Poly(butyl acrylate) gel prepared in supercritical CO2: an efficient recyclable oil-absorbent

Oil-absorbing resins containing cross-linked poly(butyl acrylate) (PBA) were synthesized via precipitation polymerization in an environment-friendly route using supercritical carbon dioxide as the reaction media. The PBA resins were then regenerated through subcritical CO2 extraction process. The PBA resins with macroporous structures, prepared at pressures ranging from 17.5 to 24.5 MPa, were characterized by field emission scanning electron microscopy and mercury porosimetry. These structures are beneficial to oil absorption. Thermogravimetric analysis results showed that the PBA resin has good thermal stability. The effect of reaction pressure, initiator ratio, cross-linker content, and absorption time on yield and oil absorption was also investigated. The results revealed a slight decrease in yield with increasing pressure, within a pressure range of 17.5-24.5 MPa. The high initiator concentrations did lead to the decrease in the oil absorption capacity of the PBA resin. A higher product yield of 55% is acquired in the presence of the higher cross-linker content of 20 wt%. The highest absorption capacity of diesel oil onto the PBA resin was 7.5 g/g with oil retention capacity of 95.2%. Moreover, oil desorption of oil-saturated PBA resin was conducted with carbon dioxide instead of the traditional extraction solvents. After 10 repetitions, PBA resin exhibited good recyclability.