M. Annesini

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Papers by M. Annesini

Selective removal of heavy metals by engineered vesicles : a simplified model for uptake kinetics

Annali Di Chimica, 1995

A simplified mathematical model is presented to describe the kinetic behaviour of lipid vesicles ... more A simplified mathematical model is presented to describe the kinetic behaviour of lipid vesicles designed to remove metal ions from dilute solutions. The vescicles contain a selective ionophore in the lipid bilayer and a chelating agent in the aqueous core. The model accounts for the facilitated diffusion of the metal species across the membrane and for the formation of the complex with the chelator. With the analytical relationships developed it was possible to emphasize the combined effect provided by the presence of the selective carrier and the chelating agent. The model can be used to predict the maximum loading capacity of a vesicle and provides useful directions for the optimization of the molecular behaviour of these microscopic devices

Oxygen uptake in the activated sludge process

The present tendency to investigate the principles underlying the activated sludge process of mun... more The present tendency to investigate the principles underlying the activated sludge process of municipal and industrial wastewater treatment is a result of the necessity to progress towards a simulation of the process.1,2 Any modeling requires a rigorous formulation of analytical expressions that allow evaluation of the kinetic and transport parameters as a function of the operating variables. The lack of adequate experimental data, despite the large and qualified literature on the subject, prohibits determination of the in fluence of numerous variables characterizing the biochemical oxidation process. In par ticular, only the concentration of the soluble biodegradable substances (substrate), the na ture and activity of the microbic population by a parameter called "biomass age," and the temperature can be examined.3 The effect of pH and the concentration of secondary nu trients and of dissolved oxygen (do) are neglected. This study is therefore limited to the operat ing co...

Polymer extraction and ex situ biodegradation of xenobiotic contaminated soil: Modelling of the process concept

Journal of Environmental Management, 2019

An integrated model of a two-step process for the ex situ bioremediation of xenobiotic contaminat... more An integrated model of a two-step process for the ex situ bioremediation of xenobiotic contaminated soil has been formulated. The process is characterized by an initial extraction step of the organic contaminants from the polluted soil by contact with inexpensive and commercially-available polymer beads, followed by release and biodegradation of the xenobiotics, with parallel polymer bioregeneration, in a Two-Phase Partitioning Bioreactor (TPPB). The regenerated polymer is cyclically reused in the extraction step, so reflecting the robust and otherwise-inert properties of such polymers. The model was calibrated and validated for a soil contaminated with 4-nitrophenol (4NP) and treated with the DuPont polymer Hytrel 8206. In the model calibration, the partition coefficient polymer-soil, P ps , and the mass transfer coefficient, K, were evaluated, as 105.3 and 0.24 h −1 respectively. A diffusion coefficient within the polymer of 6.3 10 −8 cm 2 s −1 was determined from the fitting of sorption/desorption data. The model was then tested for two alternative process configurations consisting of either one or two soil extraction units, followed by the biodegradation/bioregeneration step. The latter configuration resulted in more effective polymer utilization and is suitable if each extraction step requires a shorter time than the regeneration step. The model predicted that an extraction time of 12 h was sufficient to reach removal efficiencies ≥90% while the biodegradation/bioregeneration step required 24 h to reach efficiencies ≥93%, with a good agreement with experimental data (R 2 > 0.98 for both cases). The simulation of the process operated with two extraction units showed a better performance with a final concentration ∼0.2 g 4NP kg ds −1 vs. 1.69 g 4NP kg ds −1 obtained with single extraction unit, for a soil contaminated with 10 g 4NP kg ds −1. Corresponding extraction efficiencies were 96 and 83%, respectively.

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New solid phase of KNO3 – NaNO3 salt mixtures studied by neutron scattering and differential scanning calorimetry analysis

AIP Conference Proceedings, 2018

With the aim of supporting the thermodynamic modeling of phase equilibria of molten salt mixtures... more With the aim of supporting the thermodynamic modeling of phase equilibria of molten salt mixtures, this article investigates the solid phases present in NaNO 3 and KNO 3 binary mixtures. To that end, an innovative approach based on the combined use of high-temperature Neutron Scattering Analysis and Differential Scanning Calorimetry was proposed. A solid phase not reported before was detected close to the solidus curve in the central part of the phase diagram, and its diffraction pattern was assigned to a mixed nitrate phase, i.e. a solid solution of the two salts.

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Xenobiotic removal from wastewater in a two-phase partitioning bioreactor: Process modelling and identification of operational strategies

Chemical Engineering Journal, 2016

h i g h l i g h t s A dynamic model of a solid-liquid TPPB operated with polymers is proposed. Th... more h i g h l i g h t s A dynamic model of a solid-liquid TPPB operated with polymers is proposed. The model is applied to the biological removal of xenobiotics from wastewater. Sensitivity analysis highlights a critical reaction period determining low/high performance. A case study on 4-nitrophenol removal in a TPPB operated with Hytrel is reported. The model provides a powerful tool to identify operating strategies.

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ChemInform Abstract: Synthesis of Alkylene Carbonates with Alkaline Halides Supported on Activated Carbon

Chemischer Informationsdienst, 1986

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Adsorption kinetics of albumin on ion-exchange resin

Chemical and Biochemical Engineering Quarterly, 1987

A general model for guiding the design of biomechatronic systems implantable into the brain

The First IEEE/RAS-EMBS International Conference on Biomedical Robotics and Biomechatronics, 2006. BioRob 2006.

In the last few years mechatronic implantable drug delivery systems have been found to be suitabl... more In the last few years mechatronic implantable drug delivery systems have been found to be suitable for a large variety of applications for the treatment of pathologies such as cancer, diabetes or neurological diseases. In particular, a large part of the aforementioned pathologies asks for direct drug delivery at brain level. Unfortunately, the field of biomechatronic systems fitted for a

Interaction of cationic phospholipid vesicles with carbonic anhydrase

Biochemistry and molecular biology international, 1994

The possibility of entrapping the enzyme carbonic anhydrase into liposomes, in order to obtain sm... more The possibility of entrapping the enzyme carbonic anhydrase into liposomes, in order to obtain small, membrane-confined bioreactors for biotechnological or biomedical applications, was studied. Neutral liposomes (dipalmitoylphosphatidylcholine/cholesterol) or cationic liposomes (dipalmitoylphosphatidylcholine/cholesterol/stearylamine) with different dipalmitoylphosphatidylcholine/stearylamine ratios have been used to trap carbonic anhydrase. Kinetic experiments showed that carbonic anhydrase was being trapped into cationic liposomes, but not into neutral ones. A significant amount of carbonic anhydrase was sitting onto the external surface of liposomes when the ratio dipalmitoylphosphatidylcholine/cholesterol/stearylamine was 6:3:1, but not when it was 5:3:2. Morphological analysis by electron microscopy showed that the presence of carbonic anhydrase induced a significant swelling in the 6:3:1 cationic vesicles, related to the activity of the enzyme.

Carbon formation in the steam reforming process: a thermodynamic analysis based on the elemental composition

A thermodynamic analysis of the conditions leading to carbon formation on the catalytic bed of me... more A thermodynamic analysis of the conditions leading to carbon formation on the catalytic bed of methane steam reformers is presented. In the first part of the analysis, a closed system in which steam reforming reactions take place is considered, and elemental compositions leading to carbon formation are determined. In the second part, results of an industrial steam reformer simulation are used to locate, inside the reactor, regions with a positive affinity for coke formation.

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Surfactant-induced leakage from liposomes: a comparison among different lecithin vesicles

International Journal of Pharmaceutics, 1999

The interactions, at sublytic concentration, of Triton X-100 and sodium cholate with sonicated an... more The interactions, at sublytic concentration, of Triton X-100 and sodium cholate with sonicated and extruded liposomes of egg and soya lecithins were considered to analyze the integrity and/or the barrier efficiency of liposomal membranes. Results are discussed in terms of surfactant partition between the aqueous and the lipid phases and of the release of a fluorescent hydrophilic probe. Phospholipid nature and liposome size influence detergent partition, whereas the content release is mainly affected by the surfactant mole fraction in the bilayer, and by the liposome size.

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Solids removal efficiency of primary settling tanks in municipal wastewater treatment plants

Water, Air, and Soil Pollution, 1979

Solids removal efficiency of circular primary settling tanks was correlated, on the basis of seve... more Solids removal efficiency of circular primary settling tanks was correlated, on the basis of several literature data, with overflow velocity, solids concentration in incoming flow and the ratio between settling tank diameter and height. Also the reliability of other correlations proposed in the literature was checked by the available data.

Removal of xenobiotics in a two phase sequencing batch reactor: kinetics and modelling

Water Science & Technology, 2008

The objectives of the paper are to verify the potentialities of a sequential two phase partitioni... more The objectives of the paper are to verify the potentialities of a sequential two phase partitioning bioreactor in degrading xenobiotics and to evaluate the kinetic parameters for modelling the system. The target compound investigated was the 4-nitrophenol. Preliminary tests were carried out to define the solvent most appropriate for the compound. Among the three investigated solvents 1-undecanol, 2-undecanon and oleyl alcohol, the 2-undecanon was chosen because of the higher partition coefficient of 30 and the negligible formation of emulsions. Moreover, the tested solvent showed satisfactory “biocompatibility” characteristics for the biomass with minor effects on the intrinsic kinetics. Parallel batch kinetic tests were then performed with the conventional one phase and the two phase systems. In the two phase system the biomass is exposed for all the time to 4NP concentrations that are significantly lower if compared to the conventional system and, for the highest concentration (45...

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Removal of oxygenated pollutants from wastewater by polymeric resins: data on adsorption equilibrium and kinetics in fixed beds

Water Research, 2000

ÐThe aqueous phase adsorption of methyl-tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) onto... more ÐThe aqueous phase adsorption of methyl-tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) onto an Amberlite resin at 208C was investigated under dierent operating conditions. To this end, both batch and ®xed-bed experiments were performed on single solute and bisolute mixtures. The single-solute equilibrium data were ®tted by means of the Freundlich equation and isotherm parameters were determined. The data on bisolute adsorption showed a strong competitive eect between MTBE and TBA, which can be described by means of a theoretical model accounting for the non-ideal behaviour of adsorbed phase. Experimental breakthrough curves were determined for single-solute solutions in order to evaluate the overall mass transfer coecients between liquid and adsorbed phases. A predictive model for multisolute ®xed-bed adsorption is proposed and the theoretical results are compared with experimental data.

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Adsorption of organic compounds onto activated carbon

Water Research, 1987

ABSTRACT Adsorption isotherms of acetone, propionaldehyde, methylisobutylketone and sucrose from ... more ABSTRACT Adsorption isotherms of acetone, propionaldehyde, methylisobutylketone and sucrose from aqueous solutions onto granular activated carbon have been determined.Multi-solute data have been compared with the theoretical prediction obtained from ideal adsorbed solution model.The agreement between calculated and observed results is satisfactory. Only the system sucrosemethylisobutylketone shows significant deviation between experimental and predicted values. Therefore the model can be successfully utilized in design of activated carbon units.

Olive oil mill effluent: Ageing effects on evaporation behaviour

Water Research, 1991

Evaporation and distillation processes have been often used to treat wastewater from olive oil mi... more Evaporation and distillation processes have been often used to treat wastewater from olive oil mill effluent: the effluent COD reduction varies widely with the characteristics of the waste. In this work we report some distillation tests on centrifuged olive oil mill effluent, performed in order to analyse the effect of storage time on the evaporation behaviour of this waste. Experimental data show that the ageing processes cause an increase in the concentrations of volatile compounds. According to a preliminary model such a behaviour can be described in terms of a chemical and a biochemical reaction between a few pseudo-compounds.

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Reduction kinetics of CuO-ZnO

Solid State Ionics, 1993

... of CuO-ZnO M. Cristina Annesini, Roberto Lavecchia, Luigi Marrelli Department of Chemical Eng... more

Kinetics of surfactant-induced release from liposomes: a time-dependent permeability model

Journal of Membrane Science, 2000

The article examines membrane permeabilization and the consequent content release of lipid vesicl... more The article examines membrane permeabilization and the consequent content release of lipid vesicles due to the addition of surfactant. Experimental results show that content release involves a complex kinetics where almost instantaneous release is followed by prolonged slow leakage. The model proposed therefore regards bilayer permeability as varying with the time elapsed from the moment of surfactant addition. A delta function followed by an exponentially decaying profile is assumed for these permeability curves. The effects of surfactant concentration and type (Triton X-100, Tween 20 and Tween 60) can be compared by comparing the fitting parameters of the permeability curves.

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Treatment of substituted phenol mixtures in single phase and two-phase solid–liquid partitioning bioreactors

Journal of Hazardous Materials, 2011

The biological treatment of phenolics is constrained by the inherent cytotoxicity of these compou... more The biological treatment of phenolics is constrained by the inherent cytotoxicity of these compounds. One method to alleviate such toxicity is to add a sequestering phase to absorb, and subsequently release, the substrate(s) to the microorganisms ; such a system is termed a Two Phase Partitioning Bioreactor. Here we have compared the performance of a TPPB, relative to single phase operation, in which a small volume (5%, v/v) of beads of the polymer Hytrel 8206 was used to treat aqueous mixtures of 2,4-dimethylphenol and 4-nitrophenol. Hytrel 8206 was selected from a range of polymers that were tested for their partition coefficients (PCs) for the target molecules, with the more hydrophobic compound (2,4-dimethylphenol) having a higher PC value (201) than 4-nitrophenol (143). Significantly increased removal rates for both substrates were demonstrated in TPPB mode relative to single phase operation. Additionally, the differential release of the compounds to the aqueous phase and their distinct PC values changed the kinetic pattern of the biotreatment system, smoothing out the cellular oxygen demand. Release of the substrates by the polymer over 60 operating cycles was virtually complete (>97%) demonstrating the reusability and robustness of the use of polymers in overcoming cytotoxicity of phenolic substrates.

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Excess enthalpy and T-x data of aromatic-propylene carbonate mixtures

Journal of Chemical & Engineering Data, 1984

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