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Sulfidated zero-valent iron (SZVI) has been recognized for its enhanced reactivity in heavy metal remediation, yet its efficacies and mechanisms for sequestering thallium (Tl) from wastewater are not well understood. This study aimed to address this knowledge gap by synthesizing SZVI through one-step (OS) and two-step (TS) methods, using varying sulfur-to-iron (S/Fe) molar ratios. Results revealed that high S/Fe ratios in the OS method yielded SZVI with low crystallinity and irregular morphology, whereas the TS method produced SZVI with more crystalline and core-shell structure. Both OS and TS methods, particularly at high S/Fe ratios (2.0 for OS and 3.0 for TS), demonstrated high Tl removal capacities—645.16 mg/g for OS-2.0 and 510.20 mg/g for TS-3.0, respectively. These formulations effectively reduced Tl(I) concentrations in simulated wastewater containing complex matrixes and in industrial wastewater with intricate metal(loid) pollutants. Spectroscopic analyses, including X-ray photoelectron and 57Fe Mössbauer spectroscopy, identified three primary mechanisms for Tl sequestration: chemical precipitation facilitated by various sulfidized iron species (FeSx) as Tl2S, surface complexation through iron oxyhydroxide and FeSx, and electrostatic attraction to the negatively charged SZVI surface. The study confirmed that SZVI, when synthesized at high S/Fe ratios with elevated sulfides content, served as an efficient medium for remediating Tl-contaminated wastewater.

Membrane surface fouling is often reversible as it can be mitigated by enhancing the crossflow shear force. However, membrane internal fouling is often irreversible and thus more challenging. In this study, we developed a new superhydrophilic poly(vinylidene fluoride) (P-PVDF) membrane confined with nano-Fe3O4in the top skin layer via reverse filtration to reduce internal fouling. The surface of the P-PVDF membrane confined with nano-Fe3O4had superwetting properties (water contact angle reaching 0° within 1 s), increased roughness (from 182 to 239 nm), and enhanced water affinity. The Fe3O4@P-PVDF membrane surface showed a thicker and enhanced hydration layer, which prevented foulants from approaching membrane surfaces and pores, thereby improving the rejection. For example, when 50 ppm humic acid (HA) solution was used as the feed, the removal efficiency of the Fe3O4@P-PVDF membrane was ∼67%, while the HA removal of the P-PVDF membrane was only ∼20%. The results from the resistance-in-series model showed that nanoconfinement of Fe3O4in the top skin layer of the membrane allowed foulants to accumulate on the membrane surface (i.e., surface fouling) rather than within the internal pores (i.e., internal fouling). The filtration results under crossflow fouling and cleaning confirmed that the Fe3O4@P-PVDF membrane had higher surface fouling but it was much more reversible and much lower internal fouling compared with the control membrane. Our fouling analysis offers new insights into mass transfer mechanisms of the membrane with a nanoconfinement-enhanced hydration layer. This study provides an effective strategy to develop membranes with low internal fouling propensities.

In this paper, the consensus problem is investigated for a class of nonaffine nonlinear multiagent systems (MASs) with actuator faults of partial loss of effectiveness fault and biased fault. To deal with the control difficulty caused by the nonaffine dynamics, a neural network (NN)-based adaptive consensus protocol is developed based on the Lyapunov analysis. The neuron input of the NN uses both the state information and the consensus error information. In addition, the negative feedback term of the NN weight update law is multiplied by an absolute value of the consensus error, which is helpful in improving the consensus accuracy. With the developed adaptive NN consensus protocol, semiglobal consensus with a bounded residual consensus error of the MAS is achieved, and the bounded NN weight matrix is guaranteed. Finally, simulation results show that the developed adaptive NN consensus protocol has advantages of fast convergence rate and good consensus accuracy and has the capability of rapid response with respect to the actuator faults.

Marine fish exhibit elevated levels of arsenobetaine (AsB), while the impact and underlying mechanism of salinity on AsB biosynthesis remain inadequately explored. In this study, marine medaka (Oryzias melastigma), typically inhabiting 30‰ high salinity, were gradually acclimated to low salinities of 20, 10, and 0‰. Following acclimation, the fish were exposed to arsenate (As(V)) in their diet for 30 days. Results showed a significant accumulation of total arsenic (As) and AsB concentrations in the muscle and head tissues of the exposed fish, with these accumulations exhibiting a positive correlation with water salinity. Transcriptome analyses revealed that exposure to As(V) at low salinity may disrupt membrane components and induce cytoskeletal injuries, while at high salinity, it triggered oxidoreductase activity and transmembrane transport. Metabolome analyses indicated that low salinity induced osmotic stress, resulting in an increased requirement for amino acids to upload intracellular osmotic equilibrium in O. melastigma. Furthermore, the key organic osmolytes and amino acids, including taurine, l-methionine, guanidinoethyl sulfonate, and N-acetyl-l-aspartic acid, exhibited a negative correlation with the AsB concentration. These findings indicated that salinity can regulate osmotic balance by influencing amino acid synthesis under low salinity and stimulating AsB synthesis under high salinity conditions in O. melastigma. This study provides insights into the impact of high salinity on AsB biosynthesis, the underlying regulatory mechanisms, and implications for managing As(V) risk.

The highly efficient removal of thallium(I) from water under acidic conditions remains a challenge. In this work, a nanostructured titanium pyrophosphate (TiP2O7) was synthesized via a simple hydrothermal route. The as-prepared TiP2O7is amorphous and composed of primary irregular nano-grains, with a specific surface area of 64.4 m2/g. It shows strong adsorption ability towards thallium(I) ions over a wide pH range and is still very stable and effective for Tl(I) adsorption even at pH 2.0. The maximal adsorption capacity of thallium(I) at pH 3.0 and 7.0 is 297.8 and 408.3 mg/g, respectively, which outperforms most adsorbents reported. The TiP2O7is highly selective for thallium(I) adsorption in the presence of multiple cations such as K+, Ca2+, Mg2+, Zn2+and Cu2+. It also illustrates good reusability and high performance for thallium(I) removal from practical mining wastewater. The removal of thallium(I) is mainly achieved via electrostatic attraction and exchange with the H+in hydroxyl group on the surface of TiP2O7, forming inner-sphere surface complexes. Due to its high performance, easy preparation and feasibility over a wide pH range, the TiP2O7is a promising candidate to be used for thallium(I) removal from water and wastewater.

It is well known that arsenic is a very harmful toxin to humans. Among arsenic species, arsenite is more toxic and more difficult to remove from water than arsenate. In this study, a nanostructured Zr-Mn binary hydrous oxide was synthesized using one-step simultaneous oxidation and coprecipitation method, aiming at removing both arsenate and arsenite effectively and simultaneously. The Zr-Mn binary hydrous oxide particles were aggregated with smaller nanosized particles, resulting in a rough surface. The hydrous oxide was very effective for both As(V) and As(III) removal from water. The maximal sorption capacities for As(V) and As(III) were 52 and 96 mg/g at neutral environment, respectively. The higher sorption capacity for As(III) may be attributed to the As(III) oxidation and reductive dissolution of manganese dioxide, which resulted in the formation of new sorptive sites for arsenic at the solid surface. The presence of sulfate and carbonate had no significantly influence in the arsenic removal. However, the presence of phosphate greatly decreased the removal, especially at high concentrations. Furthermore, the performance of Zr-Mn binary hydrous oxide was further confirmed by an adsorption study with a groundwater. Additionally, the leaching of arsenic from the used sorbent was less serious, indicating that it may not be hazard to the environment after the landfill disposal. Due to its excellent arsenic removal performance and the simple, low-cost synthesis process, the Zr-Mn binary hydrous oxide could be a promising alternate for both As(V) and As(II) simultaneous removal from water or groundwater without the oxidation pretreatment.

Though powdered iron(III)-copper(II) binary oxide offers a good capacity for phosphate adsorption, it is unsuitable for direct use in fixed-bed systems, due to pore clogging and high pressure drop. To solve this problem, a novel granular iron(III)-copper(II) binary oxide sorbent (GFC) was successfully prepared using extrusion granulation method. The as-prepared GFC is cylindrical, with a diameter of ca. 2.0 mm and a length of 2.0–3.0 mm. Its adsorption for phosphate increased with temperature, decreased with an increase in pH value, but not significantly influenced by co-existing SO42–, HCO3–, and SiO32–, indicating its high selectivity for phosphate. Its maximal phosphorus (P) adsorption capacity is 20.2 mg/g at pH 5.5 ± 0.1, superior to most of the granular sorbents reported in literature. For column tests, about 1,780 bed volumes of simulated phosphate-containing wastewater were treated before the phosphorus (P) concentration in the effluent reached the limit of 50 μg/L recommended by the United States Environmental Protection Agency (USEPA). Therefore, GFC has a high potential for use in wastewater treatment to remove phosphate.

In this study, two Fe–Mn binary oxide sorbents with a same Mn:Fe molar ratio of 1:3 were prepared using two methods (coprecipitation and mechanical mixing), and they are denoted as cFe–Mn and mFe–Mn, respectively. Both mFe–Mn and cFe–Mn are amorphous and have similar structure with 2-line ferrihydrite. The cFe–Mn has a much higher specific surface area than the mFe–Mn. Selenite sorption on both mFe–Mn and cFe–Mn is pH dependent, decreasing with an increase in pH value. The estimated maximal sorption capacity of Se(IV) on the mFe–Mn and cFe–Mn is 48.6 and 70.5 mg/g at pH 7.0, respectively. In addition, the Fe–Mn binary oxide is able to adsorb selenite in the presence of competing anions and across a wide range of pH values. Among the co-existing anions, phosphate is the greatest competitor for adsorptive sites on the surface of oxide. Selenite may be sorbed onto the surface of the Fe–Mn binary oxide by formation of inner-sphere surface complexes. The high sorption capacity, low cost and environmental friendliness of the Fe–Mn binary oxide make it a potentially attractive sorbent for the removal of Se(IV) from water.

Phosphate has been proved to be one of the main elements causing eutrophication of water bodies. However, the elevated phosphate concentrations in the water bodies are often due to the excess discharge of wastewater containing phosphate. Therefore, treatment of elevated phosphate-containing wastewater is of vital importance to alleviate the situation. In this study, a novel Fe-La binary (hydro) oxide adsorbent was synthesized via a facile coprecipitation method for effective phosphate removal from wastewater. The adsorbent grains were formed of primary nanoparticles. Batch experiments were carried out to investigate adsorption kinetics and equilibrium. The adsorption was fast and well fitted by the pseudo-second-order equation, indicating that the adsorption process might be chemical sorption. The adsorption isotherms could be well described by Freundlich model and the maximal adsorption capacity reached 80.7 mg/g at pH 6.0 ± 0.1 and 67.4 mg/g at pH 9.0 ± 0.1, respectively, much higher than many reported adsorbents. The phosphate adsorption was pH dependent and weakly acidic condition was favorable for the adsorption. The phosphatead sorption might be mainly achieved via the replacement of surface hydroxyl groups at the solid surface and the formation of inner-sphere surface complexes. Moreover, the spent adsorbent could be effectively regenerated using dilute NaOH solution and used repeatedly. All these results suggest that the adsorbent maybe a promising alternative for phosphate removal.

AbstractIn all of the pollutants in the Wenyuhe River Basin, ammonia is the most important one, which changed from 0.2 mg/L to more than 70 mg/L. In order to assess habitat requirements and adaptability to the aquatic environment, the effects of different concentration ammonia (0, 0.02, 2, 10, 20, and 70 mg/L) on Daphnia magnawere tested. After 48-h, the immobility rate increased to about 60% in the exposure of 70 mg/L, which suggested that the acute toxicity occurred. Therefore, the 21-d effects of ammonia on F0 D. magnaand the 10-d effects of ammonia on F1 D. magnawere carried out in the treatments of 0, 0.02, 2, 10, and 20 mg/L. The results suggested that the body length, the dry weight, the mean spawning number, and the mean molting frequency of F0 changed from 3.17 ± 0.09 mm, 10.90 ± 0.10 mg, 125.50 ± 15.60, and 2.35 ± 0.11 to 2.85 ± 0.13 mm, 4.90 ± 0.60 mg, 88.60 ± 30.10, and 3.08 ± 0.33, respectively. The intrinsic rate of natural increase (r) decreased with increasing concentrations of ammonia nitrogen, especially in those animals exposed to 20 mg/L. The body length, the dry weight, the mean spawning number, and the mean molting frequency of F1 changed from 2.47 ± 0.18 mm, 3.09 ± 0.13 mg, 16.50 ± 3.60, and 2.13 ± 0.10 to 2.64 ± 0.04 mm, 2.64 ± 0.33 mg, 0.00 ± 0.00, and 3.22 ± 0.12, respectively. These results showed that higher ammonia concentration affected the habitat requirements of D. magnasignificantly. Meanwhile, the body length difference between F0 and F1 suggested that continuous exposure to ammonia could improve the adaptability of the offspring.

In all of the pollutants in the Wenyuhe River Basin, ammonia is the most important one, which changed from 0.2 mg/L to more than 70 mg/L. In order to assess habitat requirements and adaptability to the aquatic environment, the effects of different concentration ammonia (0, 0.02, 2, 10, 20, and 70 mg/L) on Daphnia magnawere tested. After 48-h, the immobility rate increased to about 60% in the exposure of 70 mg/L, which suggested that the acute toxicity occurred. Therefore, the 21-d effects of ammonia on F0 D. magnaand the 10-d effects of ammonia on F1 D. magnawere carried out in the treatments of 0, 0.02, 2, 10, and 20 mg/L. The results suggested that the body length, the dry weight, the mean spawning number, and the mean molting frequency of F0 changed from 3.17±0.09 mm, 10.90±0.10 mg, 125.50 ± 15.60, and 2.35±0.11 to 2.85±0.13 mm, 4.90±0.60 mg, 88.60 ± 30.10, and 3.08 ± 0.33, respectively. The intrinsic rate of natural increase (r) decreased with increasing concentrations of ammonia nitrogen, especially in those animals exposed to 20 mg/L. The body length, the dry weight, the mean spawning number, and the mean molting frequency of F1 changed from 2.47±0.18 mm, 3.09±0.13 mg, 16.50 ± 3.60, and 2.13±0.10 to 2.64±0.04 mm, 2.64±0.33 mg, 0.00 ± 0.00, and 3.22 ± 0.12, respectively. These results showed that higher ammonia concentration affected the habitat requirements of D. magnasignificantly. Meanwhile, the body length difference between F0 and F1 suggested that continuous exposure to ammonia could improve the adaptability of the offspring.

Phosphorus is an essential nutrient for biological growth, but its excessive presence in water can lead to eutrophication. Reducing phosphorus concentrations is an important way to prevent eutrophication of surface water bodies. In this study, a novel zero-valent manganese (ZVM) Mn0@Mn2O3sorbent was synthesized via a facile one-step reduction method at ambient temperature. The morphology and surface properties of the Mn0@Mn2O3were analyzed by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Zeta potential analyzer, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The obtained amorphous sample consists of many small tremella-like particles. The as-prepared sorbent shows exceptional phosphate removal performance and has a maximum adsorption capacity of 113.7 mg-P/g at pH 7.0, superior to many reported adsorbents. The removal of phosphate is obviously pH-dependent and is favorable under near-neutral and weak-alkaline conditions (pH 6.5–8.5). The kinetics data fit well to the pseudo-second-order model. The coexisting SO42-, CO32-and Cl-have no great influence on phosphate sorption, whereas, the SiO32-shows negative effect at high concentration. The sorbent is effective for phosphate removal from real municipal wastewater. The results of ionic strength effect experiment, SEM, XRD, FTIR and XPS analyses reveal that the phosphate was mainly removed through surface precipitation and formation of inner-sphere surface complexes. The Mn0@Mn2O3is a promising sorbent for phosphate removal from surface water and wastewater, owning to its exceptional performance, high selectivity, environmental friendliness and easy preparation.

Nano zero-valent manganese (nZVMn, Mn0) was prepared through a borohydride reduction method and coupled with different oxidants (persulfate (S2O82−), hypochlorite (ClO−), or hydrogen peroxide (H2O2)) to remove thallium (Tl) from wastewater. The surface of Mn0was readily oxidized to form a core-shell composite (MnOx@Mn0), which consists of Mn0as the inner core and MnOx(MnO, Mn2O3, and Mn3O4) as the outer layer. When Mn0was added alone, effective Tl(I) removal was achieved at high pH levels (>12). The Mn0-H2O2system was only effective in Tl(I) removal at high pH (>12), while the Mn0-S2O82−or Mn0-ClO-system had excellent Tl(I) removal (>96%) over a broad pH range (4–12). The Mn0-S2O82−oxidation system provided the best resistance to interference from an external organic matrix. The isotherm of Tl(I) removal through the Mn0-S2O82−system followed the Freundlich model. The Mn0nanomaterials can activate persulfate to produce sulfate radicals and hydroxyl radicals. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that oxidation-induced precipitation, surface adsorption, and electrostatic attraction are the main mechanisms for Tl(I) removal resulting from the combination of Mn0and oxidants. Mn0coupled with S2O82−/ClO−is a novel and effective technique for Tl(I) removal, and its application in other fields is worthy of further investigation.