This article, for the first time, provides a novel advanced oxidation process based on sulfate radical （SO^4·-） to degrade organic pollutants in wastewater： microwave （MW）-activated persulfate oxidation （AP...This article, for the first time, provides a novel advanced oxidation process based on sulfate radical （SO^4·-） to degrade organic pollutants in wastewater： microwave （MW）-activated persulfate oxidation （APO） with or without active carbon （AC）. Azo dye acid Orange 7 （AO7） is used as a model compound to investigate the high reactivity of MW-APO. It is found that AO7 （up to 1000 mg/L） is completely decolorized within 5-7 min under an 800 W MW furnace assisted-APO. In the presence of chloride ion （up to 0.50 mol/L）, the decolorization is still 100% completed, though delayed for about 1-2 min. Experiments are made to examine the enhancement by AC. It is exciting to find that the 100% decolorization of AO7 （500 mg/L） is achieved within 3 min by MW-APO using 1.0 g/L AC as catalyst, while the degradation efficiency maintains at 50% by MW energy without persulfate after about 5 min. Besides the destruction of visible light chromophore band of AO7 （484 nm）, during MW-APO, two bands in the ultraviolet region （228 nm and 310 nm） are rapidly broken down. The removal of COD is about 83%-95% for 500 mg/L AO7. SO^4·- is identified with quenching studies using specific alcohols. Both SO^4·- and ·OH could degrade AO7, but SO^4·- plays the dominant role. In a word, MW-APO AC is a new catalytic combustion technology for destruction of organic contamination even for high concentration.展开更多
Oxidation of aniline by persulfate in aqueous solutions was investigated and the reaction kinetic rates under different temperature, persulfate concentration and pH conditions were examined in batch experiments. The r...Oxidation of aniline by persulfate in aqueous solutions was investigated and the reaction kinetic rates under different temperature, persulfate concentration and pH conditions were examined in batch experiments. The results showed that, the aniline degradation followed pseudo first-order reaction model. Aniline degradation rate increased with increasing temperature or persulfate concentration. In the pH range of 3 to 11, a low aniline degradation rate was obtained at strong acid system （pH 3）, while a high degradation rate was achieved at strong alkalinity （pH 11）. Maximum aniline degradation occurred at pH 7 when the solution was in a weak level of acid and alkalinity （pH 5, 7 and 9）. Produced intermediates during the oxidation process were identified using liquid chromatography-mass spectrometry technology. And nitrobenzene, 4-4’-diaminodiphenyl and 1-hydroxy-1,2-diphenylhydrazine have been identified as the major intermediates of aniline oxidation by persulfate and the degradation mechanism of aniline was also tentatively proposed.展开更多
Applying spent lithium iron phosphate battery as raw material,valuable metals in spent lithium ion battery were effectively recovered through separation of active material,selective leaching,and stepwise chemical prec...Applying spent lithium iron phosphate battery as raw material,valuable metals in spent lithium ion battery were effectively recovered through separation of active material,selective leaching,and stepwise chemical precipitation.Using stoichiometric Na2S2O8 as an oxidant and adding low-concentration H2SO4 as a leaching agent was proposed.This route was totally different from the conventional methods of dissolving all of the elements into solution by using excess mineral acid.When experiments were done under optimal conditions(Na2S2O8-to-Li molar ratio 0.45,0.30 mol/L H2SO4,60℃,1.5 h),leaching efficiencies of 97.53% for Li^+,1.39%for Fe^3+,and 2.58% for PO4^3−were recorded.FePO4 was then recovered by a precipitation method from the leachate while maintaining the pH at 2.0.The mother liquor was concentrated and maintained at a temperature of approximately 100℃,and then a saturated sodium carbonate solution was added to precipitate Li2CO3.The lithium recovery yield was close to 80%.展开更多
文摘This article, for the first time, provides a novel advanced oxidation process based on sulfate radical （SO^4·-） to degrade organic pollutants in wastewater： microwave （MW）-activated persulfate oxidation （APO） with or without active carbon （AC）. Azo dye acid Orange 7 （AO7） is used as a model compound to investigate the high reactivity of MW-APO. It is found that AO7 （up to 1000 mg/L） is completely decolorized within 5-7 min under an 800 W MW furnace assisted-APO. In the presence of chloride ion （up to 0.50 mol/L）, the decolorization is still 100% completed, though delayed for about 1-2 min. Experiments are made to examine the enhancement by AC. It is exciting to find that the 100% decolorization of AO7 （500 mg/L） is achieved within 3 min by MW-APO using 1.0 g/L AC as catalyst, while the degradation efficiency maintains at 50% by MW energy without persulfate after about 5 min. Besides the destruction of visible light chromophore band of AO7 （484 nm）, during MW-APO, two bands in the ultraviolet region （228 nm and 310 nm） are rapidly broken down. The removal of COD is about 83%-95% for 500 mg/L AO7. SO^4·- is identified with quenching studies using specific alcohols. Both SO^4·- and ·OH could degrade AO7, but SO^4·- plays the dominant role. In a word, MW-APO AC is a new catalytic combustion technology for destruction of organic contamination even for high concentration.
基金supported by the Foundation of Science and Technology Planning Project of Guangdong Province(No. 2010B050200007)the Fundamental Research Funds for the Central Universities (No. 2011ZM0054)the Research Fund Program of Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (China) (No. 2011K0013)
文摘Oxidation of aniline by persulfate in aqueous solutions was investigated and the reaction kinetic rates under different temperature, persulfate concentration and pH conditions were examined in batch experiments. The results showed that, the aniline degradation followed pseudo first-order reaction model. Aniline degradation rate increased with increasing temperature or persulfate concentration. In the pH range of 3 to 11, a low aniline degradation rate was obtained at strong acid system （pH 3）, while a high degradation rate was achieved at strong alkalinity （pH 11）. Maximum aniline degradation occurred at pH 7 when the solution was in a weak level of acid and alkalinity （pH 5, 7 and 9）. Produced intermediates during the oxidation process were identified using liquid chromatography-mass spectrometry technology. And nitrobenzene, 4-4’-diaminodiphenyl and 1-hydroxy-1,2-diphenylhydrazine have been identified as the major intermediates of aniline oxidation by persulfate and the degradation mechanism of aniline was also tentatively proposed.
基金Project(Z20160605230001)supported by Hunan Province Non-ferrous Fund Project,China。
文摘Applying spent lithium iron phosphate battery as raw material,valuable metals in spent lithium ion battery were effectively recovered through separation of active material,selective leaching,and stepwise chemical precipitation.Using stoichiometric Na2S2O8 as an oxidant and adding low-concentration H2SO4 as a leaching agent was proposed.This route was totally different from the conventional methods of dissolving all of the elements into solution by using excess mineral acid.When experiments were done under optimal conditions(Na2S2O8-to-Li molar ratio 0.45,0.30 mol/L H2SO4,60℃,1.5 h),leaching efficiencies of 97.53% for Li^+,1.39%for Fe^3+,and 2.58% for PO4^3−were recorded.FePO4 was then recovered by a precipitation method from the leachate while maintaining the pH at 2.0.The mother liquor was concentrated and maintained at a temperature of approximately 100℃,and then a saturated sodium carbonate solution was added to precipitate Li2CO3.The lithium recovery yield was close to 80%.
