs) from water. In order to extend the OMP removal range, different types of high-silica zeolites need to be combined in the adsorption process. In this study, Mordernite (MOR) and ZSM-5 (MFI) high-silica zeolite powders were mixed in different mass ratios. The removal performances of eight OMPs by zeolite mixtures, as well as single MOR and MFI zeolites, were evaluated through batch adsorption experiments to investigate their adsorption behaviors and mechanisms. When there was only one solute in water, the adsorption isotherms of OMPs by zeolite mixtures were well predicted by combining the experimental adsorption isotherms of single zeolites based on the mass ratios of single zeolites. In multi-solute water, adsorption isotherms by zeolite mixtures were calculated with less accuracy when solely combining experimental isotherms of single zeolites, especially in the case of having a lower portion of more-effective zeolite in the mixture. This could be attributed to the competition for more-effective zeolite between different OMPs.

Automated summary

The study found that in single-solute water, the adsorption isotherms of zeolite mixtures can be well predicted by combining experimental adsorption isotherms of single zeolites based on mass ratios. However, in multi-solute water, especially when the proportion of more effective zeolite in the mixture is lower, the accuracy of adsorption isotherms by zeolite mixtures calculated solely by combining experimental isotherms of single zeolites is reduced, which could be attributed to the competition for more effective zeolite between different OMPs.