Nickel chloride hexahydrate

Nickel chloride hexahydrate (NiCl₂·6H₂O, ≥98.0%), ascorbic acid (AA, AR), and thiourea (CH₄N₂S, AR) were purchased from Shanghai Macklin Biochemical Co., Ltd., Shanghai, China. 3,3′,5,5′-tetramethylbenzidine (TMB, ≥98%) and p-benzoquinone (C₆H₄O₂, 99%) were purchased from Shanghai Aladdin Biochemical Technologh Co., Ltd., Shanghai, China. Sulfur sublimed (S, AR), sodium acetate trihydrate (CH₃COONa·3H₂O, AR), copper nitrate trihydrate (Cu(NO₃)₂·3H₂O, AR), ethanol (CH₃CH₂OH, AR), hydrogen peroxide (30 wt%, H₂O₂, AR), and glacial acetic acid (CH₃COOH, AR) were purchased from Chengdu Cologne Chemicals Co., Ltd., Chengdu, China. l-arginine, l-valine, l-methionine, l-histidine, l-glutamate, glycine, Dl-aspartic acid, l-threonine, l-cysteine and other amino acids were purchased from Sinopharm Chemical Reagents Co., Ltd. (BR), Shanghai, China. Gram-negative E. coli (ATCC25922) and Gram-positive S. aureus (ATCC29213) were obtained from Shanghai Jiachu Bioengineering Co., Ltd., Shanghai, China. Propidium iodide (PI) and SYTO 9 were obtained from Invitrogen Life Technology Co., Ltd., California, America. Ultra-pure water (18.2 M Ω cm) was used in all solutions and experiments. All chemicals were not further purified. Caution: These reagents are toxic, please use as required.

Nickel chloride hexahydrate (NiCl₂·6H₂O), hydrazine monohydrate (N₂H₄·H₂O), and polyvinylpyrrolidone (PVP) were purchased from Shanghai Macklin Biochemical Co., Ltd. (Shanghai, China). Melamine, ethylene glycol (EG), anhydrous ethanol, and ethanol were purchased from Tianjin Fuyu Fine Chemical Co., Ltd. (Tianjin, China). All the chemicals were analytical reagents and used without further purification.

The inhibition and bioremoval assays were performed as previously described with minor modifications (Say et al., 2003 (link)). Briefly, inductively coupled plasma mass spectrometry (ICP-MS) was used to detect the heavy metal content in the cultures every 15 days and the correction coefficient of each correction equation using standards is 0.999980 or above. The adsorption rate was calculated using the following formula, $\mathit{Adsorption}=\frac{c_0-c_{75}}{c_0}$ where c₀ refers to the initial concentration of cobalt in the solution and c₇₅ refers to the concentration of cobalt in the solution after 75 days. The standard solutions of cobalt (GBW (E)083781), nickel (GBW (E)083786), and cadmium (GBW (E)083788) were purchased from Beijing North Weiye Measurement Technology Research Institute. Cobalt chloride hexahydrate (Shanghai Macklin Biochemical Technology), nickel chloride hexahydrate (Shanghai Macklin Biochemical Technology), and cadmium chloride (Shanghai Macklin Biochemical Technology) were used as the source of heavy metal ions.