Physical and chemical characterisation of crude meat and bone meal combustion residue: “waste or raw material?”

As a result of the recent bovine spongiform encephalopathy (BSE) crisis in the European beef industry, the use of animal by-product is now severely controlled. Meat and bone meal (MBM) production can no longer be used to feed cattle and must be safely disposed of or transformed. Main disposal option is incineration, producing huge amounts of ashes the valorisation of which becomes a major concern. The aim of this work is to characterise MBM combustion residue in order to evaluate their physical and chemical properties to propose new valorisation avenues. The thermal behaviour of crude meat and bone meal was followed by thermogravimetric analysis (TGA) and (24 wt.%) inorganic residue was collected. The resulting ashes were characterised by powder X-ray diffraction (XRD), particle size distribution, specific surface area (BET), scanning electron microscopy (SEM) couple with energy disperse X-ray analysis (EDX). Elemental analysis revealed the presence of chloride, sodium, potassium, magnesium with high level of phosphate (56 wt.%) and calcium (31 wt.%), two major constituents of bone, mainly as a mixture of Ca10(PO4)6(OH)2 and Ca3(PO4)2 phases. The impact of combustion temperature (from 550 to 1000 °C) on the constitution of ashes was followed by TGA, XRD and specific surface measurements. We observed a strong decrease of surface area for the ashes with crystallisation of calcium phosphates phases without major changes of chemical compositio

Ketone Hydrogenation with Iridium Complexes with “non N–H” Ligands: The Key Role of the Strong Base

Ferrocenyl phosphine thioether ligands (PS), not containing deprotonatable functions, efficiently support the iridium catalyzed ketone hydrogenation in combination with a strong base co-catalyst. Use of an internal base ([Ir(OMe)(COD)]2 in place of [IrCl(COD)]2) is not sufficient to insure activity and a strong base is still necessary, suggesting that the active catalyst is an anionic hydride complex. Computational investigations that include solvent effects demonstrate the thermodynamically accessible generation of the tetrahydrido complex [IrH4(PS)]-and suggest an operating cycle via a [Na+(MeOH)3∙∙∙Ir-H4(PS)] contact ion pair with an energy span of 18.2 kcal/mol. The cycle involves an outer sphere stepwise H-/H+ transfer, the proton originating from H2 after coordination and heterolytic activation. The base plays the dual role of generating the anionic complex and providing the Lewis acid co-catalyst for ketone activation. The best cycle for the neutral system, on the other hand, requires an energy span of 26.3 kcal/mol. This work highlights, for the first time, the possibility of outer sphere hydrogenation in the presence of non deprotonatable ligands and the role of the strong base in the activation of catalytic systems with such type of ligands

1-(Diphenyl­phosphinothio­yl)-2-[(4-methyl­phen­yl)meth­oxy­meth­yl]ferrocene

Following our continuing inter­est in developing new chiral phosphine-containing ferrocenyl ligands, we synthesized the title compound, [Fe(C5H5)(C26H24OPS)], in which there are two nearly identical mol­ecules in the asymmetric unit. The conformation of the cyclo­penta­dienyl (Cp) rings in each ferrocenyl group are inter­mediate between eclipsed and staggered, with twist angles of 16.6 (2) and 8.9 (2)°. The protecting S atom is located endo with respect to the substituted Cp ring. In the crystal, mol­ecules are connected through inter­molecular C—H⋯π inter­actions

Characteristics of industrial and laboratory meat and bone meal ashes and their potential applications

This paper reports the characterization of four meat and bone meal (MBM) ashes obtained from specific incineration (laboratory) and from coincineration (industrial process). Three out of the fourMBMashes were mainly composed of calcium phosphates (hydroxyapatite and whitlockite). Their compositions (major and trace) were in the range for natural phosphate rocks. Trace element contents, including heavy metals, were below 0.6% and industrial ashes contained much more heavy metals than laboratory ash. The amounts of leached elements were low, especially for laboratory ash. According to the European classification of waste to be landfilled, the laboratory ash can be classified as an inert waste. Two industrial ashes are mostly inert. Only one ash is highly leachable and needs a stabilization treatment to be classified at least in the category of hazardous waste. It seems, from these results, that possibilities other than landfilling could be considered to give economic value to these ashes. Meat and bone meal ash; Bottom ash; Fly ash; Calcium phosphate; Hydroxyapatite; Whitlockite; Chemical properties; Chemical composition; Heavy metals; Leachin

Spectroscopic characterisation of hydroxyapatite and nanocrystalline apatite with grafted aminopropyltriethoxysilane: nature of silane–surface interaction

Heterogenised homogeneous catalysis is commonly performed with molecular catalysts grafted on solids via adsorption or via a covalent molecular link. Covalent grafting of organic groups on solid supports is usually carried out by silylation, using functionalised trialkoxysilanes. Among these solids supports, very few studies have been published on apatites. In the present work,aminopropyltriethoxysilane (APTES) grafting was performed in toluene on different apatitic supports: crystallised stoichiometric hydroxyapatites differing by the drying method, freeze-dried (HAP) and dried at 100 °C (HAPD), and a nanocrystalline apatite. All materials were fully characterised, before and after grafting, for better understanding of the nature of the alkoxysilane/surface interaction. The data show a clear competition between the covalent grafting of APTES and its polycondensation reaction, depending on the nature of the solid support surface. Silylation is accompanied by APTES covalent grafting to oxygen atom of the hydroxyl groups of the apatitic structure and/or of the OH− species that are present on the surface hydrated layer. This work clarifies the nature of silane grafting onto selected apatitic surfaces and especially the influence of the composition and properties of the apatitic surfaces on the process of silylation

Preliminary study of Lead (Pb) immobilization by meat and bone meal combustion residues (MBMCR) in soil: Assessment of Pb toxicity (phytotoxicity and genotoxicity) using the tobacco model (Nicotiana tabacum var. xanthi Dulieu).

Lead (Pb) is a major chemical pollutant in the environment. The present investigation evaluates the possible use of Meat and Bone Meal Combustion Residues (MBMCR), to sequester Pb from the soil compartment using the heterozygous tobacco model (Nicotiana tabacum var. xanthi Dulieu) characterized by the a1+/a1 a2+/a2 system. The toxic potential of Pbcontaminations(50, 100, 1,000, 2,000 and 10,000 mg Pb kg-1) as Pb(NO3) in standard soil was investigated in lab conditions according to three endpoints: (i) acute toxicity of plants (mortality, height and surface area parameters), (ii) Pb-accumulation in roots, stems and leaves, and (iii) genetic effects as the expression of reversion in the leaf of plants. Moreover, chemical investigations of Pb interactions with soil were realized to complete the toxicity evaluation. The results demonstrated that: (i) MBMCR were not acutely toxic or genotoxic to tobacco plants, (ii) Pb is acutely toxic to tobacco plants at 10,000 mg Pb kg-1 of soil, (ii) but is not genotoxic, and (iii) Pbbioaccumulation is significant in leaves, stems and roots (from 1,000, 2,000, and 50 mg Pb kg-1 of soil, respectively). In contrast, in the presence of MBMCR, the toxic impacts of Pb were inhibited and Pb-accumulation in tobacco plants was reduced. In complement, chemical analyses highlighted the high capacity of the standard soil to immobilize Pb. The results suggest that even if Pb is bioavailable from soils to plants, complex mechanisms could occur in plants protecting them from the toxic impact of Pb

Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N_2)SiMe_3](PEt_3)_3

Reaction of RhCl(PR_3)_n (R = Me (n = 4), Et (n = 3)) and RhCl(CO)(PEt_3)_2 with (trimethylsilyl)diazomethyl lithium at −78 °C in ether yields the three complexes Rh[C(N_2)SiMe_3](PEt_3)_3 (1), Rh[C(N_2)SiMe_3](PMe_3)_4 (2), and Rh[C(N_2)SiMe_3](CO)(PEt_3)_2 (3). 2 could not be isolated as a solid at room temperature but 1 was precipitated as red crystals that were stable enough to be handled under argon. X-ray work on 1 reveals a tetrahedrally distorted square-planar geometry with the planar (trimethylsilyl)diazomethyl ligand roughly perpendicular to the P3RhC coordination plane. This distortion makes the PEt3 ligands nonequivalent in the crystal and produces an ABB‘X pattern in the solid-state ^(31)P NMR spectrum. Photolysis of Rh[C(N_2)SiMe_3](PEt_3)_3 leads quantitatively to the dimer [Rh{C(SiMe_3)(PEt_3)}(PEt_3)_2]_2 (4). The presence of the two ylide bridges and terminal phosphines is deduced from the COSY ^(31)P−^(31)P NMR spectrum. This photochemical reactivity suggests that the transient carbene (PEt_3)_3RhC̈(SiMe_3) is electrophilic, which is typical of a singlet carbene. We believe the singlet state is stabilized by the presence of the electron-rich low-spin Rh(PEt3)3 fragment. Reaction with ^nBuNC and ^tBuNC leads to stereo- and regioselective formation of a triazole that is σ bonded to the rhodium center. The X-ray structure of the ^tBuNC derivative Rh[CC(SiMe_3)N_2N^tBu](^tBuNC)_2(PEt_3) (5) shows a distorted square-planar geometry around Rh with the planar triazolato ligand roughly orthogonal to this plane. The probable reaction mechanism involves addition and substitution reactions of isocyanides at Rh followed by insertion into the Rh−C bond

Transition Metal Diazoalkane Complexes. Synthesis, Structure, and Photochemistry of Rh[C(N_2)SiMe_3](PEt_3)_3

Reaction of RhCl(PR_3)_n (R = Me (n = 4), Et (n = 3)) and RhCl(CO)(PEt_3)_2 with (trimethylsilyl)diazomethyl lithium at −78 °C in ether yields the three complexes Rh[C(N_2)SiMe_3](PEt_3)_3 (1), Rh[C(N_2)SiMe_3](PMe_3)_4 (2), and Rh[C(N_2)SiMe_3](CO)(PEt_3)_2 (3). 2 could not be isolated as a solid at room temperature but 1 was precipitated as red crystals that were stable enough to be handled under argon. X-ray work on 1 reveals a tetrahedrally distorted square-planar geometry with the planar (trimethylsilyl)diazomethyl ligand roughly perpendicular to the P3RhC coordination plane. This distortion makes the PEt3 ligands nonequivalent in the crystal and produces an ABB‘X pattern in the solid-state ^(31)P NMR spectrum. Photolysis of Rh[C(N_2)SiMe_3](PEt_3)_3 leads quantitatively to the dimer [Rh{C(SiMe_3)(PEt_3)}(PEt_3)_2]_2 (4). The presence of the two ylide bridges and terminal phosphines is deduced from the COSY ^(31)P−^(31)P NMR spectrum. This photochemical reactivity suggests that the transient carbene (PEt_3)_3RhC̈(SiMe_3) is electrophilic, which is typical of a singlet carbene. We believe the singlet state is stabilized by the presence of the electron-rich low-spin Rh(PEt3)3 fragment. Reaction with ^nBuNC and ^tBuNC leads to stereo- and regioselective formation of a triazole that is σ bonded to the rhodium center. The X-ray structure of the ^tBuNC derivative Rh[CC(SiMe_3)N_2N^tBu](^tBuNC)_2(PEt_3) (5) shows a distorted square-planar geometry around Rh with the planar triazolato ligand roughly orthogonal to this plane. The probable reaction mechanism involves addition and substitution reactions of isocyanides at Rh followed by insertion into the Rh−C bond

Study of two hydroxyapatite/poly(alkoxysilane) implant coatings

International audienceBioactive hydroxyapatite coatings onto bioinert metallic implants have recently received considerable attention. This work presents a new low-temperature bi-layer hydroxyapatite (HA) coating. First, a thin pre-coating was made with polyalkoxysilanes to promote the adhesion of hydroxyapatite/polyalkoxysilanes composite second layer. In order to optimize the coating cohesion, various parameters were studied such as the metallic support roughness, the nature of alkoxysilanes and the drying temperature of coatings. Two polysiloxanes mixtures were studied: glycidoxypropyltrimethoxysilane (GPS) mixed either with 3-aminopropyltrimethoxysilane (APTS) or with [3-(2-aminoethylamino)propyl]trimethoxysilane (AEAPTS). The results showed that the structural cohesion of the bi-layer coating was achieved by 3D oligomerisation of silanols. Better results were obtained with the GPS/AEAPTS mixture and structural investigations showed no HA structure modification. The advantage of our process is to allow a perfect control of the apatitic phase and to open perspectives such as including biological molecules of pharmaceutical interest during the surface treatment

Crystal structure of (±)-1-({[4-(allyloxy)phenyl]sulfanyl}methyl)-2-(diphenylthiophosphoryl)ferrocene

International audienc