Z 2000

In this study, the characterization of graphite porous carbon plates was measured using Scanning Electrode Microscopy (SEM, Hitachi High-Tech Corporation, S4800, Tokyo, Japan), X-ray diffraction (XRD, Rigaku Corporation, RINT2200V, Tokyo, Japan), Raman spectroscopy (JASCO Corporation, RMP500, Tokyo, Japan), and a digital multimeter (ADVANTEST, R6450, Tokyo, Japan). The amylose and graphite porous carbon plate was used in the vacuum system and new adsorbent materials were dried in an oven at 80 °C. The adsorption of heavy metals was performed using an Electrochemical Instrument (HOKUTO DENKO CORPORATION, HZ-7000, Tokyo, Japan), with three electrodes connected. The working electrode (WE), counter electrode (CE), and reference electrode (RE) were amylose/graphite porous carbon plate,/graphite porous carbon plate, and Ag/AgCl electrode, respectively. The concentration of heavy metal ions was measured using an Atomic Absorption Spectrophotometer (AAS, Hitachi High-Tech Corporation Z-2000, Tokyo, Japan).

The mixtures of CuO NPs (100 mg/L) and different organic acids were kept for 6, 12, and 24 h at room temperature (~25 °C) until the suspensions were centrifuged at 10,000 g for 30 min. Then, Cu²⁺ concentrations in the filtrates were detected by a flame atomic absorption spectrometer (Z-2000, Hitachi High Technologies, Tokyo, Japan). The dynamic dissolution of CuO NPs can be described by a linear empirical rate law based on zero order kinetics for solid phase [27 (link)]. The dissolution rate was calculated using the following equation:
where k is the dissolution rate, and C and C₀ are the instantaneous concentrations of Cu²⁺ in the suspensions at time t and 0, respectively.

Hair samples (3-4 cm from the scalp) were taken from several places from the occipital part. The hair Zn, Cu, Se, and Mn levels and Cu/Zn ratio were determined in the Department of Bromatology, Medical University of Bialystok. Hair samples were washed with acetone, deionized water, and absolute ethanol, and then dried at 80°C for 24 hours. About 0.2 g of the sample was weighed with accuracy to 1 mg and wet mineralized in concentrated nitric acid (HNO₃) in a microwave closed system (Berghof, Germany). The concentrations of microelements were determined by atomic absorption spectrometry, with Zeemans background correction (Hitachi Z-2000, Japan), with acetylene-air flame (in the case of Cu and Zn) and electrothermal atomization in a graphite tube (in the case of Mn and Se). The accuracy control of the methods used was made on a certified reference material—Human Hair GBW 09101 (China). Validation parameters, such as accuracy, precision, and detection limit, were estimated (Table 2).
Also, the content of Cu and Zn was used to calculate Cu/Zn ratio.

A series of particles were prepared according to different mass ratios of bentonite to carbide slag, doses of Na₂CO₃, and calcination temperatures. By comparing the removal rates of Cu²⁺, the treatment effect of the particles on copper-containing wastewater was analysed. The pH was adjusted to 3.2 (± 0.05) with 10% HNO₃ and 10% NaOH. Briefly, 0.20 g composite particles were placed into a 250 mL beaker, and 100 mL simulated wastewater at a concentration of 300 mg/L was added. The solution was treated for 12 h under static conditions. The residual Cu²⁺ concentration in the solution was determined by flame atomic spectrophotometer (HITACHI Z-2000, Japan) at a wavelength of 324.8 nm.

To evaluate growth in a liquid medium of isolated bacteria, the MIC of Cd²⁺ (MIC-Cd) was determined. LB medium (800 μL) with different concentrations of Cd²⁺ was dispensed into 96-well (12 × 8) microtiter plates (96 × 2-mL wells) with a multi-channel micropipette (rows A to H: 0, 1, 2, 3, 4, 5, 6, and 7 mM). Single colonies of the test strains were inoculated into 3 mL of LB medium and cultured overnight. The test culture (15 μL) was then inoculated into each well of the prepared 96-well plate. After 24 h at 30°C and 750 rpm in an incubator (Heidolph, Viertrieb, Germany), 200 μL of the cell suspension was transferred to a 96-well plate and the turbidity at OD₆₀₀ was measured.
To determine the Cd²⁺ adsorption of isolated bacteria, growth of cells was grown in LB liquid medium supplementation with 0.1 mM CdCl₂ and shaken at 200 rpm at 30°C for 24 h. Cells were harvested by centrifugation at 12,000 rpm for 10 min and the supernatant then diluted to an appropriate concentration for analysis. Cd²⁺ concentrations in culture supernatants were measured via atomic absorption spectrophotometry (Z-2000, Hitachi, Japan), with Cd²⁺ removal rate being calculated using the following equation:
Removal rate (%) = (C_i −C_e)/C_i × 100
where C_i and C_e are the initial and equilibrium Cd²⁺ concentrations (mM), respectively.