PVA (MW 24 000–24 500 g mol−1, hydrolysis degree of 99.0%) and ethanol (99.5%) were supplied by Shanghai Macklin Biochemical Co., Ltd. n-Butanal (99.5%) was got from Shanghai Mairuier Chemical Technology Co., Ltd. Benzyltrimethylammonium chloride (BAC, 98.0%) was got from Shanghai Di Bo Chemical Co., Ltd. p-Toluenesulfonic acid monohydrate (PTSA, 99.0%) was got from Shanghai Aladdin Biochemical Technology Co., Ltd. Sodium dodecyl sulfonate (SDS, 97.0%) and sodium hydroxide (NaOH, 98.0%) was supplied by Sinopharm Chemical Reagent Co., Ltd. Hydrochloric acid (HCl, 36–38%) and hydroxylamine hydrochloride (98.5%) were bought from Shanghai Titan Scientific Co., Ltd.