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In this study, bentonite-supported nZVI (B-nZVI) was used as a catalyst to activate H 2 O 2 for atrazine (ATZ) degradation in the presence of FeS 2 . Results indicated that ATZ degradation by B-nZVI/H 2 O 2 process was significantly enhanced when FeS 2 was introduced, and nearly 98% of ATZ was degraded by B-nZVI/FeS 2 /H 2 O 2 process within 60 min under the optimum conditions. ATZ degradation of B-nZVI/FeS 2 /H 2 O 2 process was much higher than the sum of B-nZVI and FeS 2 /H 2 O 2 processes. The presence of HCO 3 - , PO 4 3- and F - exhibited significant negative effects on the ATZ degradation, whereas both Cu 2+ and Ni 2+ exhibited positive effects on that. Both citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) with lower concentration enhanced ATZ degradation rate, but significant suppression effects on that with higher concentration. The degradation of ATZ and 2,4-Dichlorophenol (2,4-DCP) could be simultaneously achieved in B-nZVI/FeS 2 /H 2 O 2 process under certain conditions. High soluble Fe 2+ induced an excellent decomposition of H 2 O 2 by B-nZVI and FeS 2 . OH was dominant radical, and contributed to nearly 86% of the overall ATZ removal. A total of five intermediate products of ATZ were identified, and ATZ degradation was achieved via de-alkylation and hydroxylation processes. An enhanced reaction mechanism for ATZ degradation by B-nZVI/FeS 2 /H 2 O 2 process was proposed, and B-nZVI/FeS 2 /H 2 O 2 process exhibited an excellect catalytic performance within four successive runs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Great amounts of nutrients discharged into the urbanized coastal areas, which are continuously subject to violently anthropogenic metal contamination, will result in eutrophication and hypoxic episode. In order to study the effects of dissolved oxygen (DO), salinity, nitrogen and phosphorus on the release of six metals including Zn, Pb, Cd, Cu, As and Cr from coastal sediments, a series of 60-days microcosm experiments consisting of sediments and seawater were conducted. Severe hypoxia could result in the enhanced peak values of Pb, Cd, Cu and Cr concentrations in the overlying water. A higher level of water salinity could elevate the peak value of As concentration in water column, and a higher level of nitrogen could increase the peak value of Zn concentration in water. The exchange fluxes demonstrated that the diffusion from the sediments was a dominant process during the first 10 days, However, a relative equilibrium of adsorption and precipitation in the sediment-water interface reached during the later periods. In addition, the bioavailability of the studied metals in sediments was elevated under severe hypoxia, or a high level of water salinity, or high levels of nitrogen and phosphorus. The results of linear regression analysis suggested that higher metal bioavailability in sediments could facilitate the metal release, but the process could be restrained by the higher aqueous phosphorus due to the precipitation of metal phosphates., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Herein, the application of a novel acid mine drainage-based nanoscale zero valent iron (AMD-based nZVI) for the remediation of nitrate and norfloxacin (NOR) was studied. Experimental results indicated that the catalytic reactivity of AMD-based nZVI toward nitrate reduction was superior to that of iron salt-based nanoscale zero valent iron (Iron salt-based nZVI). The presence of ultrasound irradiation could significantly enhance the reactivity toward both the nitrate reduction and NOR oxidation processes. The optimal efficiencies of nitrate and NOR by AMD-based nZVI/US process could be kept 96 and 94% within 120 min, respectively. Ammonia was identified as a major product in nitrate reduction process, while three oxidation products were observed in NOR degradation process. Both reduction reaction of nitrate from AMD-based nZVI and oxidation reaction of NOR from US-assisted Fenton system might be involved in AMD-based nZVI/US process. The AMD-based nZVI/US process showed a better performance on the removal of NOR compared with that of nitrate. The findings of the present work could be as a guide and show that AMD-based nZVI/US process is feasible for the remediation of both nitrate and NOR in real wastewater., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In-situ study on arsenic speciation and the release kinetics in marine sediments was scarce. In this study, the distributions of labile As and their speciation in coastal sediments of Daya Bay were obtained by separate diffusive gradients in thin films (DGT) probes. Results showed that the DGT-labile As(V) was the main speciation in surface sediments (from -20 to 0 mm) with a concentration range of 0.07-3.05 μg·L -1 , while the labile As(III) was the main speciation in deep layers of sediments (from -100 to -20 mm). In coastal areas, mariculture farms was the most dominated contributor to As(V) contamination in surface sediments. Both the apparent diffusion flux estimation and the DGT induced flux in sediments (DIFS) simulation indicated that As(V) contamination in surface sediments of mariculture, harbor and petrochemical areas suffered the potential risk of As(V) release into the overlying water from sediments. DIFS modeling also found that the sediments of mariculture farms were the main sediment As pools. Linear regression analysis indicated that the mobility of As mainly attributed to the As(V) in sediments., (Copyright © 2018. Published by Elsevier B.V.)

Cr 6+ and Pb 2+ are both highly toxic pollutants and commonly co-exist in some industrial effluents and contaminated waters. In this study, simultaneous removal of Cr 6+ and Pb 2+ by a novel sewage sludge-derived biochar immobilized nanoscale zero-valent iron (SSB-nZVI) was systematically investigated. It was well demonstrated that a porous structure was successfully formed on the SSB-nZVI when the starch was used as an additive. A synergistic effect on the adsorption and reduction over the SSB-nZVI was achieved, resulting in nearly 90 and 82% of Cr 6+ and Pb 2+ removal within 30 min, respectively. Cr 6+ was reduced prior to Pb 2+ . A low pH could accelerate the corrosion of nZVI as well as phosphate leaching. When Malachite green was added as a coexisting organic pollutant, its effective removal was found due to the formation of a Fenton-like system. The SSB-nZVI could be run consecutively three times with a relatively satisfactory performance. Most of Cr 6+ was converted into Cr 2 O 3 and Cr(OH) 3 on the SSB-nZVI surface, whereas most of Pb 2+ species existed as Pb(OH) 2 (or PbO). A possible reaction mechanism on the SSB-nZVI involved the adsorption, reduction and precipitation of both Cr 6+ and Pb 2+ over the particles. Present study sheds light on the insight of the fate and transport of Cr 6+ and Pb 2+ in aquatic environment, as well provides helpful guide for the remediation of coexistence of pollutants in real applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)