The hydrophobic SiO2 aerogel was prepared by using coal gangue as the starting material—which is viewed as waste in most coal mining and preparation plant—via ambient pressure drying through sol-gel method. The effects of different temperature, time to keep the temperature,vary in mass ratio of coal gangue to sodium hydroxide on the leaching ratio of SiO2 from coal refuses are discussed in this paper. Results showed that the leaching ratio of SiO2 extracted from gangue will be made up to 35.23% compared with the other tests on the condition that the temperature is given 750°C, holding time 2h, the value of ratio of coal gangue to sodium hydroxide 1:0.8, concentration of NaOH 20%. Trimethylchlorosilane (TMCS) is used as modifier to obtain hydrophobicity through solvent exchange and surface modification. We achieved SiO2 aerogel with low density of 0.2559g/cm3, high porosity 88.97%,Strong hydrophobicity (contact angle with water 140.61。) respectively, which demonstrated that the final product exhibits excellent property. Differences among SiO2 aerogel properties were discussed between industrial sodium silicate as precursor and sodium silicate drew from coal gangue as precursor. Results revealed that the the latter is better than the former on properties .Our work provided a potential way to synthetize high value-added product from abandoned by-product coal gangue.
The effects of pH, initial concentration, ozone flow, temperature and semi-coke dosage on 3.5-dinitro-benzoic acid wastewater in the process of carbocoal catalytic ozonation are investigated. The results show that: the removal rate of COD increases with the rise of ozone flow and reaction time in a certain range; temperature has little effect on the removal rate of COD; the removal rate of COD achieve the maximum value when the pH is about 12; the COD removal rate of carbocoal catalytic ozonation is obviously better than single ozonation.
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