| With the scale of sewage treatment facilities extended in China and sewage treatment rate improved, the problem about sludge treatment of sewage treatment plant in our country is becoming increasingly serious. Sludge carbonization is a new biological treatment way to realize reduction, stabilization, harmlessness and resource utilization. In this paper, the preparation process and influence factors of sludge carbon prepared with the aid of Fenton from dewatering sludge were studied. The carbonization products were characterized by thermal gravimetric analysis, nitrogen adsorption, X-ray diffraction analysis, Fourier transform infrared spectrum analysis and other means.The mechanism of sludge carbonization and the adsorption capacity and adsorption mechanism for Cr(VI) were investigated and explored. The research results have important practical significance and reference value for the treatment and safe disposal of sewage sludge. The results are as follows:(1) Dewatered sludge from Langdong sewage treatment plant was used as raw material on this research. A method of Fenton Activation was introduce to activate sludge before carbonized in a high temperature furnace. Orthogonal experiment and the single factor experiment was used to explore influence about iodine adsorption value of the activated sludge carbon with Fenton on different preparation conditions and the optimum preparation conditions:Sludge and H2O2 mixing ratio of 1:3, H2O2 and FeSO4·7H2O dosing ratio of 2.5:1, the initial pH of 3, activation time of 2.5h, carbonization temperature of 350℃, carbonization time of 1h, heating rate of 20℃/min. Iodine adsorption value of sludge carbon under this preparation condition was 331.90mg/g.(2) Fenton activation changes the phase composition of the sludge. Carbon sludge were characterized by thermal gravimetric analysis, nitrogen adsorption, X-ray diffraction analysis, Fourier transform infrared spectrum analysis and other means. The results showed that, BET specific surface area of activated sludge carbon with Fenton under optimum conditions was 24.265m2/g. The total pore volume was 0.146cm3/g. Microporosity was 17%. Compared with the unactivated carbon sludge, activated sludge carbon with Fenton added Fe3O4, Fe3C phase etc. becoming much large degree of aromatization.(3) Fenton activation can improve adsorption of sludge carbon for Cr (VI). Under optimal conditions on which pH of 3 and the dosage of sludge carbon was 3g/L, The adsorption amount of Cr (Ⅵ) of sludge carbon under the best preparation condition was 9.93mg/g. And similar with unactivated sludge carbon, activated sludge carbon with Fenton adsorption mechanism for Cr (VI) in water conform to pseudo-second model and intra-particle diffusion model, the diffusion on external surface and intra-particle as the main speed-controlled step of adsorption. And activated sludge carbon with Fenton adsorption mechanism for Cr (Ⅵ) in water conform to the Langmuir isotherm model and Tempkin isotherm model, which indicate that its adsorption process takes place on uniform carbon powder surface. The surface for Cr(Ⅵ) has same adsorption points and adsorption energy. The adsorption heat is influenced by the interaction of the adsorbed substance. Adsorption thermodynamic analysis showed that the adsorption reaction was spontaneous, and the adsorption mode was mainly physical adsorption. |
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