Pelletization and characterization of agricultural by-products for water uptake

Industrial gas streams contain moisture of different levels and lowering their humidity is essential to ensure compliance with standards. Sorption has been an effective method to selectively remove water vapor from gaseous mixtures. Although various types of adsorbents have been employed in adsorption, cost-effective agriculture by-products, such as oat hull (OH), canola meal (CM) and their composite, are efficient materials for developing biosorbents. For industrial application, it is crucial to pelletize the biosorbents to control their size, shape, water uptake, and related qualities. This work investigated the effects of die temperature, compressive force, and biomass type on biosorbent pellet quality and interactions. In this regard, raw oat hull and canola meal and their 50%− 50% composition were pelletized under three levels of compressive (2000, 3000 and 4000 N) at 75, 85 and 95 °C as the die temperature. Increasing die temperature and compressive force enhanced quality of the produced pellets. Canola meal was superior in water uptake, while oat hull was important in strengthening pellets. Moreover, sodium lignosulfonate (LSNa) as an additional binder improved pellet quality. By statistical optimization methods, four pelletized biosorbents (18.6% OH-81.4% CM-Without LSNa; 100% CM-4% LSNa; 54.5% OH- 45.5% CM-4% LSNa; 91.9% OH-8.1% CM-4% LSNa) were developed, which were promising for industrial application. The optimized biosorbents possessed relatively high density and strength, and their water uptake capacity was in the range of 0.32 – 0.38 g/g, which is comparable to or higher than commercial adsorbents. Therefore, the introduced biosorbents could be effective alternatives to the conventional materials for gas dehydration.