Carbon nanotubes/polyvinylidene fluoride (PVDF) nanocomposite membranes (abbreviated as CPMs) were fabricated to study their physicochemical property and separation efficiency of organic pollutants such as benzene, to...Carbon nanotubes/polyvinylidene fluoride (PVDF) nanocomposite membranes (abbreviated as CPMs) were fabricated to study their physicochemical property and separation efficiency of organic pollutants such as benzene, toluene, ethylbenzene and methylbenzene (abbreviated as BTEX) from aqueous solutions. The rejection coeffi-cients (R) of BTEX depend on the CNT content of CPM, pore size of membrane, molecule size of BTEX, permeation pressure (P), feed concentration (C<sub>f</sub>) and temperature. The CNT contents were 5%, 10% and 15% in CPM have been conducted. The 10% CNT content of CPM (10-CPM) has not only higher water flux but also the relatively higher R as comparing of 5% and 15% CNT of CPM. The R decreased with increasing P, C<sub>f</sub> and temperature but has no significant influence on ionic strength (μ). The R of BTEX were found in the order as B ≈ X which revealed the major mechanism of BTEX separation with CPM was related to molecule size of BTEX (B ≈ X). It exhibits that the size exclusion plays the important role in BTEX separation. According to the result of separation of BTEX by 10-CPM, the R of BTEX not only have above 80% with relative lower pressure but also have higher water flux as compared of other nano-filtration. This suggests that the 10-CPMs possess good potential for BTEX removal in wastewater treatment.展开更多
Excessive nitrate in water is harmful to the ecological environment and human health.Electrocatalytic reduction is a promising technology for nitrate removal.Herein,a Pd-Cu modified carbon nanotube membrane was fabric...Excessive nitrate in water is harmful to the ecological environment and human health.Electrocatalytic reduction is a promising technology for nitrate removal.Herein,a Pd-Cu modified carbon nanotube membrane was fabricated with an electrodeposition method and used to reduce nitrate in a flowthrough electrochemical reactor.The optimal potential and duration for codeposition of Pd and Cu were-0.7 V and 5 min,respectively,according to linear scan voltammetry results.The membrane obtained with a Pd:Cu ratio of 1:1 exhibited a relatively high nitrate removal efficiency and N_(2)selectivity.Nitrate was almost completely reduced(~99%)by the membrane at potentials lower than-1.2 V.However,-0.8 V was the optimal potential for nitrate reduction in terms of both nitrate removal efficiency and product selectivity.The nitrate removal efficiency was 56.2%,and the N_(2)selectivity was 23.8%for the Pd:Cu=1:1 membrane operated at-0.8 V.Nitrate removal was enhanced under acidic conditions,while N_(2)selectivity was decreased.The concentrations of Cl-ions and dissolved oxygen showed little effect on nitrate reduction.The mass transfer rate constant was greatly improved by 6.6 times from 1.14×10^(-3)m/h at a membrane flux of 1 L/(m^(2)·h)to 8.71×10^(-3)m/h at a membrane flux of 15 L/(m^(2)·h),which resulted in a significant increase in the nitrate removal rate from 13.6 to 133.5 mg/(m^(2)·h).These findings show that the Pd-Cu modified CNT membrane is an efficient material for nitrate reduction.展开更多
文摘Carbon nanotubes/polyvinylidene fluoride (PVDF) nanocomposite membranes (abbreviated as CPMs) were fabricated to study their physicochemical property and separation efficiency of organic pollutants such as benzene, toluene, ethylbenzene and methylbenzene (abbreviated as BTEX) from aqueous solutions. The rejection coeffi-cients (R) of BTEX depend on the CNT content of CPM, pore size of membrane, molecule size of BTEX, permeation pressure (P), feed concentration (C<sub>f</sub>) and temperature. The CNT contents were 5%, 10% and 15% in CPM have been conducted. The 10% CNT content of CPM (10-CPM) has not only higher water flux but also the relatively higher R as comparing of 5% and 15% CNT of CPM. The R decreased with increasing P, C<sub>f</sub> and temperature but has no significant influence on ionic strength (μ). The R of BTEX were found in the order as B ≈ X which revealed the major mechanism of BTEX separation with CPM was related to molecule size of BTEX (B ≈ X). It exhibits that the size exclusion plays the important role in BTEX separation. According to the result of separation of BTEX by 10-CPM, the R of BTEX not only have above 80% with relative lower pressure but also have higher water flux as compared of other nano-filtration. This suggests that the 10-CPMs possess good potential for BTEX removal in wastewater treatment.
基金This work was supported by grants from the National Natural Science Foundation of China(Nos.52070147 and 52270077)the Special Fund of the State Key Joint Laboratory of Environment Simulation and Pollution Control(No.22K06ESPCT)the Promotion Plan for Young Teachers’Scientific Research Ability of Minzu University of China(Nos.2021QNPY83 and 2022QNPY51).
文摘Excessive nitrate in water is harmful to the ecological environment and human health.Electrocatalytic reduction is a promising technology for nitrate removal.Herein,a Pd-Cu modified carbon nanotube membrane was fabricated with an electrodeposition method and used to reduce nitrate in a flowthrough electrochemical reactor.The optimal potential and duration for codeposition of Pd and Cu were-0.7 V and 5 min,respectively,according to linear scan voltammetry results.The membrane obtained with a Pd:Cu ratio of 1:1 exhibited a relatively high nitrate removal efficiency and N_(2)selectivity.Nitrate was almost completely reduced(~99%)by the membrane at potentials lower than-1.2 V.However,-0.8 V was the optimal potential for nitrate reduction in terms of both nitrate removal efficiency and product selectivity.The nitrate removal efficiency was 56.2%,and the N_(2)selectivity was 23.8%for the Pd:Cu=1:1 membrane operated at-0.8 V.Nitrate removal was enhanced under acidic conditions,while N_(2)selectivity was decreased.The concentrations of Cl-ions and dissolved oxygen showed little effect on nitrate reduction.The mass transfer rate constant was greatly improved by 6.6 times from 1.14×10^(-3)m/h at a membrane flux of 1 L/(m^(2)·h)to 8.71×10^(-3)m/h at a membrane flux of 15 L/(m^(2)·h),which resulted in a significant increase in the nitrate removal rate from 13.6 to 133.5 mg/(m^(2)·h).These findings show that the Pd-Cu modified CNT membrane is an efficient material for nitrate reduction.
