► All the CBZ degradation followed the pseudo-first-order kinetics model. ► The best CBZ degradation can be achieved at different pH in the three oxidation systems. ► Coexisting anions produced ...different effect on the three oxidation systems. ► Persulfate can be applied as an alternative oxidant in water treatment.
This paper systematically investigated the performance of carbamazepine (CBZ) degradation oxone by UVC (253.7nm) irradiation in the presence of different common oxidants including peroxymonosulfate (PMS), hydrogen peroxide (H2O2) and persulfate (PS). The influence of oxidant dosage, initial CBZ concentrations, solution pH and coexisting inorganic anions was also evaluated. Results revealed that all the CBZ degradation followed the pseudo-first-order kinetics well. The degradation efficiency of the three UV-based processes was in the order of UV/PS>UV/H2O2>UV/PMS. The rate of CBZ degradation increased as the oxidant dosage increased and decreased as the initial CBZ concentrations increased. The maximum CBZ degradation occurred at pH 11, 3, 5 in UV/PMS, UV/H2O2 and UV/PS system, respectively. Both Cl− and CO32- can inhibit the CBZ degradation in UV/H2O2 and UV/PS system. However, adding Cl− and CO32- into UV/PMS system can increase CBZ degradation at different degrees. Comprehensively consideration of energy requirements, oxidant costs and affecting factors, UV/PS system was the most efficient and economic process for CBZ degradation and a promising technology for water treatment.
In recent years, various modifications have been proposed to improve membrane performance. In this study, poly(vinylidene fluoride) (PVDF) membranes containing different concentrations of graphene ...oxide (GO) as an additive were prepared via a phase inversion method. It was observed that the antifouling property of the prepared membranes was greatly enhanced by the addition of GO, so higher fluxes could be maintained during permeation. However, over adding GO has a negative impact on membrane flux. The effect of GO on fabricated membranes flux and the removal of natural organic matter (NOM) was investigated in detail. Permeate water was analyzed for dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA), molecular weight distribution (MWD) and fluorescence excitation–emission matrices (EEMs). The results show that NOM removal was improved by GO addition to a certain extent and that the 0.5wt% GO composite membrane performed best. PVDF membranes with GO added still have noteworthy usability in applications coupled with other processes because permeate flux and antifouling property improved significantly without sacrificing removal rate.
•PVDF/GO membrane had better NOM removal than PVDF membrane.•GO addition improved antifouling properties of PVDF membranes.•0.5wt% GO addition showed the best overall performance.
The unique two-dimensional structure and chemical properties of graphene oxide (GO) provide a convenient method for preparing novel membranes. In this study, GO membranes were prepared through ...filtration by a pressure-assisted self-assembly method involving the cross-linking of three diamine monomers on a polyethersulfone (PES) support. The different small molecular diamines, ethylenediamine, butanediamine, and p-phenylenediamine, were introduced as cross-linking agents to investigate the effect of diamine on the properties of GO membranes. The hydrophobic substances ibuprofen, gemfibrozil, and triclosan were selected as target pharmaceuticals and personal care products (PPCPs). The adsorption and molecular sieving activities of PPCPs by cross-linked GO membranes at a pH of 3 were investigated. The permeate water was analyzed for dissolved organic carbon, ultraviolet absorption at 254 nm, molecular weight distribution, and fluorescence excitation–emission matrices. The results showed that the removal of hydrophobic PPCPs by GO membranes was mainly due to their adsorption and molecular sieving activities. Adsorption was mainly determined by the hydrophilic and hydrophobic properties of the membranes and PPCPs. The interception effect was mainly determined by the interlayer spacing between the GO membranes and the molecular weight and steric hindrance of the PPCPs. A smaller spacing of the GO membrane layers resulted in greater steric hindrance and a higher removal rate.
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•Zn–Al LDH was synthesized and incorporated into PVDF UF membranes.•The physical and chemical properties of membranes were characterized in detail.•Hybrid membranes showed improved ...hydrophilicity and water permeability.•The presence of LDH enhanced the antifouling ability of membrane.
Hybrid poly(vinylidene fluoride) (PVDF) embedded with Zn–Al layered double hydroxides (LDH) membranes were fabricated via phase inversion. The physical and chemical properties of the novel polymer membranes were characterized using different characterizations. Filtration and antifouling experiments were performed to examine the water permeability, rejection and antifouling ability of the prepared membranes. Results showed that membrane morphology was greatly changed due to the addition of LDH and that the hybrid membrane exhibited greatly improved surface hydrophilicity, water permeability and antifouling property, with contact angle decreased from 76.5° to 69.0° and pure water (PW) flux increased from 8.01L/m2hbar to 48.95L/m2hbar.
Organotin compounds (OTCs) are a category of persistent toxic substances with endocrine disrupting effects and may pose a risk to aquatic organisms and human health
via
water. This study collected 78 ...surface water samples from the drinking water source in the upper Yangtze River Estuary from July 2018 to November 2019. Out of the nine OTC targets, tributyltin (TBT), dimethyltin (DMT), trimethyltin (TMT), dibutyltin (DBT), and monobutyltin (MBT) were detected from more than 50% of the water samples, with cumulative concentrations of OTCs ranging from 42.5 ± 54.0 to 421 ± 176 ng Sn L
−1
. The composition and concentrations of OTCs in the stormy months were different from those in other months. The concentrations of OTCs with the ebbing tide exceeded those in the flooding tide and increased when the flooding tide transitioned to the ebbing tide. A pulsed trend in concentrations of OTCs in river water was evident due to the impact of rainfall runoff and tidal currents. Identified sources of OTCs included ship antifouling paints, agricultural pesticides, and plastic waste. TBT in water sources poses a low risk to human health and a risk to the ecosystem, particularly during the stormy months.
Graphene oxide (GO) as a novel and promising material has a huge market and multiple applications. The release of GO into the aquatic system during their life cycle would lead to potential risks for ...the environment and aquatic organisms. This study evaluated the impacts of GO on algal growth and algal organic matter (AOM) of Microcystis aeruginosa. GO exhibited moderate effects on algal growth and the photosynthetic system. There was no evident influence on cell density and chlorophyll-a content at GO concentrations below 10 mg/L. Variation and characteristics of AOM after the interaction between GO and algae were analyzed. The characteristics of intracellular organic matter on algae’s exposure to GO showed no significant difference compared with the control group. Conversely, GO had greater impacts on extracellular organic matter after the interaction with algae. The dissolved organic carbon and microcystin-LR showed a significant decline with the increasing GO concentration. The overall molecular weight decreased as well, typically for low molecules. Moreover, the three-dimensional fluorescence spectrum showed that the humic acid- or fulvic acid-like organics decreased obviously. These conclusions reflect that GO has a strong adsorption capacity for removing extracellular organic matter, whereas it did not inflict damage to the algal cells, so that little change could be found in intracellular organic matter. The current study is expected to be beneficial in interpreting the potential risks of GO on algal growth and the variation of AOM.
Drinking water treatment processes are highly effective at improving water quality, but pathogens can still persist in treated water, especially after extreme weather events. To identify how extreme ...weather events affected bacterial populations in source and treated water, water samples were collected from the Yangtze River Delta area and a local full-scale drinking water treatment plant. Bacterial community structure and the occurrence of pathogens were investigated in samples using 16S rRNA sequencing and qPCR techniques. In this study, the results show that intense rainfall can significantly increase levels of bacteria and opportunistic pathogens in river and drinking water treatment processes (p < 0.05); in particular, the relative abundance of Cyanobacteria increased after a super typhoon event (p < 0.05). The biological activated carbon (BAC) tank was identified as a potential pathogen reservoir and was responsible for 52 ± 6% of the bacteria released downstream, according to Bayesian-based SourceTracker analysis. Our results provide an insight into the challenges faced by maintaining finished water quality under changing weather conditions.
The membrane separation process is being widely used in water treatment. It is very important to control membrane fouling in the process of water treatment. This study was conducted to evaluate the ...efficiency of a pre-oxidation-coagulation flat ceramic membrane filtration process using different oxidant types and dosages in water treatment and membrane fouling control. The results showed that under suitable concentration conditions, the effect on membrane fouling control of a NaClO pre-oxidation combined with a coagulation/ceramic membrane system was better than that of an O3 system. The oxidation process changed the structure of pollutants, reduced the pollution load and enhanced the coagulation process in a pre-oxidation-coagulation system as well. The influence of the oxidant on the filtration system was related to its oxidizability and other characteristics. NaClO and O3 performed more efficiently than KMnO4. NaClO was more conducive to the removal of DOC, and O3 was more conducive to the removal of UV254.
Arsenic contamination of groundwater and associated health risks have been reported in many parts of China. Nanofiltration (NF) is a promising technology for arsenic removal since it requires less ...energy than traditional reverse osmosis membranes. In this study, the removal of arsenic from synthetic waters by nanofiltration (NF) membranes was investigated. Arsenic rejection experiments included variation of arsenic feed concentration, pH, and existence of other ionic compounds. The possible influence of natural organic matter on As (V) rejection by nanofiltration membranes was also explored. The study shows the nanofiltration point-of-use (POU) systems were particularly suitable to treat arsenic-rich groundwater in suburban China.
Nanofiltration (NF) membranes have been widely used in various fields including water treatment and other separation processes, while conventional thin film composite (TFC) membranes with polyamide ...(PA) selective layers suffer the problems of fouling and chlorine intolerance. Due to the abundant hydrophilic hydroxyl groups and ester bonds free from chlorine attack, the TFC membranes composed of polyester (PE) or polyester-amide (PEA) selective layers have been proven to possess enhanced anti-fouling properties and superior chlorine resistance. In this review, the research progress of PE and PEA nanofiltration membranes is systematically summarized according to the variety of hydroxyl-containing monomers for membrane fabrication by the interfacial polymerization (IP) reaction. The synthesis strategies as well as the mechanisms for tailoring properties and performance of PE and PEA membranes are analyzed, and the membrane application advantages are demonstrated. Moreover, current challenges and future perspectives of the development of PE and PEA nanofiltration membranes are proposed. This review can offer guidance for designing high-performance PE and PEA membranes, thereby further promoting the efficacy of nanofiltration.
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•Design and fabrication of polyester and polyester-amide nanofiltration membranes.•Mechanisms of optimizing membrane properties by hydroxyl-containing monomers.•Current application status of polyester and polyester-amide nanofiltration membranes.•Challenges and future research directions of polyester and polyester-amide membranes.
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