Multifunctional and fully aliphatic biodegradable polyurethane foam as porous biomass carrier for biofiltration Hynek Bene  s a, * ,V  era Vl  ckov  a b , Aleksandra Paruzel a , Olga Trhlíkov  a a , Jan Chalupa b , Lívia Kanizsov  a a , Kate  rina Skleni  ckov  a a , Martin Halecký b, ** a Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovsk eho n am. 2, Prague 6, 162 06, Czech Republic b Department of Biotechnology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology Prague, Technick a 5, Prague 6, 166 28, Czech Republic article info Article history: Received 16 January 2020 Received in revised form 16 March 2020 Accepted 21 March 2020 Available online 23 March 2020 Keywords: Polyurethane Foam Biofilter Biodegradation Enzyme abstract Water-blown fully aliphatic polyurethane foam was prepared at room temperature from trimer of hexamethylene diisocyanate and poly(diethylene glycol adipate) diol and post cured at 55  C. In contrast to aromatic-based PUR foam analog, the produced flexible PUR foam exhibited highly porous structure with open cell content of 94% and average cell size of 700 mm. Therefore, it was subsequently tested as biodegradable cellular carrier of microorganisms (fungus Fusarium solani and bacterium Pseudomonas sp.) for biofiltration. Firstly, tests on enzyme activities (lipase, protease and urease) and utilization of PUR foam as the sole carbon and nitrogen source and determination of degradation products were carried out. Fusarium solani shown much higher both enzyme and degradation activities and higher spectrum of degradation products. Finally, the performance of a biofilter packed with the developed cellular carrier was investigated for removal of a mixture of acetone, propionic acid, ethyl acetate, toluene and a-pinene. Proven sorption properties of PUR foam against all pollutants and a high maximum elimination capacity of 218 ± 33 g m 3 h 1 make the new lightweight biofilm PU carrier suitable for this application due to their multi-functionality. © 2020 Elsevier Ltd. All rights reserved. 1. Introduction Open-porous materials are nowadays highly desirable in many biotechnological processes as substrates and carriers of microbial biomass. Nowadays, various synthetic materials such as vermiculite, perlite, polyethylene or expanded polyurethane (PUR) are used. However, these materials are biologically inac- tive, i.e. they provide only a surface for the immobilization of biomass and biofilm formation, while the growth of microor- ganisms must be supplied by the added nutrient solution. From this point of view, the ideal biomass carrier should i) have a high specific surface area and a high open pore content to facilitate flow, ii) maintain its structural integrity during long-term oper- ation, and iii) should also allow effective immobilization of mi- croorganisms and nutrient supply. Advantageously, variable chemical composition of PUR foams enables to modify surface properties and thus to adjust in- teractions between foam and other substances. Therefore, be- sides traditional application fields (building industry, cushioning, automotive, etc.), recently PUR foams with different morphol- ogies have been used in new environmentally-oriented applica- tions as materials for sorption of volatile [1 ,2] and semi-volatile [3] organic compounds in air and water treatments, and as PUR sorbents for pesticides [4]. Currently, intensive research is also focused on the use of PUR (nano)particles as drug delivery sys- tems [5]. Open-cell PUR foams were used in biofilters [6] and in biotrickling filters [7] for waste air treatment as an inexpensive lightweight packing material with high surface area for cell attachment and biofilm development. Currently used commercial PUR foams based on aromatic pol- yisocyanates are not biologically active; i.e. they do not serve as a source of nutrients for microorganisms and they do not biodegrade. Moreover, presence of residual highly toxic aromatic isocyanates and formation of toxic compounds during PUR foam degradation (e.g. aromatic diamines formation during foam photo-oxidation) * Corresponding author. ** Corresponding author. E-mail addresses: benesh@imc.cas.cz (H. Bene s), martin.halecky@vscht.cz (M. Halecký). Contents lists available at ScienceDirect Polymer Degradation and Stability journal homepage: www.elsevier.com/locate/polydegstab https://doi.org/10.1016/j.polymdegradstab.2020.109156 0141-3910/© 2020 Elsevier Ltd. All rights reserved. Polymer Degradation and Stability 176 (2020) 109156