Degradation of humic acid (HA) in heterogeneous electro-Fenton/chlorine processes was investigated using a catalyst of Mn-Cu bimetallic oxides supported on Al-containing MCM-41. The catalyst was synthesized by co-precipitation method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ adsorption–desorption, and X-ray photoelectron spectroscopy (XPS) techniques. The bimetallic oxide catalyst exhibited a higher activity compared to monometallic one. Adding Al in the bimetallic oxide catalyst enhanced the stability of the catalyst, reduced metal ion leaching, increased the initial ratio of Mn³⁺/Mn⁴⁺ and Cu⁺/Cu²⁺, and slightly enhanced the degradation efficiency of HA and corresponding chemical oxygen demand (COD). The effect of Mn and Cu content in MCM-41, catalyst dosage, pH value, and initial concentration of HA and salinity on degradation efficiency were investigated. A high COD reduction about 91.5% and general current efficiency (GCE) about 41.7% have been achieved under the optimal conditions of pH 6, salinity 1000 mg/L, catalyst dosage 0.5 g/L, HA sodium salt concentration 200 mg/L, and reaction time 60 min. A possible mechanism for the reaction was suggested. Kinetic analysis showed that HA degradation in the electro-Fenton/chlorine processes was fit with first-order kinetics.

Perchlorate, a pervasive water pollutant, poses a threat to some aquatic environments. Antibiotics, as an emerging contaminant, have increasingly been found in aquatic environments in recent years. As a special co-contaminant, antibiotics modify the composition and function of microbial communities, and the biodegradation rate of perchlorate is changed in the environment. In this study, three typical antibiotics widely found in aquatic ecosystems (lincomycin (LIN), erythromycin (ETM), and sulfadiazine (SDZ)) and two input modes (once and multiple times) were selected to reveal the effects of antibiotics on perchlorate degradation and changes in the microbial community. Additionally, antibiotic resistance gene (ARG) abundance and microbial community composition were analyzed to illustrate the response of bacteria to antibiotic types and input methods by QPCR and high-throughput sequencing. The perchlorate degradation rate was inhibited by three antibiotics (LIN > ETM > SDZ) in this study. LIN and ETM had stronger inhibitory effects on perchlorate degradation, and the abundances of their ARGs increased with increasing antibiotic concentrations. With the continuous culturing and multiple inputs of antibiotics, the percentage of ARGs decreased after crossing a threshold. Additionally, the dominant degradation bacteria were different under pressure from different antibiotics. The type of the antibiotic, the background level of ARGs, and the dissemination of ARGs between bacteria were the main factors influencing the degradation system. The results presented herein will help us understand the modifications of microbial communities that occur in persistent pollutant systems contaminated with antibiotics.

In the study, an activated carbon was prepared by co-pyrolyzing rice straw and sewage sludge with ZnCl₂ activation (SS-RS AC) and used to remove Cr(VI) from wastewater. Firstly, for the preparation of SS-RS AC, the yield and iodine number were used to determine the appropriate addition percentage of rice straw. Then, a series of batch experiments including initial pH, adsorption kinetics and isotherms, and ionic strength as well as Fourier transform infrared (FT-IR) analysis of SS-RS AC before and after adsorption were performed to explore the Cr(VI) adsorption removal behavior and mechanism of SS-RS AC prepared from sewage sludge with the appropriate rice straw addition percentage. The results showed that the appropriate addition percentage of rice straw was 20%. For the Cr(VI) adsorption removal with SS-RS AC, the initial pH of solution significantly influenced the removal efficient. The highest efficiency of Cr(VI) adsorption removal (97.7%) could be attained at pH 2.0. The adsorption kinetics and isotherm data were best fitted by the pseudo-second-order model and the Langmuir-Freundlich model, respectively. The prepared SS-RS AC had the maximum Cr(VI) adsorption removal capacity of 138.69 mg/g at 40 °C. The main mechanisms for the Cr(VI) removal with SS-RS AC involve the electrostatic attraction and the reduction of Cr(VI). Carboxy, amine, and hydroxyl groups were found to act as electron donor groups, contributing to the reduction of Cr(VI). The ionic strength had an adverse effect on the Cr(VI) removal. Overall, the prepared SS-RS AC can be used as an alternative and low-cost adsorbent for the removal of Cr(VI).

Highly contaminated exposed legacy gold mine tailings from the late 1800s are present in many locations throughout North America and other parts of the world that experienced gold rushes at that time. Those tailing fields can pose risks to human health and the environment. Revegetation of tailing fields can reduce dust generation and other risks associated with these sites. The objective of this study was to investigate if native rapid-growing plants could be successfully germinated in mercury (Hg) and arsenic (As) contaminated legacy mine tailings, both untreated and treated with a low dose of sodium selenite (Na₂SeO₃) to promote growth and decrease bioaccumulation of contaminants. After screening many candidates, four wide-spread North American native plant species were selected, Juncus tenuis, Anaphalis margaritacea, Symphotrichum novi-belgii, and Panicum virgatum for their tolerance, presence near legacy gold mine sites, and ability to germinate rapidly in harsh conditions. Three of these species germinated and grew well in untreated tailings except for S. novi-belgii. The selenite treatment increased biomass, emergence, shoot height, and root length in J. tenuis; emergence in A. margaritacea; and root lengths in P. virgatum. This treatment also decreased shoot [Hg] and [As] in P. virgatum by 36% and 40%. Low-dose selenite treatments hold promise for supporting germination and growth of native plants in Hg- and As-contaminated tailing fields.

In this work, a novel functionalized graphene oxide (GO) was used as an effective and selective adsorbent for removal of mercury (Hg²⁺). The magnetic nanocomposite adsorbent (MNA) based on GO was prepared through surface reversible addition–fragmentation chain transfer copolymerization of acrylic monomers and then the formation of Fe₃O₄ nanoparticles. The structure of MNAs was characterized by using FTIR, SEM, TEM, VSM, XRD, and nitrogen adsorption/desorption isotherms. The results of ion adsorption of MNAs demonstrated high selectivity and adsorption efficiency for Hg²⁺ in the presence of competing ions. Furthermore, the removal of Hg²⁺ obeyed a pseudo-second-order model and fitted well to the Langmuir isotherm model with the maximum Hg²⁺ uptake of 389 mg g⁻¹. The MNA was also confirmed as good materials for re-use and maintained 86% of its initial adsorption capacity for mercury after the fifth regeneration cycles. Finally, the experimental results demonstrated that the solution pH, ion concentration, and temperature had a major impact on Hg(II) adsorption capacity. The results indicate that the MNAs with high adsorption abilities could be very promising adsorbents for the selective recovery of ions in wastewater treatment process. Graphical abstract

This study was aimed to investigate the adsorption and fixation effects of hydroxyapatite (HAP) on lead-contaminated soil. According to the experimental results, the microstructure of hydroxyapatite was observed by a scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) showed that OH⁻ and PO₄³⁻ were the main functional groups in HAP. Optimum adsorption conditions of Pb²⁺ were obtained: 0.2 g/L, adsorbent; initial solution pH of 5.5; and contact time of 120 min. The kinetic adsorption experiments were carried out with the initial lead solution concentrations of 50 mg/L, 150 mg/L, and 250 mg/L. The kinetics fitting was consistent with the pseudo-second-kinetic model, which indicated that the main process of HAP adsorption of Pb²⁺ was mainly controlled by surface reactions and chemical reactions. The adsorption isotherms had a satisfactory fit with the Langmuir model, which indicated that the adsorption of Pb²⁺ by HAP was a monolayer adsorption. According to the experimental results, ion exchange, phosphorus supply, precipitate, and complexation are the main immobilization mechanisms for soil remediation with HAP. In remediation of Pb²⁺-contaminated soil experiments, the adsorption rate of Pb²⁺ by HAP was significantly higher than that of non-HAP soil with increasing immobilization days. With the increasing addition of HAP, the weak acid soluble (WA), reducible (RED), oxidizable (OX), and water soluble (WS) are transformed into residue (RES). The application of HAP in contaminated soil effectively reduced the leachable and exchangeable Pb²⁺, indicating that HAP is a potential material for remediating environmental pollution with Pb²⁺.

Antimony (Sb) is increasing in the environment but effects of exposure in ecosystems are not well understood. The aim of this work was to examine effects of antimony exposure on the multifunctional, plant growth promoting, ubiquitous soil bacterium Azospirillum brasilense Sp7. Contaminated mine water with high Sb concentrations (0.13 ± 0.09 mg L⁻¹) was lethal to A. brasilense Sp7 in laboratory experiments. Exposure-dose- and time-dependent incubation toxicity assays on A. brasilense Sp7 with Sb(III) and Sb(V) at different concentrations (0.05–5 mg L⁻¹) also resulted in cell mortality which was dose and time dependent. Median effect concentrations of 0.004–0.049 and 0.019–0.467 mg L⁻¹ were estimated for Sb(III) and Sb(V), respectively. Exposure to Sb(III) resulted in greater cell mortality than Sb(V) at all concentrations tested. Exposure also resulted in the emergence of phenotypic variants that were more frequent with exposure to Sb(III). The toxicity assays demonstrated that Sb alone could have been responsible for the mortality observed with exposure to the contaminated mine water even without any other contaminants present. A. brasilense Sp7 was highly sensitive to Sb exposure and the observed effects suggest possible consequences for microbial function, plant-bacterial symbioses and ecosystem health with Sb contamination.

In order to further understand the status of the water quality of Min River’s sea-entry section, the index systems for water environmental quality assessment was built based on twenty evaluation parameters including dissolved oxygen (DO), permanganate index (CODMₙ), chemical oxygen demand (CODCᵣ), biochemical oxygen demand (BOD₅), ammonia (NH₃-N), total phosphorus (TP), and total nitrogen (TN). Water environmental quality of Min River’s sea-entry section in 2015–2017 was evaluated by utilizing the entire-array-polygon synthesis illustration method, accompanied by the time-dependent trend analysis. The results demonstrated that the water environmental quality of Min River’s sea-entry section was between the levels I and II of the Environmental Quality Standards for Surface Water (EQSSW, GB3838-2002) in 2015–2017, indicating a generally good water quality. The water quality was affected by both natural factors (such as temperature, rainfall, and runoff) and human factors and had a tendency to deteriorate at the duration of 2015–2017. The research results are of great significance for further understanding of the discharge of pollutants from the Min River basin and will be a strong support for the scientific decision-making of marine management in Fujian Province.

Fluorene-9-bisphenol (BHPF), a new derivative of bisphenol A (BPA), has been introduced for treatment with estrogen-related tumors, such as endometrial cancer. This study investigated the potential mechanism underlying the action of BHPF against endometrial cancer in vitro. We used the cell counting kit-8 (CCK8) method on Ishikawa cells to screen sub-lethal doses of BHPF and established the optimal concentration at which BHPF influenced the proliferation of Ishikawa cells. Effect of BHPF on cell migration and invasion was investigated by cell scratch assay and transwell assay, respectively. Expression levels of epithelial-mesenchymal transition (EMT)–related proteins were detected by Western blot analysis. BHPF was found to inhibit the proliferation of Ishikawa cells, whose migration and invasion abilities were also reduced. Western blot indicated that BHPF can significantly inhibit the EMT process of Ishikawa cells by blocking transforming growth factor-β (TGF-β) signaling pathway. This is the first report of the effect of BHPF on the biological behavior of endometrial cancer cells and its inhibition of endometrial cancer progression by repressing both endometrial cell proliferation and epithelial-mesenchymal transition, hence suggesting it as a novel anti-cancer drug. Graphical abstract Schematic representation of the molecular basis underlying BHPF treatment. BHPF repressed the EMT process by regulating EMT-related genes, such as E-cadherin, N-cadherin, and vimentin as well as the TGF-β signaling pathway–related genes, including p-Smad2/3 and slug, in a BHPF-dependent manner.

The reduction of wet desulfurization wastewater is one of the important tasks of coal-fired power plants, and it is important for achieving “zero emissions.” Evaporation and concentration (E&C) with waste heat is an effective way to reduce wastewater. Here, two typical types of industrial desulfurization wastewater are used to study the change rule of pH and total dissolved solids during wastewater concentration in a circulating evaporation tower. The results indicate that with the increase of concentration ratio, the pH of desulfurization wastewater is decreased rapidly and then is gradually stabilized at 2–3 when SO₂ or SO₃ is contained in flue gas, and the increase in conductivity is less for wastewater with higher SO₄²⁻ content. The characteristics of various ions are also analyzed, and the composition and microscopic morphology of the precipitates are characterized during concentration. The growth pattern of Ca²⁺ concentration is dependent on the ratio of Ca²⁺ and SO₄²⁻ in raw wastewater. When the concentration ratio is 7.21, the insoluble and slightly soluble substances undergo precipitation and the solid content is approximately 20%, which can help realize the concentration and reduction of desulfurization wastewater.