Drying of nonpolar gas in a pressure swing adsorption process using canola meal biosorbents

Drying of gases is a very important industrial operation. In the present work, drying of nonpolar gas was carried out using nitrogen as a model gas, by selective adsorption of water vapor from the moist gas using canola meal (CM)‐based biosorbents in a pressure swing adsorption process. It was demonstrated that CM did not adsorb nonpolar nitrogen but selectively adsorbed polar water vapor. Five operating parameters—temperature, pressure, input feed water concentration, input gas concentration, and particle size—were chosen to study the nitrogen drying process using a fractional factorial design. Temperature and input water concentration had significant effects on the drying process, and the maximum water adsorption capacity obtained was 0.165 kg/kg.ads. The Dubinin–Polanyi (DP) model for large pores fit the water adsorption isotherms reasonably well and indicated that water adsorption is predominantly physisorption. Furthermore, site energy distribution of water adsorption based on the DP model was carried out to determine adsorbate–adsorbent interactions. It revealed that most of the adsorption sites were in the low‐energy region of the distribution (>7,800 J/mol) and there were negligible sites with energy higher than 25,000 J/mol which again confirms that water adsorption is rapid, reversible, and low‐energy process, which is the characteristic of physisorption. The average energy and standard deviation of the site energy distribution was 5,000 J/mol. Saturated biosorbent was regenerated at 110°C and reused multiple times. The analysis of the present work can be applied to similar systems for drying of nonpolar gases.