Contaminated water with hexavalent chromium Cr(VI) is a serious environmental problem. This study aimed to evaluate the Cr(VI) removal by zero valent iron nanoparticles (nZVI) reduction process and ...the impact of Cr(VI), nZVI and combined treatment with nZVI and Cr(VI) on tomato growth performance. To evaluate the Cr(VI) toxic effect on germination capability, seeds were exposed to increasing Cr(VI) concentrations up to 1000 mg L
. The inhibition of seed germination and the decrease of hypocotyl and root length started from Cr(VI) 5 mg L
. Under treatment with Cr(VI) + nZVI 5 mg L
, seed germination, hypocotyl and root length resulted significantly higher compared to Cr(VI) 5 mg L
treatment. The impact of only nZVI was investigated on chlorophyll and carotenoid in leaves; iron levels in leaves, roots, fruits and soil; carotenoid, fat-soluble vitamin and nicotianamine in mature fruits. A significant increase of leaf chlorophyll and carotenoids was observed after nZVI 5 mg L
treatment compared to controls. No significant variations were observed in carotenoids, fat-soluble vitamins and nicotianamine levels after treatment with nZVI 5 mg L
in mature fruits. For their ability to reduce Cr(VI) and to stimulate tomato growth, nZVI might to be considered as alternative for remediation purposes.
In this work the shrinking core model was used for the mathematical modelling of Cu(II)/Fe(0)-induced chemical denitrification in aqueous system. The nano-zero valent iron particles have already been ...demonstrated their efficiency in the nitrate removal process, and various authors have investigated the influence of several parameters, such as pH and Fe(0)/NO3- molar ratio, on the process. In particular, the addition of a second metal, such as Cu, has proved to improve the kinetic of the overall process, allowing to reduce also the nano-particle surface passivation. The present study reports the classical formulation of the shrinking-core model, applying it to the Fe(0)-Cu(II)/NO3- aqueous system. The static-film simplified hypothesis was assumed and the electrolyte transport equations for dilute system were considered to take into account in the model the influence of other ion species in solution. The model was then employed to fit the experimental data reported in a previous work, in order to estimate the diffusional and kinetic parameter of the process.
The aim of this work was to investigate on the possibility to use nano-magnetite particles supported on waste biomass as heterogeneous catalyst for the production of p-aminophenol starting from a ...well-known pollutant, p-nitrophenol, in fixed-bed reactors. The kinetic and the thermodynamic of the process was firstly studied in batch system, subsequently a first scale-up was performed using a glass column packed with the supported catalyst. The experimental data obtained with the column were interpreted in light of a suitable dynamic model. The Langmuir-Hinshelwood mechanism well described the process, obtaining from the data fitting a surface rate kinetic constant k = 2.68 × 10−6 mol/m2·h, an adsorption equilibrium constants for PNP and BH4− species equal to 20.07 l/mol and 1.83 l/mol, at 25 °C. The Eyring equation was used to fit the apparent kintic constant variation with the temperature, to estimate thermodynamic parameters, obtaining a ΔH = −
1145.68 kJ/mol and ΔS = −315.02 kJ/K·mol. The process was then simulated in PROII environment, investigating the influence of initial PNP flowrate, NaBH4/PNP and reactor length/diameter ratios on PNP conversion, on required duty to maintain isothermal conditions and on pressure drops in the reactor.
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•Supported nano-magnetite were successfully used to catalyse 4-nitrophenol reduction.•Langmuir-Hinshelwood kinetic mechanism was adopted to interpret the kinetic results.•A suitable dynamic model was used to fit the results of fixed-bed experiments.•4-nitrophenol conversion of 0.99 can be achieved at low reagent flowrate and L/D = 9.
This article proposes the aqueous system Cu-Fe(0)/NO3− mathematical modelling through a classical shrinking core model, taking into account the presence of dissolved oxygen in the reaction medium and ...considering it in the model equation. In this work the nitrate reduction to ammonia was assumed to occur onto the lab-made bimetallic nano zero-valent iron (nZVI) surface, simultaneously with the nZVI consumption due to the oxidation carried out by dissolved oxygen. Kinetic tests were performed on synthetic nitrate solutions (0.5, 1, 1.5 mM) at stoichiometric Cu-Fe(0) nanoparticles concentration and the obtained data were interpreted through a bi-component shrinking core model. The nanoparticles were characterized through X-Ray powder Diffraction method at the end of the process to analyse the oxidation of the particles whereas nitrate, oxygen and Fe(0) concentration were monitored at different time steps of the experiments. The nitrate removal efficiency was close to 80% after 90 min of treatment and the oxygen concentration decreased very rapidly from about 8 mg L−1 to the asymptotic value of (<1 mg L−1). A non-linear regression of the obtained kinetic data allowed to estimate the kinetic and diffusional model parameters that were in line with theoretical considerations and experimental evidences.
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•About of 80% nitrate removal efficiency was achieved by Cu-nZVI•Bi-componentshrinking-core model was successful to interpret the experimental data•The Fe(0) oxidation due to dissolved oxygen was considered in the model•Estimated parameter values were in agreement with experimental evidences.
Li-ion batteries are already being used in several applications, from portable devices to the automotive industry, and they represent a promising option also for other critical uses, such as in the ...storage of energy from renewable sources. However, two of the main concerns that still hinder their massive introduction in these further areas, are their safety and reliability. Depending on cell characteristics and operating conditions, the heat generated within the cell can exceed that dissipated from its surface, and the cell will fail, possibly with catastrophic consequences. To identify the hazardous working conditions of a cell, a simulation model including the main exothermic reactions was set up to investigate the onset of thermal runaway in several Li-ion cell configurations under various operating conditions. The behavior of four different cathodes under thermal abuse and the influence of external factors such as the environmental temperature and the cooling system efficiency were assessed. It was found that among those investigated, the lithium iron phosphate cathode is characterized by a higher thermal stability and that an efficient superficial heat exchange can prevent thermal runaway in most of the cases.
Two composite materials were synthesized based on sodium alginate and biochar derived from licorice processing waste functionalized with silicon dioxide nanoparticles (SiO2) and iron oxide (Fe2O3), ...respectively, enabling the valorization of industrial waste. The adsorptive capacities of the two materials (Alg-SiO2 and BCL-Fe2O3) toward CO2 in the gaseous stream with nitrogen were evaluated by acid titration of carbonates present in a trap for CO2 consisting of a KOH solution placed downstream of the adsorption column. The aim of the present work is to evaluate the CO2 adsorption capacity of material functionalized by nanoparticles. Adams–Bohart, Thomas models, and % removal efficiency curves for the adsorption were examined to investigate the dynamic behavior of the column. From the tests performed in CO2 and N2 flow, the BCL-Fe2O3 material was demonstrated to have an adsorbent higher capacity than Alg-SiO2, respectively CO2 adsorbed 25 and 6 mg/g.
According to ISO/TS 80004, a nanomaterial is defined as the “material with any external dimension in the nanoscale or having internal structure or surface structure in the nanoscale”, with nanoscale ...defined as the “length range approximately from 1 nm to 100 nm” ...
In the present paper, a novel composite Graphene–Gold (Gr–Au)/TiO
2
–SiO
2
photocatalyst was synthesized and tested for the removal of methylene blue and rhodamine B in water solutions. First, Gr–Au ...nanoparticle composite was synthesized by simultaneous reduction and deposition of Au nanoparticles on Gr surface. The photodegradation of methylene blue and rhodamine B in aqueous solutions was studied using various photocatalysts, including neat TiO
2
–SiO
2
, Gr/TiO
2
–SiO
2
and Gr–Au/TiO
2
–SiO
2
composites. The Gr weight ratio in this research is 2% in the Gr/TiO
2
–SiO
2
composites. Detailed characterization (field emission scanning electron microscope, Raman, Fourier transform infrared spectra and UV–vis absorbance spectroscopy) of such material was conducted. As a result, the uniform deposition of nanometer-sized Au NPs on the graphene sheets was observed. The Gr–Au/TiO
2
–SiO
2
exhibited excellent photocatalytic efficiency because of the reduction of electron–hole recombination. The Gr2%–Au0.1%/TiO
2
–SiO
2
composite had the highest photoactivity.
Rapid industrialization, technological advancement, and innovation have led to a significant rise in carbon emissions globally, resulting in the growing problem of climate change. With the ...advancement of nanotechnology, the adsorption is becoming an effective strategy to directly capture CO2 with nanomaterials. This mini-review deals with the investigation for physical adsorption, amine-modified nanomaterials for chemisorption, and moisture-swing nanomaterials for chemisorption. The purpose is to highlight the current technologies available for a simple, environmentally safe, non-toxic, low-cost CO2 capture. In detail, this study examines several CO2 capture nanomaterials with an emphasis on economical and environmentally safe low to high temperature solid adsorbents.
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