Use of microorganism-immobilized polyurethane foams to absorb and degrade oil on water surface

Highly oil-absorbent polyurethane foam (PUF) materials were obtained by pol ymerizing polyether polyol mixture and carbodiimide-modified D-methyl diiso cyanate in a weight ratio of 10.2. The foam materials were prepared to cont ain inorganic nutrients (slow-release fertilizer; SRF) and oil-degrading ye ast cells, Yarrowia lipolytica 180, to be applied for removal of oil films on surface waters through absorption and biodegradation after oil spills. P UFs absorbed 7-9 times their own weight of Arabian light crude oil and the oil absorbency appeared to improve as the ratio of surface area to foam wei ght increased. PUFs showed excellent floatability which was maintained for more than 6 months in sea water, and less than 5% of the absorbed oil was r eleased when the foams were left on water for more than 10 days. For immobi lization of yeast cells into PUFs, various immobilization techniques were t ested to compare their oil degrading ability and the maintenance thereof. A ll immobilized cells showed oil degrading abilities as good as those of fre e cells immediately after the preparation of PUFs, however, the activity of chitin-immobilized cells remained at a high level for the longest period o f preservation. The high efficiency of oil absorption and oil degradation b y PUF-immobilized yeast cells suggested that PUF-immobilized cells have a h igh potential as a bioremediation technique for the treatment of oil films on surface waters.