Nanomaterials are used in practically every aspect of modern life, including agriculture. The aim of this study was to evaluate the effectiveness of iron oxide nanoparticles (Fe2O3 NPs) as a ...fertilizer to replace traditional Fe fertilizers, which have various shortcomings. The effects of the Fe2O3 NPs and a chelated-Fe fertilizer (ethylenediaminetetraacetic acid-Fe; EDTA-Fe) fertilizer on the growth and development of peanut (Arachis hypogaea), a crop that is very sensitive to Fe deficiency, were studied in a pot experiment. The results showed that Fe2O3 NPs increased root length, plant height, biomass, and SPAD values of peanut plants. The Fe2O3 NPs promoted the growth of peanut by regulating phytohormone contents and antioxidant enzyme activity. The Fe contents in peanut plants with Fe2O3 NPs and EDTA-Fe treatments were higher than the control group. We used energy dispersive X-ray spectroscopy (EDS) to quantitatively analyze Fe in the soil. Peanut is usually cultivated in sandy soil, which is readily leached of fertilizers. However, the Fe2O3 NPs adsorbed onto sandy soil and improved the availability of Fe to the plants. Together, these results show that Fe2O3 NPs can replace traditional Fe fertilizers in the cultivation of peanut plants. To the best of our knowledge, this is the first research on the Fe2O3 NPs as the iron fertilizer.
•Trace elements precipitation endangers the methane yield.•EDTA increased the bioavailability of trace elements.•Reductions of trace elements concentrations were compensated by EDTA.•EDTA showed ...significant positive effects when added to heavily undersupplied substrates.•EDTA addition to biogas processes is advantageous for environmental and economic reasons.
The uptake of essential trace elements by methanogenic bacteria can be obstructed by precipitation in the presence of sulfides and carbonates. The objective of this study was to investigate whether the bioavailability of trace elements, and therefore the methane yield, can be improved through the use of complexing agents. Research showed that the use of EDTA as a complexing agent in the biogas process increases the solubility of essential metals and enhances their bioavailability. If the substrate of a biogas digester has a low content of trace elements, solutions of elements essential for the methanogenic bacteria have to be added to the process. If these metals are complexed with EDTA prior to their supply, the necessary amount can be reduced by up to 75% compared to the non-complexed metals. Therefore, it would be advantageous for environmental and economic reasons to complex trace elements prior to their addition to the biogas process.
Phytoremediation is an ecofriendly technique to clean heavy metals from contaminated soil by the use of high biomass producing plant species. Chelators can help to improve this biological technique ...by increasing metal solubility. Therefore, a pot experiment was conducted to determine the effect of the chelators EDTA and citric acid (CA) in phytoremediation of Ni contaminated soil by using Brassica napus (canola). Two cultivars of B. napus, Con-II (tolerant) and Oscar (sensitive), were selected after screening and exposed to NiSO4 at 30 ppm at the time of sowing. CA (10 mM) and EDTA (1.5 mM) were applied either alone or in combination with each other after two weeks of Ni treatments. Different parameters like morpho-physiological and biochemical data were recorded after 15 days of chelate application. The results highlighted the successful use of chelating agents (CA and EDTA) not only to ameliorate Ni stress but also to enhance Ni accumulation which is prerequisite for phytoremediation. The basal application of 10 mMCA and 1.5 mM EDTA concentration proved to be effective for the growth of plants. The combination of chelating agents failed to show any synergistic effects.
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•AC-Fe@Cu shows superiority for efficient, rapid, selective Fe(II)EDTA-NO reduction.•Unique AC@Fe@Cu structure and optimal 1:1 atomic ratio are important.•Rapid electron transfer and ...nascent hydrogen formation are the origin.•Maximization of the roles of Cu as stabilizer and active site also contributes.
Fe(II)EDTA complexing absorption is a promising technology for nitric oxide removal; however, inefficient and slow Fe(II)EDTA regeneration from Fe(II)EDTA-NO reduction and undesirable NH4+ as the major N-containing product are still challenges that should be resolved. This study investigated the performance, kinetics, and product selectivity of Fe(II)EDTA-NO reduction by activated carbon supported bimetallic Fe@Cu composite (AC-Fe@Cu) and unraveled the origin of highly efficient and selective AC-Fe@Cu for Fe(II)EDTA-NO reduction. The reduction efficiency reaches 95.34 % in 30 min, accompanied by 86.78 % N2 selectivity, outperforming most of the reduction systems reported previously. AC-Fe@Cu is resilient at wide pH (3–8), temperature (20–50 °C), and O2 concentration ranges (0–10 %) and maintains high efficiency (76.23 %) after three successive cycles (3 h). Simultaneous reduction of Fe(III)EDTA and Fe(II)EDTA-NO indicates that Fe(II)EDTA-NO reduction is the rate-determining step in the Fe(II)EDTA regeneration process. The bimetal configuration and atomic ratio mediate the reduction efficiency, rate, and N2 selectivity. Unique AC@Fe@Cu structure and optimal atomic ratio of Fe to Cu (1:1) increase the dispersity and provide space proximity and abundant interfaces, which create numerous iron–carbon and iron–copper galvanic cells and promote two-way electron transmission. Fast electron transfer and nascent hydrogen formation contribute to efficient, rapid, and selective Fe(II)EDTA-NO reduction. The maximization of the roles of Cu as stabilizer and active sites for selective N2 formation also contributes. This study sheds light on reduction system design for Fe(II)EDTA regeneration.
Electro-Fenton is a promising game-changer for distributed wastewater treatments for the removal of recalcitrant compounds that it is possible to find in industrial effluent and looking for a water ...reuse approach. This electrochemical advanced oxidation process (EAOPs) is able to provide fast removal of organic compounds, like dyes, due to the in-situ H2O2 production and its reaction with Fe2+ to form hydroxyl radicals. The literature clearly reports that this reaction reaches its optimum in acid conditions (pH = 3) and low catalyst concentrations Fe2+<0.5 mM. This paper wants to investigate the effects of the shifting from optimal conditions on the removal of reactive black 5 (RB5), treating solutions which contain a higher amount of catalyst and a less acid pH. Textile effluents usually contain also other metals able to act as catalyst for Fenton reaction, like copper. Here its activity has been investigated as well as the possible synergistic effect with Fe2+. The results confirm that copper can enhance RB5 removal, especially in those conditions critical for ferrous cation. In the second part, possible process modifications to overcome the issues introduced by unfavourable operating conditions (pH > 3 and Fe2+ > 0.5 mM) are considered, such as the usage of a chelating agent (EDTA) and the application of a light source. The results show the positive impact of these two system modifications highlighting the possibility to enlarge the application window of electro-Fenton systems.
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•Reactive black 5 removal in not conventional electro-Fenton conditions.•Copper as a catalyst for Fenton reactions at weak-acid pH.•EDTA can be added as chelating agent at pH = 6 for high iron content.•Synergic effect between Cu2+ and Fe2+.•UVA irradiation improves reaction rate at weak acid pH.
Heavy metal complexes receive less attention, but they are more difficult to remove than the free heavy metals. Moreover, the high-salinity wastewaters from various industries hinder the removal of ...heavy metal complexes. Removal of the metal complexes is a top priority but a challenging task. Herein, a new strategy for removing Cu-EDTA from high-salinity wastewater with sulfide-modified nanozerovalent iron (S-NZVI) was proposed. The S-NZVI exhibited a considerable adsorption capacity for Cu-EDTA (∼83 mg Cu/g) at a high salt concentration (25 g/L NaCl). Similarly, the S-NZVI maintained excellent adsorption performance (∼83 mg Cu/g) in the presence of CaCl2, MgCl2, Na2SO4, and NaNO3 (25 g/L). The S-NZVI showed extremely high efficiency for Cu-EDTA removal; 50 mg/L of Cu-EDTA was almost completely removed in 1 min, and the kobs was approximately 1.5 g/(mg min). The S-NZVI showed an extensive pH working range, and within the pH range of 2–9, the Cu-EDTA was removed completely within 5 min. The excellent removal performance of the S-NZVI was due to the high reactivity and high affinity of NZVI for Cu, as well as the special substitution of Fe2+ and the interfacial reactions between S-NZVI and the copper complexes. Compared with other studies of Cu complex removal, removal with S-NZVI was a simpler process with higher efficiency. In brief, S-NZVI efficiently removed Cu complexes from harsh water environments and was reused many times. The process was simple and efficient and has broad application prospects.
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•S-NZVI realizes the removal of Cu-EDTA in high-salinity wastewater (25 g/L NaCl).•S-NZVI removes Cu-EDTA extremely fast, with the kobs of 1.5 g/(mg min).•Cu-EDTA can be removed by S-NZVI within 3 min, at a pH range of 2–9.•A possible mechanism for S-NZVI to resist high salinity interference is proposed.•The contribution of the interfacial reaction during displacement reactions is revealed.
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EDTA modified β-cyclodextrin/chitosan (CDCS-EDTA) was fabricated successfully by a two-step method and applied to remove Pb(II) and anionic dye acid red 73 (AR). CDCS-EDTA was ...characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and zeta potential analysis. The effects of experimental parameters including adsorbent dose, contact time and pH value on the adsorption efficiency of CDCS-EDTA for the pollutants were investigated. The maximum adsorption capacities were 114.8 mg g−1 for Pb(II) and 754.6 mg g−1 for AR under the optimal conditions. 93.4% of Pb(II) and 92.1% of AR could be adsorbed within 5 min, and the adsorptions reached equilibrium rapidly within 20 min and 10 min for Pb(II) and AR, respectively. A possible adsorption mechanism had been proposed that chelation of EDTA and electrostatic attraction of hydroxyl and amino groups dominated the adsorption of Pb(II), while the adsorption of AR mainly by the formation of inclusion complex with cyclodextrin cavities and electrostatic attraction with functional groups. For these two pollutants, the adsorption kinetic and isotherm data fitted well with the pseudo-second-order model and the Langmuir model, respectively. Thermodynamic studies implied that the adsorption process of Pb(II) and AR were spontaneous. Furthermore, the excellent regeneration performance indicated that CDCS-EDTA has a promising application in water treatment.
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•A novel Fe-MOF heterogeneous catalyst is prepared by microwave method.•Electro-Fe-MOF activated persulfate is firstly degrade Cu-EDTA with high RSE.•The redox cycle of Fe(II)/Fe(III) ...was accelerated with electric-assisted.•Deposited Cu species on Fe-MOF enhance the performance of heterogeneous catalyst.•Various metal-EDTA complexes were efficiently degraded by EC/Fe-MOF/PS system.
As a metal complex widely used in the electroplating industry, the degradation of Cu-EDTA in the wastewater treatment process is difficult for its strong stability, it is a crucial but extremely challenging task. In this study, a novel Ferreous metal–organic frameworks (Fe-MOF) heterogeneous catalyst was synthesized by a convenient and fast microwave method. Combined with electrochemical (EC) method and persulfate (PS), an EC/Fe-MOF/PS system was firstly applied to degrade the Cu-EDTA that was completely removed under the optimized conditions. During this process, the redox cycle was accelerated with electrical assistance and the ratio of Fe(II)/Fe(III) on the Fe-MOF was significantly increased, which improved the catalytic ability. Additionally, the degradation performance was obviously enhanced with the increased cycles. The phenomenon occurred because that Cu species derived from the decomposition of Cu-EDTA was deposited on Fe-MOF surface, and the additional catalytic ability was obtained from the Cu(0)/Cu(I)/Cu(II). The detailed pathway of Cu-EDTA degradation was proposed based on the intermediates identified by FT-ICR-MS and the mechanism was also investigated by Electron spin resonance (ESR) and quenching experiments of Reactive oxygen species (ROS). Furthermore, the EC/Fe-MOF/PS system could also represent excellent performance for the degradation of various metal-EDTA complexes. This study provided an efficient and sustainable approach for the degradation of refractory organic pollutants.
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•Fe3O4@EDTA-Fe (MEFe) was investigated as a model catalyst for removal of nitrogen oxides.•Electrochemical based green and self-sustainable system was developed for NOx.•The continual ...stirring and exposure to O2 degrade the coating surface of MEFe.•The ruined MEFe was reconstructed by -EDTA-Fe for long-term applications.
The development of catalysts has seen tremendous growth recently but most strategies only report utilization of catalysts for a few initial cycles without taking into account the influence of oxygen poisoning. Here, the magnetic Fe3O4@EDTA-Fe (MEFe, having a core Fe3O4 particle with EDTA-Fe coating) was investigated as a model catalyst for long-term recycling for the removal of nitrogen oxide (NOx) from NO/O2 mixture, followed by N2O recovery. The concentration of oxygen in the flue gas was found to have a strong impact on NOx absorption and catalytic response. To circumvent the oxygen poisoning, the MEFe was subjected to electrochemical treatment in the presence of neutral red (N.R.) and NO removal efficiency was ∼95 % noted. Furthermore, the surface of the catalyst degraded significantly (p < 0.05) after 6–7 repetitive cycling due to surface catalytic reactions, surface poisoning, oxidation of metallic species as well as residual stresses. The MEFe surface was reconstructed after 7 cycles using EDTA solution and Fe source to achieve similar surface coating as the fresh MEFe catalyst. The reconstructed MEFe exhibited similar NOx absorption capability as the fresh MEFe and the reconstruction loop was repeated several times to achieve long term cycling, which make the catalyst cost-effective. Hence, it is proposed that a successful regeneration process can be employed for promising, sustainable and long-lasting catalytic treatment of air pollutants.
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