Showing papers in "Annali Di Chimica in 2002"

Electrochemical oxidation of phenol at boron-doped diamond electrode. Application to electro-organic synthesis and wastewater treatment.

Abstract: The electrochemical behaviour of a synthetic boron-doped diamond thin film electrode (BDD) has been studied in acid media containing phenol using cyclic voltammetry and bulk electrolysis. The results have shown that in the potential region of water stability direct electron transfers can occur on BDD surface resulting in electrode fouling due to the formation of a polymeric film on its surface. During electrolysis in the potential region of oxygen evolution, complex oxidation reactions can take place due to electrogenerated hydroxyl radicals. Electrode fouling is inhibited under these conditions. Depending on the experimental conditions, the electrogenerated hydroxyl radicals can lead to the combustion of phenol or to the selective oxidation of phenol to benzoquinone. The experimental results have also been compared to a theoretical model that permits the prediction of the evolution with time of phenol concentration, during its combustion, or during its selective oxidation to benzoquinone.

The use of leaves of Rosmarinus officinalis L. as samplers for polycyclic aromatic hydrocarbons. Assessment of air quality in the area of Palermo.

Abstract: The quantitative analysis of polycyclic aromatic hydrocarbons (PAHs) in vegetables and animals allows us to evaluate the quality of air, in a determined geographic area, without the need of making long samplers with complicate instrumentation. In this work, Rosmarinus officinalis leaves have been used as passive samplers. In particular, this plant was chosen because it is widespread in the Mediterranean area and it is commonly found both in the metropolitan and in the peripheral areas of the city of Palermo. Results for the concentration of total polycylic aromatic hydrocarbons (the sum of the 22 compounds) and the PAHs distribution in leaves from Rosmarinus officinalis are presented. Purified extracts were analyzed by GC-MS.

Quenching of superoxide ions by curcumin. A mechanistic study in acetonitrile.

Abstract: The quenching of superoxide ions, O 2 .- , by curcumin has been studied by electrogenerating this anion radical from oxygen dissolved in acetonitrile solvent (that is, at best, a mimic of the lipofilic layer of biological membranes), containing known amounts of curcumin. Voltammetric tests, combined with coulometric and spectrophotometric measurements, pointed out that each mol of curcumin is able to react with six mols of such anion radical, through a process initiated by an acid-base step, which provides the perhydroxyl radical, HO 2 . , that disproportionates rapidly to the anionic form of hydrogen peroxide, HO 2 - , and oxygen, which is thus partially regenerated. At the same time, curcumin is converted to the corresponding three-charged anion. The strict resemblance existing between the mechanism of the rapid superoxide radical decay caused by curcumin and that involved in the presence of the superoxodismutase enzyme (SOD) is also underlined.

Free and total amino acid composition in blue-green algae.

Abstract: A simple, accurate and reproducible analytical method is described for the extraction and the simultaneous determination of 18 amino acids in different for geographical origin Spirulina alga samples using phenylisothiocianate as derivatizating agent in natural feed. The best experimental hydrolysis conditions have been studied varying the temperature, the time and the hydrolyzing reagent. The separation and the quantitative analysis of the by-products have been carried out by HPLC analysis and UV detection. An amino acid pattern is compared with that proposed by the Food Agriculture Organization (FAO) for an ideal protein and with those of some traditional feed.

Comparison of microwave digestion procedures for the determination of some elements in asphaltite ash using ICP-AES.

Abstract: A microwave digestion procedure for asphaltite ash was developed in an attempt to facilitate routine analysis and obtain reproducible conditions or comparable results. The conditions of the most effective procedure for 0.1 g asphaltite ash samples are 1 ml of HNO3 + 3 ml of HCl + 1 ml of HF + 1 ml of deionized water as acid mixture and 15 min for digestion time. The digestion was accomplished in five stages applying continuously 90% to 20% of the microwave power and 20 to 100 psi of the pressure for 10 min of total time. Concentrations of selected elements, Cr, Co, Fe, Mn, Ni and Zn were measured using inductively coupled plasma-atomic emission spectroscopy. The proposed method of digestion provided precise results with relative standard deviations generally less than 3% for investigated elements. Results for fly ash as standard reference material was in good agreement with certified values.

Optimization of square wave anodic stripping voltammetry (SWASV) for the simultaneous determination of Cd, Pb, and Cu in seawater and comparison with differential pulse anodic stripping voltammetry (DPASV).

Abstract: Square wave anodic stripping voltammetry (SWASV) was optimized for the simultaneous determination of Cd, Pb and Cu in coastal seawater samples. Background subtraction was adapted to improve peak detection and quantification. Optimum background voltammograms were obtained by applying a 7.5 s equilibration potential at -975 mV (vs. Ag/AgCl, 3M KCl) before starting the background scan. Voltammetric scan parameters were optimized to obtain maximum sensitivity while retaining good peak resolution and discrimination from background. Optimal parameters were: frequency 100 Hz, pulse amplitude 25 mV, current sampling delay time 2 ms, step height 8 mV. The sensitivity of optimized SWASV proved to be more than double that of differential pulse anodic stripping voltammetry (DPASV), and analysis time was halved. Samples containing around 13 (Cd), 30 (Pb), 200 (Cu) ng/l (typical averages of the coastal area of the Marche region) can be analyzed using a 5 min deposition time and the total analysis time using three standard additions is about 1 h and half, excluding the mercury film preparation and the outgassing of the sample, which can be made in parallel using a second cell cup.

An EPR study on wastewater disinfection by peracetic acid, hydrogen peroxide and UV irradiation.

Abstract: EPR spectroscopy was applied to obtain qualitative and quantitative information on the radicals produced in disinfection processes of wastewater for agricultural reuse The DEPMPO spin trap was employed to detect hydroxyl and carbon-centered short living radicals in two different peracetic acid solutions and a hydrogen peroxide solution used for water disinfection either in the absence or in the presence of UV-C irradiation Moreover, three different kinds of water (wastewater, demineralized water, distilled water) were analysed in order to assess the contribution of Fenton reactions to the radical production The spectroscopic results were discussed in relation to the efficiency of the different oxidizing agents and UV irradiation in wastewater disinfection evaluated as Escherichia Coli, Faecal and Total Coliforms inactivation

Carbonaceous components in atmospheric aerosol: measurement procedures and characterization.

Abstract: Carbonaceous material in the particulate matter was measured in Rome urban area. The carbonaceous material constitutes a significant component of total aerosol mass (30-40%) and it is composed by two main fractions, elemental carbon (EC) and organic carbon (OC). EC is essentially a primary pollutant emitted directly from incomplete combustion processes whereas OC has both primary and secondary origin. A chemical OC investigation has been carried out in order to determine the n-alkanes, the n-alkanoic acids, the polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs by means an HRGC-MS procedure. A different seasonal distribution of these compound classes attributed to photochemical radical activity (n-alkanes and PAH decrease in spring- and summertime) and to biogenic plant emission (n-alkanoic acid increase in summertime) has been evidenced.

Integral toxicity test of sea waters by an algal biosensor

Abstract: An integral toxicity test, based on an algal biosensor and suitable to be used in sea water, is presented. The biosensor was designed and built by coupling a Clark oxygen electrode as transducer and the marine alga Spirulina subsalsa as biological mediator; it constitutes the "core" in a lab-scale prototype of a flow apparatus suitable to continuously monitor, in sea water, the photosynthetic activity of the alga and, from its variation, the marine pollution from the toxicological point of view. Inorganic pollutants (heavy metals) were tested in previous researches while organic ones (chlorophenols, pesticides and surfactants) are the object of the present paper.

Size characterization of barley starch granules by gravitational field-flow fractionation: a rapid, low-cost method to assess the brewing capability of different strains.

Abstract: Cereal starch occurs as two types of micrometer-sized granules, large and small. Large starch granules are more susceptible to enzymatic hydrolysis. When cereal starch is used for fermentation processes, as in brewing of barley malt, the barley strains with the highest content of large starch granules should be preferred. Gravitational field-flow fractionation (GFFF) is a separation method able to fractionate starch samples at low cost and short analysis time. In this work, the search for the best GFFF conditions for the analytical separation of barley starch within an inter-laboratory approach is presented. For different barley strains cultivated under monitored conditions the size distributions of starch granules is here quickly monitored and characterized by GFFF. As a consequence, dimensional characterization of barley starch can allow for the selection of the most suitable strains with the lowest content of non-degradable starch.

Disposable electrochemical immunosensor for environmental applications.

Abstract: An Immunosensor for the detection of polychlorinated biphenyls (PCB) has been developed, using carbon-based screen-printed electrodes as solid-phase and signal transducers. The immunosensor realised is based on a direct competitive immunoassay scheme, in which the antibody against PCB was directly immobilised onto the carbon surface of the screen-printed electrode. Competition between the PCBs present in the sample and a fixed concentration of an enzyme-labelled congener was realised and evaluated by electrochemical detection. The immunosensor developed was tested on Arochlor mixtures (1242 and 1248), and was applied in environmental and food analysis by testing some real samples (from animal tissues and marine sediments). Results obtained demonstrate the ability of this device to detect PCBs in complex matrices.

The effect of ionic strength on the complexation of copper (II) with salicylate ion.

Abstract: The complexation of Cu 2+ with the hydrogen salicylate, HL - , ion has been studied, at 25°C, by potentiometric measurements with a glass electrode in NaClO 4 media for an ionic strength range from 0.5 to 3 M. The complexes found were CuL, CuL 2 2- and CuHL + . Stability constants, extrapolated to zero ionic strength by using the Specific Interaction Theory were: HL - + H + ± H 2 L, log K 12 ° = 3.03 ± 0.03 Cu 2+ + HL - ± Cu L + H + , log β 1 ° = - 2.37 ± 0.05 Cu 2+ + 2 HL - ⇄ Cu L 2 2- + 2 H + , log β 2 ° = - 8.35 ± 0.05 Cu 2+ + HL - ⇄ CuHL + , log K CuHL ° = 1.8 ± 0.2.

Ecological assessment of Santa Giusta Lagoon (Sardinia, Italy).

Abstract: The general environmental conditions of Santa Giusta Lagoon, an important Sardinian coastal lagoon often affected by dystrophic crises, are examined The study considers both the monitoring data collected over the past ten years on the relevant water quality parameters and the preliminary results on the structure and heavy metal content of the surface sediments of the lagoon These data emphasised its elevated trophic level, due to the excessive presence of plant nutrients in water, and a relative low level of heavy metal contamination At the moment, the eutrophy--brought about the urban and industrial wastes from Oristano and Santa Giusta--can be considered the main environmental issue of the lagoon

Electrochemical oxidation of p-hydroxybenzoic and protocathecuic acids at a dimensional stable anode (DSA) in the presence of NaCl.

Abstract: This work is part of a wider research programme on innovative technologies for industrial wastewater treatment. Results from electrolyses at DSA commercial anodes of synthetic solutions with composition analogous to that of agro-industrial wastes are presented. The results obtained indicate that the rate of degradation of phenolic compounds is high, provided that chloride ions are present in solution. Oxidation of phenolic compounds is faster than that of biodegradable substances, such as sugars or amminoacids. Moreover, investigation on the trend of toxicity during the treatment, seems to exclude that toxic intermediates persist in solution when phenolic compounds are removed. Experiments on olive oil mill wastewater (OMW) samples show that the results obtained from synthetic solutions are extensible to real wastewater. When phenolic compounds are completely removed, the toxicity of the solution is very low; the initial dark colour of the solution, due to the brown pigment which characterises OMW, is nearly completely disappeared.

Oxygen as redox mediator in scanning electrochemical microscopy. Application to the study of localised acid attack of marble.

Abstract: Oxygen from air-saturated aqueous solutions was employed as redox mediator in SECM experiments. Accurate approach curves under negative-feedback conditions were obtained using platinum and gold microelectrodes. Imaging experiments were also carried out, using a 2.5 mum gold microelectrode and oxygen that acted as distance mediator. The topographic images of a glass surface and that of a marble surface prior and after localised acid attack were recorded. High concentrations of hydrogen ions were produced locally, at the microelectrode tip held 3 mum above the marble surface, by applying a large enough positive potential within the oxygen evolution region. Under these conditions, the dissolution of CaCO3 occurred. Pits were produced, and the crater volumes thus obtained were linearly dependent on the electrolysis time.

Treatment options for tannery wastewater II: integrated chemical and biological oxidation.

Abstract: This is the second of two papers each dealing with a specific technological option for replacing the Fenton's reagent with simpler processes for treating industrial wastewater. In particular, the paper reports the results of an investigation aimed to check, at lab scale, the effectiveness of an alternative wastewater treatment combining biological degradation and chemical oxidation with ozone. The treatment was carried out in a lab scale hybrid reactor fed with the biological stage effluent of a plant treating the wastewater of a large tanning district in Central Italy whose residual COD result still higher than the Italian COD Maximum Allowable Concentration (MAC) value (i.e., 160 mgO2/L) The results are very promising, considering that a removal efficiency of 41% (as COD) has been achieved by treating an influent characterized by a COD content fully biorefractory. In addition, the proposed treatment presents the significant advantage of no additional sludge production, as happens with commonly utilized tertiary processes (i.e. Fenton), that is characterized by high chemical sludge production.

Interaction of alkyltin(IV) compounds with ligands of interest in the speciation of natural fluids: carboxylate and hydroxycarboxylate complexes of monomethyltin(IV) trichloride.

Abstract: The formation and stability of some carboxylate and hydroxycarboxylate (acetate, 1,2,3-propanetricarboxylate, 1,2,3,4-butanetetracarboxylate, malate and citrate) complexes of monomethyltin trichloride was studied potentiometrically at 25 degrees C and at different ionic strengths in NaNO3 aqueous solution. The following quite stable species are formed in the different systems (M = CH3Sn3+): ML(OH)+, ML2(OH)0, ML(OH)2(0) and M2L(OH)5(0) for acetate; MLH+, ML0, ML(OH)- and ML(OH)2(2-) for propanetricarboxylate; MLH2+, MLH0, ML-, ML(OH)2- and ML(OH)2(3-) for butanetetracarboxylate; ML(OH)0, ML(OH)2- and ML(OH)3(2-) for malate; ML0, ML(OH)-, ML(OH)2(2-) and ML(OH)3(3-) for citrate. Hydroxycarboxylate complexes are significantly stronger than simple carboxylate ones and this is likely to be due to the interaction of the -OH group in citrate and malate with monomethyltin(IV), whose strength was also quantified. It was found that the stability of these complexes can be roughly expressed by the simple relationship log K = a zeta, where zeta is the product of the charges of reactants and log K is the equilibrium constant. For simple carboxylic ligands we have a = 1.8 +/- 0.4 and, for hydroxycarboxylic ligands, a = 3.7 +/- 0.9. Other useful empirical relationships are reported. Moreover, hydroxycarboxylic complexes also play a prominent role in the speciation of monomethyltin(IV) under the pH conditions of interest for natural fluids.

A new microbial assay for the toxicity detection of contaminated soils.

Abstract: A comparative study to detect toxicity prior to bioremediation treatment was set in order to investigate dehydrogenase activity inhibition of a common soil bacterium caused by soil contaminated with Cu, Pb, and As. A spectrophotometric test with Pseudomonas fluorescens strain ATCC 13525 utilising the 2,3,5-triphenyl tetrazolium chloride (TTC) reduction by microbial dehydrogenase has been adapted for this purpose. Soil samples are incubated for 48 hours at 30±1°C in 18-ml tubes in the presence of TTC as an artificial electron-acceptor. The reduced TTC forms a reddish colour substance named triphenyl formazan (TPF), which can be extracted from the microbial cells and measured colorimetrically. The rapid response of biological activity in microorganisms and the reported sensitivity to the toxicants in the contaminated samples are reflected by the TTC reduction method, which is a sensitive tool for toxicity screening of contaminated sites, routine monitoring of bioremediation processes, as well as for feasibility studies of bioremediation treatments, in order to assess whether a specific pollutant or any other substance at a site location could inhibit the microbiological processes.

Collection and analytical characterisation of the atmospheric particulate in the city of Bari.

Abstract: In this paper an application of new procedures for atmospheric particulate analysis is illustrated. PM10, PAHs (benzo[a]anthracene (BaA), benzo[b]fluoranthene (BbF), benzo[j]fluoranthene (BjF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), indeno[1,2,3-cd]pyrene (Ip), dibenzo[a,h]anthracene (DbA)) and heavy metals (Cu, Ni, Zn, Co, Mn, Cd, Fe and Pb) were investigated. PM10 determination was performed by gravimetric method, PAHs were measured by GC-MS, and heavy metals by HPIC. An air quality monitoring campaign on the territory of Bari municipality has been organised, and its results are shown.

Thermodynamic analysis of the province of Ravenna (Italy).

Abstract: This is a thermodynamic analysis of the Province of Ravenna (Italy) and its districts (Ravenna, Faenza and Lugo) and an evaluation of entropy waste production based on a balance sheet of greenhouse gases. The method used is emergy analysis 1,2 . The results show that the Province and Ravenna are characterized by a heavy exploitation of local non renewable resources, Faenza strikes a good balance between economic development and environment conservation and Lugo is less sustainable than the others. The greenhouse gas balance shows that the Province emits 10.5 times the quantity of greenhouse gases that it adsorbs and that the emissions reduction is required in the energy sector, which is responsible for 92% of the total.

UV and H2O2/UV degradation of a pharmaceutical intermediate in aqueous solution.

Abstract: The degradation of 5-methyl-1,3,4-thiadiazole-2-thiol (MMTD), a pharmaceutical intermediate found in some aquifers of Northern Italy, has been investigated by means of UV and UV/H2O2 treatments. The study has been carried out with a 17 W low pressure mercury lamp at room temperature, using a (100)/(1) (H2O2)/(MMTD) molar ratio. The results have demonstrated that: (i) with an initial MMTD concentration of 1 mg/l, 90% MMTD removal can be achieved within 1 hour or less than 5 minutes by UV or UV/H2O2 respectively; (ii) the sole UV irradiation does not cause any MMTD mineralization; (iii) with an initial MMTD concentration of 50 mg/l, 4 hours of UV/H2O2 treatment lead to an almost complete mineralization of the MMTD organic sulfur and to a partial mineralization of carbon (59%) and nitrogen (14%). The identification of degradation by-products, performed by HPLC-UV-MS analysis, revealed that the sole UV irradiation gives rise to the MMTD transformation into a single by-product that continuously accumulates in the solution. Conversely, the UV/H2O2 treatment forms seven intermediates that undergo further degradation through the breakdown of the thiadiazole ring. On the basis of the obtained results a degradation pathway has been proposed.

Thermodynamic indicators for environmental certification.

Abstract: The Earth is an open thermodynamic system, that remains in a steady state far from the equilibrium, through energy and matter exchanges with the surrounding environment. These natural constraints, which prevent the system from maximizing its entropy, are threatened by human action and our ecosystem needs urgent protection. In this viewpoint the environmental certification was born, according to international standards ISO 14001, ISO 14040, and European Regulation EMAS. These are voluntary adhesions to a program of environmental protection by companies, administrations and organizations which, starting from the respect of the existing environmental laws and regulations, decide to further improve their environmental performance. To obtain and maintain certification of a system is necessary to apply some indicators to evaluate its environmental performance and to demonstrate its progressive improvement. Here we propose to use for this purpose the thermodynamic indicators produced from energy analysis by Odum. The case study is Montalcino city (Italy) and energy indicators are used to evaluate environmental performance of this system where exist different activities, from agricultural productions, to tourism. Results show that energy analysis could become a valid standard monitoring method for environmental certification, especially in consideration of its wide application field.

Validation of different commercially available cholinesterases for pesticide toxicity test.

Abstract: A systematic study of different commercially available cholinesterases (AChEs from electric eel, human erythrocytes, bovine erythrocytes and BuChE from horse serum) for the FIA determination of some frequently used organophosphate (paraoxon, oxydemeton-methyl, triazophos, diazionon) and carbamate (carbofuran, propoxur) pesticides was carried out. Responses of the previously developed photothermal FIA system were found to be dependent on the origin of cholinesterases and properties of tested pesticides. The highest sensitivity was obtained with electric eel AChE and the lowest sensitivity with horse serum BuChE. The LOD values for investigated pesticides correlate with acute toxicities expressed as LD 50 (oral, rat). The presented FIA system could serve as an alternative screening test to evaluate the toxicity of different environmental samples, new cholinesterase inhibiting pesticides or other products (e.g. nerve gases).

Electrocoagulation of textile wastewater bearing disperse dyes.

Abstract: The paper describes a study on the removal of colour from textile wastewater bearing a mixture of three disperse dyes. The experiments were carried out in a reactor equipped with an Al sacrificial anode (100 cm2) and a stainless steel cathode of the same dimensions. Decolorisation occurred as a result of destabilisation of colloids due to an effect of an electric field generated between the electrodes (polarisation coagulation) and the reactions with coagulating compounds, formed in situ during anode oxidation (volumetric coagulation), followed by a subsequent flotation of agglomerates of the particles. During the study the following parameters were varied: initial pH of the solution, current density (between 100 and 300 A m-2) and an initial concentration of the dyes. The best results of elimination of colour, equal to 99%, were obtained during 5 minutes of treatment under the conditions of pH of 9 and the G factor equal to 41.

Selective electrodehalogenation of bromophenols on Ag electrocatalyst.

Abstract: Among the innovative technologies for the detoxification and disposal of industrial effluents, our recently described electroreductive dehalogenation of organic halides on silver electrocatalyst provides a promising route, to be easily "plugged-in" into integrated waste treatments. Although electroreductions do not lead to total substrate mineralization, complete and selective dehalogenation may be achieved by the appropriate choice of the cathode material, thus decreasing the biotoxicity of the waste. In particular the use of silver as electrocatalyst greatly reduces the energy demand, and ensures higher yields and no by-products also when treating highly toxic aromatic halides. In the present work the electrocatalytic role of silver in the electroreductive dehalogenation process has been studied on mono- and polyhalogenated bromophenols, taken as model substrates, both in terms of selectivity of the reaction pathway and of reactivity of the position on the aromatic ring of the bromo leaving group. The results point to the possibility of effectively extending the methodology also to the more common and less reactive chlorinated derivatives.

Sandwich liquid membrane in the separation and concentration of Cu

Abstract: Some tests of mass transport on a sandwich liquid membrane (SwLM) for separation and concentration of Cu++ ion are reported and the results compared with the traditional supported liquid membrane (SLM) system both in terms of stability and flux. Moreover a chemical-physical model was developed evidencing the differences in the mass transport between the two systems studied. The obtained results showed an higher Cu++ flux in the SwLM (110.4 vs. 52.4 mmol/h.m2 referred to the effective pore surface) while lifetime was lower (6 vs. 15 h). The model evidenced a lower overall resistance to Cu++ ions transport through the SwLM than the SLM because the transport in the free solution did not suffer of the pores presence. Use of permanent hydrophilic membranes can improve the SwLM lifetime in view of industrial applications.

Determination of urinary t-t muconic acid as biomarker of environmental benzene intake and its interference factors.

Abstract: The target of our study was the determination of urinary t,t muconic acid concentration, as a biomarker of benzene intake in a population. Urinary samples of 101 subjects, males and females were obtained to whom. Information regarding modification and confounding factors were recorded by questionnaire. The samples were analysed by HPLC, after extraction of trans,trans muconic acid on strong anionic exchange cartridges. In these analytical conditions the detection limit with good care is 10 μg/l. A concentration range from 10 to 1300 μg/l was found. High levels found in the population could explained by confounding factors present. The obtained results were correlated with sex, age and smoking or non smoking. There was a significant difference in mean concentrations between heavy smokers (160 μg/l) and non smokers (110 μg/l), that showed tobacco as an interference factor. The study showed that it is strictly necessary carry out a thorough anamnesis before sampling with the objective of finding eventual interference factors such as smoking, diet and drugs taken.

ASV determination of cadmium complexation in seawater. Methodology evaluation.

Abstract: The methodology for using DPASV to study cadmium complexation in seawater is evaluated using EDTA as a model ligand and by analysing natural samples. The results show that the methodology gives an accurate evaluation of metal complexation when inert complexes are studied, both as regards the ligand concentration and the conditional stability constant; the error for both the parameters is lower than 10% at a ligand concentration of about 10(-8) M and a conditional stability constant of 10(9) M-1. Cadmium complexes with ligands present in natural seawater show an evident kinetic lability that may lead to underestimation of the conditional stability constant when a working electrode characterised by a very thick diffusion layer is used. The conditional stability constant in one water sample of the Adriatic coast ranged between 0.14 and 1.4 l/nmol using a rotating disk electrode at rotation rates of 300 and 6000 rpm. The results of cadmium complexation obtained for samples collected in coastal seawater show that the ligands present low specificity for the metal.

ICP-MS determination of toxic-metal release from pumping systems for food processing.

Abstract: The release of heavy metals from uncovered and nickel-covered brass pumps has been evaluated by ICP-MS analysis in both simple ultrapure water and 3% acetic acid solution (mimic of neutral and acid edible liquids, respectively), following a procedure similar to that recommended by the National Sanitation Foundation (NSF) International, Test Procedure P203. The results found highlight that the main release regards zinc, copper and lead, i.e. the three major metals present in brass alloys. The first contact of brass surfaces with the extraction solvent leads to an extensive Pb release which is comparable with that observed for Cu and Zn. Subsequent washings reduce markedly the Pb release, thus rising in evidence a progressive surface passivation. In particular, the Pb release found after four repeated washings turns out to approach the limit set by both Italian and USA governments for liquids used for food purposes when determined in neutral media, while it remains quite higher when evaluated in acid media. Release analyses conducted on nickel-covered brass pumps point out that the Niploy® nickel coating process is very effective for brass surface protection, in that the Pb release is reduced of about three orders of magnitude, but a Ni release exceeding the relevant permitted level is in this case observed.