Lactic acid

Lactic acid (90% aqueous solution) was purchased from VWR Chemicals. Choline chloride (>98%) and sulfuric acid (95–98%) were purchased from Sigma-Aldrich. After the DES preparation the water content on the DES was measured by Karl-Fischer method by Duplo giving a value of 12.90 ± 0.08 wt%. The Asplund fibers were produced from Norway spruce (see Methods) The water content of the Asplund fibers was quantified gravimetrically by weighing its mass on a wet basis and on a dry basis (after oven drying) by triplicate. Mondi AG, Austria, supplied a flash dried kraft pulp sample made of Norway spruce and Scotts pine in the approximate ratio of 3:1. The sample had a kappa number of approximately 45 and it served as a reference. Technical ethanol (100%) purchased by Boom B.V.

Maritime pine (Pinus pinaster Ait.) sawdust was kindly supplied by the Portuguese company Valco–Madeiras e Derivados, S.A (Leiria, Portugal). The sawdust was initially sieved (mesh size of 20) and oven dried at 105 °C. LA (98 w/w%, MW = 116.12 g/mol and a density of 1.13 g/mL) was purchased from Acros Organics and FA (99 wt %, MW = 46.03 g/mol and a density of 1.22 g/mL) was purchased from CARLO ERBA. Lactic acid (90 w/w%, MW = 90.08 g/mol and density of 1.21 g/mL) and glacial acetic acid (99.9 w/w%, MW = 60.05 g/mol and density of 1.05 g/mL) were acquired from VWR Chemicals, while sulphuric acid (72%) was obtained from Chem-lab NV (MW = 98.08 g/mol and a density of 1.63 g/mL). De-ionized water was used for the preparation of all solutions. Dichloromethane (DCM) was purchased from Sigma-Aldrich and the 4-nitroanisol was acquired from Dagma. Microcrystalline cellulose Avicel PH-101, with an average particle size of 50 mm and degree of polymerization of ca. 260, was acquired from Sigma Aldrich. For the intrinsic measurements and molecular weight (MW) estimation of lignin, n,n-dimethylformamide (DMF) (≥99.8%) ACS Reagent, was used.

D-glucose (98%), D-xylose (98%), and D-fructose (99%) were supplied by Sigma Aldrich lactic acid (88%) from VWR, formic acid (99%) from Biosolv LTD, levulinic acid (98%), 5-hydroxymethylfurfural (5-HMF 98%) and 2-furfural from Alfa Aesar (98%), NaCl and KI were purchased from VWR and used as received.
Seawater samples were collected from three different locations presented in Figure 3 between October and December 2017: Zeeland in the Netherlands (pH 8.04), Salakta in Tunisia collected (pH 7.93) and Kerkenah in Tunisia too (pH 8.19). Seawater samples characterization was carried out in a Laboratory called “Green lab” in Tunisia which is accredited by TUNAC according to ISO/IEC17025 standard. The composition of seawater samples is reported in Table 1.

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.

The cellulose source was spruce wood pulp pretreated by DES [32 (link)]. The DES used for the non-derivatizing pretreatment was composed of choline chloride (99%, Acros organics, Geel, AN, Belgium) and lactic acid (90%, VWR Chemicals, Radnor, PA, USA) with the molar ratio of 1:9. The surface coating experiments were performed on the commercial regenerated cellulose UF membrane RC70PP, which is manufactured by Alfa Laval. A 10 ppm methylene blue (MB) (J.T. Baker, Holland) and 10 ppm reactive orange 16 (Sigma-Aldrich, Darmstadt, Germany) solutions were used in the experiments to test the dye removal efficiency.

Medium molecular weight (MMW) chitosan polymer with 75%–85% deacetylation degree (viscosity 200 ÷ 800 cps, 1% concentration solution in 1% acetic acid at 25 °C), phosphate buffer saline (PBS), and poly(ethylene glycol) (PEG; molecular weight = 400 g/mol) were purchased from Sigma-Aldrich (Saint Louis, MO, USA). The PLA pellets were purchased from ORBI-TECH (Leichlingen, Germany). Calcium chloride, lactic acid, sodium hydroxide, sodium chloride, and chloroform were purchased from “Avantor Performance Materials Poland” (Gliwice, Poland). Carbon dioxide was bought from “Linde” (Gdansk, Poland).
The bacterial strains: Escherichia coli K-12 PCM 2560 (NCTC 10538) and Staphylococcus aureus PCM 2054 (ATCC 25923) were provided from Polish Collection of Microorganisms, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy of the Polish Academy of Sciences, Wrocław, Poland. The TSB, TSA, and peptone were purchased from “Biocorp” (Warsaw, Poland). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), medium, antibiotics, and supplements necessary for cell culture were obtained from Sigma-Aldrich (St. Louis, MO, USA). MilliQ water was used for the preparation of all aqueous solutions. All other reagents were of analytical grade or higher.