Enriching composite hydrophilic polyurethane foams with PAC to enhance adsorption of phenol from aqueous solutions

This paper summarizes physical and mechanical properties of composite hydrophilic polyurethane (HPU) foams, which were enriched with various additives, including dry biomass; clay; and powdered activated carbon (PAC). The composite foams were proposed to be used as biomass immobilization matrices in bioreactors, for physical and biological purification of contaminants. Foam morphology were evaluated by scanning electron microscopy. The PAC-enrichment capacities of the foams were measured, and the maximal capacity was found to be of the control foam: 27 mg PAC/cm3. Adsorption of phenol by enriched and non-enriched foams was investigated in batch experiments and adsorption results could be well described by a Langmuir model. The phenol adsorption capacity of the non-enriched foams was very low (2.8-5.4 mg/g foam). However, this capacity was improved by 5.8-7.3 folds following the enrichment process. An additional finding was that upon enrichment of the foams by immersing in PAC aqueous solution, the maximal adsorption capacity of the adhered PAC on the foam was about 65% lower in average compared to free PAC, while when PAC is embedded in the foam during the polymerization process, it loses almost its entire adsorption capacity. The proposed PAC enrichment process is unique, effective and friendly for immobilized biomass.