Simultaneous removal of Cr(III) from high contaminated soil and recovery of lactic acid from the spent solution.

It is proposed a closed-loop treatment cycle for Cr(III) removal from contaminated soils (2080 mg/kg). The treatment includes the use of lactic acid as washing agent, and the recovery of both Cr(II) and lactic acid from the spent solution. Results indicate that Cr(III) removal efficiency can be very high, passing 70% in all tested operative conditions. The metal forms strong complexes with lactic acid, and therefore cannot be eliminated through direct precipitation simply increasing the pH value. Therefore, lactic acid is preliminarily extracted from the solution using n-butanol at very acidic pH. The obtained extraction degree is generally high, varying between 0.5 and 1 according to the amount of used n-butanol solution. After lactic acid extraction, almost 100% of chromium can be recovered through precipitation in alkaline conditions. Lactic acid, in turns, can be purified and reused for a new washing treatment, separating it from n-butanol solution through water extraction. The extraction efficiency is once more satisfying (around 0.5), and not dependent on the operative pH.

Biodegradation, ecotoxicity and UV254/H2O2 treatment of imidazole, 1-methyl-imidazole and N,N'-alkyl-imidazolium chlorides in water.

Imidazole-based compounds are used as reagents for the manufacturing of other compounds including imidazolium-based ionic liquids, which have been recently proposed as a green alternative to conventional solvents. Since some imidazole-based compounds have been demonstrated to be harmful to aquatic organisms, the removal of imidazole, 1-methylimidazole, 1-ethyl-3-methyl-imidazolium chloride and 1-butyl-3-methyl-imidazolium chloride from aqueous solutions was attempted by biological oxidation, direct UV254 photolysis, and UV254/H2O2 process at pH 5.5 and 8.5. Results showed that UV254/H2O2 treatment is an effective tool for the removal of the selected compounds at both pHs. In fact, the kinetic constants of the reaction between the photogenerated HO radicals and the four target compounds, estimated by means of both numerical and competition kinetic method, range between 2.32·109 M-1 s-1 and 5.52 ·109 M-1 s-1. Moreover, an ecotoxicity assessment of the contaminated water before and after initial treatment without further processing was assessed by using two living aquatic organisms: Raphidocelis subcapitata and Daphnia magna. The results of this assessment not only corresponded closely to previous findings (in terms of EC50 values) reported in the literature, but also indicated that, in some cases, UV254/H2O2 oxidation by-products could be even more toxic than parent compounds.

Removal of benzoylecgonine from water matrices through UV254/H2O2 process: Reaction kinetic modeling, ecotoxicity and genotoxicity assessment.

Benzoylecgonine (BE), the main cocaine metabolite, has been detected in numerous surface water and treatment plants effluents in Europe and there is urgent need for effective treatment methods. In this study, the removal of BE by the UV254/H2O2 process from different water matrices was investigated. By means of competition kinetics method, the kinetic constant of reaction between BE and the photogenerated hydroxyl radicals (OH) was estimated resulting in kOH/BE=5.13×10(9)M(-1)s(-1). By-products and water matrices scavengers effects were estimated by numerical modeling of the reaction kinetics for the UV254/H2O2 process and validated in an innovative microcapillary film (MCF) array photoreactor and in a conventional batch photoreactor. The ecotoxicity of the water before and after treatment was evaluated with four organisms Raphidocelis subcapitata, Daphnia magna, Caenorhabditis elegans, and Vicia faba. The results provided evidence that BE and its transformation by-products do not have significant adverse effects on R. subcapitata, while D. magna underwent an increase of lipid droplets. C. elegans was the most sensitive to BE and its by-products. Furthermore, a genotoxicity assay, using V. faba, showed cytogenic damages during the cell mitosis of primary roots.

Energy recovery in wastewater decontamination: simultaneous photocatalytic oxidation of an organic substrate and electricity generation.

The contemporary removal of organic pollutants from aqueous solution and electricity generation is studied in the present work by means of an experimental device resulting from the combination of a photocatalytic reactor and an electrochemical cell. The proposed system relies on the capability of Cu2+ ions to reduce in the presence of TiO2, (solar) UV radiations and a sacrificial organic agent. In the anodic solution of the combined photoreactor-cell, Cu0 is oxidized to Cu2+ and the latter is reduced again to the lowest oxidation state. The use of different sacrificial agents ranging from formic acid (FA) to glycerol (GLY) to glucose (GLU) is investigated along with the adoption of two different cathodes for the cell, the first based again on the couple Cu2+/Cu0 and the second on the couple O2/H2O.

Toxicity of unwanted intermediates and products formed during accidental thermal decomposition of chemicals.

The problem of the formation of unwanted substances that can occur during thermal decomposition of chemicals is studied from a toxicological point of view. Two species, ethyl parathion (a widely used pesticide) and cumene hydroperoxide (an intermediate for the industrial production of phenol and acetone), are selected for this investigation. The hazards associated to their accidental thermal decomposition are estimated on the basis of the (known) intermediates and products formed by means of a computational tool (ECOSAR programme) and assessed experimentally by means of algal bioassays. Green alga Pseudokirchneriella is used as target organism for all the toxicological assessments. The results of these tests on the samples collected during the thermal decomposition of the two studied species indicate that in the case of ethyl parathion the decomposition process gives rise to a mixture of compounds which are more toxic than the parent species. On the other hand, the decomposition of cumene hydroperoxide in cumene results into the formation of different species whose toxicity towards the adopted organism is lower than that shown by the starting compound. A procedure is proposed to ascertain when it is necessary or it is avoidable to carry out further investigations that involve the analytical resolution of mixtures resulting from the thermal decomposition process. This approach is suggested as a preliminary screening to identify the hazards associated with an accidental decomposition either of pure chemicals or of mixtures of compounds.

Batch salicylic acid nitration by nitric acid/acetic acid mixture under isothermal, isoperibolic and adiabatic conditions.

Runaway phenomena and thermal explosions can originate during the nitration of salicylic acid by means of a nitric acid/acetic acid mixture when the thermal control is lost, mainly as a result of the formation and thermal decomposition of picric acid. The prediction of the behaviour of this system is thus of great importance in view of possible industrial applications and the need to avoid the occurrence of unwanted dangerous events. During a previous investigation a model was developed to simulate its behaviour when the starting concentration of the substrate is too low, thus, preventing the precipitation of poor soluble intermediates. In this work this model is extended to deal with more concentrated systems even in case of a solid phase separating during the process. To this purpose the previously assessed dependence of the solubility of 3-nitro and 5-nitrosalicylic acids upon temperature and nitric acid concentration is included in the model. It is assumed that when 3-nitro and 5-nitrosalicylic acids are partially suspended in the reacting medium a kinetic regime of "dissolution with reaction" is established; that is, the redissolution of these species is a fast process compared to the successive nitration to give dinitroderivatives. Good results are obtained in the comparison of the experimental data with those calculated both in isoperibolic and adiabatic conditions when the revised model is used.

Kinetic and safety assessment for salicylic acid nitration by nitric acid/acetic acid system.

The nitration process of salicylic acid for the production of the important intermediate 5-nitrosalicylic acid is studied from thermokinetic and safety points of view. Investigations carried out by considering, as process deviations, the loss of the thermal control point out the possibility of runaway phenomena due to the occurrence of polynitration reactions. Isothermal experiments are carried out in various conditions to assess the involved reaction network and reaction kinetics.

Estimation of biodegradation kinetic constants for aromatic derivates through aerobic batch experiments.

The kinetics of aerobic biodegradation were studied for 20 aromatic species by using sludges taken from a municipal sewage treatment plant. The reproducibility of the results is tested with respect to the period of collection of the sludges and the wastewater treatment plant where they were taken. The comparison of kinetic constants estimated for investigated chemicals allows evaluation of the effect on the reactivity due to the presence of single groups (i.e. -OH, -CH3, -Cl, -NO2) into the aromatic structures. The search for easy structure-reactivity relations is also attempted by using some group contributing methods.

Effects of advanced oxidation processes (AOPs) on the toxicity of a mixture of pharmaceuticals.

The possibility of applying main AOP techniques, namely ozonation, H2O2/UV photolysis and TiO2 photocatalysis to provide a significant reduction of toxicity of pharmaceutical mixtures has been evaluated. For the preparation of the mixture six pharmaceuticals were chosen among those found at highest concentrations in Sewage Treatment Plant effluents, namely carbamazepine, clofibric acid, diclofenac, sulfamethoxazole, ofloxacin and propranolol. The blue-green alga Synechococcus leopoliensis and the rotifer Brachyonus calyciflorus were utilised to assess the toxicity of the mixtures after AOP treatments. All the toxicity tests were performed using chronic standardized bioassays. The best results were obtained with ozonation. With this type of treatment a complete removal of mixture toxicity on S. leopolensis was obtained even after the shortest time of application (1 min). The ozonation treatment leads also to removal of all the pharmaceutical mixture toxicity on B. calyciflorus, by applying the oxidizing agent for at least for 2 minutes.

(S)-Nitroxycarnitine nitrate production from (S)-carnitine by using acetic anhydride/nitric acid/acetic acid mixtures: safety assessment.

The present work aims at assessing both thermodynamic and kinetic parameters of the esterification process of the (S)-carnitine, using calorimetric techniques. The use of the system acetic anhydride/nitric acid/acetic acid as esterifying agent and the explosive behaviour of nitric esters lead to safety considerations that have been investigated by hypothesizing some common process deviations. In particular, it has been investigated in adiabatic conditions both the batch addition of acetic anhydride and the effect of an initial temperature higher than those required by the process.

Kinetic modeling of pyruvic acid ozonation in aqueous solutions catalyzed by Mn(II) and Mn(IV) ions.

The ozonation of pyruvic acid (2-ketopropionic acid) in aqueous solutions, catalyzed by Mn(II) and Mn(IV) ions, has been studied at three different pH values (pH = 1.1, 2.0 and 3.0). A mathematical model of the unsteady operation of the experimental reactor has been developed, which takes into account the reactions occurring in the liquid phase and the ozone mass transfer from the gas bubbles. Those reactions have been described with two alternative kinetic models, both made out of four elementary steps. The two kinetic models correlate the experimental data with a fair accuracy, respectively at the lowest and at the highest pH examined. In particular, at pH = 3.0, the ozonation results are inhibited by the acetate ions produced by the reaction itself. This effect has been correctly described in the terms of a complex formed with the low oxidation-state manganese, which successively reacts with the dissolved ozone.

A kinetic model for the degradation of benzothiazole by Fe3+-photo-assisted Fenton process in a completely mixed batch reactor.

The degradation of benzothiazole in aqueous solution by a photo-assisted Fenton reaction has been studied in a batch reactor in the pH range 2.0 - 3.2 and for H2O2 and Fe(III) concentrations respectively between 1.0 x 10(-3) - 1.5 x 10(-1) and 1.0 x 10(-6) - 4.0 x 10(-6) M. A kinetic model has been developed to predict the decay of benzothiazole at varying reaction conditions. The use of kinetic constants from the literature in the model allows to simulate the system behavior by taking into account the influence of pH, hydrogen peroxide, Fe(III) and sulfate concentrations and the ionic strength.

Ozonation of p-chlorophenol in aqueous solution.

The ozonation of p-chlorophenol (CHP) in aqueous solution has been studied in the pH range 2.0-8.0, in the presence of tert-butyl alcohol, which prevents the activation of the radical mechanism of oxidation. Results indicate that the pH influences the system reactivity and that only a partial chlorine release is observed for lengthy ozonation too, after the complete substrate disappearance. For adopted experimental conditions the oxidation process develops under a quasi-diffusional regime of absorption with reaction, a transition domain between kinetic and diffusional regimes in which ozone and dissolved substances react exclusively in the liquid film. A proper mathematical model has been developed and used to simulate the system behaviour

The thermal decomposition of dimethoate.

The thermal decomposition of dimethoate, an organophosphorus pesticide, has been studied with the aim at assessing the reaction kinetics, the energy released during the process and the decomposition products. Dimethoate shows a marked tendency to undergo thermal decomposition at temperature higher than 369 K. A moderate pressure increase has been recorded at the end of all runs. Many thiophosphoric compounds have been identified among the decomposition products.

Dermatoses among poultry workers: "chicken poison disease".

To investigate the causes of skin eruptions affecting poultry workers, we reviewed our medical records and surveyed a southcentral Pennsylvania poultry processing plant. Examination of the records of routine patch test clinic patients seen from January, 1981, to July, 1982, revealed three poultry workers with allergic contact dermatitis and one with irritant contact dermatitis. We then examined one hundred fifty workers at a poultry processing plant, noting the presence of occupational dermatoses, with special interest in the occurrence of contact dermatitis. We found thirteen dermatoses in nine workers. These included Candida infections, irritant contact dermatitis, allergic contact dermatitis, abrasions and cuts, warts, and dyshidrotic eczema.

Treatment of servere psoriasis with pyrimethamine.

Pyrimethamine, a folate antagonist similar to methrotrexate without known hepatotoxcity in man, was administer orally, once a week, to seven patients with severe, long-standing psoriasis. Four patients obtained a good to excellent response; a fifth withdrew from the study early after a partial response; a sixth had minimal response to high doses, and the seventh was withdrawn due to a probable drug-induced hepatotoxic reaction. Hepatotoxic reaction was suspected in another patient with abnormal liver biopsy and experienced severe gastrointestinal toxic reactions and two developed significant thrombocytopenia, which resolved after oral treatment with folic acid or discontinuation of the drug. These did not recur at lower doses. Pyrimethamine appears to be effective in severe psoriasis, but offers no advantage, and several disadvantages over methotrexate. Pyrimethamine is probably hepatotoxic. It should be used with caution in patients with liver disease or impaired renal function; pretreatment liver biopsy is recommended.