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The natural environment is a complex system, and there is never only one kind of nanomaterial entering the environment. However, many studies only considered the plant toxicity of one kind of nanomaterial and do not consider the influence of two or more kinds of nanomaterials on plant toxicity. Multi-walled carbon nanotubes (MWCNTs) and zinc oxide nanoparticles (ZnO NPs) are two common and widely used nanomaterials in water environment, so these two kinds of nanomaterials were chosen to explore the effects of their combined toxicity on cabbage. This study investigated the toxicity of MWCNTs combined with ZnO NPs on cabbage by measuring the length of roots and stems, chlorophyll content, oxidative stress, antioxidant enzyme activity, metal element content, and root scanning electron microscopy. The toxicity of single MWCNTs toward cabbage was attributed to direct oxidative damage, while the toxicity of single ZnO NPs toward cabbage was due to the high level of zinc concentration. Moreover, ZnO NPs (10 mg/L) ameliorated MWCNTs toxicity toward cabbage by improving the activity of antioxidant enzymes. ZnO NPs (50 and 100 mg/L) because of the high content of zinc disrupted the balance of other metals in the plant and increased the toxicity of MWCNTs. In conclusion, the combined toxicity of different concentrations and types of nanomaterials should be considered for a more accurate assessment of environmental risks.

Biochar and compost were two common amendments for the polluted soil. However, few studies were conducted to study the sorption of organic pollutants on combined biochar-compost and the relative adsorption mechanisms in mixed soil. The work had studied the adsorption and desorption behaviors of sulfamethoxazole (SMX) onto wetland soil after amended with biochar and/or compost. Moreover, the physicochemical and morphology properties of biochar/compost and amended soils were analyzed to discuss the relative adsorption mechanisms. Studies showed that the adsorption capacity of amended soils increased with the total amount of biochar or/and compost added, which was positively related to SOM, CEC, and EC of amended soils, but had nothing to do with the type of additives. Compared with the compost-treated treatments, the biochar-treated treatments generally achieved lower desorption rates, which also had demonstrated both different adsorption mechanisms. Pore filling and hydrophobic partitioning were the main adsorption mechanisms for biochar and compost, respectively. Though biochar owned developed pore structure, however, pore-filling of biochar was overwhelmingly weakened due to pore-blocking in mixed soils. Hence, in soil environment, compost is a kind of a more desirable amendment than biochar in absorbing and degrading organic pollutants.

Microwave-assisted catalytic oxidation technology has become an effective technology for rapid removal of organic pollutants in wastewater. In this research, the removal of methyl orange (MO) from aqueous solution by CuFe2O4 loaded on carbon nanotubes (CuFe2O4/CNTs) under microwave irradiation was studied. The effects of different loadings (1:2, 1:4, 1:8) of CuFe2O4 on the dielectric loss, magnetic loss, dielectric loss factor, magnetic loss factor, and reflection loss of composite materials were studied. The results showed that the microwave adsorption performance was improved by loading CuFe2O4 on CNTs. These different composites were further characterized by SEM, FTIR, and XRD techniques. In addition, this article also studied the effects of different microwave irradiation time, pH, and ionic factors on the degradation of MO. In particular, the mechanism of MO degradation by composite materials under different pH conditions was also studied in detail. The results showed that the removal rate reaches 97% with 5 min under the best conditions, and the composite material had good anti-interference performance. This study may provide a new option to degrade organic dye in wastewater treating.

Antimony (Sb) has been reported to be largely taken up and accumulated by plants, although it is unessential for plant growth. The translocation and phytotoxicity of Sb in plant tissues greatly dep...

Antimony (Sb) is a non-necessary metallic element to plants, which can get largely accumulated by terrestrial plants and potentially invade the food chain, leading to concerns with regard to food safety. Considering the redox properties and widespread presence of silver nanoparticles (Ag NPs), the current study attempted to shed light on the mutual effects of Ag NPs and Sb(III)/(V) on their uptake, accumulation, and corresponding biochemical effects in Glycine max (L.) Merr. (soybean). The seedling matrix was formulated by the batch exposure of Sb(III)/(V) with/or synthesized Ag NPs (∼10 nm). Significant mutual impacts were detected with the co-presence of Ag NPs and Sb on their uptake and translocation in soybean tissues. Ag NPs stimulated the accumulation of Sb(III) in roots, while reduced its translocation into leaves. In contrast, Sb(V) uptake in tissues was improved by the presence of Ag NPs. In addition, the combined exposure of Ag NPs with Sb(V) led to significantly higher Ag accumulation in tissues as compared to other treatments. In comparison to single treatments, the co-exposure of Ag NPs with Sb(V) resulted in higher impacts on the pigment contents, enzyme activities, and lipid peroxidation. However, the combination of Ag NPs with Sb(III) led to higher reactive oxygen species (ROS) in roots. The altered accumulation of Ag and Sb in soybeans and corresponding biochemical regulations upon different amendments could be attributed to the synergistic physical, chemical, and biological interactions in the soybean rhizosphere and tissues. To the best of our knowledge, this is the first evidence of nanoparticle interactions with Sb species during their uptake and accumulation in plants, which could provide the necessary impetus for investigating the bioaccumulation and physiochemical influences mediated by the co-exposure of Sb species and engineered nanoparticles (ENPs) in plants.

Five biochars derived from lotus seedpod (LSP) were applied to examine and compare the adsorption capacity of 17β-estradiol (E2) from aqueous solution. The effect of KOH activation and the order of activation steps on material properties were discussed. The effect of contact time, initial concentration, pH, ionic strength and humic acid on E2 adsorption were investigated in a batch adsorption process. Experimental results demonstrated that the pseudo second-order model fitted the experimental data best and that adsorption equilibrium was reached within 20 hr. The efficiency of E2 removal increased with increasing E2 concentration and decreased with the increase of ionic strength. E2 adsorption on LSP-derived biochar (BCs) was influenced little by humic acid, and slightly affected by the solution pH when its value ranged from 4.0 to 9.0, but considerably affected at pH 10.0. Low environmental temperature is favorable for E2 adsorption. Chemisorption, π–π interactions, monolayer adsorption and electrostatic interaction are the possible adsorption mechanisms. Comparative studies indicated that KOH activation and the order of activation steps had significant impacts on the material. Post-treated biochar exhibited better adsorption capacity for E2 than direct treated, pre-treated, and raw LSP biochar. Pyrolyzed biochar at higher temperature improved E2 removal. The excellent performance of BCs in removing E2 suggested that BCs have potential in E2 treatment and that the biochar directly treated by KOH would be a good choice for the treatment of E2 in aqueous solution, with its advantages of good efficiency and simple technology.

In this work, a novel rGO/S-GO laminated membrane was prepared by a pressure-assembly stacked method, followed with a thermal deoxygenation process. The neighboring interlayer spacing (d) between the composite layers are tunable due to the incorporation of S-GO. The nano-filtration performances of the rGO/S-GO laminated membranes were evaluated at a low-pressure condition. Molecule dynamics (MD) simulation was used to further investigate the size distribution of spacing between GO, rGO and S-GO sheets. The results of filtration experiments indicated that the obtained rGO/S-GO membrane showed a satisfied rejection performance for the removal of dyes and salts with a pressure of two bar. The rejection rates of MB, CR, RB and MO were 99.5%, 99.9%, 97.3% and 98.6%, while the rejection rates of Na2SO4, MgSO4, MgCl2 and NaCl were 86.3%, 40.9%, 35.7% and 60.5%, respectively. Compared to the pristine rGO membrane, the water permeation of rGO/S-GO laminated membrane was significantly improved from ∼0.98 to ∼3.78 L/(m2·h·bar) due to the enlarged ‘gateway’ for transport of water molecules. The results of classical MD simulation showed that the neighboring layer spacing of rGO, GO and S-GO was ∼8.4, ∼10.2, and ∼14.3 A, respectively. Their neighboring layer spacing was dependent on the chemical functional groups on the edges of GO sheets. It was further confirmed that the introduction of chemical groups on the GO caused the expansion of the interlayer ‘gap’ between neighboring sheets, which was responsible for the enhanced permeability. These findings would contribute to the development of GO-based nanofiltration membranes with high permeability and understanding the transport mechanism of water molecule.

Heavy metals are ubiquitous in the environment, and their excessive discharge and bioaccumulation can cause cardio-vascular and urinary diseases in humans. Among them, lead ion (Pb2+) and cadmium ions (Cd2+) are designated as the most typical toxic metal ions in human blood and drinking water. Thus, high-performance monitoring of Pb2+and Cd2+ pollution is necessary. Nanomaterials have been extensively used in electrochemical sensing due to their excellent physicochemical properties. In this study, we prepared ordered mesoporous carbon doped hollow spherical bismuth oxide nanocomposites (hsBi2O3-OMC NCs), and constructed it into an electrochemical sensor for highly sensitive and specific detection of Pb2+ and Cd2+ in environmental media and human blood based on the differential pulse anodic stripping voltammetry (DPASV). The experimental results demonstrate that the detection range could be broadened to 200 nM with detection limits of 0.025 nM for Pb2+ and 0.045 nM for Cd2+. Compared with conventional detection techniques, this sensor exhibited simple operation, minimal background interference, multipath applicability and economic efficiency. Therefore, we believe that this work is significant for pollution monitoring, environmental restoration and emergency treatment.

The wide use of perfluorooctane sulfonate (PFOS) has led to increasing concern about its human health risks over the past decade. In vivo and in vitro studies are important and effective means to ascertain the toxic effects of PFOS on humans and its toxic mechanisms. This article systematically reviews the human health risks of PFOS based on the currently known facts found by in vivo and in vitro studies from 2008 to 2018. Exposure to PFOS has caused hepatotoxicity, neurotoxicity, reproductive toxicity, immunotoxicity, thyroid disruption, cardiovascular toxicity, pulmonary toxicity, and renal toxicity in laboratory animals and many in vitro human systems. These results and related epidemiological studies confirmed the human health risks of PFOS, especially for exposure via food and drinking water. Oxidative stress and physiological process disruption based on fatty acid similarity were widely studied mechanisms of PFOS toxicity. Future research for assessing the human health risks of PFOS is recommended in the chronic toxicity and molecular mechanisms, the application of various omics, and the integration of toxicological and epidemiological data. Keywords: PFOS, Human health risk, In vivo, In vitro

Substantial consumption and widespread contamination of the available freshwater resources necessitate a continuing search for sustainable, cost-effective and energy-efficient technologies for reclaiming this valuable life-sustaining liquid. With these key advantages, capacitive deionization (CDI) has emerged as a promising technology for the facile removal of ions or other charged species from aqueous solutions via capacitive effects or Faradaic interactions, and is currently being actively explored for water treatment with particular applications in water desalination and wastewater remediation. Over the past decade, the CDI research field has progressed enormously with a constant spring-up of various cell architectures assembled with either capacitive electrodes or battery electrodes, specifically including flow-by CDI, membrane CDI, flow-through CDI, inverted CDI, flow-electrode CDI, hybrid CDI, desalination battery and cation intercalation desalination. This article presents a timely and comprehensive review on the recent advances of various CDI cell architectures, particularly the flow-by CDI and membrane CDI with their key research activities subdivided into materials, application, operational mode, cell design, Faradaic reactions and theoretical models. Moreover, we discuss the challenges remaining in the understanding and perfection of various CDI cell architectures and put forward the prospects and directions for CDI future development.

In this study, a series of In2S3/UiO-66 composites were fabricated through a one-step solvothermal method for the first time. The diffraction peaks, composition, morphology, and chemical states of the composites were first characterized through X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, or transmission electron microscope. Then, the performances of as-obtained In2S3/UiO-66 composites were assessed by the removal of tetracycline under 1 h dark condition and 1 h visible-light irradiation. Experimental results showed that all the In2S3/UiO-66 composites exhibited greater tetracycline removal, as compared with the two parent materials (i.e., UiO-66 and In2S3). The highest tetracycline removal was obtained by the developed In2S3/UiO-66 composite with Zr: In molar ratio of (0.37:1), labelled as ISUO-0.37, with the maximal tetracycline removal capacity of 106.3 mg/g being achieved, which was greater than that of UiO-66, In2S3, or other photocatalysts documented in the literature. The mechanism investigations revealed that compared with UiO-66 and In2S3, ISUO-0.37 had higher adsorption capability and photocatalytic performance. Although the specific surface area of ISUO-0.37 (74.57 m2/g) was lower than that of either UiO-66 (388.6 m2/g) or In2S3 (76.36 m2/g), the former possessed greater pore diameter and adsorption sites such as single bondOH, Cdouble bondO, Osingle bondCsingle bondO, Cdouble bondC, and Csingle bondH, which might be the reason for ISUO-0.37 showing the enhanced adsorption capability. The trapping experiment and electron spin resonance measurements demonstrated that radical dotO2− and h+ were the major contributors to the photo-degradation of tetracycline in this work, and more radical dotO2− and h+ were produced by ISUO-0.37, as compared with In2S3. Further investigation with the diffused spectra of reflectance showed that ISUO-0.37 had better visible light absorption than either In2S3 or UiO-66, which may be the reason for ISUO-0.37 producing more radical dotO2−. In addition, photoluminescence emission spectra confirmed that the recombination rate of photoexcited electron-hole pairs of ISUO-0.37 composite is much lower than that of In2S3, which may increase h+. It was also found that ISUO-0.37 showed excellent structural stability and recyclability. This research was financially supported by the project of National Natural Science Foundation of China (NSFC) (51779089, 51521006 and 21776066), the Natural Science Funds of Hunan Province for Distinguished Young Scholar (2018JJ1002), Science and Technology Project of Hunan Province (2018SK1010) and Huxiang youth talent plan of Hunan Province (2017RS3022).

As a photocatalyst, bismuth vanadate coupled with reduced oxide graphene (BiVO4-rGO) has been reported for dye degradation. However, this catalyst faced the disadvantages of low catalytic efficiency and long catalytic time. In this paper, BiVO4-rGO composites were synthesized by a modified hydrothermal method, and characterization results showed the monoclinic BiVO4 surface successfully coupled with a layer of rGO. The dye removal performance of BiVO4-rGO composites were evaluated by the degradation of malachite green and rhodamine B under visible light irradiation and photocatalytic results showed that the BiVO4 with rGO modification could effectively enhance the dyes removal performance. In a specific photocatalytic experiment, BiVO4-rGO-300 could remove 99.5% MG in two hours and 99.84% RhB in four hours, which was superior to previous studies. Furthermore, application of catalyst in practical wastewater was also taken into account. MG and RhB were degraded by BiVO4-rGO in several kinds of actual wastewater and experimental results showed that this catalyst could efficiently remove dye in actual environment. This improvement could be ascribed to the increase of special surface area, efficient charge transfer and reduction of electron-hole pair recombination with the incorporation of rGO. The influences of pH, supporting electrolyte and mechanism of the dye degradation were also investigated in details.

Nanoparticles (NPs) are widely used for their special physical properties and released into the natural environment. When two types of NPs exist in the same environment, the presence of one type of NP may affect the properties of the other type of NP. This study investigated the toxic effects of multi-walled carbon nanotubes (MWCNTs) and copper oxide nanoparticles (CuO NPs) on Tetradesmus obliquus. Both NPs had toxic effects on algae, and the toxic effects of MWCNTs were significantly stronger than CuO NPs which the 96-hr median effective concentration to algae were 33.8 and 169.2 mg/L, respectively. Oxidative stress and cell membrane damage were the main reasons for the toxicity of NPs to algae, and they were concentration-dependent, and the existence of CuO NPs in some groups reduced cell membrane damage caused by MWCNTs which may because that CuO NPs formed heteroaggregation with MWCNTs, reducing the contact of nanoparticles with cell membranes, then reducing physical damage. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) results indicated cell damage, the heteroaggregation of MWCNTs-CuO NPs and obvious nanoparticles internalization. In some groups, the presence of CuO NPs significantly reduced reactive oxygen species (ROS) level induced by MWCNTs. However, for the highest concentration group, the ROS level was much higher than that of the two NPs alone treatment groups, which might be related to the high concentration of MWCNTs promoting the internalization of CuO NPs. MWCNTs and CuO NPs affected and interacted with each other, causing more complex toxic effects on aquatic organisms.

Plastic discharged into the environment would break down into microplastics (MPs). However, the possible impact of MPs on heavy metals in the aquatic sediment remains unknown. In order to evaluate the potential role of MPs as carriers of coexisting pollutants, the adsorption capacity of lead ions from sediment onto aged degradable and conventional MPs were investigated as a function of lead ions concentration, contact time, temperature, MPs dosage, aging time, and fulvic acid concentration. MPs were exposed to UV to obtain aged polyethylene (A-PE) and aged polylactic acid (A-PLA). The aging treatment increased the oxygen content, specific surface area and hydrophilicity of MPs. The adsorption capacity of A-PE for Pb(II) in sediment increased from 10.1525 to 10.4642 mg g−1 with the increasing aging time. However, the adsorption capacity of A-PLA for Pb(II) in sediment decreased from 9.3199 to 8.7231 mg g−1 with the increasing aging time. The adsorption capacity of MPs in sediment for Pb(II) was in the following order: A-PE > PLA > PE > A-PLA. Fulvic acid could promote the adsorption of Pb(II) by MPs in sediment. These results indicated that the aging process of the plastics in the environment would affect its role as a carrier of coexisting pollutants.

Nowadays, more and more attention is focused on the environmental harm brought by the wide production and use of carbon nanotubes. In this study, the metabolic function of sediment microbial community was investigated after unfunctionalized or functionalized multi-walled carbon nanotubes (MWCNTs) were incorporated. The surface functional groups on the studied functionalized MWCNTs in this work were hydroxyl, carboxyl, and amino, respectively. The metabolic functional diversity was determined by Biolog EcoPlates after one-month exposure to MWCNTs. Incorporating 0.5 wt% amino functionalized MWCNTs significantly decreased the microbial activity and diversity, and all types of MWCNTs caused great inhibition on the microbial metabolism at the dosage of 2.0 wt%. The sediment microbes preferred polymers and amino acids. Principal component and similarity analysis indicated that the microbial carbon metabolism was more affected by the MWCNT dosage compared with the functionalization, and 2.0 wt% amino functionalized MWCNTs made the greatest difference in metabolic function of sediment microbial community. These consequences may help to assess the environmental risks of MWCNTs from the aspect of ecological relevance of sediment microbial community.

The development of carbon materials brings a new two-dimensional catalyst support, graphdiyne (GDY), which is attracting increasing interest in the field of catalysis. This article presents a systematical review of recent studies about the characteristics, design strategies, and applications of GDY-supported catalysts. The sp- and sp2-hybridized carbon, high electrical conductivity, direct band gap, and high intrinsic carrier mobility are key characteristics for GDY to serve as a competitive catalyst support. Hydrothermal method (or solvothermal method), GDY in-situ growth, and electrochemical deposition are commonly used to load catalysts on GDY support. In the applications of GDY-supported photocatalysts, GDY mainly serves as an electron or hole transfer material. For the electrocatalytic hydrogen production, the unique electronic structure and high electrical conductivity of GDY can promote the electron transfer and water splitting kinetics. This review is expected to provide meaningful insight and guidance for the design of GDY-supported catalysts and their applications.

Here we demonstrated an alternative partial reduction graphene oxide/metal-organic frameworks nano-scale laminated membrane for dyes and heavy metal ions removal at low pressure. Compared with pure prGO membranes, the novel UiO-66-(COOH)2/prGO membranes with loose structure and excellent selective permeability demonstrated significant enhancements of permeation for low-pressure nanofiltration. The UiO-66-(COOH)2/prGO membranes possess more nanochannels structure, high surface charge and stability, which were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The experiment result indicated that the flux of composite membranes for pure water was 20.0 ± 2.5 Lm-2h-1bar-1, about 2.9 times higher than that (6.5 ± 1.2 Lm-2h-1bar-1) of the pristine prGO membranes at the same prGO loading. The high rejection of UiO-66-(COOH)2/prGO membranes for organic dyes (98.2 ± 1.7% for negatively charged congo red and 92.55 ± 2.5% for positively charged methylene blue) were exhibited. Moreover, the rejection for heavy metal ions also can be efficiently improved up to 96.5-83.1% for Cu2+ and 92.6-80.4% for Cd2+, indicating the positive effect of the electrostatic interaction on the nanochannels for ions. Therefore, it is reasonable to believe that novel UiO-66-(COOH)2/prGO membranes have great potential application in water treatment.

The rise in manufacture and use of carbon nanotubes has aroused the concern about their potential risks associated with coexisting pollutants in the aquatic environment. 2,4-dichlorophenol (2,4-DCP), with a high toxicity to many aquatic organisms, is a widespread pollutant resulting from the extensive use of pesticides and preservatives. In this article, the adsorption of 2,4-DCP by riverine sediment and the responses of sediment microbial community to 2,4-DCP were studied in the presence of multi-walled carbon nanotubes (MWCNTs). Adding MWCNTs significantly increased the adsorption amount of sediment for 2,4-DCP from 0.541 to 1.44 mg/g as the MWCNT concentration increased from 0 to 15 mg/g. The responses of sediment microbial community were determined after one-month exposure to MWCNTs at different concentrations (0.05, 0.5, 5, and 50 mg/g). The microbial biomass carbon in the sediment contaminated with 2,4-DCP increased in the presence of 5 mg/g of MWCNTs (from 0.06 to 0.11 mg/g), but not significantly changed at other MWCNT concentrations. For the sediments contaminated with 2,4-DCP, the presence of MWCNTs made no difference to urease activity, while the dehydrogenase activity slightly increased with the addition of 5 mg/g of MWCNTs and decreased in the presence of 50 mg/g of MWCNTs. The changes of sediment bacterial communities were further determined by 16S rRNA gene sequencing. Based on the weighted UniFrac distance between communities, the clustering analysis suggested that the contamination of 2,4-DCP affected the bacterial community structure in a greater degree than that caused by MWCNTs at relatively low concentrations (≤5 mg/g). Bacteroidetes, Planctomycetes, and Nitrospirae were feature bacterial phyla to reflect the effects of MWCNTs and 2,4-DCP on sediment bacterial community. These results may contribute to the understanding of microbial community response to co-exposure of MWCNTs and 2,4-DCP and the assessment of associated ecological risks.

Carbon nanotubes (CNTs) show great potential and bright prospect in the field of environment. It is believed that this new kind of material will bring opportunities and benefits to the environmental protection and pollution control. In recent years, a lot of CNT-based environmental technologies have been developed and applied with successful results, but the adequate understanding and large-scale industrial applications of these technologies are lacking. This paper systematically reviews current environmental applications of CNTs, including pollution treatment and environmental remediation, environmental sample analysis, environmental monitoring and sensing, and design of environment-friendly products. The adopted properties of CNTs are introduced. The main roles of CNTs in these technologies are illustrated. Additionally, the main current challenges to realizing their practical applications are analyzed and discussed, involving toxicity and ecological risks, production costs, general applicability, long-term effect, and public acceptance. Further studies should give priority to the toxicity and environmental risk of CNTs when developing new CNT-based technologies. Research on standardizing toxicity testing and risk assessment of CNTs is highly recommended and a large number of toxicity data of CNTs are needed.

The environmental risks of carbon nanotubes have received considerable attention. In this work, the effects of multi-walled carbon nanotubes (MWCNTs) on the adsorption of sodium dodecyl benzene sulfonate (SDBS) by riverine sediment and the transport of SDBS in sediment were studied. MWCNTs could significantly increase the adsorption capacity of the sediment for SDBS, thus affecting the transport of SDBS in sediment. Maximum adsorption capacity of the sediment for SDBS increases from 2.29 to 2.99 mg/g with the increasing content of MWCNTs from 0% to 1.5%. Breakthrough curves (BTCs) of SDBS obtained from the column experiments were described by the convection-dispersion equation, Thomas model, and Yan model. The estimated retardation factor R increases with the incorporation of MWCNTs, either in water or sediment. Additionally, the value of R is well correlated to the content of MWCNTs in sediment. Compared with Thomas model, Yan model is more suitable for fitting the BTCs with all the values of R2 ≥ 0.951, but it tends to overestimate the maximum adsorption capacity when the content of MWCNTs in sediment is relatively higher. The results of SDBS retention in sediment indicate that MWCNTs can increase the accumulation of SDBS in the top sediment layer, while they can impede the transport of SDBS into deeper sediment layer when incorporated into the sediment. These effects should be taken into consideration for risk assessment of CNTs in the aquatic environment.

The treatment of dye pollutant and salts by nanofiltration membrane technology usually has the difficulty of low permeability and higher pressure in the case of maintaining a high rejection. In this study, high flux polyester membranes of β-cyclodextrin/trimesoyl chloride - multiwalled carbon nanotubes (β-CD/TMC-MWCNTs) were fabricated on a modified multiwalled carbon nanotubes (MWCNTs) substrate via interfacial polymerization (IP) process. The modified MWCNTs substrate was not only beneficial to modulating the permeation and distribution of aqueous phase monomer (β-cyclodextrin, β-CD), but also in favor of the formation of an ultrathin loose selective polyester active layer due to the porous network structure. The optimization experiments about the reaction time and monomer concentrations were conducted. The experimental results showed that the pure water flux of the as-prepared β-CD/TMC-MWCNTs membrane was 179.93 L m-2h-1 bar-1 (at the pressure of 0.1 MPa) when the reaction time of IP process was 5 min. The single dye removal efficiency of β-CD/TMC-MWCNTs membrane was 97.41% for Brilliant Green (BG) and 96.39% for Congo red (CR), respectively. The removal efficiency of dye/salt mixture by the membrane was above 84% for BG and over 98% for CR, respectively. The results indicated that the membrane had the efficient selective separation performance for the dye/salt mixture benefiting from the special molecular sieving architectures with the precisely intrinsic inner cavity of β-CD/TMC-MWCNTs membrane. Furthermore, the reusability, chlorine resistance, and antifouling ability of the β-CD/TMC-MWCNTs membrane was relatively excellent, and the membrane could effectively remove BG (>93%) and CR (>98%) simultaneously for mixed BG/CR dyes in real water body. These results suggested that the as-prepared β-CD/TMC-MWCNTs membrane had the potential of practical application in dye wastewater treatment.

River sediments are considered as sinks of microplastics (MPs). Although numerous studies have been conducted on MPs pollution in river sediments, the impact of MPs on the environmental behavior of Cd (II) in river sediments is still unknown. In this work, the effects of six MPs (polyethylene, polypropylene, polystyrene, polyvinyl chloride, polymethyl methacrylate and polylactic acid) on the adsorption of Cd (II) by Xiangjiang River sediment and the transport of Cd (II) in sediment were studied. The results showed that the adsorption ability of sediment to Cd (II) decreased with the increase of the content of MPs in sediment. When the content of MPs in sediment increased to 10%, polypropylene had the greatest effect on the adsorption affinity of sediments to Cd (II). Moreover, the addition of MPs accelerated transport of Cd (II) in sediment, and the transport of Cd (II) in sediment increased with the increase of the content of MPs. The reason may be that after adding MPs, the adsorption capacity of sediment to Cd (II) decreases, and the mass transfer resistance of Cd (II) to sediment reduces, which leads to faster transport of Cd (II) in sediment. Especially, when the content of MPs in sediment increased to 10% (w/w), the saturation point of the breakthrough curve decreased by about 70 pore volumes. This work hopes to provide helpful views on the environmental behavior and risk assessment of Cd (II) in the presence of MPs.

The pollution of microplastics and their potential environmental hazards have attracted considerable attention of the public. Cigarette butts, composed of cellulose acetate, are one of the most common plastic pollutants in the environment. Of all the litter that is discarded at will, cigarette butts are the most acceptable. Cigarette butts are dangerous pieces of plastic, but are usually not handled properly and consist of more than 15,000 detachable strands of plastic fiber. Discarded cigarette butts may be carried into rivers and lakes, and finally into the ocean. The plastic fibers will continuously release microplastic fibers into the environment. About 300,000 tons of potential microplastic fibers may enter the aquatic environment from this source per annum. Additionally, toxic substances, such as nicotine, carcinogenic tar, and polycyclic aromatic hydrocarbons, have strong toxic effect, which will cause serious damage to aquatic organisms. However, the mechanism and rate of microplastic fibers release from smoked cigarette butts and the joint toxicity of microplastic fibers and toxic pollutants to aquatic organisms are still in the initial stage. Therefore, it is necessary to understand the mechanism of cigarette butts releasing microplastic fibers, the potential impact on the environment and possible measures to reduce the impacts of cigarette butt litter. The aim of this paper is to evaluate the potential sources of smoked cigarette butts as environmental fiber microplastics and the potential ecological effects of the released microplastic fibers on the ecosystem. In addition, some ways which could help to tackle problem of smoked cigarette butts pollution have also been proposed.

Antimony (Sb) is the ubiquitous re-emerging contaminant greatly accumulated in sediments which has been revealed risky to ecological environment. However, the impacts of Sb (III/V) on microbes and plants in sediments, under different water management with presence of engineering materials are poorly understood. This study conducted sequential incubation of sediments (flooding, draining and planting) with presence of multiwall carbon nanotubes (MWCNTs) and Sb to explore the influence on microbial functional diversity, Sb accumulation and alfalfa traits. Results showed that water management and planting led to greater impacts of sediment enzyme activities and microbial community metabolic function and bioavailable Sb fractions (defined as sum of acid-soluble fraction and reducible fraction, F1 + F2). Available fractions of Sb (V) showed higher correlation to microbial metabolism (r = 0.933) than that of Sb (III) (r = −0.480) in planting stage. MWCNTs with increasing concentrations (0.01 1%, w/w) positively correlated to microbial community metabolic function in planting stage whereas resulted in decreasing of Sb (III/V) concentrations in alfalfa, although 0.01% MWCNT led to increase of Sb (V) and decrease of Sb (V) by 50.97% and 32.68% respectively. This study provided information for investigating combined ecological impacts of heavy metal and engineering materials under different water managing sediments.

The unique physicochemical properties of fullerenes are to a great extent determined by their purity. Pure fullerenes separated from fullerene soot are currently promising nanomaterials for versatile potential applications. But there are few efficient methods to obtain fullerenes in pure form, most of fullerene properties remain unclear. To gain their optimal properties in potential applications, more efficient methods to separate pure fullerenes are supposed to develop. One of the most active researches in fullerene separation is to find suitable receptors to bind fullerenes and then release them through host–guest interactions based on supramolecular chemistry to obtain pure products. So this review highlights the recent advances in the design of molecular receptors that feature corresponding size, shape or electronic complementary to fullerenes as the primary recognizing factor. The method using designed molecular receptors for fullerene separation here is called as selective complexation technology. And some designed polymers that can be used as supports to achieve fullerene selective separation via reversible Diels-Alder addition are also described. Besides, other two common practical separation methods, improved chromatography and fractional crystallization, are presented. All separation methods mentioned in this review can achieve selective fullerene separation with recycling process and no special equipment, which conform to the requirement of environment friendly development in 21st century. Each method has its own characteristic depending on the applied fields. Our purpose is to show the readers efficient designed methods exploitable for scalable preparation of high-quality pure fullerenes and stimulate their boarder potential applications.

Biodegradable plastics attract public attention as promising substitute for non-degradable plastics that trigger serious plastic pollution, and they are claimed to be environmentally harmless and biodegradable by microorganisms. However, not all biodegradable plastics are completely degradable under natural conditions. Some of them may be disintegrated into microplastics more rapidly than conventional plastics, emerging as another threat to soil environments. As a part of microplastics, biodegradable microplastics may pose stronger negative effects on several soil species than oil-based microplastics under some conditions. Currently, there is a fiercely increasing trend to replace nondegradable plastic commodities with biodegradable ones. Therefore, to discuss the ecological safety of biodegradable plastics is essential before promoting wide application of them during commercial use. This review provided a brief introduction on biodegradable plastics and summarized their deterioration behaviors in terrestrial environments, together with evidences on releases of additives and biodegradable microplastics. Then, potential adverse effects of biodegradable microplastics in soil ecosystems, including responses on soil properties, microbial communities, and several soil species were discussed, suggesting biodegradable microplastics as a potential threat to ecological safety of soil ecosystems. By this token, biodegradable plastics might not be a panacea to the existing “white pollution” and need further exploring.

The photocatalytic degradation of norfloxacin by bismuth tungstate (Bi2WO6) with different hierarchical architectures was investigated under visible light irradiation. Bi2WO6 was prepared by hydrothermal method with the reaction solution pH ranging from 4 to11. The relatively ultrathin Bi2WO6 nanoflakes prepared at pH 4 showed excellent adsorption and photodegradation efficiency towards norfloxacin. The characterization results showed that Bi2WO6 prepared at pH 4 had a larger specific area and faster photo-generated carrier separation rate. The decay rate reached the maximum in weak alkaline reaction solution, which could be attributed to the presence of moderate OH− anions. The present study demonstrated that the smaller size of Bi2WO6 could be an efficient photocatalyst on the degradation of norfloxacin in the aquatic environment.

Although graphene oxide framework-based membranes separation represent an effective and potential process in water purification and desalination, instability and low flux of the membrane make them still challenging in industrial application. Herein, isophorone diisocyanate (IPDI) was selected as cross-linking for covalent modification of graphene oxide nanosheets to design the newly graphene oxide-framework membranes (GOF) by a facile vacuum-assisted filtration method. The cross-linked GO-IPDI membrane can be used to effectively remove dyes and heavy metals via filtration. Results of filtration experiments and microstructure characterization confirmed that IPDI cross-linking GO not only enhanced structural stability but also enlarged the nano-channels among GO sheets for higher water permeability. The GO-IPDI membrane exhibited a high flux of 80–100 L m−2 h−1 bar−1 under an extremely low external pressure (1.0 bar). It exhibited a high rejection rate (above 96%) for dyes including methylene blue, methylene orange and rhodamine-B and congo red. While the retention was moderate for Pb2+, Cu2+, Cd2+, Cr3+ ranging from 40% to 70%. These results demonstrated the potential application of GO-IPDI in wastewater and provided a novelty way of design and fabrication of high water permeability and excellent separation performance of graphene-based membranes product.

Soil and sediment contamination has become a critical issue worldwide due to its great harm to the ecological environment and public health. In recent years, many remediation technologies including physical, chemical, biological, and combined methods have been proposed and adopted for the purpose of solving the problems of soil and sediment contamination. However, current research on evaluation methods for assessing these remediation technologies is scattered and lacks valid and integrated evaluation methods for assessing the remediation effectiveness. This paper provides a comprehensive review with an environmental perspective on the evaluation methods for assessing the effectiveness of in situ remediation of soil and sediment contaminated with organic pollutants and heavy metals. The review systematically summarizes recent exploration and attempts of the remediation effectiveness assessment based on the content of pollutants, soil and sediment characteristics, and ecological risks. Moreover, limitations and future research needs of the practical assessment are discussed. These limitations are not conducive to the implementation of the abatement and control programs for soil and sediment contamination. Therefore, more attention should be paid to the evaluation methods for assessing the remediation effectiveness while developing new in situ remediation technologies in future research. Keywords: In situ remediation, Soil, Sediment, Evaluation method, Remediation effectiveness

Organochlorine pesticides (OCPs) in sediment were a potential damage for humans and ecosystems. The aim of this work was to determine the effectiveness of carbon materials remedy hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethanes (DDTs) in sediment. Two different carbon materials including activated carbon (AC) and multi-walled carbon nanotubes (MWCNTs) were used in the present research. Sediment treated with 2 wt% AC and MWCNTs after 150 d contact showed 97%, and 75% reduction for HCH, and 93% and 59% decrease for DDTs in aqueous equilibrium concentration, respectively. Similarly, the reduction efficiencies of DDT and HCH uptake by semipermeable membrane devices (SPMDs) treated with AC (MWCNTs) were 97% (75%) and 92% (63%), respectively under the identical conditions. Furthermore, for 2 wt% AC (MWCNTs) system, a reduction of XAD beads uptake up to 87% (52%) and 73% (67%) was obtained in HCH and DDT flux to overlying water in quiescent system. Adding MWCNTs to contaminated sediment did not significantly decrease aqueous equilibrium concentration and DDTs and HCH availability in SPMDs compared to AC treatment. A series of results indicated that AC had significantly higher remediation efficiency towards HCH and DDTs in sediment than MWCNTs. Additionally, the removal efficiencies of two organic pollutants improved with increasing material doses and contact times. The greater effectiveness of AC was attributed to its greater specific surface area, which was favorable for binding contaminants. These results highlighted the potential for using AC as in-situ sorbent amendments for sediment remediation.

To implement effective control and abatement programs for contaminants accumulating in sediments, strategies are needed for evaluating the quality of amended sediments. In this study, phytotoxicity of the sediments contaminated by cadmium and phenanthrene was evaluated after in situ remediation with multi-walled carbon nanotubes (MWCNTs) as adsorbents. Adsorption experiments and measurement of aqueous concentrations of the contaminants in overlying water were used to investigate the remediation effectiveness from physical and chemical aspects. The results indicated that MWCNTs showed a much better adsorption performance towards phenanthrene and Cd(II) compared with the sediments. The in situ remediation with MWCNTs could distinctly decrease the aqueous concentrations of phenanthrene and Cd(II) released from the sediments, reducing environmental risk towards overlying water. Influences of MWCNTs dose, MWCNTs diameter, and contact time on phtotoxicity of the contaminated sediments were studied. No significant inhibition of the amended sediments on germination of the test species was observed in the experiments, while the root growth was more sensitive than biomass production to the changes of contaminant concentrations. The analysis of Pearson correlation coefficients between evaluation indicators and associated remediation parameters suggested that phytotoxicity of sediments might inaccurately indicate the changes of pollutant content, but it was significant in reflecting the ecotoxicity of sediments after remediation.

This paper reports the fabrication of melamine sponge decorated with silver nanoparticles-modified graphene (G/AgNPs-MS) for water disinfection. The G/AgNPs-MS composites with the high porosity and elasticity were used in an antibacterial process in which the composite was first immersed in bacterial suspension, and subsequently squeezed via hand compression. G/AgNPs-MS exhibited more excellent bactericidal activity against Escherichia coli and Staphylococcus aureus bacteria compared with melamine sponge (MS), melamine sponge decorated with graphene (G-MS), and melamine sponge decorated with silver nanoparticles (AgNPs-MS). The superior antibacterial effect was possibly ascribed to the coordination of graphene oxide (GO) and silver nanoparticles (Ag NPs). Compared to AgNPs-MS, G/AgNPs-MS displayed better stability with fewer Ag+ release. G/AgNPs-MS composites were highly reusable with no significant differences in the loss of bacterial viability over 12 operational cycles. The possible antibacterial mechanism of G/AgNPs-MS was also investigated. It was found that the destruction of bacterial membrane by G/AgNPs-MS played an important role in the bactericidal activity. The generation of intercellular ROS and scavenging assays confirmed the involvement of Ag+ and ROS in the antibacterial process of G/AgNPs-MS. All the results demonstrated that the prepared G/AgNPs-MS composites, as innovative antibacterial materials, showed a great potential for water disinfection.

A visible light-responsive graphene oxide–Ag3PO4 (GO–Ag3PO4) was prepared using a facile electrostatically driven self-assembly method. Ag3PO4 particles were uniformly deposited on the surface of graphene oxide (GO) sheets. The GO–Ag3PO4 composite was more active in photocatalytically killing both Gram-positive and Gram-negative bacteria compared with pure Ag3PO4. The significantly enhanced photocatalytic and bactericidal performance of GO–Ag3PO4 composite could be attributed to (i) the more active adsorption sites on the GO surface for bacteria, and (ii) the reduced recombination of photogenerated electron–hole pairs relying on the excellent electronic conductivity and store electricity of GO. According to the results, most of Escherichia coli (E. coli) bacteria were killed within 30 min under visible light irradiation, while Staphylococcus aureus (S. aureus) bacteria were almost completely killed within only 25 min. The difference could be due to the outer membrane of E. coli, which made them more resistant to the cell membrane damage caused by GO–Ag3PO4 than S. aureus lack of the outer membrane. In addition, the radical capture experiments confirmed the involvement of active holes and reactive oxygen species (ROS) in the antibacterial process of GO–Ag3PO4. All the results demonstrated that the synthesized GO–Ag3PO4 composite, as a visible light-responsive antibacterial material, has a great promising for water disinfection.

Organochlorine pesticides (OCPs) were largely sprayed on the floodplain soils before the project of Returning Farmland to Lake in China, which caused contamination of sediment in Dong-ting Lake with dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) and posed threats to human health and other organisms. In this study, single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) at different concentrations of 0.058, 0.145 and 0.29 wt% were used to manage residual DDTs and HCHs in Dong-ting Lake sediment. The efficacy was assessed by DDTs and HCHs deriving from the aqueous equilibrium experiment and uptake in semipermeable membrane devices (SPMDs). Desorption experiment and the quiescent flux experiment were conducted as well. The results showed that DDTs and HCHs were released from sediment. The p , p′ -DDT was desorbed less readily than its metabolites and similarly α -HCH was desorbed less easily than other HCH isomers from sediment. Carbon nanotubes had great effects on treating DDTs and HCHs. The effectiveness of carbon nanotube amendment was dependent on type, dose and sediment-sorbent contact time In addition, carbon nanotubes being sprinkled on the surface of sediment as a cap and being injected into sediment as a mixture were considered as two effective ways to prevent DDTs and HCHs being released from sediment. Carbon nanotubes can be potentially useful as sorbents in in-situ remediation.

Organochlorine pesticides (OCPs) in sediments could be released into water, posing great threats to human health and organisms. In this study, the treatment effectiveness of in situ sequestration of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethane (DDTs) in sediments was explored using multiwalled carbon nanotubes (MWCNTs) as adsorbents. Physicochemical tests (aqueous equilibrium concentrations, semipermeable membrane device (SPMD) uptake, and quiescent flux to overlying water) were conducted to evaluate the sequestration effectiveness of MWCNTs. Compared to the control, the MWCNT-treated sediments showed great reductions of HCHs and DDTs in aqueous equilibrium concentrations, SPMD uptake, and quiescent flux to overlying water. And the effects of dose of MWCNTs, diameter of MWCNTs, and contact time between MWCNTs and sediments on sequestration effectiveness were studied. Increased dose, decreased MWCNT diameter, and prolonged contact time resulted in a better sequestration effectiveness. The results indicated that the addition of MWCNTs to sediment could reduce the content of HCHs and DDTs released from sediments, reducing bioavailability of HCHs and DDTs and minimizing risks to ecosystem and human. MWCNTs have potential applications as adsorbents for in situ treatment of OCP-contaminated sediments.

Among the technologies for removal of deposited heavy metals and degradation of persistent organic pollutants, TiO2 semiconductor catalysts have gained extensive attention owing to their excellent catalytic ability, relatively stable physical and chemical properties and competitive price. But there are still some drawbacks associated with these TiO2 semiconductor catalyst materials such as their weak adsorption and photocatalytic abilities in managing the organic pollutants and difficulties in recycling the TiO2 powder (P25). Therefore, a new class of TiO2 nanotube (TiO2-NT) arrays was synthesized using the silane coupling agent KH570 as a modifier and applied in the reduction of heavy metals, and degradation of phenol and persistent organic pollutants like Poly Brominated Diphenyl Ethers (PBDEs). The products were thoroughly characterized by SEM, TEM, DTG, AFM, BET, EDS, DRS and XRD, which confirmed that the surface of TiO2 was well modified by KH570. From the degradation experiment of phenol and BDE47, along with the heavy metal reduction experiment we can see that the catalytic efficiency (2 h) of the modified catalyst was 5%, 15% and 3–20% higher than that of the unmodified catalyst, respectively. As a kind of hole scavenger on the surface of catalysts, the modified TiO2 nanotube arrays could not only enhance the adsorption effect of catalysts on organic pollutants, but also increase the electronic separation efficiency of holes. The results also indicated that this new class of catalyst had advantages both in surface modification and materials recycling, providing a new direction in environment pollution control.

The fabrication of montmorillonite (Mt) decorated with lysozyme-modified silver nanoparticles (Ag/lyz-Mt) was reported. The lysozyme (lyz) was served as both reducing and capping reagent. Coupling the bactericidal activity of the lyz with AgNPs, along with the high porous structure and large specific surface area of the Mt, prevented aggregation of AgNPs and promoted nanomaterial-bacteria interactions, resulting in a greatly enhanced bactericidal capability against both Gram positive and Gram negative bacteria. This paper systematically elucidated the bactericidal mechanisms of Ag/lyz-Mt. Direct contact between the Ag/lyz-Mt surface and the bacterial cell was essential to the disinfection. Physical disruption of bacterial membrane was considered to be one of the bactericidal mechanisms of Ag/lyz-Mt. Results revealed that Ag(+) was involved in the bactericidal activity of Ag/lyz-Mt via tests conducted using Ag(+) scavengers. A positive ROS (reactive oxygen species) scavenging test indirectly confirmed the involvement of ROS (O2(-), H2O2, and OH) in the bactericidal mechanism. Furthermore, the concentrations of individual ROS were quantified. Results showed that Ag/lyz-Mt nanomaterial could be a promising bactericide for water disinfection.

The dye wastewater treatment by membrane separation technology has obtained extensive attention in recent years. Nevertheless, it was rare for research on the removal of differently charged mixed dyes. In this study, several UiO-66-NH

Copyright © 2018 American Chemical Society. In this study, the effect of initial pH ranging from 3 to 11 on waste activated sludge solubilization and dewaterability in the freezing and thawing (F/T) process was investigated. Experimental results showed that alkaline conditions enhanced the solubilization of sludge in F/T treatment, whereas acidic conditions improved the dewaterability of sludge. Optimum solubilization with organic substances being 189.7 mg COD/g VSS occurred at initial pH 10, which was 12.9 times higher and more biodegradable than the control. Optimal dewaterability performance was achieved at initial pH 4, with capillary suction time and specific resistance to filterability reduction being reached to 85.4% and 87.8%, respectively. It was found that F/T treatment at initial alkaline condition also obtained good dewatering performance, and F/T treatment at initial acidic condition acquired fine solubilization too. Mechanism explorations exhibited that the OH- and freezing had synergetic effects on the degradation of extracellular polymeric substances (EPS) to enhance sludge solubilization, and OH- can be concentrated to a much higher level in the liquid-like boundary region upon freezing, which further strengthened this effects. The H+ and freezing also showed synergetic effects on the protonation of functional groups of EPS and flocculation of the colloidal sludge to improve sludge dewaterability. This study clearly reveals the role and mechanisms of initial pH on the F/T process aiming at solubilization and dewaterability of sludge, and might provide supports for the application of F/T-based strategy in field situations in the future.

With the most active Sb mines, the "dominance" on Sb production of China lead to increasingly release and omnipresence of Sb in environment through mining activities as well as the life cycle of Sb-containing productions. The introduction of engineered nanoparticles (ENPs) accidentally or intentionally (such as NP-containing sludge as fertilizer) might increase the probability of co-exposed with Sb to plants. In this study, CeO2 NPs, one of the most widely used nanomaterials in industries with potential oxidizing or reducing properties, was selected and co-exposed with Sb (III) or Sb (V) to investigate their mutual effects on uptake, accumulation and physiological effects in soybeans. The results showed that CeO2 NPs increased the Sb (III) and Sb (V) concentrations in roots by 36.7% and 14.0% respectively, while Sb (III) and Sb (V) inhibited the concentration of Ce in roots by 97.1% and 86.9% respectively. In addition, the impacts of extra common ions (Mn2+, Cu2+, Fe3+ and Zn2+) on the fate of Ce and Sb in soybeans in co-exposure of CeO2 NPs with Sb were investigated as well. Mn2+ and Fe3+ increased the accumulations of Ce and Sb (III) in the co-exposure of CeO2 NPs with Sb (III), but reduced that in the co-exposure of CeO2 NPs with Sb (V). Notably, the addition of Cu2+ and Zn2+ consistently increased the uptake and accumulation of Ce and Sb in the co-exposure treatments. Moreover, the effects of Sb on the dissolved portion of CeO2 NPs in soybean roots were also investigated. This study provided a perspective that extra ingredient (mineral elements, organic element or other nutrients) might regulated the interactions in ENPs-heavy metals-plants system which need further explorations.

Providing clean and affordable drinking water without harmful disinfection byproducts generated by conventional chemical disinfectants gives rise to the need for technological innovation. Nanotechnology has great potential in purifying water and wastewater treatment. A graphene oxide-silver (GO-Ag) nanocomposite with excellent antibacterial activity was prepared and characterized by transmission electron microscope and X-ray photoelectron spectroscopy. The tests were carried out using Escherichia coli and Staphylococcus aureus as model strains of Gram-negative and Gram-positive bacteria, respectively. The effect of bactericide dosage and pH on antibacterial activity of GO-Ag was examined. Morphological observation of bacterial cells by scanning electron microscope showed that GO-Ag was much more destructive to cell membrane of Escherichia coli than that of Staphylococcus aureus. Experiments were carried out using catalase, superoxide dismutase and sodium thioglycollate to investigate the formation of reactive oxygen species and free silver ions in the bactericidal process. The activity of intracellular antioxidant enzymes was measured to investigate the potential role of oxidative stress. According to the consequence, synergetic mechanism including destruction of cell membranes and oxidative stress accounted for the antibacterial activity of GO-Ag nanocomposites. All the results suggested that GO-Ag nanocomposites displayed a good potential for application in water disinfection.

Nanomaterials have been intensively used as antibacterial agents, due to their efficient disinfection without harmful disinfection byproducts. Silver nanoparticles have attracted considerable attention. However, silver nanoparticles are likely to aggregate. In this work, we used a simple and facile one-step approach for the preparation of carbon nanotubes-silver (including single-walled carbon nanotubes-silver (SWCNTs-Ag) and multi-walled carbon nanotubes-silver (MWCNTs-Ag)) and graphene oxide-silver (GO-Ag) nanoparticles. The synthesized carbon-silver nanocomposites were characterized by XPS, TEM, EDS and Zeta-sizer. We compared the disinfection activity of six materials (i.e. GO, SWCNTs, MWCNTs, GO-Ag, SWCNTs-Ag and MWCNTs-Ag) toward two strains including Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Under similar concentration and incubation conditions, GO-Ag showed the highest disinfection activity. Antioxidant enzyme activities and lipid peroxidation assays induced by GO-Ag proved that GO-Ag was capable of inducing O2.− oxidative stress on bacterial. Subsequently affected the cell membrane integrity and thus resulted in cell death. GO-Ag with excellent disinfection efficiency against E. coli and S. aureus highlighted the potential application of GO-Ag in water disinfection.