Persulfate activation has been applied as one of the efficient advanced oxidation processes(AOPs) to remediate polluted environments. In this study, a novel α-FeOOH anchored by graphene oxide(GO)-carbon nanotubes(CNT...Persulfate activation has been applied as one of the efficient advanced oxidation processes(AOPs) to remediate polluted environments. In this study, a novel α-FeOOH anchored by graphene oxide(GO)-carbon nanotubes(CNTs) aerogel(α-FeOOH@GCA) nanocomposite activated persulfate system(α-FeOOH@GCA + K2S2O8) was applied for decolorization of Orange Ⅱ(OⅡ). The decolorization of OⅡ was remarkably enhanced to a level of ~ 99% in this system compared with that of pristine α-FeOOH(~ 44%) or GO-CNTs(~18%). The enhanced catalytic activity of α-FeOOH@GCA was due to the formation of a heterojunction byα-FeOOH and GO-CNTs as confirmed by the presence of Fe–O–C chemical bonds. The degradation intermediates of OⅡ were comprehensively identified. The proposed degradation pathway of OⅡ begins with the destruction of the conjugated structures of OⅡ by the dominant reactive oxygen species, surface-bound SO4·-. The decolorization efficiency of OⅡ by the α-FeOOH@GCA activated persulfate system decreased from the first to third cycle of recycling. Ultraviolet(UV) irradiation or introduction of a small amount of Fe2+ could restore the activation of this system. The results show that the α-FeOOH@GCA persulfate activation system promises to be a highly efficient environmental remediation method for organic pollutants.展开更多
Problems associated with excessive propagation and leakage of invertebrates in drinking water have received increasing attention in recent years.We performed a monthly survey of invertebrate abundance and taxa in the ...Problems associated with excessive propagation and leakage of invertebrates in drinking water have received increasing attention in recent years.We performed a monthly survey of invertebrate abundance and taxa in the effluent of each treatment stage in a drinking water treatment plant between May 2015 and April 2016 and analyzed seasonal and treatment-process variations in invertebrates.The results showed that invertebrate abundances in raw water,effluent of the biological activated carbon(BAC)filter,and finished water significantly correlated with water temperature,whereas no correlation was observed between water temperature and invertebrate abundance in the effluents of the sedimentation tank and sand filter.The dominant taxa in the effluent of each treatment stage were rotifers,nematodes,and crustaceans.The sedimentation tank could efficiently remove invertebrates with an annual average removal rate of 92%.The propagation and leakage of invertebrates occurred in the sand and BAC filters but more seriously in the latter.The average reproduction rate in the BAC filter was 268.8%with rotifers as the taxon that leaked the most.Invertebrate survival and reproduction were also observed in the chlorine-disinfected clean water reservoir with an average reproduction rate of 41.9%.Owing to differences in chlorine resistance,the reproduction ability of the dominant taxa was in the order nematodes>crustaceans>rotifers.The proportion of endogenous invertebrates gradually increased along the treatment process.The average proportion of endogenous invertebrates in the finished water was higher than 79.0%.Our findings suggested that waterworks should pay more attention to endogenous invertebrate growth.展开更多
基金supported by China’s National Science Foundation(No.21377039)
文摘Persulfate activation has been applied as one of the efficient advanced oxidation processes(AOPs) to remediate polluted environments. In this study, a novel α-FeOOH anchored by graphene oxide(GO)-carbon nanotubes(CNTs) aerogel(α-FeOOH@GCA) nanocomposite activated persulfate system(α-FeOOH@GCA + K2S2O8) was applied for decolorization of Orange Ⅱ(OⅡ). The decolorization of OⅡ was remarkably enhanced to a level of ~ 99% in this system compared with that of pristine α-FeOOH(~ 44%) or GO-CNTs(~18%). The enhanced catalytic activity of α-FeOOH@GCA was due to the formation of a heterojunction byα-FeOOH and GO-CNTs as confirmed by the presence of Fe–O–C chemical bonds. The degradation intermediates of OⅡ were comprehensively identified. The proposed degradation pathway of OⅡ begins with the destruction of the conjugated structures of OⅡ by the dominant reactive oxygen species, surface-bound SO4·-. The decolorization efficiency of OⅡ by the α-FeOOH@GCA activated persulfate system decreased from the first to third cycle of recycling. Ultraviolet(UV) irradiation or introduction of a small amount of Fe2+ could restore the activation of this system. The results show that the α-FeOOH@GCA persulfate activation system promises to be a highly efficient environmental remediation method for organic pollutants.
基金This work was supported by the National Five-year Water Special Project(No.2017ZX07207004).We acknowledge the support of the waterworks that participated in this investigation.We would like to thank the anonymous reviewers for their helpful comments.
文摘Problems associated with excessive propagation and leakage of invertebrates in drinking water have received increasing attention in recent years.We performed a monthly survey of invertebrate abundance and taxa in the effluent of each treatment stage in a drinking water treatment plant between May 2015 and April 2016 and analyzed seasonal and treatment-process variations in invertebrates.The results showed that invertebrate abundances in raw water,effluent of the biological activated carbon(BAC)filter,and finished water significantly correlated with water temperature,whereas no correlation was observed between water temperature and invertebrate abundance in the effluents of the sedimentation tank and sand filter.The dominant taxa in the effluent of each treatment stage were rotifers,nematodes,and crustaceans.The sedimentation tank could efficiently remove invertebrates with an annual average removal rate of 92%.The propagation and leakage of invertebrates occurred in the sand and BAC filters but more seriously in the latter.The average reproduction rate in the BAC filter was 268.8%with rotifers as the taxon that leaked the most.Invertebrate survival and reproduction were also observed in the chlorine-disinfected clean water reservoir with an average reproduction rate of 41.9%.Owing to differences in chlorine resistance,the reproduction ability of the dominant taxa was in the order nematodes>crustaceans>rotifers.The proportion of endogenous invertebrates gradually increased along the treatment process.The average proportion of endogenous invertebrates in the finished water was higher than 79.0%.Our findings suggested that waterworks should pay more attention to endogenous invertebrate growth.
