Risk assessment of ammonium salt crystallisation in wax oil hydrogenation cooling exchange equipment

Environmental Fate, Aquatic Toxicology and Risk Assessment of Polymeric Quaternary Ammonium Salts from Cosmetic Uses

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Abedin, J., Beckett, P. and Spiers, G. 2012. An evaluation of extractants for assessment of metal phytoavailability to guide reclamation practices in acidic soilscapes in northern regions. Can. J. Soil Sci. 92: 253-268. Although soil organic matter and nutrient bioavailability in metal-impacted soilscapes of Sudbury, Ontario, are potentially limiting full ecological recovery, total metal content was used as the critical driver for a 2008 ecological risk assessment. The current greenhouse study evaluated chemical extractants to predict bioavailability of nutrients and contaminant metals to indigenous grasses (Deschampsia). Single extraction methods (0.01 M strontium nitrate, water, 0.01 M calcium chloride, 0.1 M sodium nitrate, 1.0 M ammonium nitrate, 0.1 M lithium nitrate, 1.0 M magnesium chloride, 0.11 M acetic acid, 1.0 M ammonium acetate, 0.05 M ammonium-EDTA, pore water) were examined to assess availability of potentially phytotoxic metals and nutrients in smelter-impacted soils. Extraction procedures to predict phytoavailability were either soil concentration or plant tissue concentration and element dependent. Total and extractable metal concentrations were more correlated for regional contaminant metals (e.g., copper, lead, arsenic, selenium) released by the smelting industry than non-contaminant ones (e.g., iron, calcium, potassium, boron, zinc, molybdenum). The lack of relationship between total and extractable concentrations for most non-contaminant metals suggests total concentration is not a good indicator of phytoavailability for nutrient elements. Stronger correlations between shoot tissue and extractable concentrations were observed for less aggressive extractants (pore water, water, lithium nitrate) reflecting their suitability in predicting phytoavailability over most aggressive ones (except ammonium nitrate).

Xenobiotics are continually introduced into the environment and it is very important to draw up an “environmental risk assessment” for these pollutants. Xenobiotics can be persistent and accumulate in the environment or undergo biotic and/or abiotic transformations leading to transformation products. The latter are known as environmental metabolites and may be more toxic and/or persistent than the parent compounds. Therefore, it is important to have information on the xenobiotic behavior in the different compartments (water, atmosphere, soil) as well as on the nature of their transformation products. The photochemical processes play an essential role in the environmental degradation of pollutants. Phototransformation studies may be used in combination with physical chemical properties and data from other studies (abiotic hydrolysis; biotransformation; adsorption/desorption) to help the assessment of the overall environmental transformations and transport of chemical pollutants. The photochemical behavior of a molecule depends on the presence of peculiar functional groups. However, given the heterogeneity and complexity of xenobiotics, it is often difficult to predict or rationalize the photochemical behavior of these molecules. In this PhD thesis the photochemical behavior of some chemical pollutants (mainly drugs and pesticides) under environmental-like conditions has been investigated. The selected xenobiotics are characterized by the presence in the molecular structure of a carbamate function or an indole moiety, two functions present in widely used bioactive compounds. In particular, direct photolysis studies have been carried out on drugs indomethacin, etodolac, loratidine and rivastigmine, on pesticides chlorpropham and phenisopham and on carbamic model compounds. Indirect photolysis of rivastigmine and nicotine have also been investigated. Moreover, for some xenobiotics photochemical experiments in soil have been performed. Direct photolysis studies have led to the determination of phototransformation kinetics, isolation and characterization of photoproducts and interpretation of the involved mechanisms. Investigation on indomethacin, a non-steroidal anti-inflammatory drug (NSAID), has evidenced the role of the aryl portion in the formation of ionic species prior to the decarboxylation, and the results give a further support to the general photodecarboxylation mechanism of arylalkanoic acids. The photochemical oxidative cleavage of C2-C3 bond through the intermediacy of peroxidic species has also been observed, and this supports the tendency of indoles to give self-sensitized photooxygenation. This type of reaction has also been observed for the other indolic drug examined, etodolac. Investigation on rivastigmine and its main human metabolite has evidenced a peculiar photochemical behavior. Both compounds undergo a β-cleavage of the benzylamine moiety resulting in photosolvolysis reaction, previously reported for benzyl ethers or esters. In particular, the photodegradation involves the tertiary amino site and leads mainly to ion-derived products characterized by departure of the Me2N-group. It is reported that amines bearing N-substituents that are capable of stabilizing the formed aminium radicals have lower oxidation potentials as compared to those with N-electron with¬drawing substituents as amides and carbamates. This could account for the unreactivity of the carbamic-N function of rivastigmine as compared with the reactivity of the benzylaminic function. Loratidine is rapidly transformed either under UV-B or by sunlight exposure. In this case the reactive site is the double bond, while the carbamate moiety is unreactive. Pesticides chlorpropham and phenisopham contain a carbamate and a bis-carbamate function, respectively; in phenisopham one of the functions is similarly substituted as in chlorpropham. Neverthless, the two pesticides behave differently: the first one undergoes a nucleophilic photosubstitution of chlorine with water on the aromatic ring, while in phenisopham photo-Fries rearrangements occur involving the cleavage of the N-aryl O-aryl carbamate moiety. However investigation on model compounds evidences that N-aryl O-aryl substitution is not a sufficient condition to have a photo-induced breaking of the carbamate bond. This breaking is completely overcome in the presence of a chlorine on the aromatic ring. Moreover, substitution on the carbamic nitrogen as well as the presence of a N-substituent in the O-aryl moiety appears determinant to accelerate the photo-Fries reaction. All photochemical experiments evidence the determinant role of water. This is probably due to the fact that water can favor photoionization reactions, stabilize ionic intermediates and trap electrophilic species. Indirect photolysis investigations have been performed on rivastigmine and nicotine in Clermont-Ferrand (France) in collaboration with Laboratoire de Photochimie Moléculaire et Macromoléculaire-University Blaise Pascal. The results show that the degradation rate of both compounds depends on the HO• source (H2O2, nitrates, nitrites). Faster degradation has been observed in the presence of nitrates and nitrites and is probably due to reactions between the xenobiotics and photogenerated reactive nitrogen species. For rivastigmine the formation of nitro derivatives has been confirmed by LC-MS. Nitro compounds are often more toxic than the parent compounds, and hence for a complete environmental risk assessment the reactivity toward hydroxyl radical and also toward nitro reactive species that are naturally present in surface waters should be considered. Less satisfying has been the investigation on the photochemistry in soils. Despite the simple synthetic model soils used each compound examined behaves differently depending on the light absorption property and on the formation of saline bonds due to the presence of acidic or basic reactive sites. In addition to these factors in real soils other factors should be considered as the presence of microorganisms or xenobiotics, the type of texture, the pH, etc. In conclusion, the whole of the results give information on the photochemical behavior of different xenobiotics under environmental-like conditions. From a chemical point of view they give a deeper insight into the substituent and solvent effects in the photochemistry of some important compound classes as indoles, benzyl derivatives and carbamates. Therefore, these studies could allow to develop theoretical models for the prediction of the environmental fate of xenobiotics.

Perfluorinated compounds (PFC) are special surfactants which have been used since the 1950s. Their detection in the environment started at the beginning of the 2000s. A lot has to be explored in different fields such as method development, understanding of their environmental distribution, human exposure and their transport to remote areas such as the Artic region. No degradation pathways are known for perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), two predominant perfluorinated compounds in the biota and the environment. Their persistence in the environment emphasized the increasing interest of environmental scientists for this class of pollutant. In this work, besides method development, special attention was paid to the characterization of the isomers present in technical mixtures of PFC and in environmental samples. Methodologies and quantification Methodologies based on high performance liquid chromatography (HPLC) combined with mass spectrometry (MS) with electrospray in negative mode as ionization (ESI(-)) were developed for the analysis of perfluorinated compounds in biota. The extraction procedure consists of an ion pairing extraction using tetra-alkyl ammonium and methyl tert-butylether. Triple quadrupole (TQ) mass spectrometry was better suited for quantification compared to ion trap MS. TQMS enabled the detection of perfluorinated compounds in lower limits of detection (pg range) required for ultra trace analysis. The possibility of systematic errors of the applied methods was investigated. Possible artefacts in the analysis of perfluorinated compounds were identified. One major drawback was the risk of contamination originated by TEFLON®, which can contain perfluorocarboxylic acids. Matrix interference induced also ionization suppression/enhancement and emphasized the still need of method improvement. Moreover, the presence of by-products such isomers and homologues compounds in technical mixtures and in environmental samples make a proper quantification more difficult. Determination of isomer patterns in technical mixture Reversed phase chromatography was used to study the isomer composition of technical PFOS mixtures. Diperfluoromethyl, mono-perfluoromethyl substituted isomers and the linear isomer were identified. Seven isomers present in a technical PFOS mixture could be separated by HPLC. A new derivatization procedure was developed for PFOS and perfluorocarboxylic acids to allow high resolution gas chromatography (HRGC) separation by converting them into iso-propyl esters. An improvement of the separation of eleven PFOS isomers with a maximum of two coeluting isomers was achieved applying HRGC. It offers a promising alternative for the perfluorinated isomers separation in technical mixture. Structural elucidation of PFOS, PFOA and PFOSA monosubstituted isomers was possible applying tandem MS. It allowed the differentiation of up to ten isomers in a technical PFOS mixture. Ion trap tandem MS was more suitable to elucidate the position of the CF3 branching at the perfluorinated chain of monosubstituted PFOS isomers due to more structure-characteristic spectra. Tandem MS spectra of PFOA and perfluorooctanesulfonamide (PFOSA) monosusbtituted isomers were more complex. Only slight differences were observed between their MS/MS spectra due to a different charge stabilization. Currently, the lack of available pure isomer standards limits the isomerspecific analysis. Determination of isomer patterns in technical mixture, water and human blood Finally, the HPLC-MS method for isomer identification in technical mixtures was applied to water and human blood extracts. Isomer profile is indicative of the origin of PFAS contamination. Branched isomers are typical to an electrochemical fluorination (ECF) source, whereas mainly linear structures suggest a telomer source. PFOS detected in human blood collected in Sweden, Australia and United Kingdom was found to be produced by ECF process. However, the sources of PFOA in human were both an ECF and a telomerization processes. Moreover, the comparison of isomer pattern in human blood and water indicated different routes of exposure. The isomers present in technical mixtures were also present in environmental samples. These results showed the potential of isomer pattern for source characterization. This can be useful for risk assessment of humans and other living organisms. However, they could not be completely identified due to insufficient sensitivity. Improvement of the extraction procedure to lower matrix interferences is needed. The development of an alternative GC-MS method combined with a derivatization step could improve separation but not the detection limits due to low derivatization yield. Additional data about isomer patterns in different biota and human bloods from other geographic origins are required for comparison with present results.

Efflorescence and subflorescence are frequent phenomena occurring in buildings of porous inorganic materials such as bricks, stone, and concrete. Since the above phenomena have detrimental effects, they were the subject of detailed physicochemical investigations. Efflorescence on wooden material was commonly observed on collection artefacts treated with preservatives such as inorganic salts or organic pesticides. Occurrence of efflorescence in historical wooden buildings was less studied although it could cause serious conservation concerns. This paper describes an examination of chemical and mineralogical composition of salt efflorescence in wooden buildings. In situ analysis by X-ray fluorescence spectrometry was followed by investigation of plain efflorescence by infrared spectrometry, X-ray diffraction, electron microscopy, and electron probe microanalysis. Quantitative analysis of purified efflorescence was performed by plasma atomic emission spectrometry, ion chromatography and absorption spectrophotometry. In addition, depth-profiling of characteristic ions in wood was performed. The objects of study were a series of log houses of the Sverresborg Trøndelag Folk Museum in Trondheim, Norway. It was found that the efflorescence in these buildings includes a series of metal ions, the most abundant being Al3+, Mg2+, Zn2+, K+, Na+, and Fe2+. In addition the ammonium ion is present in a large amount. The single detected anion is sulfate. Actually, the efflorescence consists of a mixture of simple and double sulfate salts of alum and Tutton’s compound types. Identified Tutton’s compounds are mohrite ((NH4)2Fe(SO4)2·6H2O), ammonium zinc sulfate hexahydrate ((NH4)2Zn(SO4)2·6H2O)), and boussingaultite ((NH4)2Mg(SO4)2·6H2O)). Among the alums, both tschermigite (NH4Al(SO4)2·12H2O), and potassium alum (KAl(SO4)2·12H2O)) were detected. The composition of efflorescence suggests that the wooden material was treated with a blend of sulfate salts ((NH4)2SO4, Al2(SO4)3·18H2O, MgSO4·7H2O, FeSO4·7H2O, ZnSO4·7H2O, and Na2SO4·10H2O)) for protection against fire and biological degradation. The efflorescence appeared as a consequence of water leakage through the roof that led to the dissolution of the salts contained in the wood, followed by evaporation and salt crystallization at the surface in the form of double sulfate salts. Although the occurrence of efflorescence in this case was accidental, a natural and more frequent cause of efflorescence could be the deliquescence of inorganic preservatives impregnated in the wood.

Understanding how climate change accelerates or slows down the process of material deterioration is the first step towards assessing adaptive approaches for the preservation of historical heritage. Analysis of the climate change effects on the degradation risk assessment parameters like freeze-thaw cycles and salt crystallization is also a key parameter when considering mitigating actions. Due to the vulnerability of cultural heritage in Iran to climate change, the impact of this phenomenon on basic parameters like temperature was analyzed. Choosing an appropriate regional climate model is the first and most crucial step in the analysis of climate change effects on heritage. The outputs of two different regional climate models: the ALARO-0- SURFEX model (Ghent University, Belgium) and the REMO model (HZG-GERICS, Germany) were analyzed to find out which model is more adapted to the region. So the focus of this research is mainly on the evaluation process to find a feasible approach for validation study to determine the reliability of each model. For model validation, a comparison between model data and observations was performed for 30 years from 1980-2017. Besides, some climatic parameters which are likely critical for heritage like freeze-thaw cycles were studied to find out how reliable these models are in the field of building pathology.

Understanding how climate change accelerates or slows down the process of material deterioration is the first step towards assessing adaptive approaches for the preservation of historical heritage. Analysis of the climate change effects on the degradation risk assessment parameters like salt crystallization cycles is of crucial importance when considering mitigating actions. Due to the vulnerability of cultural heritage in Iran to climate change, the impact of this phenomenon on basic parameters plus variables more critical to building damage like salt crystallization index needs to be analyzed. Regional climate modelling projections can be used to asses the impact of climate change effects on heritage. The output of two different regional climate models, the ALARO-0 model (Ghent University-RMI, Belgium) and the REMO model (HZG-GERICS, Germany), is analyzed to find out which model is more adapted to the region. So the focus of this research is mainly on the evaluation to determine the reliability of both models over the region. For model validation, a comparison between model data and observations was performed in 4 different climate zones for 30 years to find out how reliable these models are in the field of building pathology.

Groundwater quality and human health assessment in the vicinity of landfills can be performed with the use of numerous index methods. The aim of this paper is to present the results of the Environmental Risk Assessment (ERA) and Health Risk Assessment (HRA) in the vicinity of a municipal landfill complex for monitoring data from 1995, 2003, 2010, and 2021 and in the context of average statistical data about Poles. The calculations take into account an extended range of parameters, including sulphates, chlorides, and ammonium ions. The calculation results for the Horizontal ratio indicate that it should not be used for all parameters. This was mainly reflected in the low sulfate content of the water monitored by a piezometer directly below the old landfill. Other indicators, reaching as high as around 2000 (the Nemerow Pollution Index) or approx. 18,000 (the enrichment factor), confirm the negative impact of the landfill. The Hazard Index values reached almost 700, which would indicate a high risk to human health when consuming water with similar parameters. Overall, the results illustrate that using the selected indices to assess groundwater risk can be a valuable method for supporting long-term observations of groundwater quality, which can be used to make predictions using artificial intelligence methods.

Organic and inorganic nitrogen ions in the environment play important role across environmental matrices. Rainwater samples collected from ambient and different roofing surfaces (zinc, aluminium, asbestos and stone-coated roofing sheets) from selected locations at Ogale, Rumuodomaya/Rumuodome, Diobu and Chokocho within Rivers State, Niger Delta, Nigeria, from April to June, July to August and September to October depicting three regiments of early, mid and late rains. The samples were analysed for Kjeldahl nitrogen, ammonium, nitrate and nitrite using APHA methodology. Quantitative assessment showed that Kjeldahl nitrogen were in range of 0.11 to 28.05mg/L; ammonium 0.50 to 20.22mg/L, nitrate from 0.12 to 22.69mg/L and nitrite from 0.15 to 3.90mg/L. Parameters decreased from early to late rain, which can be attributed to rain dilution factor potential, wind pattern and emission from anthropogenic sources that influenced the rainwater quality across surfaces. Nitrogen results showed that dry and wet deposition has great impact; atmospheric aerosols and biogeochemical interactions can affect water quality. Monthly variation showed that Ogale had high regression compared to other locations due to close proximity to oil and gas emission and marine contribution. Neutralization factor showed that nitrate-nitrite compounds have strong correlation with ammonium ion. Non-carcinogenic risk assessment using US EPA model showed hazard index less than one (1), thus no associated health effect of nitrate and nitrite in rainwater. In conclusion, it is evident that nitrate/nitrite levels and other nitrogen derivatives in rainwater in crude oil-producing Niger Delta and its continuous consumption can cause negative health outcome.

The operation of heat exchange equipment is associated with the formation of scale deposits as a result of the crystallization of calcium and magnesium salts. E ffective sediment removal is still a challenge. The paper presents the results of a study that shows that 10% sulfamic acid dissolves the precipitate up to 46% in the PP-1 chemical water treatment (ChWT) heat exchanger tube, while the average corrosion rate of the heat exchanger tube metal is 0,31 g/m2·h. Deposits from the tubes of the PP-1 ChWT heat exchanger were also subjected to dissolution with hydrochloric acid. A kn own method for producing inhibited hydrochloric acid, including the introduction of a nitrogen-containing corrosion inhibitor. Thiourea was used as a nitrogencontaining inhibitor. According to the results of laboratory tests, it was shown that 20% hydrochloric acid with the addition of thiourea 1%, 5%, 10%, 15% and 20% completely dissolves the precipitate, while the corrosion rate of the metal of the heat exchanger tube was 0,685 g/m2·h, 1,17 g/m2·h, 2,12 g/m2·h, 2,76 g/m2·h, 4,79 g/m2·h. It should be noted the negative effect of zinc present in brass on the protective properties of such corrosion inhibitors as urotropine and thiourea, which show good protective effects on pure metals (iron, copper). This is apparently due to its predominant dissolution from the alloy upon contact with acids and further dissolution of the base metal itself. The optimum protective effect of a corrosion inhibitor of 55,2% was shown on a coppe plate immersed in a solution of 5% hydrochloric acid + 100 mg/d m3 of AZ 8104 inhibitor.

Proper hazard identification has become progressively more difficult to achieve, as witnessed by several major accidents that took place in Europe, such as the Ammonium Nitrate explosion at Toulouse (2001) and the vapour cloud explosion at Buncefield (2005), whose accident scenarios were not considered by their site safety case. Furthermore, the rapid renewal in the industrial technology has brought about the need to upgrade hazard identification methodologies. Accident scenarios of emerging technologies, which are not still properly identified, may remain unidentified until they take place for the first time. The consideration of atypical scenarios deviating from normal expectations of unwanted events or worst case reference scenarios is thus extremely challenging. A specific method named Dynamic Procedure for Atypical Scenarios Identification (DyPASI) was developed as a complementary tool to bow-tie identification techniques. The main aim of the methodology is to provide an easier but comprehensive hazard identification of the industrial process analysed, by systematizing information from early signals of risk related to past events, near misses and inherent studies. DyPASI was validated on the two examples of new and emerging technologies: Liquefied Natural Gas regasification and Carbon Capture and Storage. The study broadened the knowledge on the related emerging risks and, at the same time, demonstrated that DyPASI is a valuable tool to obtain a complete and updated overview of potential hazards. Moreover, in order to tackle underlying accident causes of atypical events, three methods for the development of early warning indicators were assessed: the Resilience-based Early Warning Indicator (REWI) method, the Dual Assurance method and the Emerging Risk Key Performance Indicator method. REWI was found to be the most complementary and effective of the three, demonstrating that its synergy with DyPASI would be an adequate strategy to improve hazard identification methodologies towards the capture of atypical accident scenarios.

Ammonium salt crystallization corrosion failure is an essential problem in the failure of high-pressure hydrogenation heat exchangers. The crystallization equilibrium curves of NH4Cl and NH4HS under different pressures were established according to the ammonium salt crystallization process in the high-pressure hydrogenation heat exchange unit, and the crystallization equilibrium temperatures of NH4Cl and NH4HS were obtained based on Aspen Plus. In addition, a prediction model for the crystallization temperature of ammonium salt was established, then the relationship between crystallization temperature and rate of ammonium salts was elaborated. The results indicate that the initial crystallization temperatures of NH4Cl and NH4HS are respectively 198.95°c and 134.45°c when the system pressure is 10MPa, and the temperature is 433.15K. The maximum crystallization rate of NH4Cl and NH4HS occur at the initial crystallization temperature, respectively 0.104kg/h and 29.23kg/h. The crystallization rate of NH4HS is three orders of magnitude higher than that of NH4Cl.

Salt weathering is one of the most important causes of deterioration in the built environment. Two crucial aspects need further investigation to understand the processes and find suitable measures: the impact of different climatic environments and the properties of salt mixture crystallization. We demonstrate the importance of kinetics in quantifying crystallization and dissolution cycles by combining droplet and capillary laboratory experiments with climate data analysis. The results proved that dissolution times for pure NaCl are typically slower than crystallization, while thermodynamic modelling showed a lower RHeq of NaCl (65.5%) in a salt mixture (commonly found in the built heritage) compared to its RHeq as a single salt (75.5%). Following the results, a minimum time of 30 min is considered for dissolution and the two main RHeq thresholds could be applied to climate data analysis. The predicted number of dissolution/crystallization cycles was significantly dependent on the measurement frequency (or equivalent averaging period) of the climatic data. An analysis of corresponding rural and urban climate demonstrated the impact of spatial phenomena (such as the urban heat island) on the predicted frequency cycles. The findings are fundamental to improve appropriate timescale windows that can be applied to climate data and to illustrate a methodology to quantify salt crystallization cycles in realistic environments as a risk assessment procedure. The results are the basis for future work to improve the accuracy of salt risk assessment by including the kinetics of salt mixtures.

A self-assembled solid-phase extraction column-ultra performance liquid chromatography-tandem mass spectrometer was established for the rapid and effective detection of diazepam in aquatic products from China. Carps, Grass carp, Hypophthalmichthys nobilis, Tilapia, Crucian Carp, Turbot, Shrimp, Hypophthalmichthys molitrix, Catfish and Mussel samples, a total of 50, were extracted using dipotassium hydrogen phosphate solution and acetonitrile, concentrated, and then eluted with acetonitrile-saturated n-hexane. Diazepam showed strong linearity with limits of detection and quantification from 0.03–0.08 μg/kg and 0.10–0.24 μg/kg, respectively. The matrix effect was low, at 5.5–10.9%, with average recoveries between 81.6–113% and relative standard deviations of 0.9–7.5%. Intraday and interday precision ranged from 2.0–5.6%, indicating good sensitivity, precision, and stability of the method for diazepam detection with minimal matrix effect. High-resolution mass spectrometry non-targeted screening was employed to distinguish unpurified from purified samples by visual analyses, such as principal component analysis (PCA), heat maps, and volcanic maps, identifying compounds containing hydroxyl, ester, quaternary ammonium, and phosphoric acid ester groups. The effect of the eluent on the separation mechanism of impurities from the target was also explored. Dietary risk assessment showed hazard quotient (HQ) values between 3.45 × 10−5 and 1.45 × 10−3, well below the threshold of 1, indicating that diazepam residues in aquatic products pose a low and acceptable risk to human health.