•The preparation achieved a higher value for algae biomass.•N-S-C-dots can pass through the heavily thickened wall easily and quickly.•Multicolor luminescence provides an effective way to avoid autofluorescence in guard cells.The challenge of controlling algal blooms and reusing algal biomass remain unsolved worldwide. We introduce a facile method to reuse Nannochloropsis biocrude oil (NBO) for the synthesis of nitrogen and sulfur co-doped carbon dots (N-S-C-dots). N-S-C-dots can pass through the heavily thickened wall of mature Arabidopsis thaliana (A. thaliana) guard cells because of high solubility and excellent biocompatibility. N-S-C-dots exhibit multicolor luminescence and could effectively reduce the interference of autofluorescence in plant cells by changing filters. Bioimaging of root tissues reveals that 2 major factors affect the transmission of N-S-C-dots: high osmotic pressure and intensity of cellular metabolism. This study highlights the potential application of CDs for bioimaging in plant cells and demonstrates the significance of investigating the reuse of algal biomass.

•Series of oxidized carbon nitride (OCN) were synthesized via a rapid acid-assistant approach.•OCN is able to removal muli-herbicides simultaneously rather than a single one.•Effect of microplastics was evaluated firstly during photocatalytic process.•This work induces a chance to remediate contaminated soil and water under simulated sunlight.This work focuses on photodegradation of multi-herbicides simultaneously with series oxidized carbon nitrides (OCN), which were synthesized via a rapid acid-assisted method. Carbon nitrides, after treating with nitric acid solution at several concentrations, revealed variant oxygen content, surface morphology and structure characteristic. The photocatalytic activity was verified by degradation of ten typical herbicides in water. The influence of microplastics on the photocatalytic performance of OCN sample was investigated for the first time. Experimental results showed that microplastics contained in environmental matrix significantly influenced the photodegradation ratio. Moreover, holes (h+) and OH radicals were found to be the main reactive species during this process. The OCN-10 sample demonstrated favourable reusability in recycling tests and exhibited satisfactory degradative capability for ten investigated herbicides both in soil and aqueous phase under simulated diurnal cycle.Download high-res image (140KB)Download full-size image

This study prepares a new form of cellulose/graphene composite (CGC) by mixing dissolved cellulose with graphene oxide and reducing it with hydrazine hydrate. The composite particles achieve higher adsorption levels than five other sorbents (graphite carbons, primary secondary amine (PSA), graphite carbon black (GCB), cellulose, and graphene) for six triazine pesticides. The adsorption process only requires adding 30 mg of CGC for 10 mL of solution of triazine pesticides. The mixture is hand-shaken five times at pH 9. The equilibrium adsorption isotherm reveals that the Langmuir model describes the adsorption process better. Thermodynamic parameters indicate that adsorption is spontaneous, favorable, and endothermic in nature. Furthermore, the CGC is very stable and can easily be recycled using a simple organic solvent. The adsorption efficiency of the CGC is still over 85% after six times of recycling.Keywords: Adsorbent; Cellulose; Graphene; Thermodynamics; Triazine pesticides;

Imidacloprid has become a research hotspot, due to its high toxicity to bees and other nontarget organisms. Photodegradation is a common method for removing imidacloprid in an aquatic environment. Traditional methods of pesticide photodegradation have generally been confined by many factors, such as response to only high-energy ultraviolet light. Herein, the visible-light-driven photocatalyst graphitic carbon nitride (g-C3N4) was applied to the photodegradation of imidacloprid. Visible-light illumination (λ >400 nm) resulted in nearly 90% substrate transformation in 5 h. With the illumination of an energy-saving lamp, imidacloprid has also been mostly removed. 1-((6-chloropyridin-3-yl)methylhydroxy)imidazolidin-2-ylidene nitramide) and 4,5-dihydro-N-nitro-1-(3-pyridinylmethyl)-1H-imidazol-2-amine were the main photoproducts identified by LC-MS analysis. The photocatalytic mechanism has also been discussed. This work could provide new perspective that g-C3N4, as a good visible-light photocatalyst could be applied to the cleanup of environmental pesticide pollution.

Unique graphitic carbon nitride (g-C3N4) nanovessels have been prepared and applied as solid phase extraction (SPE) adsorbent for determining benzoylurea pesticides (BUs) in different juice samples using high performance liquid chromatography (HPLC) equipped with ultraviolet detection (UVD). The g-C3N4 nanovessels were obtained on a large scale by thermally converting low-cost urea without additive assistance, which avoided a complex synthesis process, consumption of organic solvent, and limits of tailoring the reaction pressure and atmosphere. The g-C3N4 nanovessels have been characterized using transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, and elemental analysis. The conditions affecting the extraction efficiency were optimized, including adsorbent amount, extraction time, sample volume, and choice and volume of desorption solvent. Under the optimal conditions, comparable detection limits of 6 μg/L and good recoveries of 70.4–96.4 % for six BUs have been achieved. Meanwhile, g-C3N4 nanovessels showed excellent reuse potential for ten times. The results indicated that g-C3N4 nanovessels repesented a promising SPE adsorbent for the enrichment and trace analysis of pollutants.

A new form of graphene-coated silica (GCS) has been prepared by mixing exfoliated graphene oxide with acid-treated silica and reducing it with hydrazine hydrate so that it coats the silica particles. This method is simple, convenient, and robust. The GCS composite particles have been characterized using optical photographs, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) analysis, and elemental analysis. These analyses show that the reaction effectively coats silica particles with graphene. The composite particles achieve higher levels of adsorption and are more widely applicable than five other sorbents (graphite carbons, activated carbon, pure graphene, C18 silica, and silica) for the eleven pesticides assayed. We discuss the adsorption mechanism and consider it to be dependent on the electron-donating abilities of the S, P, and N atoms and the strong π-bonding network of the benzene rings. This research demonstrates that graphene-based composite materials could be used to remove pesticide residues in aqueous environments.

Amine modified graphene is successfully synthesized via a one-pot solvothermal reaction between graphene oxide and ammonia water, methylamine or n-butyl amine. The presence of amine groups in graphene is identified by Fourier-transform infrared spectrometry, X-ray photoelectron spectroscopy and an X-ray diffractometer. The ability of amine modified graphene to cleanup fatty acids and other interfering substances from acetonitrile extracts of oil crops has been evaluated. It is found that the resulting CH3NH-G exhibits the best performance in interfering substances removal. Meanwhile, a multi-residue method is validated on 28 representative pesticide residues in four oil crops (rapeseed, peanut, sesame seeds and soybean). This method is based on modified QuEChERS sample preparation with CH3NH-G as reversed-dispersive solid phase extraction material and liquid chromatography–tandem mass spectrometry. Use of matrix-matched standards provides acceptable results for most pesticides with overall average recoveries between 70.5 and 100% and consistent RSDs < 13%, except for pymetrozine, thidiazuron and diuron. In any case, this method still meets the 0.1–8.3 μg/kg detection limit needs for most pesticides and may be used for qualitative screening applications, in which any identified pesticides can be quantified and confirmed by a more intensive method that achieves >70% recovery.Highlights► CH3NH-G and nBuNH-G have been synthesized first. ► The ability of amine modified graphene to cleanup interfering substances has been evaluated. ► Amine modified graphene is used as d-SPE materials. ► Amine modified graphene is used for pesticide multi-residue analysis in oil crops.

The residue and dissipation of florasulam in wheat and soil were determined by high performance liquid chromatography–tandem mass spectrometry. The dissipation half-lives for florasulam in soil were 0.66 days in Zhejiang and 0.64 days in Hebei. In wheat plant, half-lives of florasulam were 5.16 days in Zhejiang and 2.07 days in Hebei. The residues of florasulam in wheat grain, wheat straw and soil were below the detection limit (i.e., 0.01 mg/kg, the maximum residue level of florasulam). These results would be helpful in setting MRL guidance of florasulam in wheat in China.

A novel series of acyclic imine-substituted nitenpyram analogues were designed and synthesized from nitroaminoguanidine, and their structures were confirmed using X-ray diffraction crystallography. Preliminary bioassays showed that the target molecules exhibited good activities against aphids in laboratory (Myzus persicae Sulzer) and field trials (M. persicae Sulzer and Brevicoryne brassicae Linnaeus). Comparative molecular field analysis and comparative molecular similarity indices analysis were employed to develop a three-dimensional quantitative structure–activity relationship model that describes the insecticidal activity of 21 neonicotinoid derivatives. Simple synthesis, low cost, and good insecticidal activity have made this series of compounds become very promising candidates for future commercial pesticides.

ObjectiveThis study was aimed to investigate the toxic effects of 3 nanomaterials, i.e. multi-walled carbon nanotubes (MWCNTs), graphene oxide (GO), and reduced graphene oxide (RGO), on zebrafish embryos.MethodsThe 2-h post-fertilization (hpf) zebrafish embryos were exposed to MWCNTs, GO, and RGO at different concentrations (1, 5, 10, 50, 100 mg/L) for 96 h. Afterwards, the effects of the 3 nanomateria on spontaneous movement, heart rate, hatching rate, length of larvae, mortality, and malformations ls were evaluated.ResultsStatistical analysis indicated that RGO significantly inhibited the hatching of zebrafish embryos. Furthermore, RGO and MWCNTs decreased the length of the hatched larvae at 96 hpf. No obvious morphological malformation or mortality was observed in the zebrafish embryos after exposure to the three nanomaterials.ConclusionMWCNTs, GO, and RGO were all toxic to zebrafish embryos to influence embryos hatching and larvae length. Although no obvious morphological malformation and mortality were observed in exposed zebrafish embryos, further studies on the toxicity of the three nanomaterials are still needed.

A new form of graphene-coated silica (GCS) has been prepared by mixing exfoliated graphene oxide with acid-treated silica and reducing it with hydrazine hydrate so that it coats the silica particles. This method is simple, convenient, and robust. The GCS composite particles have been characterized using optical photographs, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) analysis, and elemental analysis. These analyses show that the reaction effectively coats silica particles with graphene. The composite particles achieve higher levels of adsorption and are more widely applicable than five other sorbents (graphite carbons, activated carbon, pure graphene, C18 silica, and silica) for the eleven pesticides assayed. We discuss the adsorption mechanism and consider it to be dependent on the electron-donating abilities of the S, P, and N atoms and the strong π-bonding network of the benzene rings. This research demonstrates that graphene-based composite materials could be used to remove pesticide residues in aqueous environments.