Synthesis and Characterization of Biodegradable Oil-Adsorbent Microspheres with a Low Nitrogen Release Rate

摘要

Oil spill issues are of great environmental concerns due to the carcinogenic, teratogenic and mutagenic properties of the pollutants such as polycyclic aromatic hydrocarbon (PAH). Biodegradable oil-absorbent microspheres derived from poly-p-hydroxybutyrate (PHB) were synthesized by the double emulsion- solvent (water-in-oil-in-water, W1/O/W2) evaporation techniques in this study. The urea-formaldehyde (UF) molar ratio of 4.63 was adopted in the preparation process to allow the nitrogen release at a low rate when they are applied in oil absorption practices. From the emission scanning electron microscopy (SEM) images, the microspheres were found to be porous spherical particles with diameters ranging from 3 to 100 nm. The Fourier transform infrared spectroscopy (FT-IR) spectrum of the oil-absorbent microspheres was proved to be in accordance with that of PHB. The adsorption capability of the microspheres on diesel oil was investigated initially with three serial oil concentrations in water within 240 min. The results showed that the equilibration time was around 60 min and the oil absorbed by the microspheres from oil-water mixture at concentrations of 18.78 and 11.47 mg/g are 53.52 and 49.48% of the adsorption saturation amount in 5 min respectively. The nitrogen release property from the absorbents was also examined and was compared with that of UF through the shaking water-extraction method. Both of the amount and the rate of nitrogen accumulative release were employed as indicators in the process and the maximum total nitrogen concentrations reached at 3 and 4 days for the absorbents and UF respectively.