Effect of Processing Conditions on the Absorption Behavior of 3D Boron Nitride Foams in Various Aqueous Mixtures

Abstract

In this work, we successfully fabricated boron nitride foams by assembling boron nitride into a 3D porous structure using freeze drying. Boron nitride was modified by Hummers method and NaOH, which results in the functionalization with OH groups. Such chemical functionalization enabled the attachment of the surfactant molecules, leading to a 3D foam structure. We found that the type of the surfactant molecules and method of freezing (in liquid nitrogen or in a deep freezer) have significant impact on the structure of the foams and consequently their absorbent properties. Fast freezing technique (with liquid nitrogen) created more stable and porous structures compared to the slow freezing technique (in a deep freezer). The best foam structures were obtained for the samples coded as h-BN-B-H-SA and h-BN-N-DA. The highest absorption capacity was found as 2014.3% for h-BN-B-H-SA. Absorption capacity results show that foams can absorb approximately 2-20 times their own weight. The method we use here is easy to apply, environmentally friendly, and can be readily scaled up for industrial use.