Hybrid gel reinforced with coating layer for removal of phenol from aqueous solution

Following our preceding results of fabricating phenol adsorbing hydrogel, we aimed to complete adsorbent gel material for removal of phenol. As a practical requirement, it needs to be mechanically more durable for repeated use of adsorption and desorption. In earlier works, we succeeded in fabricating N-isopropylacrylamide (NIPAM) hydrogel incorporated with tributyl phosphate (TBP). This hybrid gel was shown to be effective for removal of phenol dissolved in water. In this work, we succeeded in sealing the above hybrid gel completely with poly(vinyl alcohol) (PVA) thin layer coating by repeated freezing and thawing. The coated hybrid gel was remarkably improved in its mechanical durability. In the performance of adsorption of phenol, the PVA thin layer coating hardly hindered the mass transfer of phenol. The mechanical durability was sufficiently improved for the desorption (stripping) of the adsorbed phenol by immersing the adsorbent gel in sodium hydroxide solution. The cycle of the adsorption and desorption could be repeated without loss of the phenol adsorbing ability.