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The aim of the experiment was to highlight the toxicity of the CrVI, administered during three generations, on the haemoglobin and on the osmotic resistance of the erythrocyte membrane in female ...rats. The determinations have been carried out on rat blood collected from female rats that reached sexual maturity, from F0, F1, F2 generation, exposed to LOAEL, of CrVI, as potassium dichromate, in drinking water (3 months). F1 and F2 were obtained from female rats from generation F0 and respectively F1 exposed for 3 months to chromium dose, mated with male rats exposed to the same dose for three months, before mating. The results of the experiment indicated a high significant decrease of haemoglobin, (p<0,01) under to the control lot and under physiologic limits, in the three generations. The decrease of hemoglobin, registered also high significant differences (p<0,01) as well between generation F0 and respectively generation F1 and F2. The chromium toxicity impact on erythrocyte membrane was shown by the progressive decrease of osmotic resistance even from the first generation and by the increase of the haemolysis degree in hypotonic solutions. The exposure to LOAEL CrVI during three generations produces toxic effects on erythrocytes inducing hemolytic effect.
The present study investigates ameliorative effect of silicon nanoparticles (SiNPs) and indole acetic acid (IAA) alone and in combination against hexavalent chromium (CrVI) toxicity in rice ...seedlings. The results of the study revealed protective effects of SiNPs and IAA against CrVI toxicity. The 100 μM of CrVI imposed toxic effects in rice seedlings at morphological, physiological and biochemical levels which coincided with increased level of intracellular CrVI and declined level of endogenous nitric oxide (NO). The CrVI enhanced levels of superoxide radicals (SOR) (59.51% and 50.1% in shoot and root, respectively) and H2O2 (19.5% and 23.69% in shoot and root, respectively). However, when SiNPs and IAA were applied to plants under CrVI stress, they enhanced tolerance and defence mechanisms as manifested in terms of increased biomass, endogenous NO, photosynthetic pigments, and antioxidants level. It was also noticed that CrVI arrested cell cycle at G2/M phase whereas growth was restored as compared to control when SiNPs and IAA were supplemented. Thus, the hypothesis that combined application of SiNPs and IAA will be effective in alleviating CrVI toxicity is validated from the results of this study. Moreover, in SiNPs and IAA-mediated mitigation of CrVI toxicity, endogenous NO has a positive role. The importance of the study will be that the combination of SiNPs and IAA can be utilized against heavy metal stress and even when supplied alone, they will enhance the crop productivity parameters with and without stress conditions.
•Evaluation of synergistic action of silica nanoparticles (SiNPs) and indole acetic acid (IAA).•SiNPs and IAA together is capable in mediating CrVI stress in rice seedlings.•CrVI enhanced the levels of reactive oxygen species whereas ROS were detoxified by SiNPs and IAA application under stress.•SiNPs and IAA enhanced tolerance and defence mechanisms of plants.
Our previous study reported that a more dispersed palygorskite (Pal) with a multiparous structure can be fabricated from rigid nano-rods by ion beam bombardment. In this study, the new multiparous ...structure of Pal (MPal) was used to carry a nanocomposite prepared from graphitic carbon nitride (CN) and nano zero-valent iron (NZVI) following a simple thermopolymerisation method for the first time. The as-prepared sample (MPal/NZVI/CN) achieved broader light absorption in the visible light region and low recombination, according to the characterisation results of the UV–vis diffuse reflectance and photoluminescence (PL) spectra of the photocatalysts. The photocatalysis of CrVI and methylene blue (MB) in an aqueous solution by MPal/NZVI/CN revealed that the MPal/NZVI/CN-1:5:6 composites exhibited superior catalytic activity, with CrVI and MB removal efficiencies of 98.48% and 99.2% in 120 min, respectively. Additionally, the reaction rate constants (kCr and kMB) of MPal/NZVI/CN were much higher than those of CN, NZVI/CN, and MPal/CN because the formation of MPal and NZVI composites with CN promoted the separation of photo-generated electron-hole pairs. After four cycles, MPal/NZVI/CN exhibited great photoactivity, which could not only be attributed to the improved dispersion of MPal, but also to the ability of the photo-generated electrons of CN to reduce the FeIII/FeII to Fe0. This study opens new opportunities for modifying photocatalysts using the inorganic nanomaterials readily formed by physical irradiation.
•A new dispersed structure of palygorskite was used to modify a complex.•The complex was based on nano zero valent iron and carbon nitride.•The ternary composite demonstrates improved photocatalytic degradation ability.•Cycle effect in the ternary composite can be improved by the new palygorskite.•The dispersed structure and negative charges of palygorskite play the key roles.
Graphene Oxide (GO) was successfully deposited on TiO2 NPs through sol‐gel process. The fabricated TiO2/GO (T/G) nanocomposite was used for reduction of CrVI under simulated solar light illumination. ...10 wt. % GO was used for the preparation of T/ G nanocomposite. Several analytical methods such as powder X‐ray diffraction (PXRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and UV‐visible diffuse reflectance spectra (DRS) spectrophotometer was used to characterize the samples. The PXRD revealed the formation of the anatase phase of TiO2 NPs and T/G nanocomposites, as per literature more favourable form of TiO2 for photocatalytic activity. The average crystallite size was found 5.1 nm and 23 nm for TiO2 NPs and T/G nanocomposite respectively. Under the simulated sunlight illumination, the TiO2 NPs was excited to generate the electron‐hole pairs and then the photo‐generated electron transferred by the GO to the CrVI which further converted into CrIII. The band gap for T/G nanocomposite was calculated 2.92 eV. Under visible light,27.3 % photoreduction of (10 mg/L) CrVI solution at λmax=347 nm was achieved within 90 min on the T/G sample at the pH 5–6 while overall reduction was 48 % including adsorption. The rate of reaction was found 0.00305 min−1 and the order of reaction was pseudo first order.
Sol‐gel process is used for TiO2/GO (T/G) nanocomposite fabrication and was used for reduction of CrVI under simulated solar light illumination. 10 wt. % GO was used for the preparation of T/ G nanocomposite.. Under the simulated sunlight illumination, the TiO2 NPs was excited to generate the electron‐hole pairs and then the photo‐generated electron transferred by the GO to the CrVI which further converted into CrIII. The band gap for T/G nanocomposite was calculated 2.92 eV. Under visible light,27.3 % photoreduction of (10 mg/L) CrVI solution at λmax=347 nm was achieved within 90 min on the T/G sample at the pH 5–6 while overall reduction was 48 % including adsorption. The rate of reaction was found 0.00305 min−1 and the order of reaction was pseudo first order
A novel spherical anatase TiO2 mesocrystal/SrTiO3 heterojunction with favored CrVI adsorption, bolstered charge carrier separation and well-preserved reduction capability was successfully produced, ...which exhibited enhanced activity toward photocatalytic reduction of CrVI.
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•Spherical anatase mesocrystal/SrTiO3 nanodot type-II heterojunction was prepared.•Favored CrVI adsorption and bolstered charge carrier separation were realized.•The heterojunction showed remarkably enhanced photocatalytic reduction of CrVI.
Mesoporous anatase TiO2 sphere based materials has long been the focus of intensive research dealing with environmental-related issues due to their significant advantages in terms of structural isotropy, high surface area, structural stability, and low cost. However, in most cases, the employed mesoporous anatase spheres were comprised of nanocrystalline subunits with random crystalline orientations, which means that numerous grain boundaries exist in the sphere-shaped particles, suppressing their performance in various applications. Herein, by using mesocrystalline anatase submicrospheres that were synthesized via utilizing SO42- ions to modulate the growth dynamics of anatase crystals in the green mixed solvents of PEG-400 and H2O as both template and reactant, novel sphere-shaped anatase mesocrystal/SrTiO3 nanodot heterostructures were successfully produced. These spherical anatase mesocrystal/SrTiO3 heterostructures exhibited noticeably enhanced activity toward reduction of hexavalent chromium (CrVI) under stimulated solar light irradiation, which was largely attributed to their favored adsorption of CrVI, bolstered photogenerated charge carrier separation and well-preserved reduction capability due to the construction of a well-defined type-II heterojunction with tight interfacial contacts and strong interactions. This work will be useful for the designed fabrication of micro/nanostructured TiO2 based photocatalysts with complex spherical morphologies for photocatalytic applications in environmental purification.
This study investigates the conversion of biotite, a subgroup of clay minerals, into photocatalysts through heat treatment with CaCl2. The resulting reaction products were analyzed in terms of their ...composition, structure, optical properties, and photocatalytic activity against CrVI and salicylic acid (SA). Biotite and CaCl2 mixtures could be heated to 600 °C while retaining the biotite crystal structure, whereas heating to 700 °C resulted in transformation to octahedral wadalite crystals. The band gap of the wadalite obtained after heat treatment was approximately 3.10 eV. The photocatalytic reduction rate per unit surface area increased markedly with increasing heat-treatment temperature, and the CrVI reduction and SA degradation rates of the sample calcined at 800 °C were approximately 18 and 9 times greater, respectively, than those of the sample calcined at 500 °C. Leaching tests of the reaction products revealed that the elution of Ca2+ and Cl− was particularly significant. Even the samples that retained the biotite structure after heat treatment displayed some photocatalytic activity, indicating that this method may be applicable to preparing photocatalysts from mica and related minerals with similar structures.
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•Photocatalytic clays were obtained by easy heat treatment of photo-inert biotite.•The heated biotite demonstrated photocatalytic redox reactions towards CrVI and salicylic acid.•Biotite, a ubiquitous material, could be used as an advanced redox material.
Fe3O4 nanoparticles functionalized polyvinyl alcohol/chitosan magnetic composite hydrogel (Fe3O4-MCH) was successfully synthesized via crosslinking method. The Fe3O4-MCH was explored to be used as an ...adsorbent for removing chromium (Ⅵ) (CrⅥ) from aqueous solution and it exhibited encouraging adsorption performance for CrⅥ both under neutral and acidic conditions. In neutral condition, sharing electron may be one of the possible adsorption reasons, while in acidic condition, the electrostatic attraction was a possible adsorption mechanism. The pseudo-first-order rate model can be well described the adsorption and the equilibrium isotherm was better matched with the Langmuir model. In addition, the swelling ratio of the blank hydrogel was conspicuously higher than that of the hydrogel containing Fe3O4 nanoparticles (Fe3O4 NPs). The loading capacity of CrⅥ on the adsorbent remained at a high level even after five cycles, which showed that the as-prepared hydrogel can be widely used for repeated CrⅥ removal in wastewater in near future.
•The hydrogel was synthesized via combining co-precipitation with crosslinking method.•The as-prepared hydrogel exhibits outstanding adsorption performance for CrⅥ.•The composite hydrogel can be easily separated after the adsorption experiment.•The possible CrⅥ removal mechanism is proposed.
Fabricating a high‐performance photocatalyst to efficiently solve serious environmental problems is an urgent affair. Herein, a series of MoS2/ZnO composites were successfully fabricated through a ...facile hydrothermal route using Na2MoO4, (NH2)2CS and urchin‐like ZnO as precursors. According to the results of XRD and XPS, it was found that ZnS appeared in MoS2/ZnO composite; meanwhile, the content was positively correlated with the weight of the precursor (NH2)2CS. It should be noted that the morphology and the metallic phase content of MoS2 grown in situ on the surface of ZnO were affected by the molar ratio of Na2MoO4 and ZnO. Benefiting from the special dual II heterojunctions of MoS2/ZnS/ZnO ternary composite, the material exhibited excellent charge separation and transfer performances. In the photocatalytic measurements, the MoS2/ZnS/ZnO (Na2MoO4:ZnO 1:2 MZ2) composite not only exhibits excellent photocatalytic CrVI reduction activity of 42.3×10−3 min−1, but also displays remarkable adsorption performance (nearly 32.1 %) for Cr2O2-7
. In addition, the ternary composite shows dominant photocatalytic CrVI reduction activities compared to other photocatalysts. This work provides a high‐efficient MoS2/ZnS/ZnO ternary photocatalyst for environmental treatment.
Photofit: Fabricating a high‐performance photocatalyst to efficiently solve serious environmental problems is an urgent affair. A series of MoS2/ZnO composites were successfully fabricated through a facile hydrothermal route, leading to a highly efficient MoS2/ZnS/ZnO ternary photocatalyst for environmental treatment.
The removal of groundwater contamination is a complex process due to the hydro-geochemical characteristics of the specific site, related maintenance and the possible presence of several types of ...pollutants, both organic and inorganic. In recent decades, there has been an increasing drive towards more sustainable treatment for contaminated groundwater as opposed to “intensive” treatments, i.e. with high requirements for onsite infrastructure, energy and resource use. In this study, a new remediation technology is proposed, combining the use of advanced drainage systems with adsorption processes, termed “In-situ reactive DRAINage system for groundwater TREATment” (In-DRAIN-TREAT). By taking advantage of the groundwater natural gradient, In-DRAIN-TREAT collects the contaminated groundwater via a drainage system and treats the polluted water directly into an active cell located downstream, avoiding external energy inputs. Preliminary results indicate the applicability and high efficiency of In-DRAIN-TREAT when compared with a permeable reactive barrier (PRB). In-DRAIN-TREAT is applied to remediate a theoretical aquifer with low permeability, contaminated by a 13 m wide hexavalent chromium (CrVI) plume. This is achieved in less than a year, via a drain DN500, 32 m long, a 30 m3 treatment cell filled with activated carbon and no energy consumption. A comparison with permeable barriers also shows a preliminary 63% volume reduction, with a related 10% decrease of remediation costs.
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•In-DRAIN-TREAT is a passive in-situ treatment technique for polluted groundwater.•In-DRAIN-TREAT allows for a sustainable remediation of low permeability aquifers.•An aquifer contaminated by hexavalent chromium is considered as case study.•Pollutant transport and adsorption treatment are numerically evaluated via a 3D model.•Compared with PRBs, In-DRAIN-TREAT reduces treatment volume and remediation costs.
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