Glass microfiber filter

For electrochemical testing, composite electrodes were prepared. Carbon black (99+ % purity, Alfa Aesar) was ball-milled with the active material with a weight ratio of 15:85 at 600 rpm for 1 hour. Then the mixture, additional Carbon black, and Polyvinylidene fluoride (PVDF) (Sigma-Aldrich) were blended with a weight ratio of 8:1:1, using N-Methyl-2-pyrrolidone (NMP) (J.T.Baker) as solvent. The slurry was then applied on aluminum foil and dried in an oven at 60 °C for 2 h. The dried film was pressed with using a roller-press (MTI Corp.) to densify the electrode. The film was then cut into circular discs of 15 mm diameter using a disc cutter (MTI Corp. MSK-T-07). Standard CR2016 coin cell was assembled by using sodium foil (99.95% purity metal basis, Sigma-Aldrich) as anode, NaAlTi₃O₈ composite electrode as cathode, 1 M NaPF₆ (Sigma-Aldrich) in ethylene carbonate/diethylene carbonate (EC : DEC) as electrolyte, and Glass Microfiber Filter (VWR) as separator, in an argon filled glove box (MBraun). The cycling of coin cell was conducted with using a battery cycler (Arbin, BT2043), with voltage windows of 0.01 - 2.5 V or 0.1 - 2.5 V under rates of C/10, C/5, and 1 C. All electrochemical tests were performed under ambient temperature.

Culture samples of L. platensis PCC7345 were analysed using a UV/VIS spectrophotometer (GENESYS 150, Thermo Fisher, Waltham, MA, USA). The optical density (OD₇₅₀) was measured at 750 [nm] and was calibrated against C_x [g L⁻¹] of L. platensis PCC7345 using the following correlation (in triplicate, [26 (link)]): $$C_x^{}=0.86\times O{D}_{750}$$
Aiming to assess C_x, 15 mL of L. platensis PCC7345 suspension was passed through a glass microfiber filter (VWR International, Delaware Valley, PA, USA, mesh size: 1 [µm], in triplicate) and was then washed three times using 15 mL deionised water and dried for 24 h at 103 °C (Memmert GmbH + Co.KG, Schwabach, Germany). Finally, the weight difference of dried biomass was determined to calculate C_x [26 (link)].