Fabrication of novel nanocomposite nanofibrous matrices retaining high concentration of microbial cells for heavy crude oil biodegradation

Abstract

Microbial cells immobilized in porous carriers as an effective technique has been recently studied and applied in various applications including wastewater treatment. High mechanical stability and large specific surface area are the key advantages of an ideal porous carrier. Immobilization of microbial cells in novel nanocomposite nanofibrous webs (NC-NFWs) for use in bioremediation of heavy crude oil as sole carbon and energy sources in aqueous phase was the main focus of this study. Polyvinyl alcohol (PVA) and alginate (ALG) were selected as the polymer matrices for the electrospinning of nanofibrous webs (NFWs). In this study, preparation and application of PVA/ALG webs that were reinforced by halloysite nanotubes (HNTs) followed by cross-linking with glyoxal (GO) are described for the first time. The synthesized NFWs were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and tensile tests. Results showed that NC-NFWs have a great potential for bioremediation of crude oil, and removal performances were higher in immobilized systems (85 and 64%) compared to freely suspended cell system (48%) after 14 days. Also, maximal bacterial growth in culture containing 500 ppm crude oil was achieved by PVA/ALG/GO/ HNT7.5% which was almost 1.4 and 2.4 times higher than PVA/ALG/GO/HNT5% and free cell system at same inoculum concentration, respectively.