A novel bionanocomposite from doped lipase enzyme into magnetic graphene oxide-immobilized-cellulose for efficient removal of methylene blue and malachite green dyes

Abstract

Immobilized biosorbents with enzymes have become a topic of interest in the fields of environmental and energy science owing to their numerous advantages such as ease of separation, non-toxicity, biocompatiblity, high activity, and regeneration capability for further reuse. In this respect, lipase fromCandida rugose was selected to covalently immobilize ontoa supporting matrix of magnetic graphene oxide-immobilized-cellulose via glutaraldehyde to produce a magnetic bionanocomposite (MGO@Cellulose@Lipase) for the effective removal of methylene blue (MB) and malachite green (MG) from water as two target cationic pollutants. The as-synthesized bionanocomposite was characterized by various techniques to confirm the structure composition, surface morphology, thermal and magnetic properties. The SEM and HR-TEM examinations referred to good homogeneity and surface porosity with 23.80–32.69 nm as the identified particle size. Based on the BET analysis, MGO@Cellulose@Lipase exhibited a mesoporous structure with a mean pore size 11.56 nm, while the VSM results showed that the prepared bionanocomposite particles exhibited a saturation magnetization value 14.78 emu/g. To evaluate the adsorption performance of the newly designed bionanocomposite, batch adsorption experiments was carried out, under the influence and impact of various experimental controlling parameters. The adsorption correlations of MB and MG pollutants were fitted to Langmuir isotherm and pseudo-second order kinetics. The maximum computed adsorption capacity (qmax) for MB and MG were 66.79 and 51.87 mg/g, respectively. Thermodynamic studies confirmed the spontaneity and the endothermic nature of the adsorption process. Moreover, excellent removal efficiency of MB and MG by MGO@Cellulose@Lipase after five consecutive adsorption–desorption cycles were confirmed as 97.43% and 87.60%, respectively. The validity and applicability of MGO@Cellulose@Lipase in removal of MB and MG pollutants from real water samples were characterized in the range 95.09–96.24% and 91.01–92.58%, respectively. Therefore, the outlined results prove that the MGO@Cellulose could be used as a promising carrier alternative for enzymes immobilization and the assembled MGO@Cellulose@Lipase bionanocomposite was also characterized as an innovative green material for solving the environmental dye pollution.