The adsorption of Cd and Zn on a standard montmorillonite (SAZ-1) in the presence of the cationic... more The adsorption of Cd and Zn on a standard montmorillonite (SAZ-1) in the presence of the cationic pesticide chlordimeform, both in solution (simultaneous adsorption) and when the pesticide is previously adsorbed on the clay (successive adsorption) has been studied. The adsorption of Zn decreases when the chlordimeform concentration increases in both simultaneous and successive adsorptions, following the sequence: chlordimeform-free solutions > successive > simultaneous. In the adsorption of Cd the sequence is different: successive > chlordimeform-free solutions > simultaneous, indicating that a small amount of pesticide adsorbed favours Cd adsorption. In all cases, the apparent affinity of the metal for adsorption on montmorillonite, on the basis of distribution coefficients, KD, is higher for lower metal surface coverage, and decreases largely with the amount of the metal adsorbed. This indicates the existence of high affinity sites on the clay, probably those of variab...
Abstract. The interaction in solution between 2,4-dichlorophenoxyacetic acid with α- and β-cyclod... more Abstract. The interaction in solution between 2,4-dichlorophenoxyacetic acid with α- and β-cyclodextrins was evaluated by phase solubility studies. Association constants were calculated by this technique. The stoichiometries were 1: 2 and 1: 1 for the α- and β-cyclodextrin complexes, respectively. In order to corroborate the complexation and the knowledge of structural aspects of the host: guest interaction, proton nuclear magnetic resonance (1H-NMR) spectroscopy was employed. The application of the continuous variation technique corroborated the calculated complex stoi-chiometries by solubility assays. Complementary NOE studies were applied in order to corroborate the proposed complex structures. Key words: solubility, 1H-NMR, stoichiometry, cyclodextrins 1.
The formation of crystalline inclusion complex of triamterene with ~cyclodextrin ([LCD) was studi... more The formation of crystalline inclusion complex of triamterene with ~cyclodextrin ([LCD) was studied, evaluating the thermal behaviour and dispersion state of this drug in different types of binary systems. Spray-drying and co-grinding (oscillating mill) mixtures of triamterene with [~-CD were prepared in 1:1 molar ratio. The changes of crystalline properties of original (untreated) triamterene, [~-CD, and composites obtained by co-grinding and spray-drying were investigated in comparison with those produced in simple physical mixtures. The thermal behaviour of the different samples was investigated using DTA. X-ray diffraction was applied as a complementary technique. The results have been explained by formation of amorphous drug particles on spray-drying samples and co-grinding or alternatively by means of a solid dispersion formation or a combination of these two. A contamination effect by grinding media was also observed as increasing grinding time.
Remediation of soils contaminated by organic pollutants has become an urgent necessity worldwide.... more Remediation of soils contaminated by organic pollutants has become an urgent necessity worldwide. A wide variety of techniques have been developed but many of them are associated with drawbacks (complexity, high costs, environmental risks, etc.). Bioremediation, the use of living organisms to remediate polluted sites, is an alternative approach considered a cost-effective and more environmentally friendly technique, but the low bioavailability of the organic pollutants in soils is its main limitation. Cyclodextrins have been proposed as a ́greeneŕ alternative to organic solvents or synthetic surfactants for increasing organics bioavailability in soils. Cyclodextrins can form inclusion complexes with hydrophobic pollutants increasing their aqueous solubility and enhancing their bioremediation in soils. This review gives an overview on the use of cyclodextrins for this purpose, highlighting the advantages and disadvantages and perspectives of this technology for future research. The effect of those cyclodextrins more commonly used is analyzed, particularly hydroxypropyl-β-cyclodextrin (HPBCD) and randomly methylated-β-cyclodextrin (RAMEB), as well as some of the more common contaminants treated (almost 80% are industrial chemicals and the rest are pesticides) and the bioremediation strategies used (by microorganisms and/or phytoremediation). The review also provides a critical view on knowledge gaps and limitations of this technology which must be overcome to bring it for field-scale application.
Sewage sludge generated by Waste Water Treatment Plants (WWTPs) are frequently used as organic am... more Sewage sludge generated by Waste Water Treatment Plants (WWTPs) are frequently used as organic amendments in agriculture, but they contain pollutants such as Potentially Toxic Elements (PTEs) and organic contaminants which contaminate the agricultural soils. The study presented here is part of a larger study based on the application of environmentally friendly chemical and biological techniques to decrease the content of organic pollutants in sewage sludge before agricultural application. The aim of this study was to evaluate the performance of biodegradable extractants, such as some cyclodextrins (CDs), β-cyclodextrin (BCD), hydroxypropyl-β-cyclodextrin (HPBCD) and randomly methylated-β-cyclodextrin (RAMEB), and a biosurfactant (rhamnolipid, RL) on the removal and availability of pyrene (PYR), phenanthrene (PHE) and nonylphenol (NP) from several biosolids samples in order to improve their subsequent biodegradation. The influence of pollutants retention time on biosolids was studied, as well as the effect of each extractant on PTEs solubilization. Results obtained were pollutant and extractant-dependent. BCD extracted similar amounts of pollutants compared to water, whereas HPBCD and RAMEB actually increased the availability of the three pollutants in most of the samples and aging times. RL seems to be the best election for Polycyclic Aromatic Hydrocarbons (PAHs) extraction from biosolids, with percentages of extraction multiplied by more than 80 and 40 times for PHE and PYR, respectively, relative to water extraction. The extraction enhancement was the highest for NP, the most hydrophobic pollutant, reaching more than 500-fold higher with HPBCD and RAMEB. PTEs extractability was not affected by the different CDs used, but RL caused an increment in their soluble content what could endanger a subsequent biodegradation of the organic pollutants.
Palygorskite has been characterized in soils classified as typic argixerolls, located in an exten... more Palygorskite has been characterized in soils classified as typic argixerolls, located in an extensive Quaternary zone in the north of Seville (Spain), where the geological and climatic conditions suggest its genesis. The soils contain a Ck horizon which has different textural characteristics to the other horizons in the profiles. The presence of large white calcareous nodules and cristobalite is the principal difference between them. The formation of palygorsltite at textural discontinuities is in agreement with the characteristics of these soils. Under the present conditions of the soils (pH, magnesium and silicon concentration and soluble salts), the alteration of palygorsltite to smectite is suggested. The sporadic nucleation of large fibres of palygorsltite on silica crystal suggests that this latter mineral could provide the necessary silicon for palygorsltite formation.
The purpose of this study was to determine the degree of contamination with polycyclic aromatic h... more The purpose of this study was to determine the degree of contamination with polycyclic aromatic hydrocarbons (PAHs) in samples of urban soil from three European cities: Glasgow (UK), Torino (Italy) and Ljubljana (Slovenia). Fifteen PAHs (naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene, indeno[1,2,3-c,d]pyrene) were measured in urban soil samples, using harmonised sampling, sample extraction and analyte quantification methods. Although the mean concentration of each PAH in urban soils of each city showed a wide range of values, high levels of contamination were only evident in Glasgow, where the sum of concentrations of 15 PAHs was in the range 1487-51,822 microg kg(-1), cf. ranges in the other two cities were about ten-fold lower (89.5-4488 microg kg(-1)). The three predominant PAHs were phenanthrene, fluoranthene and pyrene, with the sum of these compounds about 40% of the total PAH content. These data, together with some special molecular indices based on ratios of selected PAHs, suggest pyrogenic origins, especially motor vehicle exhausts, to be the major sources of PAHs in urban soils of the three cities. The largest concentrations for PAHs were often found in sites close to the historic quarters of the cities. Overall, the different climatic conditions, the organic carbon contents of soil, and the source apportionment were the dominant factors affecting accumulation of PAHs in soil.
Decomposition of decylammonium cations on vermiculite surfaces as a result of acidity has been st... more Decomposition of decylammonium cations on vermiculite surfaces as a result of acidity has been studied. The vermiculite-decylammonium complex was treated with solutions of HCl in water and butanol, and solutions of chlordimeform in butanol. X-ray powder diffraction and IR spectroscopy data showed the presence after treatment of ammonium cations in addition to aliphatic chain compounds in the interlamellar space. The ammonium cation is produced by breaking of the C-N bond of alkylammonium due to the low pH of the medium and, when using butànol as solvent, to the dissociation of the scarce water molecules on the clay surface. The influence of the different solutions on the period of decomposition of alkylammonium cations is discussed. Vermiculite-decylammonium complex treated with HCl solutions for a year released structural Mg2+ due to the acidity of the medium. This Mg2+ partially displaced ammonium cations from the interlamellar space.
The adsorption of Cd and Zn on a standard montmorillonite (SAZ-1) in the presence of the cationic... more The adsorption of Cd and Zn on a standard montmorillonite (SAZ-1) in the presence of the cationic pesticide chlordimeform, both in solution (simultaneous adsorption) and when the pesticide is previously adsorbed on the clay (successive adsorption) has been studied. The adsorption of Zn decreases when the chlordimeform concentration increases in both simultaneous and successive adsorptions, following the sequence: chlordimeform-free solutions > successive > simultaneous. In the adsorption of Cd the sequence is different: successive > chlordimeform-free solutions > simultaneous, indicating that a small amount of pesticide adsorbed favours Cd adsorption. In all cases, the apparent affinity of the metal for adsorption on montmorillonite, on the basis of distribution coefficients, KD, is higher for lower metal surface coverage, and decreases largely with the amount of the metal adsorbed. This indicates the existence of high affinity sites on the clay, probably those of variab...
Abstract. The interaction in solution between 2,4-dichlorophenoxyacetic acid with α- and β-cyclod... more Abstract. The interaction in solution between 2,4-dichlorophenoxyacetic acid with α- and β-cyclodextrins was evaluated by phase solubility studies. Association constants were calculated by this technique. The stoichiometries were 1: 2 and 1: 1 for the α- and β-cyclodextrin complexes, respectively. In order to corroborate the complexation and the knowledge of structural aspects of the host: guest interaction, proton nuclear magnetic resonance (1H-NMR) spectroscopy was employed. The application of the continuous variation technique corroborated the calculated complex stoi-chiometries by solubility assays. Complementary NOE studies were applied in order to corroborate the proposed complex structures. Key words: solubility, 1H-NMR, stoichiometry, cyclodextrins 1.
The formation of crystalline inclusion complex of triamterene with ~cyclodextrin ([LCD) was studi... more The formation of crystalline inclusion complex of triamterene with ~cyclodextrin ([LCD) was studied, evaluating the thermal behaviour and dispersion state of this drug in different types of binary systems. Spray-drying and co-grinding (oscillating mill) mixtures of triamterene with [~-CD were prepared in 1:1 molar ratio. The changes of crystalline properties of original (untreated) triamterene, [~-CD, and composites obtained by co-grinding and spray-drying were investigated in comparison with those produced in simple physical mixtures. The thermal behaviour of the different samples was investigated using DTA. X-ray diffraction was applied as a complementary technique. The results have been explained by formation of amorphous drug particles on spray-drying samples and co-grinding or alternatively by means of a solid dispersion formation or a combination of these two. A contamination effect by grinding media was also observed as increasing grinding time.
Remediation of soils contaminated by organic pollutants has become an urgent necessity worldwide.... more Remediation of soils contaminated by organic pollutants has become an urgent necessity worldwide. A wide variety of techniques have been developed but many of them are associated with drawbacks (complexity, high costs, environmental risks, etc.). Bioremediation, the use of living organisms to remediate polluted sites, is an alternative approach considered a cost-effective and more environmentally friendly technique, but the low bioavailability of the organic pollutants in soils is its main limitation. Cyclodextrins have been proposed as a ́greeneŕ alternative to organic solvents or synthetic surfactants for increasing organics bioavailability in soils. Cyclodextrins can form inclusion complexes with hydrophobic pollutants increasing their aqueous solubility and enhancing their bioremediation in soils. This review gives an overview on the use of cyclodextrins for this purpose, highlighting the advantages and disadvantages and perspectives of this technology for future research. The effect of those cyclodextrins more commonly used is analyzed, particularly hydroxypropyl-β-cyclodextrin (HPBCD) and randomly methylated-β-cyclodextrin (RAMEB), as well as some of the more common contaminants treated (almost 80% are industrial chemicals and the rest are pesticides) and the bioremediation strategies used (by microorganisms and/or phytoremediation). The review also provides a critical view on knowledge gaps and limitations of this technology which must be overcome to bring it for field-scale application.
Sewage sludge generated by Waste Water Treatment Plants (WWTPs) are frequently used as organic am... more Sewage sludge generated by Waste Water Treatment Plants (WWTPs) are frequently used as organic amendments in agriculture, but they contain pollutants such as Potentially Toxic Elements (PTEs) and organic contaminants which contaminate the agricultural soils. The study presented here is part of a larger study based on the application of environmentally friendly chemical and biological techniques to decrease the content of organic pollutants in sewage sludge before agricultural application. The aim of this study was to evaluate the performance of biodegradable extractants, such as some cyclodextrins (CDs), β-cyclodextrin (BCD), hydroxypropyl-β-cyclodextrin (HPBCD) and randomly methylated-β-cyclodextrin (RAMEB), and a biosurfactant (rhamnolipid, RL) on the removal and availability of pyrene (PYR), phenanthrene (PHE) and nonylphenol (NP) from several biosolids samples in order to improve their subsequent biodegradation. The influence of pollutants retention time on biosolids was studied, as well as the effect of each extractant on PTEs solubilization. Results obtained were pollutant and extractant-dependent. BCD extracted similar amounts of pollutants compared to water, whereas HPBCD and RAMEB actually increased the availability of the three pollutants in most of the samples and aging times. RL seems to be the best election for Polycyclic Aromatic Hydrocarbons (PAHs) extraction from biosolids, with percentages of extraction multiplied by more than 80 and 40 times for PHE and PYR, respectively, relative to water extraction. The extraction enhancement was the highest for NP, the most hydrophobic pollutant, reaching more than 500-fold higher with HPBCD and RAMEB. PTEs extractability was not affected by the different CDs used, but RL caused an increment in their soluble content what could endanger a subsequent biodegradation of the organic pollutants.
Palygorskite has been characterized in soils classified as typic argixerolls, located in an exten... more Palygorskite has been characterized in soils classified as typic argixerolls, located in an extensive Quaternary zone in the north of Seville (Spain), where the geological and climatic conditions suggest its genesis. The soils contain a Ck horizon which has different textural characteristics to the other horizons in the profiles. The presence of large white calcareous nodules and cristobalite is the principal difference between them. The formation of palygorsltite at textural discontinuities is in agreement with the characteristics of these soils. Under the present conditions of the soils (pH, magnesium and silicon concentration and soluble salts), the alteration of palygorsltite to smectite is suggested. The sporadic nucleation of large fibres of palygorsltite on silica crystal suggests that this latter mineral could provide the necessary silicon for palygorsltite formation.
The purpose of this study was to determine the degree of contamination with polycyclic aromatic h... more The purpose of this study was to determine the degree of contamination with polycyclic aromatic hydrocarbons (PAHs) in samples of urban soil from three European cities: Glasgow (UK), Torino (Italy) and Ljubljana (Slovenia). Fifteen PAHs (naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene, indeno[1,2,3-c,d]pyrene) were measured in urban soil samples, using harmonised sampling, sample extraction and analyte quantification methods. Although the mean concentration of each PAH in urban soils of each city showed a wide range of values, high levels of contamination were only evident in Glasgow, where the sum of concentrations of 15 PAHs was in the range 1487-51,822 microg kg(-1), cf. ranges in the other two cities were about ten-fold lower (89.5-4488 microg kg(-1)). The three predominant PAHs were phenanthrene, fluoranthene and pyrene, with the sum of these compounds about 40% of the total PAH content. These data, together with some special molecular indices based on ratios of selected PAHs, suggest pyrogenic origins, especially motor vehicle exhausts, to be the major sources of PAHs in urban soils of the three cities. The largest concentrations for PAHs were often found in sites close to the historic quarters of the cities. Overall, the different climatic conditions, the organic carbon contents of soil, and the source apportionment were the dominant factors affecting accumulation of PAHs in soil.
Decomposition of decylammonium cations on vermiculite surfaces as a result of acidity has been st... more Decomposition of decylammonium cations on vermiculite surfaces as a result of acidity has been studied. The vermiculite-decylammonium complex was treated with solutions of HCl in water and butanol, and solutions of chlordimeform in butanol. X-ray powder diffraction and IR spectroscopy data showed the presence after treatment of ammonium cations in addition to aliphatic chain compounds in the interlamellar space. The ammonium cation is produced by breaking of the C-N bond of alkylammonium due to the low pH of the medium and, when using butànol as solvent, to the dissociation of the scarce water molecules on the clay surface. The influence of the different solutions on the period of decomposition of alkylammonium cations is discussed. Vermiculite-decylammonium complex treated with HCl solutions for a year released structural Mg2+ due to the acidity of the medium. This Mg2+ partially displaced ammonium cations from the interlamellar space.
Uploads
Papers by E. Morillo