CRYSTAL STRUCTURES OF TWO PHOSPHONATE SALTS: MONOCYCLOHEXYLAMMONIUM HYDROGEN PHOSPHONATE AND MONOCYCLOHEXYLAMMONIUM PHENYL PHOSPHONATE

Hydrogen phosphonate anions and monocyclohexylammonium cations interacting through hydrogen bonds conduct to the formation of a salt namely monocyclohexylammonium hydrogen phosphonate. In this structure, hydrogen phosphonate anions are linked by pairs through O—H···O hydrogen bonds leading to anionic dimers. Each dimer is connected to its two neighbours through cations via N—H···O hydrogen bonds leading to infinite chains which are then connected by N—H···O hydrogen bonds giving rise to a layered structure. The phenyl phosphonates form dimers that are connected through an expended hydrogen bonding network involving the cations into a layer

CRYSTAL STRUCTURES OF TWO PHOSPHONATE SALTS: MONOCYCLOHEXYLAMMONIUM HYDROGEN PHOSPHONATE AND MONOCYCLOHEXYLAMMONIUM PHENYL PHOSPHONATE

Hydrogen phosphonate anions and monocyclohexylammonium cations interacting through hydrogen bonds conduct to the formation of a salt namely monocyclohexylammonium hydrogen phosphonate. In this structure, hydrogen phosphonate anions are linked by pairs through O—H···O hydrogen bonds leading to anionic dimers. Each dimer is connected to its two neighbours through cations via N—H···O hydrogen bonds leading to infinite chains which are then connected by N—H···O hydrogen bonds giving rise to a layered structure. The phenyl phosphonates form dimers that are connected through an expended hydrogen bonding network involving the cations into a layer

Anodic oxidation of 4-chlorophenoxyacetic acid on synthetic boron-doped diamond electrodes

The anodic oxidn. of 4-chlorophenoxyacetic acid (CPA) on synthetic B-doped diamond thin film electrodes in acid media was studied, using cyclic voltammetry and bulk electrolysis. The results showed that in the potential region where the supporting electrolyte is stable, reactions occur, resulting in the loss of activity due to electrode fouling. Electrolysis at high anodic potentials in the region of electrolyte decompn. causes complex oxidn. reactions that lead to the complete incineration of CPA. There is no indication of electrode fouling under these conditions. The exptl. were compared with a theor. model. This model is based on the assumption that the electrochem. oxidn. of CPA by electrogenerated hydroxyl radicals is a fast reaction and that the process is diffusion-controlled. [on SciFinder (R)

SYNTHESIS AND CHARACTERIZATION BY INFRARED AND MOSSBAUER SPECTROSCOPIES OF SOME NEW SnR2 (R = Me, Ph, Bu) RESIDUE CONTAINING ARBOXYALKYLPHOSPHONATE ADDUCTS AND DERIVATIVES

Four new carboxyalkylphosphonate SnR2 residue (R = Me, Ph, Bu) containing adducts and derivatives i.e. {(Cy2NH2)3(O2CCH2PO3)(SnBu2Cl2)} (1), {[(SnMe2Cl)(O2CCH2PO3H2)]4[Cy2NH2Cl]} (2), {(Me4N)(SnPh2Cl)[O2C(CH2)2 PO3H](SnPh2)[O2C(CH2)2PO3H]} (3) and {(Cy2NH2)2(O2CCH2PO3H)(SnPh2Cl2)2} (4), have been synthesized from one-pot reactions carried out in solution. All compounds have been investigated by spectral techniques (infrared and Mossbauer). The spectral studies have evidenced presence of several characteristic bands, especially υ (C=O), υ (OH), υ (CO2–), υ (PO32–) vibrations coming from carboxyalkylphosphonate ions, with wide absorption due to the NH2 groups coming from the dicyclohexylammonium counter ion (for 1, 2 and 4) and the intense doublet which show the presence of phenyl groups (for 3 and 4). In the solid state, the proposed structures are discrete or of infinite chain however hydrogen bonding patterns may occur. Event in this investigation is the presence, for compound 3, of two types of arrangement at Sn centers viz. an octahedron and a trigonal bipyramidal whose presence are ascertained by the Mossbauer parameters. The neutral or acidic carboxyalkylphosphonate ions exhibit a diversity of coordination behavior towards the Sn atoms: monochelating (carboxylate and phosphonate O-donor), monochelating through the carboxylate and unidentate coordinating O-donor through the phosphonic acid or acidic phosphonate, bichelating with chelations from carboxylate and acidic phosphonate, and unidentate from both the carboxylate and phosphonic aci

SYNTHESIS AND CHARACTERIZATION BY INFRARED AND MOSSBAUER SPECTROSCOPIES OF SOME NEW SnR2 (R = Me, Ph, Bu) RESIDUE CONTAINING ARBOXYALKYLPHOSPHONATE ADDUCTS AND DERIVATIVES

Four new carboxyalkylphosphonate SnR2 residue (R = Me, Ph, Bu) containing adducts and derivatives i.e. {(Cy2NH2)3(O2CCH2PO3)(SnBu2Cl2)} (1), {[(SnMe2Cl)(O2CCH2PO3H2)]4[Cy2NH2Cl]} (2), {(Me4N)(SnPh2Cl)[O2C(CH2)2 PO3H](SnPh2)[O2C(CH2)2PO3H]} (3) and {(Cy2NH2)2(O2CCH2PO3H)(SnPh2Cl2)2} (4), have been synthesized from one-pot reactions carried out in solution. All compounds have been investigated by spectral techniques (infrared and Mossbauer). The spectral studies have evidenced presence of several characteristic bands, especially υ (C=O), υ (OH), υ (CO2–), υ (PO32–) vibrations coming from carboxyalkylphosphonate ions, with wide absorption due to the NH2 groups coming from the dicyclohexylammonium counter ion (for 1, 2 and 4) and the intense doublet which show the presence of phenyl groups (for 3 and 4). In the solid state, the proposed structures are discrete or of infinite chain however hydrogen bonding patterns may occur. Event in this investigation is the presence, for compound 3, of two types of arrangement at Sn centers viz. an octahedron and a trigonal bipyramidal whose presence are ascertained by the Mossbauer parameters. The neutral or acidic carboxyalkylphosphonate ions exhibit a diversity of coordination behavior towards the Sn atoms: monochelating (carboxylate and phosphonate O-donor), monochelating through the carboxylate and unidentate coordinating O-donor through the phosphonic acid or acidic phosphonate, bichelating with chelations from carboxylate and acidic phosphonate, and unidentate from both the carboxylate and phosphonic aci

Demetallizzazione ecocompatibile di oggetti plastici cromati ed estensione a substrati metallici passivabili

Domanda di brevetto per invenzione industriale PD 2004 A 000106, del 27/04/200

Rimozione di tannini mediante elettrocoagulazione: analisi e simulazione del processo in continuo.

Bench\ue9 l\u2019idoneit\ue0 dei processi elettrochimici per il trattamento di reflui sia largamente documentata in letteratura, la loro applicabilit\ue0 \ue8 fortemente condizionata dai significativi consumi energetici che li caratterizzano. Incoraggianti prospettive in questo settore sono rappresentate dai processi combinati di ossidazione/coagulazione/precipitazione che permettono da un lato di ottenere elevate rese di abbattimento e dall\u2019altro di contenere i costi associati al trattamento. Studi precedenti, condotti dagli stessi Autori su apparecchiature da laboratorio, avevano evidenziato l\u2019efficacia del processo di elettrocoagulazione per la rimozione di tannini. Nel presente lavoro, ai fini della realizzazione di tale processo a livello industriale, ne viene studiato il comportamento su impianto pilota. Sono state dapprima condotte prove in discontinuo con apparecchiature da laboratorio, per individuare le condizioni operative ottimali. Quindi, si \ue8 passati allo studio del processo in continuo su impianto pilota, appositamente progettato e realizzato, che opera in ciclo chiuso fino al raggiungimento delle condizioni ottimali di lavoro e successivamente come sistema aperto, in condizioni di stazionariet\ue0. Modelli matematici formulati per le diverse apparecchiature hanno permesso di simulare l\u2019impianto nelle diverse modalit\ue0 di funzionamento. Il confronto fra i dati sperimentali ottenuti in condizioni di riciclo totale e quelli teorici hanno confermato l\u2019ottima capacit\ue0 di previsione dei modelli sviluppati

Removal of vegetal tannins from wastewater by electroprecipitation combined with electrogenerated Fenton oxidation

Synthetic solutions containing up to 2000 ppm of gallotannic acid and real wastewater from vegetal tanning processes with values of chemical oxygen demand (COD) exceeding 100 000 ppm were decontaminated by electrolysis using a sacrifical iron anode coupled to either a titanium-platinised or an O2-diffusion cathode. Experiments were performed in the presence of oxidants and oxidation promoters such as air, oxygen and hydrogenperoxide, the latter being directly added to the solution or electrogenerated by the O2-diffusion cathode. COD and UV-visible absorbance evolution showed that tannins are removed from electrolysed solutions down to relatively low values, permitting more than 94% elimination. Partial oxididation of the mother compound generates short-chain by-products (mostly carboxylic acids) responsible for the remaining low COD values. Contaminants (tannins and non-tannins) containedin industrial wastewater were removed by combining electroprecipitation with a Fenton-assisted process; a final oxidation step, carried out on a boron-doped diamond electrode, was performed in order to decerase the COD to very low final values

Electro-Fenton_based treatments of real effluents from tanning processes and landfills

Leather industry uses high quantities of water, from 50 to 200 m3 per day, the whole amount of which is usually sent to depuration. At the same time it is noteworthy that tanning processes use large quantities of tannin-based organic compounds, which with all the protein, lipids, greases and hairs, constitute an overcharge of COD (Chemical Oxygen Demand) and BOD (Biological Oxygen Demand) in the tanning effluents. These effluents contain many biorefractory compounds, so low biodegradability index, with COD charge varying from 5000 to 120,000 ppm. This, undoubtedly, causes troubles in the depuration processes. Effective treatment with recycling option of such large quantities of technological waters would: (i) ensure a high diminution in the costs of the entire tanning process (as for that of water consumption and that of salt expenses), (ii) allow to easily depurate the issuing waters with lower costs and (iii) eliminate progressively the negative environmental impact of the final rejects in rivers by reducing considerably (or eliminating) the remaining COD and the quantities of sludge at the end of the depuration process. Depuration sludges are usually stocked in specially conceived landfills. Percolating waters from such landfills contain also high quantities of contaminants, COD from 5000-15000 ppm, and are currently sent to the top of the depuration. Periodical recirculation of the same is done, which, in fact, does not always suffer subsequent treatment. The main process which is presented in this work, Assisted Electroprecipitation, combines physico-chemical aspects of the treatment of water effluents with (electro-)Fenton-based electrochemical oxidation and partial coagulation/precipitation of the ending carbonic compounds. This treatment allows complete COD removal from the effluents. The issued technology is suitable to industrial application specially for the recycling tanning effluents and landfills percolates

A small-scale pilot plant using an oxygen-reducing gas-diffusion electrode for hydrogen peroxide electrosynthesis

A pilot plant for electro-generation of hydrogen peroxide using an oxygen-reducing gas-diffusion electrode (GDE) was built and a mathematical model was developed to simulate the overall system. The electrode was made of a web coated with layers of VULCAN XC-72 Carbon catalyst on both sides of the assembly and a coating of SAB (Shawinigan Acetylene Black) on the gas-side. Electrolyses were carried out in galvanostatic mode, using catholyte consisting of 0.07 M NaCl solution, pH 2.7 and adopting a batch recycle mode of operation. Mathematical analysis was based on a three-phase model, and simulated the evolution of hydrogen peroxide concentration profiles in liquid-filled pores. Various models were developed to represent the behaviour of the cathode compartment in the electrochemical cell. The result is a tool which shows how hydrodynamics affect the performance of the overall system. Hydrogen peroxide production achieved during electrolysis can be calculated by means of this tool. Comparison of numerical simulations against experimental data validated the model developed in this study