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The present study assessed the bioaccumulation potential of per- and polyfluoroalkyl substances (PFAS) in ferns and linked root uptake behaviors to root characteristics and PFAS molecular structure. Tissue and subcellular-level behavioral differences between alternative and legacy PFAS were compared via an electron probe microanalyzer with energy dispersive spectroscopy (EPMA-EDS) and differential centrifugation. Our results show that ferns can accumulate PFAS from water, immobilize them in roots, and store them in harvestable tissue. The PFAS loading in roots was dominated by PFOS; however, a substantial amount of associated PFOS could be rinsed off by methanol. Correlation analyses indicated that root length, surface and project area, surface area per unit length of the root system, and molecular size and hydrophobicity of PFAS were the most significant factors affecting the magnitude of root uptake and upward translocation. EPMA-EDS images together with exposure experiments suggested that long-chain hydrophobic compounds tend to be adsorbed and retained on the root epidermis, while short-chain compounds are absorbed and quickly translocated upward. Our findings demonstrated the feasibility of using ferns in phytostabilization and phytoextraction initiatives of PFAS in the future.

Changes in solution chemistry and transport conditions can lead to the release of deposited MnO 2 nanoparticles from a solid interface, allowing them to re-enter the aqueous environment. Understanding the release behavior of MnO 2 nanoparticles from naturally occurring surfaces is critical for better prediction of the transport potential and environmental fate of MnO 2 nanoparticles. In this study, the release of MnO 2 nanoparticles was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D), and different environmental surface types, solution pH values and representative macromolecular organics were considered. MnO 2 nanoparticles were first deposited on crystal sensors at elevated NaNO 3 concentrations before being rinsed with double-deionized water to induce their remobilization. The results reveal that the release rate of MnO 2 depends on the surface type, in the decreasing order: SiO 2 > Fe 3 O 4  > Al 2 O 3 , resulting from electrostatic interactions between the surface and particles. Moreover, differences in solution pH can lead to variance in the release behavior of MnO 2 nanoparticles. The release rate from surfaces was significantly higher at pH 9.8 that at 4.5, indicating that alkaline conditions were more favorable for the mobilization of MnO 2 in the aquatic environment. In the presence of macromolecular organics, bovine serum albumin (BSA) can inhibit the release of MnO 2 from the surfaces due to attractive forces. In presence of humic acid (HA) and sodium alginate (SA), the MnO 2 nanoparticles were more likely to be mobile, which may be associated with a large repulsive barrier imparted by steric effects., (Copyright © 2020. Published by Elsevier B.V.)

A novel synergetic mechanism of hydroxyl radical ( • OH) oxidation and an intra-electron-transfer nonradical reaction was found in the catalytic ozonation of ketoprofen (KTP) with the in situ N-doped hollow sphere carbon (NHC). Outperforming the conventional • OH-based catalytic ozonation process, O 3 /NHC not only realized an enhancement of the pseudo-first-order rate constant of 11 times in comparison with that of O 3 alone, but was also endowed with a high stability over a wide pH (4-9) and temperature (15-35 °C) range for the degradation of KTP. The high graphitization degree ( I D / I G = 0.78-0.88) and low unsaturated oxygen content (0.10-1.38%) of NHC highlighted the dominant role of N-heteroatoms in the O 3 /NHC system. The specific effects of different N species were confirmed by a relationship study (N property vs catalytic activity) and X-ray photoelectron spectroscopy characterization. The graphitic N forming in the bulk of the graphitic structure served as the "electron-mobility" region to promote KTP degradation with the transfer of electrons from the KTP molecule to O 3 via a nonradical reaction process. The pyrrolic and pyridinic N located at defects of the graphitic structure acted as the "radical-generation" region to decompose O 3 into • OH for degrading KTP by a radical oxidation process. This finding provided a brand new insight into engineering N-doped carbonaceous catalysts precisely in the catalytic ozonation process for the efficient treatment of organic-contaminated water.

Innovative carbonaceous nano-chlorapatites (CNClAPs) which originated from the pyrolyzation of the mixture of bamboo residues and chlorapatites varying from 400 °C to 600 °C were used to investigate the decontamination efficacy of lead (Pb 2+ ) and tetracycline (TC) from wastewater. Rising pyrolytic temperature can highly improve the decontamination efficacy, of which CNClAP600 exhibited the most remarkable effects for Pb 2+ and TC decontamination (90.37% for Pb 2+ and 86.58% for TC at pH = 7). The kinetic, isotherm and characterization analysis demonstrated that the inner mechanisms for the decontamination of Pb 2+ and TC involved precipitation, electrostatic interaction, hydrogen bonding, π-π interaction and pore filling. Experiment indicated that the enhancement and competitive adsorption resulted from the interaction between Pb 2+ and TC could facilitate their joint decontamination under low concentrations. This research shed light on the management of coexisting heavy metals and organic matters contamination in wastewater by CNClAPs under different temperatures., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Very recently, several studies have found that homogeneous reducing agents (e.g., sodium thiosulfate (Na 2 S 2 O 3 ), and sodium sulfite (Na 2 SO 3 )) can activate ferrate to enhance the degradation of selected contaminants. In this work, it was found that heterogeneous carbon nanotube (CNT) could accelerate ferrate (Fe(VI)) for the degradation of bromophenols (BrPs) of environmental concerns and alleviate the appearance of undesired by-products in effluent. Fe(VI) could react with BrPs over a wide pH range of 6-10 with apparent second-order rate constants of 1.8-1850 M -1  s -1 . Electrospray ionization-triple quadrupole mass spectrometry (ESI-QqQMS) analysis showed that dibrominated dihydroxylated biphenyls and dibrominated phenoxyphenols were possibly formed via coupling reaction of BrPs radicals generated from Fe(VI) oxidation through one-electron transfer. The presence of CNT could remarkably accelerate the degradation rates of BrPs by Fe(VI) in a wide pH range from 7 to 10. Moreover, the formed undesired polybrominated products during Fe(VI)/CNT oxidation were absorbed on CNT surface and thus removed from treated water. The Fe(VI)/CNT system was capable of selectively oxidizing electron-rich pollutants (e.g., BrPs, and sulfamethoxazole (SMX)), but reluctant to iopamidol (IPM) and nitrobenzene (NB). High-valent metal-oxo intermediates Fe(V)/Fe(IV) formed in situ from the reaction of CNT with Fe(VI) were likely responsible for this activation effect of CNT, which was further confirmed via using methyl phenyl sulfoxide (PMSO) as a probe compound. Comparatively, homogeneous reducing agent Na 2 S 2 O 3 could enhance Fe(VI) degradation of BrPs at pH 7 and 8, while undesired polybrominated products were detected in effluent from Fe(VI)/Na 2 S 2 O 3 system. These findings have crucial implications for the development of a promising oxidation process by combination of Fe(VI) and CNT for water and wastewater treatment., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In order to attain a high-efficiency and low-cost adsorbent for both arsenate (As(V)) and arsenite (As(III)) removal from As-contaminated water, a novel nanostructured Fe-Ti-Mn composite oxide (FTMO) was fabricated through a one-step simultaneous oxidation and co-precipitation method. Batch control experiments and series of spectroscopy detection technologies were carried out to investigate the surface change of the FTMO adsorbent and the respective role of Fe, Ti and Mn content in the arsenic adsorption process. The results showed that the FTMO adsorbent had a high adsorption capacity for both As(V) and As(III) (especially for the latter one) via the formation of inner-sphere complexes at the water/oxide interface under both darkness and light conditions. The material could effectively oxidize As(III) to As(V) and light illumination could further apparently enhance the As(III) oxidation, thus achieving high adsorption efficiency of As(III). Combined with the characterizations from FTIR, ESR and XPS, it was assumed that the predominant As(III) removal mechanism could be attributed to the coupling of various processes including photooxidation, oxidation and adsorption. The Ti and Mn contents were dominant for the As(III) oxidation, while the Fe content mainly played an important role for the adsorption of newly formed As(V). However, the involvement of surface hydroxyl groups and the formation of inner-sphere surface complexes were primarily responsible for the As(V) adsorption mechanism. Moreover, the successful removal of arsenic from real water matrices made the FTMO a potentially attractive adsorbent for both As(V) and As(III) removal., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The hydrochemical characteristics of groundwater in Songnen Plain's agricultural area were analyzed based on aquifer types and topography classification to evaluate irrigation suitability and factors influencing groundwater quality. Samples of different groundwater types and topographical conditions within the research area were collected and chemical indices, such as sodium adsorption ratio, %Na + , residual sodium carbonate, and magnesium hazard values, were calculated to assess the groundwater suitability for irrigation. The results indicated that groundwater was generally neutral, with low total dissolved solids and slightly high hardness; the dominant anion in groundwater was HCO 3 - , while Ca 2+ was the relatively stable primary cation found in water samples from the high plain and river valley plain. The nitrate in groundwater significantly exceeded WHO drinking water standards, especially in the unconfined water of the high plain, which was due to the large-scale agricultural production activities in the eastern regions. The main reactions in the groundwater system were weathering and dissolution of carbonates and sulfates and ion-exchange reactions. Horizontal zoning in water chemical characteristics was prominent; from the high plain to river valley plain and low plain, the hydrochemistry gradually transitioned from HCO 3 -Ca-Na to HCO 3 -Na-Ca and HCO 3 -Na. Based on the chemical indices, the majority of samples were suitable for agricultural irrigation except for some in the western area with high salinity and sodium hazards. Treatment measures to groundwater and soil should be taken to reduce the possibility of soil salinization and promote crop growth in these latter regions.