Production and characterization of biopolymer schzophyllan using sago starch as a carbon source

Abstract

A significant amount of oil gets left behind in the reservoir after the application of primary and secondary recovery methods. Water flooding is the most widely used secondary recovery method because of its availability and low cost. However, this method leads to high water/oil mobility ratio leaving behind most of the oil in the reservoir. To overcome this effect, polymers are added which increases the water viscosity due to their high molecular weight. Polymer flooding reduces the mobility ratio leading to a greater oil recovery. In recent years, biopolymers have attracted the attention of petroleum industries. There are very few reports on the production of biopolymers from fungi and even fewer among them have been produced commercially. Schizophyllan produced by the fungus schizophyllum commune in presence of a carbon source (usually glucose) via submerged fermentation process, has attracted attention of researchers recently. This biopolymer is currently available as an expensive grade material, whereby limiting its applications in the industry. We hereby report a method for schizophyllan production using cheaply available sago starch as a carbon source. Physico-chemical characterization of schizophyllan was carried out using Fourier Transform Infrared (FTIR) spectroscopy which showed characteristic spectral signature for the biopolymer. Using Thermo Gravimetric (TG) analysis, the biopolymer was observed to be thermally stable upto 125°C, showing potential applications in high temperature reservoir conditions. Gel Permeation Chromatography (GPC) revealed a high molecular weight of 14.73 million Dalton, while viscosity measurements show shear-thinning behaviour, desirable in polymer flooding applications. The obtained properties of the biopolymer, coupled with a cheap production process based on locally available carbon source, makes them ideal candidates for applications in polymer flooding for enhanced oil recovery.