Effective adsorption of carbamazepine from water by adsorbents developed from flax shives and oat hulls: Key factors and characterization

In this work, flax shives and oat hulls representative of cellulosic materials of agricultural byproducts were used to develop hydrochars and steam-activated hydrochar adsorbents. They were used to adsorb carbamazepine (CBZ) as a model pharmaceutical pollutant from artificially contaminated water. The adsorbents were characterized by surface properties and composition. CBZ equilibrium adsorption was investigated at various temperatures (20-40 degrees C) and solution pH (2-10). Steam-activation enhanced the CBZ equilibrium uptake of hydrochars made from either flax shives or oat hulls; however, both the hydrochars with or without steamactivation demonstrated effective CBZ adsorption in comparison with numerous adsorbents reported in the literature. The achieved CBZ uptake was insignificantly affected by solution pH, indicating that the adsorbents developed in this work could be applied to remove CBZ and similar pharmaceutical pollutants from water/ wastewater with a wide range of pH values. The CBZ adsorption was effective at room temperature which was enhanced at a higher temperature, showing the adsorption was endothermic in nature. The results demonstrated that flax shives and oat hulls were a promising feedstocks for making into adsorbents for water treatment.