Technical acetone

‘Jonagold’ apples (Malus domestica), yellow onions (Allium cepa), ‘Nerac’ carrots (Daucus carota) and ‘Hokkaido’ pumpkins (Cucurbita maxima) were bought at a local shop.
Technical ethanol (99%), technical acetone, Na₂CO₃ and NaOH pellets were bought from VWR (Leuven, Belgium). HCl, NaOH (0.1 M), H₂SO₄ (concentration ≥ 95% w/w) and disodium tetraborate decahydrate were obtained from Fisher Scientific (Merelbeke, Belgium). Rhamnose monohydrate, 3-phenylphenol and HNO₃ were bought from Acros Organics (Geel, Belgium). H₂SO₄ (72% w/w) and NaOH (50% w/w) were obtained from Alfa Aesar (Kandel, Germany) and J.T. Baker (Gliwice, Poland), respectively. Galacturonic acid monohydrate and fucose were bought from Sigma-Aldrich (Diegem, Belgium), arabinose from Fluka Biochemika (Buchs, Switzerland), galactose from Merck (Darmstadt, Germany), glucose monohydrate from Riedel-de-Haën (Seelze, Germany), xylose from UCB (Leuven, Belgium) and mannose from Fluka Analytical (Buchs, Switzerland). The ultrapure water (organic free, 18.2 MΩ·cm resistance) was provided by a SimplicityTM 150 system. Unless otherwise mentioned, all chemicals used were of analytical grade.

Ethanol (Merck, absolute for analysis, Darmstadt, Germany), Tetrathylorthosilicate (TEOS) (VWR International S.A.S.), Pluronic^® F-127 (Sigma-Aldrich Darmstadt, Germany), hydrochloric acid, technical acetone (VWR Chemicals, UN 1090), acetone (Technic France, UN 1090), isopropanol (Technic France, UN 1219), deionized water, ultrapure water. Argon gas (99.996%, MTI Industriegas AG), Hydrochloric acid 37% (p.a. EMSURE^®, Merck, Darmstadt, Germany), Mercury standard solution (traceable to SRM from NIST, Hg(NO₃)₂ in HNO₃ 2 mol·L⁻¹, Merck, Darmstadt, Germany), Vanadium standard solution (traceable to SRM from NIST, NH₄VO₃ in HNO₃ 0.5 mol·L⁻¹, CertiPUR^®, Merck, Darmstadt, Germany), Tin(II) chloride (≤0.000001% Hg, p.a. EMSURE^®, Merck, Darmstadt, Germany).

For the materials of this study, air-dry birch (Betula pendula) wood was provided by a local wood mill. In addition, the commercially sized chips (typically 25–35 × 0–25 × 2.5–6 mm, L × W × T) were milled to the size of 1 mm using a hammer mill. The lignin content was determined by acid hydrolysis using the standard NREL method. Lactic acid (LA, 90% purity), ethanol (ETAX A, 99.9% purity), and technical acetone (99.5% purity) were acquired from VWR (Radnor, PA, USA), while choline chloride (ChCl, 99% purity) was supplied by Acros Organics (Geel, Belgium). Ethanol (ETAX B, 92% purity) and sodium chloride (>99.5% purity) were purchased from Altia Industrial (Colorado Springs, CO, USA) and Sigma-Aldrich (St. Louis, MO, USA), respectively. Throughout this work, ultra-pure deionized water (DI, 15 MΩ, 0.5–1 μS/cm), which was produced with CENTRA-R 60\120 system (Elga purification system, Veolia Water, UK) and is referred to as DI water in this work, was used for washing and as an anti-solvent in all the preparations of the solutions.
Ultrafiltration was performed with the RC70PP membrane (Alfa Laval company, Lund, Sweden) and the Ultracel UF Discs 5 kDa (Millipore company, Burlington, MA, USA). Table 1 presents information on the technical characteristics of the membranes used in the experiments, which is based on data provided by the manufacturers.