Biotransformation of phenol in synthetic wastewater using the functionalized magnetic nano-biocatalyst particles carrying tyrosinase

Abstract

Low conversion efficiency and long-processing time are some of the major problems associated with the use of biocatalysts in industrial processes. In this study, modified magnetic iron oxide nanoparticles bearing tyrosinase (tyrosinase-MNPs) were employed as a magnetic nano-biocatalyst to treat phenol-containing wastewater. Different factors affecting the phenol removal efficiency of the fabricated nano-biocatalyst such as catalyst dosage, pH, temperature, initial phenol concentration, and reusability were investigated. The results proved that the precise dosage of nano-biocatalyst was able to degrade phenol at the wide range of pHs and temperatures. The immobilized tyrosinase showed proper phenol degradation more than 70%, where the substrate with a high concentration of 2500 mg/L was subjected to phenol removal. The nano-biocatalyst was highly efficient and reusable, since it displayed phenol degradation yields of 100% after the third reuse cycle and about 58% after the seventh cycle. Moreover, the immobilized tyrosinase was able to degrade phenol dissolved in real water samples up to 78% after incubation for 60 min. It was also reusable at least seven cycles in the real water sample. The results proved the effectiveness and applicability of the fabricated nano-biocatalyst to treat phenol-containing wastewaters in a shorter time and higher efficiency even at high phenol concentration. The developed nano-biocatalyst can be promising for the micropollutants removal and an alternative for the catalysts used in traditional treatment processes.

Applications of Biocatalysts for Sustainable Oxidation of Phenolic Pollutants: A Review

“…Furthermore, 100% of phenol was removed after reusing the immobilized tyrosinase for three consecutive treatment cycles, and this efficiency dropped to 58% after the seventh reaction cycle. This study also showed that the immobilized enzyme degraded up to 78% of phenol pollutant in a real wastewater sample, with the initial phenol concentration of 250 mg/L within 60 min treatment period [130]. The immobilization of lignin and manganese peroxidases via the encapsulation method within three various polymeric matrices, including carboxymethylcellulose, gelatin and pectin, was reported previously for the degradation of bisphenol A from wastewater [131].…”

“…One of the remarkable achievements in the field of water and wastewater treatment utilizing enzymes-nanomaterials conjugates is the use of immobilized laccase onto the modified surface of silica nanoparticles for the removal of a mixture of micropollutants or recalcitrant pollutants, such as endocrine-disrupting chemicals, from wastewater in a bioreactor [169]. Based on the relevant reports, it is believed that nanozymes and enzyme-nanomaterial technology can be applicable approaches for the advancement of enzymatic wastewater treatment, due to its exceptional advantages such as reusability, the capability of providing better performance and cost-effectiveness over the other conventional methods [130].…”

Enzymatic treatment of phenolic pollutants by a small laccase immobilized on APTES-functionalised magnetic nanoparticles

“…This could provide an additional advantage for the physical separation of the polymerized products from a wastewater sample using filtration methods. Separation of precipitates by filtration methods has also been previously reported (Abdollahi et al 2018).…”

“…Residual phenolic compound concentrations were measured using a simple colorimetric assay as described by Modaressi et al (2005). The assay is based on the electrophilic attack of the phenolic compound by a primary amine (4-AAP) under alkaline conditions, and its subsequent oxidation by potassium ferricyanide to a red quinone-type dye (Abdollahi et al 2018). The reaction mixture consisted of 700 µL of Tris-HCl buffer (100 mM, pH 8), 300 µL laccase treated phenolic compounds, 10 µL 4-AAP (0.1 M) and 10 µL potassium ferricyanide solution (0.2 M) and was incubated at 25 °C for 15 min, with gentle shaking (50 rpm).…”

Enhanced Wastewater Treatment by Immobilized Enzymes

“…Finally, the degradation of phenol, p-chlorophenol, and catechol was carried out, achieving 76%, 60%, and 95% removal efficiency levels, respectively. Abdollahi et al [67] in their research developed a nanobiocatalyst which is promising for micropollution degradation and an alternative to catalysts used in traditional wastewater treatment processes. To improve the catalytic activity, they modified magnetic iron oxide nanoparticles with APTES, and then before tyrosinase immobilization, the particles were further functionalized with 2,4,6-trichlorotriazine as an activating agent to obtain magnetic nanoparticles.…”