Euphorbia leaf extract-assisted sustainable synthesis of Au NPs supported on exfoliated GO for superior activity on water purification: reduction of 4-NP and MB

Environmental Science and Pollution Research - In the present work, the effect of graphene oxide (GO) architecture and synthesis of gold nanoparticles (AuNPs) on the surface of GO by using...     

Facile fabrication of highly catalytic-active Ag2CO3/AgBr/graphene oxide ternary composites towards the photocatalytic wastewater treatment

Environmental Science and Pollution Research - Ag2CO3/AgBr/graphene oxide (Ag2CO3/AgBr/GO) ternary composites with different percentages of GO were fabricated by a facile co-precipitation strategy....     

Enhanced photocatalytic activity using GO/TiO<Subscript>2</Subscript> catalyst for the removal of DCA solutions

This work aimed to optimize high-performance photocatalysts based on graphene oxide/titanium dioxide (GO/TiO₂) nanocomposites for the effective degradation of aqueous pollutants. The catalytic activity was tested against the degradation of dichloroacetic acid (DCA), a by-product of disinfection processes that is present in many industrial wastewaters and effluents. GO/TiO₂ photocatalysts were prepared using three different methods, hydrothermal, solvothermal, and mechanical, and varying the GO/TiO₂ ratio in the range of 1 to 10%. Several techniques were applied to characterize the catalysts, and better coupling of GO and TiO₂ was observed in the thermally synthesized composites. Although the results obtained for DCA degradation showed a coupled influence of the composite preparation method and its composition, promising results were obtained with the photocatalysts compared to the limited activity of conventional TiO₂. In the best case, corresponding to the composite synthesized via hydrothermal method with 5% of GO/TiO₂ weight ratio, an enhancement of 2.5 times of the photocatalytic degradation yield of DCA was obtained compared to bare TiO₂, thus opening more efficient ways to promote the application of photocatalytic remediation technologies.     

Heterogeneous Fenton degradation of bisphenol A catalyzed by efficient adsorptive Fe3O4/GO nanocomposites

A new method for the degradation of bisphenol A (BPA) in aqueous solution was developed. The oxidative degradation characteristics of BPA in a heterogeneous Fenton reaction catalyzed by Fe₃O₄/graphite oxide (GO) were studied. Transmission electron microscopic images showed that the Fe₃O₄ nanoparticles were evenly distributed and were ～6 nm in diameter. Experimental results suggested that BPA conversion was affected by several factors, such as the loading amount of Fe₃O₄/GO, pH, and initial H₂O₂ concentration. In the system with 1.0 g L^?1 of Fe₃O₄/GO and 20 mmol L^?1 of H₂O₂, almost 90 % of BPA (20 mg L^?1) was degraded within 6 h at pH 6.0. Based on the degradation products identified by GC–MS, the degradation pathways of BPA were proposed. In addition, the reused catalyst Fe₃O₄/GO still retained its catalytic activity after three cycles, indicating that Fe₃O₄/GO had good stability and reusability. These results demonstrated that the heterogeneous Fenton reaction catalyzed by Fe₃O₄/GO is a promising advanced oxidation technology for the treatment of wastewater containing BPA.     

Graphene oxide as a tool for antibiotic-resistant gene removal: a review

Environmental pollutants, including antibiotics (ATBs), have become an increasingly common health hazard in the last several decades. Overdose and abuse of ATBs led to the emergence of antibiotic-resistant genes (ARGs), which represent a serious health threat. Moreover, water bodies and reservoirs are places where a wide range of bacterial species with ARGs originate, owing to the strong selective pressure from presence of ATB residues. In this regard, graphene oxide (GO) has been utilised in several fields including remediation of the environment. In this review, we present a brief overview of resistant genes of frequently used ATBs, their occurrence in the environment and their behaviour. Further, we discussed the factors influencing the binding of nucleic acids and the response of ARGs to GO, including the presence of salts in the water environment or water pH, because of intrinsic properties of GO of not only binding to nucleic acids but also catalysing their decomposition. This would be helpful in designing new types of water treatment facilities.

     

Heterogeneous UV/Fenton degradation of bisphenol A catalyzed by synergistic effects of FeCo2O4/TiO2/GO

A new method for bisphenol A (BPA) degradation in aqueous solution was developed. The characteristics of BPA degradation in a heterogeneous ultraviolet (UV)/Fenton reaction catalyzed by FeCo₂O₄/TiO₂/graphite oxide (GO) were studied. The properties of the synthesized catalysts were characterized using scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometry. FeCo₂O₄ and TiO₂ were grown as spherical shape, rough surface, and relatively uniform on the surface of GO (FeCo₂O₄/TiO₂/GO). Batch tests were conducted to evaluate the effects of the initial pH, FeCo₂O₄/TiO₂/GO dosage, and H₂O₂ concentration on BPA degradation. In a system with 0.5 g L⁻¹ of FeCo₂O₄/TiO₂/GO and 10 mmol L⁻¹ of H₂O₂, approximately 90 % of BPA (20 mg L⁻¹) was degraded within 240 min of UV irradiation at pH 6.0. The reused FeCo₂O₄/TiO₂/GO catalyst retained its activity after three cycles, which indicates that it is stable and reusable. The heterogeneous UV/Fenton reaction catalyzed by FeCo₂O₄/TiO₂/GO is a promising advanced oxidation technology for treating wastewater that contains BPA.

     

Promotion effect of graphene on phytoremediation of Cd-contaminated soil

Echinacea purpurea (L.) Moench was selected as a remediation plant in this study, and different concentrations of graphene oxide (GO) were added to Cd-contaminated soil. Through pot experiments, the effect of E. purpurea on Cd-contaminated soil was determined at 60 days, 120 days, and 150 days. A preliminary study on the remediation mechanism of GO was explored through changes in the forms of Cd in the rhizosphere soil, soil pH, and soil functional groups. Results showed that the optimal concentration of GO was 0.4 g/kg, and under the condition, the accumulation of Cd in the roots of E. purpurea was as high as 113.69 ± 23.86 mg/kg, and the maximum EF reached 5.87 ± 1.34. Compared with those of the control group, accumulated Cd concentration and EF in the roots increased by 60.34% and 2.32, respectively. Correlation analysis showed that the absorption and accumulation of Cd was negatively correlated with the exchangeable Cd content at 120 days, and the exchangeable Cd was negatively correlated with the relative content of functional groups in the soil with 0.4 g/kg GO (E2). The artificial application of GO to the soil can be used as an effective way to improve the effect of E. purpurea in the remediation of Cd soil pollution, and it has great application potential in the stabilization of plants and vegetations and restoration of high-concentration Cd-contaminated soil.

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Role of solution chemistry in the attachment of graphene oxide nanoparticles onto iron oxide minerals with different characteristics

Environmental Science and Pollution Research - Given the ubiquity and abundance of the iron oxide minerals and their important roles in affecting the environmental fate of graphene oxide (GO)...     

Purifying arsenic and fluoride-contaminated water by a novel graphene-based nanocomposite membrane of enhanced selectivity and sustained flux

Environmental Science and Pollution Research - A novel graphene-based nanocomposite membrane was synthesized by interfacial polymerization (IP) through chemical bonding of the graphene oxide (GO)...     

Physical properties of PVDF-GO/black-TiO2 nanofibers and its photocatalytic degradation of methylene blue and malachite green dyes

Environmental Science and Pollution Research - Black TiO2 and graphene oxide (GO) have attracted intensive attention as an effective catalyst on visible light driven for photodegrading of dyes. In...     

Functional rGO aerogel as a potential adsorbent for removing hazardous hexavalent chromium: adsorption performance and mechanism

Environmental Science and Pollution Research - A novel functional rGO aerogel was synthesized by a facile hydrothermal method. In this process, graphene oxide (GO) was used as the precursor and...     

Photocatalytic degradation of amoxicillin from aqueous solutions by titanium dioxide nanoparticles loaded on graphene oxide

Environmental Science and Pollution Research - The photocatalytic degradation of amoxicillin (AMX) by titanium dioxide nanoparticles loaded on graphene oxide (GO/TiO2) was evaluated under UV light....     

Synthesis and application of graphene oxide as a nanoadsorbent to remove Cd (II) and Pb (II) from water: adsorption equilibrium,kinetics, and regeneration

Environmental Science and Pollution Research - In this work, graphene oxide (GO) was synthesized by the modified Hummers method. The nanomaterial was characterized by FTIR and Raman spectroscopy,...     

Coagulation-flocculation of turbid water using graphene oxide: simulation through response surface methodology and process characterization

Environmental Science and Pollution Research - It was aimed to precisely investigate the coagulation properties of graphene oxide (GO) as a novel coagulant for turbidity removal from water. For...     

Preparation of GO/MIL-101(Fe,Cu) composite and its adsorption mechanisms for phosphate in aqueous solution

Environmental Science and Pollution Research - In this study, MIL-101(Fe), MIL-101(Fe,Cu), and graphene oxide (GO)/MIL-101(Fe,Cu) were synthesized to compose a novel sorbent. The adsorption...     

Application of polyamide thin-film composite layered on polysulfone-GO/TiO2 mixed matrix membranes for removal of nitrotoluene derivatives from petrochemical wastewaters

Release of harmful organic intermediates or byproducts during the manufacture of petrochemical compounds is a serious problem in petrochemical plants. In this work, polysulfone membranes blended with GO/TiO₂ nanocomposite were synthesized by phase inversion method and coated with a polyamide layer formed by interfacial polymerization to prepare a thin-film composite (TFC) sample. Analysis and characterization of the sample were carried out by XRD, FE-SEM, BET, FTIR/ATR, AFM, TGA, and zeta potential. Results indicated that incorporation of GO/TiO₂ into the membrane structure enhanced porosity, surface roughness, and macrovoid formation along the cross-section of the sublayer and permeability of the membrane. The TFC membranes were applied to remove mononitrotoluene (MNT) and dinitrotoluene (DNT) as the basic intermediates of toluene diisocyanate (TDI). The membranes demonstrated high efficiency (>?90%) for the removal of MNT and DNT according to the charge exclusion mechanism and Donnan effect. Application of the TFC membrane for treatment of wastewater in the TDI plant showed that the removal of pollutants is variable in the range of 45–65% and 53–69% for the membrane with the highest flux and highest rejection in different transmembrane pressure, respectively.

     

Modelling of stomatal conductance and ozone flux of Norway spruce: comparison with field data

It has been proposed that stomatal flux of ozone would provide a more reliable basis than ozone exposure indices for the assessment of the risk of ozone damage to vegetation across Europe. However, implementation of this approach requires the development of appropriate models which need to be rigorously tested against actual data collected under field conditions. This paper describes such an assessment of the stomatal component of the model described by Emberson et al. (2000. Modelling stomatal ozone flux across Europe. Environmental Pollution 110). Model predictions are compared with field measurements of both stomatal conductance (g(s)) and calculated ozone flux for shoots of mature Norway spruce (Picea abies) growing in the Tyrol Mountains in Austria. The model has been developed to calculate g(s) as a function of leaf phenology and four environmental variables: photosynthetic flux density (PFD), temperature, vapour pressure deficit (VPD) and soil moisture deficit (SMD). The model was run using climate data measured on site, although the SMD component was omitted since the necessary data were not available. The model parameterisation for Norway spruce had previously been collected from the scientific literature and therefore established independently from the measurement study. Overall, strong associations were found between model predictions and measured values of stomatal conductance to ozone (GO(3)) and calculated stomatal ozone flux (FO(3)). Average diurnal profiles of GO(3) and FO(3) showed good agreement between the field data and modelled values except during the morning period of 1990. The diurnal pattern of ozone flux was determined primarily by PFD and VPD, as there was little diurnal variation in ozone concentration. In general, the model predicted instances of high ozone flux satisfactorily, indicating its potential applicability in identifying areas of high ozone risk for this species.     

Preparation of various thiol-functionalized carbon-based materials for enhanced removal of mercury from aqueous solution

In this work, biochar (BC), activated carbon (AC), and graphene oxide (GO) were thiol-functionalized using 3-mercaptopropyltrimethoxysilane (3-MPTS) (named as BCS, ACS, and GOS, respectively). BCS, ACS, and GOS were synthesized mainly via the interaction between hydrolyzed 3-MPTS and surface oxygen-containing functional groups (e.g., –OH, O–C=O, and C=O) and π-π interaction. The materials before and after modification were characterized and tested for mercury removal, including sorption kinetics and isotherms, the effects of adsorbent dosage, initial pH, and ionic strength. Pseudo-second-order sorption kinetic model (R² = 0.992~1.000) and Langmuir sorption isotherm model (R² = 0.964~0.998) fitted well with the sorption data of mercury. GOS had the most –SH groups with the largest adsorption capacity for Hg²⁺ and CH₃Hg⁺ (449.6 and 127.5 mg/g), followed by ACS (235.7 and 86.7 mg/g) and BCS (175.6 and 30.3 mg/g), which were much larger than GO (96.7 and 4.9 mg/g), AC (81.1 and 24.6 mg/g), and BC (95.6 and 9.4 mg/g). GOS and ACS showed stable mercury adsorption properties at a wide pH range (2~9) and ionic strength (0.01~0.1 mol/L). Mercury maybe removed by ligand exchange, surface complexation, and electrostatic attraction.

     

Vapour pressures, aqueous solubilities, Henry's law constants, partition coefficients between gas/water (Kgw), n-octanol/water (Kow) and gas/n-octanol (Kgo) of 106 polychlorinated diphenyl ethers (PCDE)

Modelling the environmental fate of persistent organic pollutants like polychlorinated diphenyl ethers (PCDE) requires the knowledge of a number of fundamental physico-chemical properties of these compounds. We report here the physico-chemical properties of 106 PCDEs, which are over 50% of all possible congeners. Vapour pressures P(OL), water solubilities S(H2O), and n-octanol/water partition coefficients K(OW) were determined with chromatographic methods. With these experimental data the Henry's law constants H, gas/water K(GW) and gas/n-octanol K(GO) partition coefficients were calculated. Vapour pressures and water solubilities and n-octanol/water partition coefficients of the PCDEs are close to those of similar groups of organochlorine compounds like polychlorinated biphenyls (PCBs) and dibenzofurans (PCDFs). A similar environmental fate can be predicted and was partially already been observed.     

Determination of 2,4-Dichlorophenoxyacetic acid in food and water samples using a modified graphene oxide sorbent and high-performance liquid chromatography

Abstract

In the present work, dispersive micro-solid phase extraction (D-μ-SPE) method using magnetic graphene oxide tert-butylamine (GO/Fe₃O₄/TBA) nanocomposite, as an efficient sorbent, was applied for determining 2,4-dichlorophenoxyacetic acid (2,4-D) in water and food samples. Detection was carried out using high-performance liquid chromatography (HPLC) instrument. Influential parameters of D-μ-SPE such as sorbent and its amount, elution solvent and its volume, adsorption and desorption times and pH of sample solution were investigated and optimized. Under the optimized conditions, limit of detection and quantitation values were 0.007 and 0.02?μg/mL, respectively. Recovery data for several real samples were obtained within the range of 88.0–94.0% with a relative standard deviation (RSD) less than 7.5%. The proposed method was successfully applied to quantitative determination of 2,4-D in several vegetables and water samples.