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Nanoscale zero-valent iron (NZVI) and NZVI supported onto montmorillonite (NZVI-Mt) were synthetized and used in this study to remove Se-VI and As-V from water in monoand binary-adsorbate systems. The adsorption kinetics and isotherm data for Se-VI and As-V were adequately described by the pseudo-second-order (PSO) (r(2)>0.94) and Freundlich (r(2)>0.93) equations. Results from scanning electron microscopy showed that the dimension of the NZVI immobilized on the Mt was smaller than pure NZVI. Using 0.05 g of adsorbent and an initial 200 mg L-1 As-V and Se-VI concentration, the maximum adsorption capacity (q(max)) and partition coefficient (PC) for As-V on NZ(VI)-Mt in monocomponent system were 54.75 mg g(-1) and 0.065 mg g(-1).mu M-1, which dropped respectively to 49.91 mg g(-1) and 0.055 mg g(-1).mu M-1 under competitive system. For Se-VI adsorption on NZ(VI)-Mt in monocomponent system, q(max) and PC were 28.63 mg g(-1) and 0.024 mg g(-1).mu M-1, respectively. Values of q(max) and PC were higher for NZVI-Mt than NZVI and montmorillonite, indicating that the nanocomposite contained greater adsorption sites for removing both oxyanions, but with a marked preference for As-V. Future research should evaluate the effect of different operational variables on the removal efficiency of both oxyanions by NZVI-Mt. usc Refereed/Peer-reviewed

Imogolite and magnetic imogolite-Fe oxide nanocomposites (Imo-Fe50 and Imo-Fe25, at 50 and 25 % Fe loading (w/w), respectively) were synthesized and tested for the removal of aqueous copper (Cu), cadmium (Cd), and arsenic (As) pollutants. The materials were characterized by transmission electron microscopy, and specific surface area and isoelectric point measurements. The Fe-containing samples were additionally characterized by Mössbauer spectroscopy and vibrating-sample magnetometry. Significant differences were found in the morphological, electrophoretic, and magnetic characteristics between imogolite and the nanocomposites. The in-situ Fe-oxide precipitation process modified the active surface sites of the imogolite. The Fe–oxide, mainly magnetite, favored the contaminants’ adsorption over the pristine imogolite. The adsorption kinetics of these pollutants were adequately described by the pseudo-second order and intraparticle diffusion models. The kinetic models showed that surface adsorption was more important than intraparticle diffusion in the removal of the pollutants by all the adsorbents. The Langmuir-Freundlich model described the experimental adsorption data, and both nanocomposites showed greater adsorption capacity than the imogolite. The adsorption of Cu and Cd was sensitive to cationic competition, showing a decrease of the adsorption capacity when the two cations coexisted, while their adsorption increased in the presence of arsenate. Refereed/Peer-reviewed

To evaluate the potential role of phenolic compounds in Al and Cd stress tolerance mechanisms, Vaccinium corymbosum cv. Legacy plantlets were exposed to different metal concentrations. The present study used an in vitro plant model to test the effects of the following treatments: 100μM Al; 100μMAl + 50μMCd; and 100μMAl + 100μMCd during periods of 7, 14, 21 and 30 days. The oxidative damage was determined by the accumulation of malondialdehyde (MDA) and hydrogen peroxide (H2O2). The antioxidant activity values were determined using 1,1-diphenyl-2-picrylhydrazine (DPPH) and the ferric reducing antioxidant power test (FRAP). Additionally, the phenolic compound concentrations were determined using HPLC-DAD. The exposure to Al and Cd increased the MDA and H2O2 contents differentially, while the antioxidant capacity values showed differences between DPPH and FRAP with the largest changes in FRAP relative to Cd. SOD had the highest activity in the first 7 days, leading to a significant increase in phenolic compounds observed after 14 days, and chlorogenic acid was the major compound identified. Our results revealed that phenolic compounds seem to play an important role in the response to ROS. Therefore, the mechanisms of tolerance to Al and Cd in V. corymbosum will be determined by the type of metal and time of exposure.

Refereed/Peer-reviewed We studied the sorption of As(V) in single and multi-component (As(V)-Se(VI)) aqueous systems using nanoscale zero-valent iron (nZVI) and nZVI-functionalized zeolite (Z-nZVI) adsorbents. Morphological and physicochemical characterization of the adsorbents was conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area and electrophoretic mobility measurements. SEM and XRD analyses showed that Fe-nanoparticle size and crystallinity were better preserved in Z-nZVI than nZVI after As(V) sorption. Highly efficient As(V) removal was achieved for all tested adsorbents with a minimal competition effect of Se(VI). In the single-component system, the equilibrium As(V) sorption time on nZVI and Z-nZVI was 40 and 60 min, respectively, while in the multi-component system, this time was 90 min for both the adsorbents. The Freundlich and pseudo-second-order models provided good fittings for the experimental sorption data (r(2) > 0.96). The As (V) removal capacity was higher using Z-nZVI than nZVI both in the single and multi-component systems, suffering minimal differences in removal in both cases. The results suggested that Z-nZVI had more specific surface sites for As(V) than nZVI and zeolite, which makes Z-nZVI a more effective adsorbent than nZVI for the removal of As(V) from aqueous solutions in the presence of other oxyanions.

The application of iron nanoparticles (FeNPs) to the removal of various pollutants has received wide attention over the last few decades. A synthesis alternative to obtain these nanoparticles without using harmful chemical reagents, such as NaBH 4 , is the use of extracts from different natural sources that allow a lesser degree of agglomeration, in a process known as green synthesis. In this study, FeNPs were synthesized by ‘green’ (hereafter, BB-Fe NPs) and ‘chemical’ (hereafter, nZVI) methods. Extracts of leaves and blueberry shoots ( Vaccinium corymbosum ) were used as reducing agents for FeCl 3 ·6H 2 O solution in the green synthesis method. FeNPs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), electrophoretic migration, Brunauer-Emmett-Teller (BET) surface area analysis and X-ray diffraction (XRD) and evaluated for the removal of As(V) from aqueous systems. In both synthesis methods, XRD analysis confirmed the presence of the different kinds of iron nanoparticles. SEM analysis showed that the average size of BB-Fe NPs was 52.4 nm and that a variety of nanoparticles of different forms and associated structures, such as lepidocrocite, magnetite, and nZVI, were present, while the dimensions of nZVI were 80.2 nm. Comparatively significant differences regarding the electrophoretic mobility were found between both materials pre- and post-sorption of As(V). The velocity of As(V) removal by BB-Fe NPs was slower than that by nZVI, reaching equilibrium at 120 min compared to 60 min for nZVI. The removal kinetics of As(V) were adequately described by the pseudo-second-order kinetic model, and the maximum adsorbed amounts of this analyte are in close accordance with the experimental results. The Langmuir-Freundlich model is in good agreement with our experimental data, where the sorption capacity of nZVI and BB-Fe NPs was found to be 52.23 ± 6.06 and 50.40 ± 5.90 (mg·g −1 ), respectively. The use of leaves of Vaccinium corymbosum affords an easy-to-synthesize, low-cost, and eco-friendly material with capabilities similar to nZVI. BB-Fe NPs are promising for arsenic remediation, which has emerged as a new alternative for water purification and sanitation.