Sodium hydroxide nabh4

Halloysite was purchased from China-Kaolinite Company (Suzhou, China). Ferric chloride hexahydrate (FeCl₃·6H₂O), sodium acetate (NaAc), polyethylene glycol (PEI), ethylene glycol (EG), potassium tetrachloropalladate (K₂PdCl₄)m and hydrogen tetrachloroaurate (HAuCl₄) were obtained from Sinopharm Chemistry Reagent Co., Ltd. (Beijing, China). 4-nitrophenol, p-nitroaniline, m-nitroaniline, o-Nitroaniline (o-NA), 2,4-Nitroaniline and sodium hydroxide (NaBH₄) were bought from Sigma Aldrich. All of the chemicals were of chemical reagent grade and used without any further purification. Ultrapure water was prepared by using NANO Pure Infinity System (Barnstead/Thermolyne Corp, Dubuque, IA, USA).

Palygorskite was purchased from Jiangsu Autobang Corporation (Huaian, China). Potassium tetrachloropalladate (K₂PdCl₄), hydrogen tetrachloroaurate (HAuCl₄) starch, sucrose, Congo red (CR), reactive red (RR), acetic acid, sulphuric acid, sodium hydroxide, sodium carbonate, sodium chloride and sodium dodecyl sulphate were obtained from Sinopharm Chemistry Reagent Co., Ltd. (Beijing, China). 3-aminpropyltriethoxysilane, 4-nitrophenol, p-nitroaniline, m-nitroaniline, o-Nitroaniline (o-NA), 2,4-Nitroaniline, and sodium hydroxide (NaBH₄) were bought from Sigma Aldrich (Burlington, NJ, USA). All chemicals were of chemical reagent grade and used without any further purification. Ultrapure water was prepared by using NANO Pure Infinity System (Barnstead/Thermolyne Corp., Dubuque, IA, USA) and was used throughout all the experimental processes.