Tannic acid

Silver(I) nitrate (AgNO₃, 99.9%), trisodium citrate dihydrate (C₆H₅Na₃O₇·2H₂O, ≥99.5%), adenosine monophosphate (99%), tetraethyl orthosilicate (99%) and sodium hydroxide (98%) were obtained from Merck KGaA, Darmstadt, Germany. Tannic acid (98%), was obtained from Alfa-Aesar, Ward Hill, MA, USA. Cetyltrimethylammonium chloride (95%) was obtained from TCI Europe NV, Zwijndrecht, Belgium. All reagents were used as received without further purification. Ultrapure water (type I) was used for the preparation of all the water-based solutions. The glassware was cleaned with aqua regia prior to the experiments.

Glucose oxidase (EC 1.1.3.4, type VII, from Aspergillus niger, 201 units mg⁻¹ protein) and D-(+)-glucose, D(−)-fructose, D(+)-mannose, D(+)-galactose, D(+)-xylose, D(+)-saccharose were obtained from Fluka (Buchs, Switzerland) and Carl Roth GmbH+Co.KG (Karlsruhe, Germany). Tetrachloroauric acid and tannic acid were purchased from Alfa Aesar GmbH&Co KG and Carl Roth GmbH + Co (Karlsruhe, Germany), sodium citrate—from Penta (Praha, Czech Republic). 0.05 mol L⁻¹ solution of sodium acetate (SA) buffer with 0.1 mol L⁻¹ potassium chloride (KCl) was prepared from sodium acetate trihydrate and potassium chloride, whose were obtained from Reanal (Budapest, Hungary) and Lachema (Neratovice, Czech Republic). Aniline and sodium hydroxide were purchased from Merck KGaA (Darmstadt, Germany), pyrrole—from Acros Organics (New Jersey, NJ, USA), graphite rod (GR, Ø = 3 mm) and hydrochloric acid—from Sigma-Aldrich (Saint Louis, MO, USA), α alumina powder (Al₂O₃, 0.3 μm, Type N)—from Electron Microscopy Sciences (Hatfield, MA, USA). The solution of 25% glutaraldehyde was obtained from Fluka Chemie GmbH (Buchs, Switzerland), phenazine methosulfate, L-ascorbic acid (AA) and uric acid (UA)—from AppliChem GmbH (Darmstadt, Germany). 2.3 × 10¹⁶ particles L⁻¹ of AuNPs_{(6 nm)} were prepared as was described in previous research [28 (link)].

Our study utilized: Sudan III from Waldeck (Germany), isopropanol from Chemsolute (Poland), sulfuric acid, chloroform, sodium hydroxide, silver nitrate, barium chloride, hydrochloric acid and acetone from Avantor (Poland), ninhydrin from Sigma Aldrich (USA), sodium bicarbonate from Honeywell (USA), copper sulphate pentahydrate from Chempur (Poland), potassium sodium tartrate tetrahydrate from Merck (Germany), and tannic acid from Alfa Aesar (USA).

The PAN powder was obtained from Tong-Hwa Synthesis Fiber Co., Ltd. (Taipei, Taiwan). The PAN solvent was a reagent grade N-Methyl-2-pyrrolidone (NMP) procured from Tedia Company Inc. (Fairfield, OH, USA). PVP, MW = 1,300,000 g/mol and tannic acid were purchased from Alfa Aesar (Haverhill, MA, USA). Sodium hypochlorite was obtained from Nihon Shiyaku Industries Ltd. (Tokyo, Japan). Sodium hydroxide (NaOH), Sodium dodecyl sulfate (SDS), and iron(III) chloride anhydrous 97% EP were supplied by Showa Chemical Co., Ltd. (Tokyo, Japan). Glycerin was bought from Mingtai Chemical Co., Ltd. (Taoyuan, Taiwan). The diesel used for separation experiments was provided by PetroChina Co., Ltd. (Taipei, Taiwan).

Silver(I) nitrate (AgNO₃) (99.9%), trisodium citrate dihydrate (C₆H₅Na₃O₇·2H₂O, ≥99.5%), Adenosine monophosphate (99%), Gold(III) chloride trihydrate (HAuCl₄·3H₂O, 99.9%), sodium hydroxide (NaOH, BioXtra ≥ 98%, pellets, anhydrous), absolute ethanol (CH₃CH₂OH, ≥99.8%) and absolute methanol (CH₃OH ≥ 99.9%) were obtained from Merck. Tannic acid (98%), Tetraethoxysilane (C₈H₂₀O₄Si, 99+%), (3-Aminopropyl) triethoxysilane (C₉H₂₃NO₃Si, 97%) were obtained from Alfa Aesar. Hexadecyltrimethylammonium Chloride (C₁₉H₄₂ClN, 95%) was obtained from TCI Chemicals. IROGRAN^® A92P4637 was provided by Huntsman GmbH (Osnabruck, Germany). All reagents were used as received without further purification. Ultrapure water (type I) was used for the preparation of all the water-based solutions. The glassware was cleaned with aqua regia and rinsed with ultrapure water prior to the experiments.

Methylcellulose (MC, η = 8 × 10³ cPs at 2
wt % in H₂O, 1.78 ± 0.14 methoxy
groups per anhydroglucose unit) and tannic acid (94.0 wt %) were purchased
from Alfa Aesar and used as received. A 0.87 ± 0.01 wt % suspension
of TEMPO-oxidized cellulose nanofibrils (CNF) was prepared by oxidizing
never-dried softwood sulphite pulp (Domsjö dissolving pulp,
3:2 spruce/pine, Sweden) with TEMPO (2,2,6,6-tetramethylpiperidin-1-yl)oxyl)
according to the method of Saito et al.^{24 (link)} and disintegrating in a high-pressure microfluidizer.^{25 (link)} Conductometric titration²⁶ indicated a surface carboxyl content of 1.10 mmol/g, and
atomic force microscopic measurements showed an average CNF diameter
of 3.0 ± 0.6 nm.^{27 (link)} Deionized water
was used for all experiments.