Nickel sulphate

Bisphenol S, bisphenol A, methylene violet, methylene blue, 1-octanesulphonic acid sodium salt, graphite flakes, sodium nitrate (99.0%), hydrochloric acid, sulphuric acid (35%), potassium permanganate (99.0%), hydrogen peroxide (35%), methanol (99.9%), cadmium nitrate, sodium arsenate, copper nitrate, lead nitrate, nickel sulphate, cobalt chloride, mercury(ii) acetate, zinc nitrate and lithium chloride were purchased from Sigma-Aldrich, USA. Analytical grade reagents were used throughout the entire study. De-ionized water was used for all studies.

Low molecular weight chitosan (263 kDa, 83% deacetylation degree) was purchased from Sigma-Aldrich Co. (USA) and used as received. 10-(-4-Hexyloxy-phenyl)-10H-phenothiazine-3-carbaldehyde was obtained in our laboratory [56 (link)]. Inorganic salts: copper sulphate (CuSO₄ · 5H₂O, 98%), sodium sulphate (Na₂SO₄ anhydrous, 99%), cadmium sulphate (CdSO₄ · 8/3H₂O), zinc sulphate (ZnSO₄ · 7H₂O, 99%), manganese sulphate (MnSO₄ · H₂O, 99%), nickel sulphate (NiSO₄ · 6H₂O, 98%), cobalt sulphate (CoSO₄ · 7H₂O, 99%), lead sulphate (PbSO₄, 98%), and barium sulphate (BaSO₄, 99%) were purchased from Sigma-Aldrich and used as received. Polyethyleneimine (branched, M.W. 10,000, 99%) was purchased from Alfa Aesar and used without further modifications.

Chitosan having degree of deacetylation >75% and with high molecular weight (800–2000 cP), was purchased from Sigma Aldrich, Ireland. Sodium hydroxide, sodium borohydride and salts of copper sulphate, nickel sulphate, cobalt nitrate and silver nitrate were also bought from Sigma-Aldrich. Acetic acid was obtained from NTN Ltd, U.K. The required reagents such as nitrophenols (3-nitrophenol (3-NP), 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2,6-dinitrophenol (2,6-DNP)) and methylene blue (MB), acridine orange (AO), methyl orange (MO) and congo red (CR) were bought from BDH chemicals, England and other dyes were obtained from the chemical store in King Abdulaziz University. The chemical formulae of these pollutants are nitrophenols (C₆H₅NO₃), 2,6-DNP (C₆H₄N₂O₅), MO (C₁₄H₁₄N₃NaO₃S), MB (C₁₆H₁₈ClN₃S), AO (C₁₇H₁₉N₃), CR (C₃₂H₂₂N₆Na₂O₆S₂). Titanium dioxide (TiO₂) powder in anatase form was purchased from Sigma Aldrich. The particles size was <25 nm. The deionized water used for preparation of samples was obtained from departmental Millipore-Q water purification system having resistivity of 18.2 MΩ.