Zinc nitrate zn no3 2 6h2o

All the reagents used were of analytical purity and were used without further purification. Polyethylene glycol-6000 (PEG-6000), polyvinylpyrrolidone (PVP-1300000), dopamine hydrochloride (DA·HCl), and 2-methylimidazole (C₄H₆N₂) were purchased from Shanghai Aladdin Industrial Co., Ltd. (Shanghai, China). Cupric chloride anhydrous (CuCl₂) and other reagents, such as ferric chloride hexahydrate (FeCl₃·6H₂O), ammonium acetate (NH₄OAc), ethylene glycol (EG), silver nitrate (AgNO₃), 4-nitrophenol(4-NP), sodium borohydride (NaBH₄), and zinc nitrate (Zn(NO₃)₂·6H₂O) were purchased from Sigma-Aldrich (Shanghai, China). Cellulose nanocrystals (CNCs) were purchased from Tianjin Haojia Cellulose Co., Ltd. (Tianjin, China).

The materials used in the biosynthesis were dry Peumus boldus leaves locally purchased in Ensenada, Baja California. Deionized water, with a pH of 6.8 (±0.2), from Sumilab, B.C. The Zinc nitrate [Zn(NO₃) 2·6H₂O], at a 98% purity, and the organic dyes were purchased commercially (Sigma Aldrich, St. Louis, MO, USA). Methylene Blue (MB) with a molecular weight of 373.9 g/mol and a purity of 90%, Methyl Orange (MO) with a molecular weight of 327.34 g/mol and a purity of 99%, and Rhodamine B (RhB) with a molecular weight of 479.01 g/mol and a purity of 95%.

ZSCs were collected from Al-Madinah Al-Munawwarah fruit market. The metal salts including cadmium (II) nitrate (Cd(NO₃)₂.4H₂O), lead (II) nitrate (Pb(NO₃)₂) and zinc nitrate Zn(NO₃)₂.6H₂O used for the preparation of a stock solution of metals were purchased from Sigma-Aldrich [St Louis, MO, USA]. Sodium nitrate (NaNO₃) (Sigma-Aldrich) was used for the adjustment of the ionic strength. Sodium acetate trihydrate (C₂H₃NaO₂.3H₂O) and acetic acid from Sigma-Aldrich were used for buffer preparation. Potassium hydroxide (KOH), hydrochloric acid (HCL), sulfuric acid (H₂SO₄) (Sigma-Aldrich), anhydrous citric acid (C₆H₈O₇) (FlukaBioChemika) and hydrogen peroxide (H₂O₂) (Sigma-Aldrich) were used as modifying agents for the biosorbent.