Effect of humidity on VOC adsorption on honeycomb zeolite

Zeolite honeycombs have shown great promise for the adsorption of volatile organic compounds (VOCs). However, humidity can affect their adsorption performance. In this study we developed and validated a model to examine the effect of the relative humidity (RH) on the adsorption of isopropyl alcohol (polar) and 1,2,4-trimethyl benzene (1,2,4-TMB, non-polar), onto zeolite honeycomb adsorbent. Extended Langmuir model was used to predict the binary adsorption isotherm of VOC/water vapor from pure component adsorption isotherms. Using the binary adsorption isotherm and physical properties of the adsorbates and adsorbent, coupled mass and momentum equations were solved to predict the adsorption breakthrough profile of VOCs under different RH levels (40, 60, 80%). Experimental adsorption breakthrough profiles of VOCs in presence of water vapor were used to validate the model results. Mean absolute relative error (MARE) and normalized root mean square error (NRMSE) values showed that the model predictions and experimental measurements were in good agreement. The MARE for isopropyl alcohol and 1,2,4-TMB were 15.0% and 8.6%, respectively. The NRMSE for the adsorption of both VOCs under humid condition was 4%. For isopropyl alcohol, a reduction in the breakthrough time was observed even for low RH (~40%). On the other hand, for 1,2,4-TMB, only when the RH exceeded 60% the breakthrough time decreased. The performance of the developed model allows predicting VOC adsorption under realistic environmental conditions and reduce the need for experimental testing.