The biogeochemical cycling of sulfur in soil is closely associated with the mobility and bioavailability of heavy metals; however the influence of sulfur on the behavior of metal-based nanoparticles has not yet been studied. The influence of S fertilizer (S⁰ and Na₂SO₄) applied in paddy soils on CuO NPs behavior in soil pore water was explored in the present study. Synchrotron-based techniques were applied to investigate the migration and speciation transformation of CuO NPs in soil pore water colloids. The application of sulfur fertilizer increased the zeta potential of soil colloids from the rice rhizosphere region and reduced the size of the colloids. Sulfur fertilization decreased the concentration of Cu in soil pore water in the rice rhizosphere region. S⁰ fertilizer reduced the Cu concentration in soil colloids (by 55.8%–73.5%), while Na₂SO₄ increased the Cu concentration in soil colloids (by 173.8%–265.1%). Sulfur fertilization changed the spatial distribution of Fe³⁺ and Cu²⁺ in colloids, making these ions more likely to be aggregated on the edges of soil colloids. Speciation transformation of CuO NPs happened during the process of migration. The main Cu speciation in the soil colloids were CuO NPs, Cu-Cysteine, Cu₂S and Cu-Citrate. Sulfur fertilization increased the proportion of Cu₂S (by 40.5%) in soil pore water colloids from the rice rhizosphere region, while the proportion of CuO NPs was reduced (by 18.4%). Sulfur fertilization changed the morphology and elementary composition of colloids in soil pore water, thus influencing the migration of CuO NPs in the soil column through soil colloids.

Porous carbon, which can be functionalized, is considered as a potential carbon material. Herein, two-dimensional (2D) nitrogen-doped magnetic Fe₃C/C (NMC) was prepared by a simple carbonization method using potassium humate (HA-K) as raw material. Remarkably, two templates, g-C₃N₄ and KCl, were formed in situ during the carbonization process, which provide the necessary conditions for the formation of 2D NMC. The NMC was comprehensively studied by different characterization methods. The results show that NMC has a large surface area and mesoporous structure. The prepared NMC-0.50 was used to test the removal performance of Cr(VI). The effects of pH value, coexisting ions and time on Cr(VI) removal performance were investigated, and the adsorption kinetics, isotherm and thermodynamics were studied. The results showed that the adsorption isotherm model of NMC-50 accorded with the Langmuir model, and the maximum adsorption capacity was 423.73 mg g⁻¹. The reaction mechanism of Cr(VI) is adsorption and redox reaction. In addition, NMC-0.50 exhibit high selectivity, separability and regeneration performance. A convenient means for the synthesis of NMC was designed in this work, and demonstrate that NMC has practical value as an adsorbent.

A series of phosphorus containing ZnO (P–ZnO) photocatalysts with various percentages of phosphorus were successfully synthesized using the hydrothermal method. The structural, physical and optical properties of the obtained microparticles were investigated using diverse techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, ultraviolet–visible diffusion reflectance spectroscopy (UV–Vis DRS), photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and N₂ adsorption-desorption analysis. The photocatalytic activities of the pure and P–ZnO samples were evaluated for the degradation of Rhodamine B (RhB) under visible light irradiation. The parameters such as pH, catalyst dosage, contaminant concentration and effect of persulfate as an oxidant were studied. It was found that the P–ZnO1.8% photocatalyst could destroy 99% of RhB (5 ppm) in 180 min at pH = 7; furthermore, it degraded ∼100% of 5 and 10 ppm of the RhB pollutant in 120 and 180 min, respectively, only by adding 0.01 g of persulfate into the reaction solution. To determine the photocatalytic mechanism, 2-propanol, benzoquinone and EDTA were used and it was indicated that hydroxyl radicals, superoxide ions and holes, all had major roles in the photocatalytic degradation but the hydroxyl radical effect was the most significant. The phenol degradation was also investigated using the P–ZnO1.8% optimum photocatalyst which could destroy 53% of the phenol (5 ppm) in 180 min. According to the reusability test, it was proved that after 5 cycles, the catalyst activity was not highly changed and it was potentially capable of pollutant degradation.

To compare aquatic organisms’ responses to the toxicity of copper oxide (CuO) nanoparticles (NPs) with those of CuO microparticles (MPs) and copper (Cu) ions, a global metabolomics approach was employed to investigate the changes of both polar and nonpolar metabolites in microalga Chlorella vulgaris after 5-day exposure to CuO NPs and MPs (1 and 10 mg/L), as well as the corresponding dissolved Cu ions (0.08 and 0.8 mg/L). Unchanged growth, slight reactive oxygen species production, and significant membrane damage (at 10 mg/L CuO particles) in C. vulgaris were demonstrated. A total of 75 differentiated metabolites were identified. Most metabolic pathways perturbed after CuO NPs exposure were shared by those after CuO MPs and Cu ions exposure, including accumulation of chlorophyll intermediates (max. 2.4–5.2 fold), membrane lipids remodeling for membrane protection (decrease of phosphatidylethanolamines (min. 0.6 fold) and phosphatidylcholines (min. 0.2–0.7 fold), as well as increase of phosphatidic acids (max. 1.5–2.9 fold), phosphatidylglycerols (max. 2.2–2.3 fold), monogalactosyldiacylglycerols (max. 1.2–1.4 fold), digalactosylmonoacylglycerols (max. 1.9–3.8 fold), diacylglycerols (max. 1.4 fold), lysophospholipids (max. 1.8–3.0 fold), and fatty acids (max. 3.0–6.2 fold)), perturbation of glutathione metabolism induced by oxidative stress, and accumulation of osmoregulants (max. 1.3–2.6 fold) to counteract osmotic stress. The only difference between metabolic responses to particles and those to ions was the accumulation of fatty acids oxidation products: particles caused higher fold changes (particles/ions ratio 1.9–3.0) at 1 mg/L and lower fold changes (particles/ions ratio 0.4–0.7) at 10 mg/L compared with ions. Compared with microparticles, there was no nanoparticle-specific pathway perturbed. These results confirm the predominant role of dissolved Cu ions on the toxicity of CuO NPs and MPs, and also reveal particle-specific toxicity from a metabolomics perspective.

Recently, sulfate radical-based advanced oxidation processes (SR-AOPs) have been studied extensively for the removal of pollutants, however, few researches focused on the activation of bisulfite by nanoscale zerovalent iron (nZVI), especially, surface reaction mechanism and sulfate radical-mediated degradation pathway have not been elucidated in detail. In this study, influencing factors, the kinetics, transformation pathway and mechanism of triphenyl phosphate (TPHP) degradation in the nZVI/bisulfite system were systematically discussed. Compared with Fe²⁺, nZVI was found to be a more efficient and long-lasting activator of bisulfite via gradual generation of iron ions. The optimal degradation efficiency of TPHP (98.2%) and pseudo-first-order kinetics rate constant (kₒbₛ = 0.2784 min⁻¹) were obtained by using 0.5 mM nZVI and 2.0 mM bisulfite at the initial pH 3.0. Both Cl⁻ and NO₃⁻ inhibited the degradation of TPHP and the inhibitory effect of Cl⁻ was stronger than that of NO₃⁻ due to the higher reaction rate of Cl⁻ with •SO₄⁻. Furthermore, SEM, XRD and XPS characterization revealed that a thin passivation layer (Fe₂O₃, Fe₃O₄, FeOOH) deposited on the surface of fresh nZVI and a few iron corrosion products generated and assembled on the surface of reacted nZVI. Radical quenching tests identified that •SO₄⁻ was the dominant reactive oxidative species (ROS) for TPHP removal. Based on HRMS analysis, six degradation products were determined and a sulfate radical-mediated degradation pathway was proposed. In a word, this study revealed that the nZVI/bisulfite system had a great potential for the TPHP elimination in waterbody.

The co-precipitation method was used to synthesize nano-magnetic adsorbent MnFe₂O₄ (nMFO), characterized through XRD, SEM, EDS, and BET techniques. The synthesized nMFO was used for hexavalent and trivalent chromium ions elimination from the aqueous phase. The optimum pH for the adsorption of Cr (VI) and Cr (III) was determined as 2 and 5, respectively. The chromium ions adsorption behavior was well interpreted through the pseudo-second order kinetics model. Furthermore, isotherm studies were conducted, and the obtained results indicated that Langmuir isotherm model could well justify the chromium ions adsorption process. Quick removal (less than 10 min) of both chromium ions and high removal efficiency were occurred using nMFO. The utmost adsorption capacity of trivalent and hexavalent chromium ions were determined as 39.6 and 34.84 mg g⁻¹, respectively. Thermodynamic studies on chromium adsorption revealed positive value for ΔH and negative value for ΔG, representing that chromium ions adsorption was an endothermic and spontaneous process. The multilinearity in the graphs of chromium ions adsorption was observed using intra-particle diffusion model. In this regard, the external mass transfer of chromium ions on synthesized nanoparticles was the important and controlling step in the adsorption process.

Whether toxicity of silver nanoparticles (AgNPs) to organisms originates from the nanoparticles themselves or from the dissolved Ag-ions is still debated, with the majority of studies claiming that extracellular release of Ag-ions is the main cause of toxicity. The objective of this study was to determine the contributions of both particles and dissolved ions to toxic responses, and to better understand the underlying mechanisms of toxicity. In addition, the pathways of AgNPs exposure to plants might play an important role and therefore are explicitly studied as well. We systematically assessed the phytotoxicity, internalization, biodistribution, and antioxidant responses in lettuce (Lactuca sativa) following root or foliar exposure to AgNPs and ionic Ag at various concentrations. For each endpoint the relative contribution of the particle-specific versus the ionic form was quantified. The results reveal particle-specific toxicity and uptake of AgNPs in lettuce as the relative contribution of particulate Ag accounted for more than 65% to the overall toxicity and the Ag accumulation in whole plant tissues. In addition, particle toxicity is shown to originate from the accumulation of Ag in plants by blocking nutrient transport, while ion toxicity is likely due to the induction of excess ROS production. Root exposure induced higher toxicity than foliar exposure at comparable exposure levels. Ag was found to be taken up and subsequently translocated from the exposed parts of plants to other portions regardless of the exposure pathway. These findings suggest particle related toxicity, and demonstrate that the accumulation and translocation of silver nanoparticles need to be considered in assessment of environmental risks and of food safety following consumption of plants exposed to AgNPs by humans.

A facile method was developed to fabricate porous tube-like ZnS by sulfurizing rod-like ZIF-L with thioacetamide (TAA) at different durations and the formation mechanism of the porous tube-like ZnS was discussed in detail. The series of sulfide products (ZS-X) were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance spectroscopy (SSNMR), transmission electron microscopy (TEM), UV–visible diffuse-reflectance spectroscopy (UV–vis DRS). The photocatalytic performances of ZS-X toward Cr(VI) reduction and organic pollutant degradation were explored. It was discovered that ZS-3 (porous tube-like ZnS) exhibited excellent activities under UV light and displayed good reusability and stability after several experimental cycles. In addition, Cr(VI) reduction and organic pollutant degradation were investigated under different pH values and existence of different foreign ions. The photocatalytic activities of ZS-3 were tested toward the matrix of Cr(VI) and reactive red X–3B. The mechanism was proposed and verified by both electrochemical analysis and electron spin resonance (ESR) measurement.

A rapid method based on solvent extraction followed by direct injection in liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-Q-TOF-MS) was developed for the targeted and suspect screening of contaminants in the soft tissues of the pearl oyster Pinctada imbricata radiata. The quantification method was first validated for the targeted analysis of 21 contaminants including some pharmaceutically active compounds, with the relative recoveries ranging from 88 to 123%, and method detection limits generally below 1 ng g⁻¹ on the wet weight (ww) basis. This targeted analysis method was then applied to oyster samples collected around the Qatari coast between 2017/2018, and none of the 21 compounds were detected in these samples. The post-acquisition data treatment based on the accurate mass measurement in both full MS scan and All Ions MS/MS was further used for mining other contaminants in oyster extracts, as well as 21 targeted compounds spiked in oyster extracts (suspect screening). The 21 spiked compounds were identified successfully and the estimated limit of identification for the individual 21 compounds ranged from 0.5 to 117 ng g⁻¹ ww of oyster tissues. A phthalate, di(2-ethylhexyl) phthalate (DEHP) was identified to be present in oyster extracts from 2018 batches, at a concentration level significantly higher than that in procedure blanks. These results confirmed that high resolution MS data obtained using the targeted method can be exploited through suspect screening workflows to identify contaminants in the tissues of bioindicator mollusks. However, a number of false identifications could be obtained and future work will be on improving the success rate of the correct identifications using this workflow.