Immobilized CotA Laccase for Efficient Recovery of HEAVY OIL

Abstract

AbstractCotA laccase was successfully expressed from Pichia pastoris. Magnetic reduced graphene oxide (MRGO) nanocomposite was synthesized and functionalized with iminodiacetic acid (IDA-NH2), and then chelated with Cu2+ for effective immobilization with His-tagged CotA laccase. The Cu2+-chelated MRGO (MRGO-IDA-Cu2+) showed 175 mg/g-support adsorption capacity. The immobilization of CotA laccase with MRGO-IDA-Cu2+ nano-hybrid composite was confirmed by Raman spectroscopy, Thermal Gravimetric Analysis, and X-ray diffraction. The use of nano-hybrid MRGO-IDA-Cu2+ composite to improve heavy oil recovery was investigated. The findings revealed that the interfacial tension between oil and water was reduced to ~ 90% of its original value, and the wettability was changed from the oil-wet state [θ = ∼ 115.2 − 124.5°] to the water-wet state [θ = ∼ 8.9 − 30.1°]. The increase of immobilized CotA laccase concentration and the ratio of nano-hybrid MRGO-IDA-Cu2+ composite decreases the value of interfacial tension (IFT) and contact angle (CA). The core-flooding studies revealed that the oil recovery process of 0.3 wt% nano-hybrid MRGO-IDA-Cu2+ composite was enhanced by 82.8%. Graphical Abstract