Chemical surface modification of beaded activated carbon: A strategy to inhibit heel accumulation from VOC

Abstract

This study elucidates the factors responsible for the deterioration of beaded activated carbon (BAC), used in the abatement of volatile organic compounds that stem from painting processes in industries. In practice, continuous use of adsorbents during periodic adsorption–desorption results in the formation of heel (non-desorbable polymeric complex) in its pore structures, rendering the adsorbent eventually unusable. Here, the adsorption–desorption characteristics of VOCs from porous BAC are investigated, and an effective surface modification strategy is developed to impede heel formation and extend the operational life of the BAC. This modification protocol increases porosity by up-to 55 % and modifies the functional groups on the BAC surface without altering its structural integrity. Consequently, the adsorption capacity of the BAC increased by nearly 38% while decreasing the peak desorption temperature by as much as 50 °C due to lowered adsorption strength. Additionally, to provide mechanistic insights, the resultant changes in porosity, surface morphology, and adsorption–desorption characteristics of the BAC are investigated by N2 physisorption, SEM, TGA, and DRIFTS. Finally, cyclic adsorption–desorption studies conducted under conditions mirroring the industrial setup proved that the percentage heel accumulation in surface modified BAC is significantly lower (≤ 3%) compared to unmodified BAC.