Separations 2023 , 10 , 148
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2. Materials and Methods 2.1. Materials and Natural Wastewater
The experimental water was obtained from a paper mill in Dongguan after anaerobic biological treatment. As shown in Table 1, the water had COD 953 mg/L, pH 7.8, ammonia nitrogen (NH 3 -N) 14.23 mg/L, total nitrogen (TN) 13.55 mg/L, total phosphorus (TP) 0.61 mg/L, chromaticity 3841, and suspended solid (SS) 2439 mg/L. Guangdong Guanghua Technology Co. Ltd (Shantou, China) The supplied methylene chloride, and Shanghai Maclean Biochemical Technology Co supplied the potassium bromide. Chengdu Kolon Chemical Co., Ltd (Chengdu, China) provided the hydrochloric acid, and Nanjing Chemical Reagent Co. provided the ethanol. An ozone generator (Anseros, Anshan, China, COM- AD-02: the concentration ranges from 10 mg to 100 mg), a pH meter, Fourier transform infrared spectrophotometer (Shimadzu, Kyoto, Japan, IRTracer-100), magnetic stirrer, and gas chromatography-mass spectrometry were the main instruments used (GC-MS).
Table1. Pulp and paper mill wastewater quality indicators.
COD mg/L BOD 5 mg/L NH 3 -N mg/L TN mg/L
TP mg/L Chromaticity SS mg/L
Wastewater
953
254
14.23
13.55
0.61
3841
2439
2.2. Sponge Cubes and Titanium Dioxide Coating Procedure For the polyurethane sponge purchased from Shandong Banhor Environmental Pro- tection Technology Co., Ltd. (Linyi, China), according to the information provided by the company, the polyurethane sponge carrier is a 1 cm 3 cube (98% porosity, 1.01–1.02 g/cm 3 wet density, 422.2% water absorption, 100% retention, 4000 specific surface area, and 40PPI average aperture). The average particle size of titanium dioxide is 15 nm. Titanium dioxide was fixed on the surface of the sponge carrier, and a layer of TiO 2 film was formed on the surface of the sponge carrier. It is a heterogeneous catalyst, and was characterized in our previous publication by SEM-EDS (1000 × ) [17]. Figure 1 depicts the specific preparation procedure. Forty polyurethane sponge car- riers were placed in beakers and ultrasonically treated with ultra-pure water, ethanol, and acetone in that order. One g of TiO 2 powder was weighed and placed in a beaker, followed by 10 mL and 0.3 g/L dioctyl sodium sulfosuccinate (DSSC) solution, which was magnetically stirred to form solution A. Approximately 0.3 g of hydroxypropylmethyl cellulose (HPMC) powder was weighed and placed in a beaker, followed by 20 mL of DSSC solution and mechanical stirring to form solution B. Solution A and B were mixed and mechanically stirred to form TiO 2 slurry; the sponge carrier, which had been cleaned, was placed in the TiO 2 slurry and mechanically stirred; to obtain the TiO 2 /sponge composite material, the polyurethane sponge carrier was removed and heated in an oven at 70 ◦ Cfor 8 h. The material was then ultrasonically cleaned with ultra-pure water to remove excess TiO 2 on the surface. Subsequently, the TiO 2 /sponge composite material cleaned to produce noTiO 2 shedding was placed in the oven at 70 ◦ C and dried to a constant weight to obtain TiO 2 -coated sponge composite carriers.
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