Phenol

Plasmid DNA was isolated according to the protocol of Anderson and McKay [34 (link)] with the following modifications: after the addition of lysozyme (10 mg/mL, SERVA Electrophoresis GmbH, Heidelberg, Germany), 20 µL RNase A (100 mg/mL, Qiagen GmbH, Hilden, Germany) was added to the reaction mixes, which were incubated at 37 °C for 60 min. Phenol, which was saturated with TE-buffer and chloroform-isoamyl alcohol (both Carl Roth GmbH & Co. KG, Karlsruhe, Germany), was used for the protocol. Purified plasmid DNA was dissolved in 30 µL of TE-buffer and analyzed by electrophoresis on 0.8% (w/v) agarose gels.

For the base catalysed depolymerisation, Metsä Fibre Oy (Espoo, Finland) kindly provided precipitated pine kraft lignin, which was generated using carbon dioxide from the black liquor of a pulp mill [22 (link)]. The used kraft lignin comprises of 93.1% Klason lignin and 2.9% acid-soluble lignin [22 (link)].
Phenol (≥99.5%) and sodium hydroxide (NaOH; 97%) were purchased from Carl Roth GmbH & Co. KG (Karlsruhe, Germany). Industrial formaldehyde (54.5%), which contained 0.55% methanol and <100 ppm formic acid, was provided by Prefere resins Austria GmbH (Krems, Austria) and was stored at 60 °C.
For mechanical testing beech veneer strips with a thickness of 0.58 mm and beech boards with a thickness of 10 mm were acquired at J. u. A. Frischeis GmbH (Stockerau, Austria). Both veneers and boards had an average density of 591 kg/m³ and were selected by focusing on homogenous and straight fibre alignment.

Phenol (99.5%, Roth, Karlsruhe, Germany) was used as the pollutant in the photocatalytic degradation tests. Synthetic air (20.5 ± 0.5 vol% O₂, Air Liquide, Berlin, Germany) and hydrogen peroxide (H₂O₂, 30 wt%, Fisher Chemical, Schwerte, Germany) were used as the oxygen sources. For the immobilization of the photocatalysts onto the steel plates, a silica binder prepared from tetraethylorthosilicate (TEOS, 98%, Sigma-Aldrich, Schnelldorf, Germany), hydrochloric acid (HCl, 37%, Roth, Karlsruhe, Germany), 1-propanol (99.5%, Roth, Karlsruhe, Germany), 2-propanol (HPLC, VWR Chemicals, Dresden, Germany), and Levasil (Obermeier, Bad Berleburg, Germany) was used. As eluents in the HPLC analysis, acetonitrile (ACN, HPLC, VWR Chemicals, Dresden, Germany) and ultrapure water (Synergy UV system, Burlington, MA, USA) were used. As commercial titanium dioxide (TiO₂) photocatalysts, P25 (99.5%, Evonik, Essen, Germany), P90 (100%, Evonik, Essen, Germany), PC105 (100%, Millenium/Cristal ACTivTM, Thann, France), and PC500 (100%, Millenium/Cristal ACTivTM, Thann, France) were investigated. All photocatalysts have been extensively characterized in our previous publications and the main characteristics are summarized in Table 1.