Laccase@ZIF-8, Laccase@GO and Laccase@ZIF-8/GO Nanomaterials for the Remediation of Complex Phenolic and Industrial Wastewaters Aided by the Presence of Biosurfactant

The release of phenolic compounds to environment poses a serious threat to the Earth ecosystem as well as to human health. Phenolic pollutants are hazardous, toxic, and some of them are mutagenic and/or carcinogenic. Several chemical and physical processes have been proposed to treat wastewater polluted by phenolic compounds. However, most of these methods are either costly or detrimental to the environment (i.e., generate serious secondary pollutions). Unlike other treatment methods, enzymatic treatment is environmentally friendly, more selective towards the targeted phenolic pollutant(s) and uses sustainably produced materials (i.e., enzymes). Accordingly, we aim in this project to investigate the remediation of phenol, bisphenol A, 4-chlorophenol, 4-aminophenol and 2-nitrophenol as well as their mixtures using laccase enzyme augmented with the addition of biosurfactant (i.e., rhamnolipid). These phenolics are key pollutants in water effluents from a number of chemical and petrochemical industries. The novelty of the proposed work in this project lies in the implementation of environmentally friendly, sustainable and non-toxic hybrid enzyme-biosurfactant technology for the remediation of a mixture of different types of phenolic pollutants. Additional novelty is the treatment of industrial wastewater, to be collected from relevant local industrial sites, using the developed hybrid biosurfactant-enzyme technology. Both homogeneous (i.e., mobile enzyme) and heterogeneous (i.e., immobilized enzyme) enzymatic processes in the presence of biosurfactant will be developed. Zeolitic Imidazolate Framework-8 (ZIF-8) and graphene oxide (GO) and their composites (ZIF-8/GO) will be utilized to covalently anchor the enzyme; covalent attachment of laccase to these attractive supports, possessing large surface areas, is another novel contribution of this proposed project. To assess the level of enhancement of phenolic remediation upon the addition of biosurfactant, treatment using homogeneous and heterogeneous enzymatic processes in the absence of biosurfactant will also be evaluated. Furthermore, the effectiveness of the homogeneous and heterogeneous (laccase@ZIF-8, laccase@GO and laccase@ZIF-8/GO) enzyme under harsh conditions (extreme pH, temperature and salinity) in the presence of the biosurfactant will also be investigated and benchmarked to the case when biosurfactant is not added; this is also a novel contribution that has not been addressed yet in the published literature to the best of our knowledge.