Formulation of Laccase Nanobiocatalysts Based on Ionic and Covalent Interactions for the Enhanced Oxidation of Phenolic Compounds

Oxidative biocatalysis by laccase arises as a promising alternative in the development of advanced oxidation processes for the removal of xenobiotics. The aim of this work is to develop various types of nanobiocatalysts based on laccase immobilized on different superparamagnetic and non-magnetic nanoparticles to improve the stability of the biocatalysts. Several techniques of enzyme immobilization were evaluated based on ionic exchange and covalent bonding. The highest yields of laccase immobilization were achieved for the covalent laccase nanoconjugates of silica-coated magnetic nanoparticles (2.66 U mg−1 NPs), formed by the covalent attachment of the enzyme between the aldehyde groups of the glutaraldehyde-functionalized nanoparticle and the amino groups of the enzyme. Moreover, its application in the biotransformation of phenol as a model recalcitrant compound was tested at different pH and successfully achieved at pH 6 for 24 h. A sequential batch operation was carried out, with complete recovery of the nanobiocatalyst and minimal deactivation of the enzyme after four cycles of phenol oxidation. The major drawback associated with the use of the nanoparticles relies on the energy consumption required for their production and the use of chemicals, that account for a major contribution in the normalized index of 5.28 × 10−3. The reduction of cyclohexane (used in the synthesis of silica-coated magnetic nanoparticles) led to a significant lower index (3.62 × 10−3); however, the immobilization was negatively affected, which discouraged this alternativeThis work was financially supported by the Spanish Ministry of Economy and Competitiveness (CTQ2013-44762-R and CTQ2016-79461-R, program co-funded by FEDER). The authors belong to the Galician Competitive Research Group GRC 2013-032, program co-funded by FEDER. Yolanda Moldes-Diz thanks the Spanish Ministry of Economy and Competitiveness for her predoctoral fellowshipS

Assessing of the most appropriate biotechnological strategy on the recovery of antioxidants from beet wastes by applying the life cycle assessment (LCA) methodology

The valorization of agro-industrial waste streams and residues for the production of antioxidant compounds is a good strategy for circular economy approaches. However, to demonstrate its suitability and operational feasibility, it is necessary to develop environmental assessments to ensure the effectiveness of the production strategy. In this sense, a large-scale simulation has been developed, obtaining ten different scenarios in which both leaves and steam residues are used as process inputs, and five different extraction techniques are applied, both conventional: Soxhlet and maceration, and emerging technologies: ultrasonic assisted extraction (UAE), supercritical fluid extraction (SFE) and pressurized liquid extraction, (PLE). Environmental results have shown that SFE and PLE technologies have the lowest environmental burdens, while UAE has the worst profile due to high energy demand. Electricity could be considered as the main hotspot with the highest impact, followed by steam requirements and the use of extraction solvent. To improve the environmental profile, sensitivity analyses were performed, considering the use of renewable resources for the production of the energy requirements and the selection of the extraction solvent. Although significant improvements were obtained when electricity and steam production is based on hydropower and waste incineration, the environmental profile did not improve when considering ethanol: water mixture or hexane for extraction. Future research should focus on reducing energy requirements and optimizing the solvent dosage for the extraction processThis research has been supported by the project Enhancing diversity in Mediterranean cereal farming systems (CerealMed) project funded by PRIMA Programme and FEDER/Ministry of Science and Innovation-Spanish National Research Agency (PCI2020-111978) and by a project granted by Xunta de Galicia (project ref. ED431 F 2016/001). The authors belong to the Galician Competitive Research Group (GRC ED431C 2017/29) and to the Cross-disciplinary Research in Environmental Technologies (CRETUS Research Center, ED431E 2018/01)S

Evaluation of Starch as an Environmental-Friendly Bioresource for the Development of Wood Bioadhesives

The environment is a very complex and fragile system in which multiple factors of different nature play an important role. Pollution, together with resource consumption, is one of the main causes of the environmental problems currently affecting the planet. In the search for alternative production processes, the use of renewable resources seeks a way to satisfy the demands of resource consumption based on the premises of lower environment impact and less damage to human health. In the wood sector, the panel manufacturing process is based on the use of formaldehyde-based resins. However, their poor moisture resistance leads to hydrolysis of amino-methylene bonds, which induces formaldehyde emissions throughout the lifetime of the wood panel. This manuscript investigates the environmental profile associated with different wood bioadhesives based on starch functionalization as a renewable alternative to formaldehyde resins. Considering that this is a process under development, the conceptual design of the full-scale process will be addressed by process modeling and the environmental profile will be assessed using life cycle assessment methodology. A comparative study with synthetic resins will provide useful information for modify their development to become real alternatives in the wood-based panel industry. The results obtained show the enormous potential of starch bioadhesives, as their environmental impact values are lower compared to those based on petrochemicals. However, certain improvements in the energy process requirements and in the chemical agents used could be developed to provide even better resultsThis research has been financially supported by ERA-CoBIOTECH project (PCI2018-092866) Programación Conjunta Internacional 2018—WooBAdh project. The authors belong to the Galician Competitive Research Group (GRC ED431C 2017/29) and to CRETUS Strategic Partnership (ED431E 2018/01).S