Nano tio2

Nanoparticles ZnO (nano-ZnO), TiO₂ (nano-TiO₂), Ni (nano-Ni) and their bulk counterparts (bulk-ZnO, bulk-TiO₂ and bulk-Ni) were purchased from Sigma–Aldrich (St. Louis, USA). The primary particle size of nanoparticles and Zeta potential was as follows: nano-ZnO <100 nm and 1.53 mV; nano-TiO₂ < 21 nm and −7.30 mV; nano-Ni <100 nm and 15.53 mV. Surface area of nano-ZnO, nano-TiO₂ and nano-Ni was 15–25, 35–65 and 8–12 m²/g, respectively (data from Sigma–Aldrich). The size of nanoparticles was determined by transmission electron microscope (JEM-3010 TEM JEOL, Ltd., Tokyo, Japan). The TEM pictures of nanoparticles used in the experiment are presented elsewhere (Jośko and Oleszczuk 2013a (link), b ).

We used the anatase form of nano-TiO₂ purchased from the Sigma-Aldrich Corporation with a particle size of less than 25 nm and a purity of > 99.7%. A nano-TiO₂ stock suspension (1 g L^-1) was prepared by first suspending nanoparticles in ultrapure water. We then sonicated the solution at 33 W for 30 min. The average hydrodynamic size of nano-TiO₂ was 193 ± 10 nm, as measured by the dynamic light scattering technique (DLS, Malvern Instruments, UK) at automatic attenuator mode. Experimental nano-TiO₂ concentrations of 100 μg L⁻¹ and 2 mg L⁻¹ were diluted from the stock suspension. The aggregate morphology of nano-TiO₂ was observed by a scanning electron microscope (SEM, S-4800, Hitachi, Japan). We used Na₃AsO₄·12H₂O and NaAsO₂ to prepare As stock solutions at 1 mM, which were stored at 4 °C in the dark until further use. Additionally, we measured the average hydrodynamic diameter (d_H) and zeta potential (ζ) using DLS, and pH levels of nano-TiO₂ in BG-11 culture media with As(III) and As(V) of 10 μM at 0.1 mg L⁻¹ and 2 mg L^-1 TiO₂ concentrations.

Poly(3-hydroxybutyrate) (PHB, 330,000 g/mol, Biomer, Schwalbach, Germany), titanium (IV) oxide (nanoTiO₂) (99.7% anatase nanopowder, <25 nm, Sigma–Aldrich, St. Louis, MO, USA) and chitosan oligomers (COS, average molecular weight 3000–5000 g/mol, Kitto Life Co. LTD, Korea) were used. N,N-dimethylformamide (DMF), chloroform (CHCl₃) and ethanol were delivered from Merck (Darmstadt, Germany) and used as received. Potato dextrose agar medium was purchased also from Merck (Darmstadt, Germany). Disposable consumables were supplied by Orange Scientific, Braine-l’Alleud, Belgium.