Desorption of cesium from Fukushima soils using a mechanochemical (MC) method

A mechanochemical (MC) method was employed for the remediation of soil contaminated with fluoranthene (C16H10, FL) a four-ringed polycyclic aromatic hydrocarbon (PAH) containing three benzene rings and a central five-membered heterocyclic ring, with the effects of soil inorganic components, milling conditions, and the degradation mechanism investigated. Results showed that the addition of SiO2 and kaolin to soil resulted in a greater increase in the effectiveness of FL removal than other inorganic additives. After 3 hours of milling at 500 rpm, the FL removal rate from SiO2 containing soil, reached 99.26%, with the removal efficiency increasing in accordance with an increase in milling duration and speed. The milled samples were characterized by FT-IR, Raman spectroscopy, and GC-MS analysis, revealing the mechanism of FL degradation, including destruction of the aromatic skeleton structure and the formation of amorphous carbon and graphite. The MC remediation method was applied to FL contaminated soil, showing that FL was efficiently degraded in soil without any soil additives, resulting in a significant reduction in the biotoxicity of the remediated soil. The organic matter, moisture content and pH of the actual soil changed slightly after mechanical ball milling. Thus, the MC method has high potential in the remediation of PAH-contaminated soils. HIGHLIGHTS A mechanochemical (MC) method for the degradation of fluoranthene was assessed. The use of silica and kaolin as soil additives enhances fluoranthene remediation. Fluoranthene can be efficiently removed from contaminated soil by milling alone. The degradation mechanism was skeleton structure destruction and carbonization. The biotoxicity of soil was significantly reduced by milling.

15 - Materials for lithium-ion batteries by mechanochemical methods

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MgO@SiO2 nanocomposite was synthesized using mechanochemical method and its formation was confirmed by FTIR and Uv-visible spectroscopic techniques. The antibacterial effect of MgO@SiO2 nanocomposite was carriedout on bacterial isolates; gram-positive bacteria (Bacillus subtilis, Klebsiella pneunoniae) and gram-negative bacteria (Pseudomonas aeruginasa, Escherichia coli, and Salmonella typhi) using Agar well diffusion method. The results showed that MgO@SiO2 nanocomposite can find application as antibiotics against the investigated microbes. MgO@SiO2 nanocomposite was synthesized using mechanochemical method and its formation was confirmed by FTIR and Uv-visible spectroscopic techniques. The antibacterial effect of MgO@SiO2 nanocomposite was carriedout on bacterial isolates; gram-positive bacteria (Bacillus subtilis, Klebsiella pneunoniae) and gram-negative bacteria (Pseudomonas aeruginasa, Escherichia coli, and Salmonella typhi) using Agar well diffusion method. The results showed that MgO@SiO2 nanocomposite can find application as antibiotics against the investigated microbes. MgO@SiO2 nanocomposite was synthesized using mechanochemical method and its formation was confirmed by FTIR and Uv-visible spectroscopic techniques. The antibacterial effect of MgO@SiO2 nanocomposite was carriedout on bacterial isolates; gram-positive bacteria (Bacillus subtilis, Klebsiella pneunoniae) and gram-negative bacteria (Pseudomonas aeruginasa, Escherichia coli, and Salmonella typhi) using Agar well diffusion method. The results showed that MgO@SiO2 nanocomposite can find application as antibiotics against the investigated microbes.

Perfluorooctanoic acid (PFOA) is a persistent organic pollutant that has received concerns worldwide due to its extreme resistance to conventional degradation. A mechanochemical (MC) method was developed for complete degradation of PFOA by using alumina (Al2O3) and potassium persulfate (PS) as comilling agents. After ball milling for 2 h, the MC treatment using Al2O3 or PS caused conversion of PFOA to either 1-H-1-perfluoroheptene or dimers with a defluorination efficiency lower than 20%, but that using both Al2O3 and PS caused degradation of PFOA with a defluorination of 100% and a mineralization of 98%. This method also caused complete defluorination of other C3∼C6 homologues of PFOA. The complete defluorination of PFOA attributes to Al2O3 and PS led to the weakening of the C-F bond in PFOA and the generation of hydroxyl radical (•OH), respectively. During the MC degradation, Al2O3 strongly anchors PFOA through COO--Al coordination and in situ formed from Lewis-base interaction and PS through hydrogen bond. Meanwhile, mechanical effects induce the homolytic cleavage of PS to produce SO4•-, which reacts with OH group of Al2O3 to generate •OH. The degradation of PFOA is initiated by decarboxylation as a result of weakened C-COO- due to Al3+ coordination. The subsequent addition of •OH, elimination of HF, and reaction with water induce the stepwise removal of all carboxyl groups and F atoms as CO2 and F-, respectively. Thus, complete defluorination and mineralization are achieved.

Synthesis of Mg–Al–Fe–NO3 layered double hydroxides via a mechano-hydrothermal route

Mechanochemical dehalogenation of brominated flame retardants and preliminary application for recycling BFR-containing plastic waste

Perovskite oxyhydrides have attracted recent attention due to their intriguing properties such as ionic conductivity and catalysis, but their repertoire is still restricted compared to perovskite oxynitrides and oxyfluorides. Historically, perovskite oxyhydrides have been prepared mostly by topochemical reactions and high-pressure (HP) reactions, while in this study, we employed a mechanochemical (MC) approach, which enables the synthesis of a series of ABO2H-type oxyhydrides, including those with the tolerance factor (t) much smaller than 1 (e.g., SrScO2H with t = 0.936) which cannot be obtained by HP synthesis. The octahedral tilting, often present in perovskite oxides, does not occur, suggesting that the lack of π-symmetry of the H 1s orbital and the large polarization destabilize tilted low-symmetry structures. Interestingly, SrCrO2H (t = 0.997), previously reported with the HP method, was not achieved with the MC method. A comparative analysis revealed a correlation between the feasibility of MC reactions and the (calculated) shear modulus of the starting reagents (binary oxides and hydrides). Notably, this indicator is not exclusive to oxyhydride perovskites but extends to oxide perovskites (SrMO3). This study demonstrates that MC synthesis offers unique opportunities not only to expand the compositional space in oxyhydrides in various structural types but also to provide a guide for the choice of starting materials for the synthesis of other compounds.

Present paper reports synthesis of zinc oxide and its application as liquefied petroleum gas sensor. The structural and morphological characterizations of the sample were analyzed by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The average value of crystallite size of ZnO calculated from Scherrer's formula is found to be 50 nm. SEM images exhibit the porous nature of sensing material with a number of active sites. The LPG sensing properties of the zinc oxide were investigated at room temperature for different vol.% of LPG. The variations in electrical resistance were measured with the exposure of LPG as a function of time. The maximum value of sensitivity was found to be 12.3 for 4 vol. % of LPG. These experimental results show that nanostructured zinc oxide is a promising material for LPG sensor.

This project was focused on the design, by means of crystal engineering, of organic molecular solids and on their interactions with light. My research project can be divided into two main themes: i)[2+2] and [4+4] photoreactions in the solid state; ii)Thermo- and photochromic phenomena in salicylidene aniline crystals. A knowledge of how molecules are located in the crystal packing is essential to understand the structure-properties relationships. My investigation was focused on how is possible to tune some properties in crystalline materials by making changes in the crystal packing. I then looked at the relationship between the crystal packing and the effect of the stimulation by light. In both points (i) and (ii) a suitable alignment of molecules in the crystal packing was required. In order to favour photoreactions in the solid-state, it was essential for adjacent double bonds to be parallel and with a distance of maximum 4.2A. In order for thermo- and photochromism in crystals of salicylidene anilines to occur, the main conditions required were “close” and “open” packings, respectively. Crystal packing modifications have been achieved by the use of co-crystallization, salts formation and formation of coordination compounds, both in solution and via mechanochemical methods. Different crystallization methods were used, e.g. liquid diffusion, solvent evaporation, vapour diffusion, crystallization from melt, crystal grow from gel. In some cases, no single crystals have been obtained, thus some compounds have been structurally characterized using powder diffraction data. The solid-state characterization of all the compounds was performed by means of the following techniques: Single Crystal X-Ray Diffraction (SCXRD); Powder X-Ray Diffraction (PXRD); Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC); Infrared (FT-IR and ATR-FTIR) spectroscopy; Solid state absorption and emission spectroscopy (at ISOF-CNR); Scanning Electron Microscopy (SEM) and Raman spectroscopy (in collaboration with UniBO), and NMR spectroscopy (in collaboration with UniTO).

Synthesis and Regeneration of Raney Catalysts by Mechanochemical Methods

Strontium carbonate (SrCO3) is one of the most important strontium compounds that have been used in a variety of technological and industrial applications. In the present investigation, nano-structured strontium carbonate was synthesized by mechano-chemical reaction of celestite ore (SrSO4) collected from Dasht-e kavir, Iran and sodium carbonate during high energy mechanical milling.The milling were performed for different durations of time up to 16 hours in a high-energy planetary ball mill with the rotational speed and ball to powder weight ratio of 300 rpm and 30, respectively. X-Ray diffraction (XRD), X-ray fluorescence spectrometer (XRF) and scanning electron microscope (SEM) were used to characterize the obtained samples. XRD results showed that at a Na2CO3:SrSO4 molar ratio of 1.05:1, mechano-chemical reaction started after 1 hour of milling. Although the longer milling times gives a more conversion of SrSO4 to SrCO3 but it has not been completed even after 16 hours of milling. However, by increasing the molar ratio of Na2CO3:SrSO4 to 1.25:1, the SrCO3 formation was completed after 2 hours. The results also showed that the mean crystallites sizes of produced nano-powder were approximately 32 nm. XRF result indicated that the final product was obtained with a purity of 95 wt.%. SEM studies confirmed the formation of SrCO3 nano-powder with a mean particle size of 80 nm.

Development and application of quantum chemical methods for the description of molecules under mechanical stress

The present study reports the synthesis of N-doped TiO2 photocatalyst for the degradation of caffeine using mechanochemical grinding method from the mixture of titania/urea followed by calcination at 400 ⁰C. The phase composition, particle size, surface area, morphology and optical properties were characterized. The XRD results revealed that anatase is dominant and the size of crystal is decreased from 35.8 to 33 nm after mechanical doping. An improved surface area of 42.9 m2g-1 is also reported. The morphology from SEM also showed a uniform yellow-like powder indicating complete dispersion of nitrogen on the TiO2 surface. The prepared sample showed visible-light absorption in the region 430 nm corresponding to band gap energy 2.88 eV, indicating its potential applications as a visible light induced photocatalyst. Photocatalytic oxidation of caffeine were investigated in 300 minutes irradiation time and N-doped TiO2 demonstrated the higher removal efficiency of 97% compared to commercial TiO2 powder with 91% efficiency at the same experimental condition.

Applying mechanochemical (MC) method to treat waste containing dioxins is our research area. Two fly ash samples are collected from baghouse filters cleaning the effluent of a rotary kiln pyrolysis+ fluidized bed post-combustor and of a simple fixed bed medical waste incinerator (MWI). Dioxins and other organics in fly ash are removed, octa-chlorinated dibenzo-p-dioxin and -furan (OCDD/OCDF) are used to dope the fly ash before their MC treatment in a laboratory developed planetary ball mill. In the case of fly ash from a simple fixed bed MWI, the contents of OCDD and OCDF are decreased by 64.7% and 63.6% respectively and the degree of chlorination decreases from 6.86 to 5.53. The treated fly ash is characterized by a more homogeneous distribution, a significant decrease in overall particle size as well as great enlargement in surface area and significant reduction of the original CaCO3 content. The experimental results show that the MC degradation of dioxins is significant, and certain compounds (CaCO3 et al.) in fly ash may act as dechlorinating reductant (e.g. CaO) in the process. The experiment may be practically helpful for removal of dioxin-like POPs in medical waste incineration fly ash. 660 化 学 学 报 Vol. 70, 2012