The gradient copolymers of acrylic acid and trifluoroethyl methacrylate（coded as P（TFEMAgrad-AA）） were synthesized via reversible addition-fragmentation transfer（RAFT） emulsifier-free emulsion polymerization. Th...The gradient copolymers of acrylic acid and trifluoroethyl methacrylate（coded as P（TFEMAgrad-AA）） were synthesized via reversible addition-fragmentation transfer（RAFT） emulsifier-free emulsion polymerization. The spontaneous batch feeding approach was used to control the gradient chain sequence. Transmission electron microscopy（TEM） analysis revealed that the P（TFEMA-grad-AA） can self-assemble to form spherical micelles, rodlike micelles or vesicles in selective solvents. Morphological transition of the P（TFEMA-grad-AA） micelles was sensitive to the water content of the dioxane/water mixed solvent. More interestingly, Ag nanoparticles（NPs） were encapsulated by the P（TFEMA-grad-AA） micelles during the selfassembly process. The gradient chain sequence made the Ag NPs easily enter the core of the micelles, even when P（TFEMA-grad-AA） had less hydrophobic fluoro-units and more hydrophilic units. TEM images with energy dispersive spectrometer indicated that the nanocomposite micelles consisted of a Ag NPs core and a gradient copolymer shell.展开更多
This paper describes the removal of COD and nitrogen from wastewater with modified sequencing batch biofilm reactor. The strategy of simultaneous feeding and draining was explored.The results show that introduction of...This paper describes the removal of COD and nitrogen from wastewater with modified sequencing batch biofilm reactor. The strategy of simultaneous feeding and draining was explored.The results show that introduction of a new batch of wastewater and withdrawal of the purified water can be conducted simultaneously with the maximum volumetric exchange rate of about 70%.Application of this feeding and draining mode leads to the reduction of the cycle time, the increase of the utilization of the reactor volume and the simplification of the reactor structure. The treatment of a synthetic wastewater containing COD and nitrogen was investigated. The operation mode of F(D) O ( i.e ., simultaneous feeding and draining followed by the aerobic condition) was adopted. It was found that COD was degraded very fast in the initial reaction period of time, then reduced slowly and the ammonia nitrogen and nitrate nitrogen concentrations decreased and increased with time respectively, while the nitrite nitrogen level increased first and then reduced. The relationship between the COD or ammonia nitrogen loading and its removal rate was examined, and the removal of COD, ammonia nitrogen and total nitrogen could exceed 95%, 90% and 80% respectively. The fact that nitrogen could be removed more completely under constant aeration (aerobic condition) of the SBBR operation mode is very interesting and could be explained in several respects.展开更多
基金the National Natural Science Foundation of China(Nos.50803048 and 50703030)
文摘The gradient copolymers of acrylic acid and trifluoroethyl methacrylate（coded as P（TFEMAgrad-AA）） were synthesized via reversible addition-fragmentation transfer（RAFT） emulsifier-free emulsion polymerization. The spontaneous batch feeding approach was used to control the gradient chain sequence. Transmission electron microscopy（TEM） analysis revealed that the P（TFEMA-grad-AA） can self-assemble to form spherical micelles, rodlike micelles or vesicles in selective solvents. Morphological transition of the P（TFEMA-grad-AA） micelles was sensitive to the water content of the dioxane/water mixed solvent. More interestingly, Ag nanoparticles（NPs） were encapsulated by the P（TFEMA-grad-AA） micelles during the selfassembly process. The gradient chain sequence made the Ag NPs easily enter the core of the micelles, even when P（TFEMA-grad-AA） had less hydrophobic fluoro-units and more hydrophilic units. TEM images with energy dispersive spectrometer indicated that the nanocomposite micelles consisted of a Ag NPs core and a gradient copolymer shell.
文摘This paper describes the removal of COD and nitrogen from wastewater with modified sequencing batch biofilm reactor. The strategy of simultaneous feeding and draining was explored.The results show that introduction of a new batch of wastewater and withdrawal of the purified water can be conducted simultaneously with the maximum volumetric exchange rate of about 70%.Application of this feeding and draining mode leads to the reduction of the cycle time, the increase of the utilization of the reactor volume and the simplification of the reactor structure. The treatment of a synthetic wastewater containing COD and nitrogen was investigated. The operation mode of F(D) O ( i.e ., simultaneous feeding and draining followed by the aerobic condition) was adopted. It was found that COD was degraded very fast in the initial reaction period of time, then reduced slowly and the ammonia nitrogen and nitrate nitrogen concentrations decreased and increased with time respectively, while the nitrite nitrogen level increased first and then reduced. The relationship between the COD or ammonia nitrogen loading and its removal rate was examined, and the removal of COD, ammonia nitrogen and total nitrogen could exceed 95%, 90% and 80% respectively. The fact that nitrogen could be removed more completely under constant aeration (aerobic condition) of the SBBR operation mode is very interesting and could be explained in several respects.
