Silver sulfate

Two types of low-pressure Hg lamps with electrical power of 40 W were purchased from Bright Star Light & Electricity Co., Ltd, Guangdong, China. The UV_{185+254 nm} lamp transmitted both 185 nm VUV and 254 nm UV light through high-purity quartz glass, but the UV_{254 nm} lamp only transmitted 254 nm UV light. The UV_{254 nm} irradiation intensity of UV_{185+254 nm} lamp was about 90% of UV_{254 nm} lamp. The lamps had a length of 1199 mm and a diameter of 19 mm.
The PEX and SDD with analytical grade were purchased from Aladdin Chemical Reagent Co., Ltd, Shanghai, China. The industrial grade IET and DDA were purchased from Tieling Flotation Reagents Co., Ltd, Liaoning, China. Their molecular structures, molecular formulas and abbreviations are summarized in table 1. Other chemicals such as cupric acetate, lead acetate, diethylamine, triethanolamine, silver sulfate and mercury sulfate were of analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd, Beijing, China. Deionized water was used in the degradation experiments.
Table 1.

Collector name, molecular structure, molecular formula and abbreviation.

collector name	molecular structure	molecular formula	abbreviation
potassium ethyl xanthate		C2H4OCSSK	PEX
sodium diethyl dithiocarbamate		(C2H5)2NCSSNa	SDD
O-isopropyl-N-ethyl thionocarbamate		(CH3)2CHOCSNHC2H5	IET
dianilino dithiophoshoric acid		(C6H5NH)2PSSH	DDA

Copper sulfate pentahydrate (CuSO₄·5H₂O, analytical reagent (AR)), ferric chloride hexahydrate (FeCl₃·6H₂O, AR), nickel acetate tetrahydrate (C₄H₆NiO₄·4H₂O, AR), silver sulfate (Ag₂SO₄, AR), sodium hydroxide (NaOH, AR), methylene blue (MB, AR), 30.0% hydrogen peroxide (H₂O₂, AR), absolute ethanol (EtOH, C₂H₅OH, AR), and t-butanol (TBA, (CH₃)₃COH, AR) were purchased from Sinopharm Chemical Reagent (Shanghai, China) and were used as received without further purification.