Showing: 10 from total: 2401 publications
31. Research on the volatility, phase transitions and thermodynamic stability of five organochlorine compounds
Almeida, RRP ; Pinheiro, DA ; Monte, JS
in Chemosphere, 2024, ISSN: 0045-6535,  Volume: 351, 
Article,  Indexed in: crossref, scopus, unpaywall 
Abstract The present investigation describes the experimental evaluation of relevant physicochemical properties of five organochlorine compounds (OCs), including some that are related to their environmental mobility. The vapor pressures of (2,4′-Dichlorodiphenyl)dichloroethane (2,4′-DDD, CASN:53-19-0), 1,1-Dichloro-2,2-bis(4-chlorophenyl)ethane (4,4′-DDD, CASN:72-54-8) and 2,2-Bis(4-chlorophenyl)acetic acid (4,4′-DDA, CASN:83-05-6), as well as of the bactericide Nitrapyrin (CASN:1929-82-4) and of the rodenticide Crimidine (CASN:535-89-7) were determined at different temperatures. The Knudsen mass-loss effusion technique was employed to determine the sublimation vapor pressures of the referred compounds, apart from Crimidine. For the latter compound, a static method using a capacitance diaphragm manometer enabled the measurement of vapor pressures of both condensed (crystalline and liquid) phases. This technique was also used to measure the vapor pressures of the crystalline phase of Nitrapyrin over a larger temperature range, as well as its vaporization vapor pressures. The results of the standard molar enthalpies, entropies, and Gibbs energies of sublimation for all five compounds and of vaporization for Crimidine and Nitrapyrin, at reference temperatures, were derived. For these two compounds the phase diagram representations of the (p,T) results, in the vicinity of the triple point, were obtained. DSC analysis enabled the determination of the crystalline heat capacities of the five OCs studied and also of their temperatures and enthalpies of fusion. Gas-phase thermodynamic properties were estimated using quantum chemical calculations. The thermodynamic stability of the compounds studied was evaluated and compared in the crystalline and gaseous phases, at 298.15 K, in consideration with estimated results of the standard Gibbs energies of formation. Combined with other physical and chemical properties, the results derived from this study can be used to predict the mobility, and environmental fate of these pollutants. © 2024 Elsevier Ltd

32. Thermochemical Research on Furfurylamine and 5-Methylfurfurylamine: Experimental and Computational Insights
Amaral, LMPF ; Almeida, ARRP ; da Silva, MAVR
in MOLECULES, 2024, ISSN: 1420-3049,  Volume: 29, 
Article,  Indexed in: crossref, scopus, unpaywall, wos 
Abstract The need to transition from fossil fuels to renewables arises from factors such as depletion, price fluctuations, and environmental considerations. Lignocellulosic biomass, being abundant, and quickly renewable, and not interfering with food supplies, offers a standout alternative for chemical production. This paper explores the energetic characteristics of two derivatives of furfural-a versatile chemical obtained from biomass with great potential for commercial sustainable chemical and fuel production. The standard (p degrees = 0.1 MPa) molar enthalpies of formation of the liquids furfurylamine and 5-methylfurfurylamine were derived from the standard molar energies of combustion, determined in oxygen and at T = 298.15 K, by static bomb combustion calorimetry. Their standard molar enthalpies of vaporization were also determined at the same temperature using high-temperature Calvet microcalorimetry. By combining these data, the gas-phase enthalpies of formation at T = 298.15 K were calculated as -(43.5 +/- 1.4) kJmol-1 for furfurylamine, and -(81.2 +/- 1.7) kJmol-1 for 5-methylfurfurylamine. Furthermore, a theoretical analysis using G3 level calculations was performed, comparing the calculated enthalpies of formation with the experimental values to validate both results. This method has been successfully applied to similar molecules. The discussion looks into substituent effects in terms of stability and compares them with similar compounds.

33. Application of Engineered Nanomaterials as Nanocatalysts in Catalytic Ozonation: A Review
Cardoso, RMF ; da Silva, JCGE ; da Silva, LP
in MATERIALS, 2024, ISSN: 1996-1944,  Volume: 17, 
Review,  Indexed in: crossref, scopus, unpaywall, wos 
Abstract Given the growing scarcity of water and the continuous increase in emerging pollutants detected in water bodies, there is an imperative need to develop new, more effective, and sustainable treatments for wastewater. Advanced oxidation processes (AOPs) are considered a competitive technology for water treatment. Specifically, ozonation has received notable attention as a promising approach for degrading organic pollutants in wastewater. However, different groups of pollutants are hardly degradable via single ozonation. With continuous development, it has been shown that using engineered nanomaterials as nanocatalysts in catalytic ozonation can increase efficiency by turning this process into a low-selective AOP for pollutant degradation. Nanocatalysts promote ozone decomposition and form active free radicals responsible for increasing the degradation and mineralization of pollutants. This work reviews the performances of different nanomaterials as homogeneous and heterogeneous nanocatalysts in catalytic ozonation. This review focuses on applying metal- and carbon-based engineered nanomaterials as nanocatalysts in catalytic ozonation and on identifying the main future directions for using this type of AOP toward wastewater treatment.

34. Phase transition study of bathophenanthroline and bathocuproine: A multitechnique approach
Ferraz, JMS ; Romagnoli, L ; Brunetti, B ; Ciccioli, A ; Ciprioti, SV ; Freitas, VLS ; da Silva, MDMCR
in JOURNAL OF CHEMICAL THERMODYNAMICS, 2024, ISSN: 0021-9614,  Volume: 198, 
Article,  Indexed in: crossref, scopus, wos 
Abstract The thermal behaviour of bathophenanthroline and bathocuproine has been studied using several techniques, namely, differential scanning calorimetry and thermogravimetry. To determine their respective enthalpies of sublimation, vapor pressure measurements were carried out using different methods, such as Knudsen effusion mass loss/mass spectrometry, isothermal thermogravimetry, and a quartz crystal microbalance technique. Furthermore, the enthalpies of sublimation were determined by measuring the heat change of the sublimation process using high-temperature Calvet microcalorimetry. The results obtained in this work allowed the determination of the standard molar enthalpies of sublimation at 298.15 K, for bathophenanthroline and bathocuproine. The values obtained were (183.8 +/- 2.2) kJ & sdot;mol- 1 and (206.2 +/- 2.8) kJ & sdot;mol- 1, respectively. Additionally, the standard molar enthalpies of fusion were determined to be (30.4 +/- 0.4) kJ & sdot;mol- 1 and (26.5 +/- 1.6) kJ & sdot;mol- 1 for bathophenanthroline and bathocuproine, respectively. The analysis of the results allows a deeper understanding of the phase transition behavior for these compounds from the condensed to the gaseous phases, elucidating molecular decomposition and the inherent intermolecular forces governing the species.

35. Concentrations of Potentially Toxic Elements in Topsoils of Urban Agricultural Areas of Rome
Chandramohan, MS ; da Silva, IM ; da Silva, JE
in ENVIRONMENTS, 2024, ISSN: 2076-3298,  Volume: 11, 
Article,  Indexed in: crossref, scopus, wos 
Abstract Urban agricultural soils have important social, environmental, and economic roles in big cities, contributing to their sustainability. However, food production in urban soils may be compromised due to soil pollution that resulted from decades of industrial, non-regulated environmental activity and mobile transport. In this study, 12 soils from the urban agricultural area of Rome (Italy) were analyzed for the potentially toxic elements (PTEs) Be, Ba, Pb, Co, Ni, V, Zn, Hg, Cd, As, Cu, and Cr. All but one of the soils under analysis were characterized by at least one PTE concentration above the threshold limit defined by the D.Lgs 152/06 for agricultural soils. Multivariate analysis showed that the soils could be classified into five clusters: clusters I and II had relatively lower mean PTE concentrations; clusters III, IV, and V had relatively higher mean PTE concentrations with several PTE concentrations above the threshold proposed by ILD. Three factors contributing to the variability of the PTE's concentration in the soils under investigation were identified: a geological factor related to PTE As, Ba, Be, and V; an anthropogenic factor related to Pb and Cu; and a mixed factor related to Co, Cr, Ni, and Zn. High PTE content may limit the utilization of urban soils for food production.

36. Metal Concentrations in Topsoils of Urban Agricultural Areas of Rome
Chandramohan, MS ; Silva, IM ; Marinari, S ; Marabottini, R ; Silva, JEd
2024,
Unpublished,  Indexed in: crossref 
Abstract <jats:p>Urban gardens have important social, environmental and economic roles in big cities, contributing to their sustainability. However, food production in urban gardens may be compromised due to soil pollution that resulted from decades of industrial non-regulated environmental activity and mobile transport. In this study, 12 soils from the urban agricultural area of Rome (Italy) were analyzed for the metals Be, Ba, Pb, Co, Ni, V, Zn, Hg, Cd, As, Cu, and Cr. All but one of the soils under analysis were characterized by at least one metal concentration above the threshold limit defined by the Italian Legislative Decree 152/2006 (ILD) for agricultural soils. Multivariate analysis showed that the soils could be classified into five clusters: clusters I and II had relatively lower mean metal concentrations; clusters III, IV, and V had relatively higher mean metal concentrations with several metal concentrations above the threshold proposed by ILD. Three factors contributing to the variability of the metal’s concentration in the soils under investigation were identified: geological factor, related with metals As, Ba, Be, and V; anthropogenic factor, related with Pb and Cu; and, a mixed factor related with Co, Cr, Ni, and Zn. High metal content may limit the utilization of urban soils as urban gardens for food production.</jats:p>

37. Environmental Stressors of Mozambique Soils Quality
Pereira, MJ ; Esteves da Silva, JC
2024,
Unpublished,  Indexed in: crossref 
Abstract <jats:p>Mozambique is one of the poorest countries of the world. However, it has natural resources and if they are managed under sustainable development principles, Mozambique can overcome the current problems. In the present socio-economic status, soil is one of its most important resources and must be protected from pollution and from degradation. This review focuses on the identification and discussion of the main soil quality stressors, namely: soil fertility; deforestation and its sources: agriculture, timber harvesting, charcoal production and uncontrolled fires; mining activities, manly gold artisanal explorations and industrial open-pit coal mining. The sustainable use of the natural resources is mandatory to allow future generations to continue profiting for this nature-based wealth.</jats:p>

38. Assessment of the Quality of Agricultural Soils in Manica Province (Mozambique)
Pereira, MJSL ; da Silva, JE
in ENVIRONMENTS, 2024, Volume: 11, 
Article,  Indexed in: crossref, scopus, wos 
Abstract Agriculture is the main economic activity of Mozambique and there is a lack of information about the quality of agricultural soils. In this paper, five soils from the Manica and Sussundenga districts (Manica province) sampled in the years 2021/2022 and 2022/2023 (before and after the rainy seasons) were subjected to an agronomical and environmental chemical analysis to assess their quality, from the fertility and environmental contamination points of view. Standard analytical methodologies from external certified laboratories and local X-ray fluorescence measurements were used. All the studied soils were acidic (pH ranging from 4.5 to 5.4), had no salinity problems (conductivity ranging from 4.2 to 11.8 mS/m), and had a low amount of soil organic matter (0.90% to 1.81%). Soils from the Sussundenga district had a very low cation exchange capacity (CEC) (average of 3.33 cmol(c)/kg), while that of those from the Manica district ranged from very low to average CEC (3.59 to 13.11 cmol(c)/kg). Sussundenga soils also had a phosphorous deficiency (values ranging from <20 to 38.5 mg/kg) and there were deficiencies and/or excesses of some macro and micronutrients in all soil samples. Manica soils were contaminated, apparently from geogenic origin, with Cr (280 to 1400 mg/kg), Co (80 mg/kg), Ni (78 to 680 mg/kg) and V (86 mg/kg). Agricultural soil monitoring must be fostered in Mozambique in order to improve food quality and quantity to ensure economic and environmental sustainability.

39. Photodynamic activation of phytochemical-antibiotic combinations for combatting Staphylococcus aureus from acute wound infections
Gonçalves, ASC ; Leitao, MM ; Fernandes, JR ; Saavedra, MJ ; Pereira, C ; Simoes, M ; Borges, A
in JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY, 2024, ISSN: 1011-1344,  Volume: 258, 
Article,  Indexed in: crossref, scopus, unpaywall, wos 
Abstract Staphylococcus aureus is characterized by its high resistance to conventional antibiotics, particularly methicillinresistant (MRSA) strains, making it a predominant pathogen in acute and chronic wound infections. The persistence of acute S. aureus wound infections poses a threat by increasing the incidence of their chronicity. This study investigated the potential of photodynamic activation using phytochemical-antibiotic combinations to eliminate S. aureus under conditions representative of acute wound infections, aiming to mitigate the risk of chronicity. The strategy applied takes advantage of the promising antibacterial and photosensitising properties of phytochemicals, and their ability to act as antibiotic adjuvants. The antibacterial activity of selected phytochemicals (berberine, curcumin, farnesol, gallic acid, and quercetin; 6.25 - 1000 mu g/mL) and antibiotics (ciprofloxacin, tetracycline, fusidic acid, oxacillin, gentamicin, mupirocin, methicillin, and tobramycin; 0.0625 - 1024 mu g/mL) was screened individually and in combination against two S. aureus clinical strains (methicillin-resistant and-susceptible - MRSA and MSSA). The photodynamic activity of the phytochemicals was assessed using a lightemitting diode (LED) system with blue (420 nm) or UV-A (365 nm) variants, at 30 mW/cm 2 (light doses of 9, 18, 27 J/cm 2 ) and 5.5 mW/cm 2 (light doses of 1.5, 3.3 and 5.0 J/cm 2 ), respectively. Notably, all phytochemicals restored antibiotic activity, with 9 and 13 combinations exhibiting potentiating effects on MSSA and MRSA, respectively. Photodynamic activation with blue light (420 nm) resulted in an 8- to 80-fold reduction in the bactericidal concentration of berberine against MSSA and MRSA, while curcumin caused 80-fold reduction for both strains at the light dose of 18 J/cm 2 . Berberine and curcumin-antibiotic combinations when subjected to photodynamic activation (420 nm light, 10 min, 18 J/cm 2 ) reduced S. aureus culturability by approximate to 9 log CFU/mL. These combinations lowered the bactericidal concentration of antibiotics, achieving a 2048-fold reduction for gentamicin and 512-fold reduction for tobramycin. Overall, the dual approach involving antimicrobial photodynamic inactivation and selected phytochemical-antibiotic combinations demonstrated a synergistic effect, drastically reducing the culturability of S. aureus and restoring the activity of gentamicin and tobramycin.

40. Thermodynamic study of tin tetraiodide (SnI4) 4 ) sublimation by effusion techniques
Romagnoli, L ; Almeida, ARRP ; Ferraz, JMS ; Latini, A ; Freitas, VLS ; da Silva, MDMCR ; Schiavi, PG ; Ciprioti, SV ; Ciccioli, A
in JOURNAL OF CHEMICAL THERMODYNAMICS, 2024, ISSN: 0021-9614,  Volume: 199, 
Article,  Indexed in: crossref, scopus, wos 
Abstract This study presents the first investigation of the sublimation behavior of tin tetraiodide, SnI4, 4 , using effusion- based techniques, within a low temperature range (313-340) K. The temperature range covered in the experiments was lower than in previously reported studies based on static methods. Knudsen Effusion Mass Loss (KEML) measurements were performed in the range of (317.1-339.6) K using effusion cells with different orifice sizes. The vapor pressures were measured in the range (0.13-1.13) Pa and were found to be independent of the orifice size. The standard molar enthalpy and Gibbs energy of sublimation at 298.15 K obtained by the Clarke and Glew fit of experimental data are (88.1 +/- 0.9) kJ & sdot;mol-1 & sdot; mol- 1 and (38.96 +/- 0.08) kJ & sdot;mol-1, & sdot; mol- 1 , respectively. Knudsen Effusion Mass Spectrometry (KEMS) experiments were also performed in the range (313.3-331.7) K, resulting in a sublimation enthalpy value in good agreement with the KEML values and not negligibly higher vapor pressure values. KEMS vapor pressure data were also analyzed by the third-law method. A comparison of our experimental results with the literature data available for both sublimation and evaporation properties of SnI4 4 is reported. Additionally, ancillary DFT and ab initio calculations were performed to estimate the molecular properties of SnI4(g) 4 (g) and the extent of the gas-phase dissociation to SnI2 2 and I2. 2 .