Potassium hydroxide

The shell of pumpkin seeds (SPS) were recycled from kitchen waste. In order to wipe off the impurities, the SPS have been washed three times with ethanol and distilled water, respectively. Potassium hydroxide (KOH) and hydrochloric acid (HCl) were bought from the Nanjing chemical reagent Co., LTD. All the chemical materials were analytically pure and no procedure has been made for further purification.

The precursor material used in this study is commercial CSAC, supplied by Nanjing Wood Linsen Carbon Company. Acetone, ethanol, hydrochloric acid (HCl), potassium hydroxide (KOH), and carbon black, used as a conductive agent, and polytetrafluoroethylene (PTFE) latex (60 wt.%), used as a binder, were purchased from Nanjing Chemical Reagent Co., Ltd (Jiangsu Province, China). All mentioned agents were used as received. The nickel foam (Nanjing Chemical Reagent Co., Ltd) was first immersed in Acetone solution with an ultrasonic bath for 1 h then dipped in HCl (5%) for 1 h after ethanol cleaning. Finally, it was cleaned in ethanol again and dried in a vacuum oven at 40°C for 12 h.

NHJDT (Batch No.151221090, 0.27 g/tablet) were purchased from Beijing Tong Ren Tang Technologies Co., Ltd (Beijing, China). Arsenic trioxide and the arsenate reference standard were provided by National Institutes for Food and Drug Control (Beijing, China). Dimethylarsenic acid (DMA) was obtained from Huamai Biotechnology Co., Ltd (Beijing, China). Monosodium methanearsonicacid (MMA) was purchased from Laboratories of Dr. Ehrenstorfer GmbH (Augsburg, Germany). Thiourea, ascorbic acid, and potassium borohydride of analytical grade and hydrochloric acid, nitric acid, and sulfuric acid of guaranteed grade were all supplied by Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). Potassium hydroxide, potassium dihydrogen phosphate, and potassium sulfate were provided from Nanjing Chemical Reagent Co., Ltd. (Nanjing, China). HPLC grade methanol was from Tedia Company, Inc (Fairfield, United States). All the other chemicals were of analytical reagent grades. Deionized water was purified on a Millipore Milli Q-Plus purification system (Millipore, MA, United States).