Potassium chloride (kcl)

An AA500 continuous flow analyzer (SEAL, Germany), anSL252 electronic balance (Shanghai Mingqiao Electronic Instrument Factory, China), and a Milli-Q ultrapure water meter (Merck Millipore, USA) were used. All chemicals used in this work were analyticalgrade, and deionized water was used in all experiments. Hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, chloroform, ethanol, sodium tetraborate, isonicotinic acid, and 4-aminoantipyrine were purchased from Sinopharm Chemical Reagent Co., Ltd. (China). Triton X-100, sodium hydroxide, and potassium chloride were obtained from Tianjin Damao Chemical Reagent Factory (China). Potassium ferricyanide, sodium nitroprusside, sodium salicylate, and N, N-dimethylformamide were supplied by Tianjin Tianli Chemical Reagent Co., Ltd. (China). Potassium dihydrogen phosphate, disodium hydrogen phosphate, pyrazolone, and methylene blue trihydratewere prepared from Tianjin Kemiou Chemical Reagent Co., Ltd. (China). Trisodium citrate dihydrate, polyoxyethylene lauryl ether, and sodium dichloroisocyanurate were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. (China). The standard solutions of volatile phenol, cyanide, anionic surfactant, and ammonia nitrogen in water were purchased from the China Academy of Metrology.

Caffeic acid, protoporphyrin IX (PPIX), chitosan, N, N-dicyclohexyl carbodiimide (DCC), bicarbonate, D-glucose, uric acid, L-ascorbic acid, acetaminophen, ferric chloride, cobaltous chloride, nickel chloride hexahydrate, cupric chloride, zinc chloride, and manganese (II) chloride tetrahydrate were purchased from Sigma-Aldrich (Saint Louis, MO, USA). N, N-dimethylformamide (DMF), and MWCNTs (30–50 nm diameter, 2 μm average length and 95% purity) were purchased from Aladdin. Acetic acid, KCl, ethanol, K₃Fe[(CN)₆], Na₂HPO₄, and citric acid were purchased from Tianjin Damao Chemical Reagent Factory (Tianjin, China). All the chemicals and reagents were of analytical-reagent grade and used as received without further purification. Deionized water was used throughout the experiments unless otherwise indicated.

Al₂(SO₄)₃·18H₂O, NaCl, and KCl were obtained from Tianjin Damao Chemical Reagent Factory. Na₂CO₃ was provided by Shanghai Hushi Laboratory Equipment Co. Ltd. Na₃PO₄ was purchased from Tianjin Hengxing Chemical Reagent Manufacturing Co. Ltd. TiOSO₄ was supplied by Shandong Xiya Reagent Co. Ltd. Ethanol was obtained from Tianjin Fuyu Fine Chemical Co. Ltd. The silane coupling agent (KH550) was obtained from Aladdin Industrial Corporation.

The cattle manure anaerobic digested slurry was taken from a cow dung anaerobic digestion tank in the HeiLongJiang ShuangCheng biogas fermentation project. After centrifuging at 10,000 rpm for 30 min, all samples were stored below 4 °C for further experiments. The NaOH, NH₄Cl, Na₂HPO₄·12H₂O, KCl and MgCl₂·6H₂O used in the experiments were purchased from Tianjin Damao Chemical Reagent Co., Ltd. (Tianjin, China). All the chemicals and reagents used were analytical grade.