2.2 Preparation and modification of magnetic diatomite
4.1 g of FeCl3·6H2O and 2.6 g of FeCl2·4H2O were dissolved in a quantity of deionized water and mixed ultrasonically. After sufficient shaking, 6.0 g of diatomaceous earth was added and stirred at 80 °C for 30 min using nitrogen protection. Add ammonia, adjust pH to 10, and continue mixing for 1 h. Cooling slowly to room temperature and crystallize for 2 h. The precipitate obtained after magnetic field separation was sequentially washed with deionized water and ethanol. After drying, magnetic diatomite (MD) was obtained.
1.0 g of MD was added to 50.0 mL of toluene, sonicated, and mixed for 0.5 h. After that, 0.8-2.4 g of 3-mercaptopropyltriethoxysilane and 1.4-4.2 g of n-octadecyltriethoxysilane were added. Using nitrogen protection, the reaction was heated to reflux for 12 hours. Then, the diatomite was separated by a magnetic field, washed several times with ethanol, and the product was dried under vacuum at 45°C to obtain octadecyl and thiol co-bonded magnetic diatomite. The obtained octadecyl and thiol co-bonded magnetic diatomite was added to a certain concentration of H2O2and stirred at 40°C for 24 h and then washed with water to remove the excess H2O2. After drying under vacuum at 60°C, octadecyl and sulfonyl co-bonded magnetic diatomite (OSMD) was obtained.