Diuron desorption and mineralisation were studied on an amended and artificially contaminated soil. The amendments used comprised two different composted organic residues i.e., sewage sludge (SS) mixed with pruning wastes, and urban solid... more
Diuron desorption and mineralisation were studied on an amended and artificially contaminated soil. The amendments used comprised two different composted organic residues i.e., sewage sludge (SS) mixed with pruning wastes, and urban solid residues (USR), and two different solutions (with inorganic salts as the micronutrients and hydroxypropyl-β-cyclodextrin (HPBCD)). After applying micronutrients to activate the soil flora, 15.5% mineralisation could be reached after 150 days, indicating that the soil has a potential capacity to mineralise the herbicide through biostimulation-assisted attenuation. Diuron mineralisation was also improved when HPBCD solutions were applied. Indeed, the extent of herbicide mineralisation reached 29.7% with this application. Moreover, both the lag phase and the half-life time (DT50) were reduced to 33 and 1,778 days, respectively, relative to the application of just micronutrients (i.e., 39 and 6297 days, respectively). Organic amendments were also applied (i.e., USR and SS) on the contaminated soil: it was found that the diuron mineralisation rate was improved as the amendment concentration increased. The joint application of all treatments investigated at the best conditions tested was conducted to obtain the best diuron mineralisation results. The micronutrient amendment plus 4% USR or SS amendment plus HPBCD solution (10-fold diuron initially spiked) caused an extent of diuron mineralisation 33.2 or 46.5%, respectively.
Research Interests:
Sorption-desorption experiments of fluorene (FLU) and fluoranthene (FLT) in soils were carried out and correlated to their removal from aged contaminated soils using aqueous solutions in the absence and in the presence of... more
Sorption-desorption experiments of fluorene (FLU) and fluoranthene (FLT) in soils were carried out and correlated to their removal from aged contaminated soils using aqueous solutions in the absence and in the presence of hydroxypropyl-β-cyclodextrin (HPBCD) as the extraction agent. FLU became more resistant to extraction in aged contaminated soils due to its initial adsorption onto the mineral and amorphous soil organic matter (SOM) domains, sites of lower binding energy from which, due to its small size, it could spread towards the condensed SOM as the contact time increased. Therefore, FLU will not be easily desorbed from aged contaminated soils due to physical entrapment mechanisms, even when using HPBCD as extractant, presenting FLU low risks to the environment. On the contrary, FLT was extracted from aged soils in the presence of HPBCD in solutions to a much greater extent than in its absence. Due to its more hydrophobic character FLT sorption in soils was relatively quicker, remaining more or less fixed on hydrophobic sites of the organic matter (OM) with different energies, and therefore the amount of FLT extracted was almost constant for different ageing times. During extraction experiments, the influence of the OM quality of the soils was also highlighted because an inverse proportionality between OM content of soil and extractability of sorbed FLT was observed. It was concluded that soils with lower OM content that had more diagenetically processed OM could block the extraction of FLT more effectively than soils with higher OM content that are less humified. This indicates the need to use not only adsorption-desorption data in contaminant fate and transport models, but also extraction studies in aged contaminated soils and other complementary analytical approaches when assessing soil contamination-related risks.
Research Interests:
ABSTRACT The effects of application of composted olive mill wastewater sludge (A) and depotassified sugarbeet vinasse (V) on total diethylenetriaminepentaacetic acid (DTPA) and sequential extracted micronutrients were investigated. The... more
ABSTRACT The effects of application of composted olive mill wastewater sludge (A) and depotassified sugarbeet vinasse (V) on total diethylenetriaminepentaacetic acid (DTPA) and sequential extracted micronutrients were investigated. The mineralogy of the fine fraction of soils was also studied. The soils used were a Typic Rhodoxeralf (soil R), a Typic Xeropsamment (soil S), and a Typic Xerorthent (soil C). Fertilization with A and V during 3 years, in general did not significantly affect the total concentration of Fe, Cu, Mn, and Zn versus the control. However, the elements extracted with DTPA generally increased with the organic amendments, more with A than with V. The BCR (European Community Bureau of Reference) sequential extraction indicated that the addition of organic matter generally increased Zn and Mn in the two more available fractions. A great amount of Fe was found in the second and third fractions from the unamended and amended soils. Nevertheless, the sum of the three fractions was enhanced for the organic amendment, except for calcareous soil. The distribution of these elements in the different fractions was significantly affected by the type of soil. The addition of both fertilizers caused modifications in particle size and consequence redistribution of the calcite content between the different fractions.
Research Interests:
... Cyclodextrins and Their Complexes. Edited by Helena Dodziuk Copyright 8 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 3-527-31280-3 450 Page 2. to the abandonment of the generally accepted models of their action).... more
... Cyclodextrins and Their Complexes. Edited by Helena Dodziuk Copyright 8 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 3-527-31280-3 450 Page 2. to the abandonment of the generally accepted models of their action). ... For this reason, Lezcano et al. ...
The application of organic amendments to agricultural soils may influence metal distribution in soil fractions and, in turn, can influence the availability of micronutrients to plants. However, in the literature, there is a great lack of... more
The application of organic amendments to agricultural soils may influence metal distribution in soil fractions and, in turn, can influence the availability of micronutrients to plants. However, in the literature, there is a great lack of data on micronutrient behavior in soils ...
Research Interests:
Research Interests:
ABSTRACT The competitive adsorption of the cationic pesticide chlordimeform and the heavy metal cadmium on montmorillonite was studied. For the different pesticide concentrations used, cadmium adsorption decreases with increasing... more
ABSTRACT The competitive adsorption of the cationic pesticide chlordimeform and the heavy metal cadmium on montmorillonite was studied. For the different pesticide concentrations used, cadmium adsorption decreases with increasing chlordimeform concentration, indicating a high competition between both cations for interlamellar positions. In contrast, pesticide adsorption increases in the presence of Cd in relation to Cd‐free treatments. This adsorption is independent of metal concentration used, and therefore adsorption isotherms are practically the same in all cases where cadmium is present.
Research Interests:
ABSTRACT Chemical analysis, DSC and solubility determinations have been applied to the study of solid inclusion complexes of a pesticide, 2,4-dichlorofenoxyacetic acid (2,4-D) as guest, and β-cyclodextrin (β-CD) as host, in order to... more
ABSTRACT Chemical analysis, DSC and solubility determinations have been applied to the study of solid inclusion complexes of a pesticide, 2,4-dichlorofenoxyacetic acid (2,4-D) as guest, and β-cyclodextrin (β-CD) as host, in order to produce experimental evidence of the inclusion process and of the stoichiometry of the inclusion compound. Three processing methods have been studied and compared: physical (mechanical) mixing; kneading; and spray-drying. The phase–solubility diagram of complex formation in solution has been also established. The stoichiometric ratio of the complexes was found to be 1:1 by solubility and DSC, being confirmed by chemical analysis. Spray-drying was found to be most suitable method for preparing the complexes.
Research Interests:
ABSTRACT The disposal of wastewater, known as vinasse, from the sugarcane (Saccharum officinarum L.) industry creates environmental problems. Agriculture can offer a potential solution to these problems by using organic residues as... more
ABSTRACT The disposal of wastewater, known as vinasse, from the sugarcane (Saccharum officinarum L.) industry creates environmental problems. Agriculture can offer a potential solution to these problems by using organic residues as substitutes for chemical fertilizers. This study was conducted in Ultisol profiles from Cuba irrigated with vinasse for 40 yr. The effects of this application on physicochemical and mineralogical properties of soils were investigated. Sods fertilized with traditional inorganic fertilizers were used for comparison. Fertilization with the wastewater caused a decrease of soil pH to a depth of 100 cm. There was an increase, however, in electrical conductivity because of the large concentration of K in the wastewater. The amendment also increased the organic matter content throughout the profile. Vinasse application yielded the intercalation of some compounds in the clay mineral smectite. The formation of organo-mineral complexes produced little change in the particle size distribution, but an increase in the poorly crystalline Fe oxyhydroxides in the upper horizon up to 22%, and the crystallinity of Fe oxyhydroxide in the soil decreased substantially. This was probably due to dissolution and reprecipitation of these oxides by the acid pH of the wastewater. Total and poorly crystalline Mn contents also decreased. The amendment material increased the mobility of metals because of the formation of water-soluble complexes with organic ligands. The results showed that long-term wastewater irrigation could be of agricultural interest due mainly to its organic matter concentration, but micronutrient concentrations in the upper horizons were negatively affected because complexing of metals favored their transport throughout the sod profile, which may eventually lead to deterioration of groundwater quality and micronutrient deficiency.
Research Interests:
ABSTRACT Alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] is one of the most commonly found herbicides in surface and groundwaters of the United States and Europe, and it contaminates these environments even when it is... more
ABSTRACT Alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] is one of the most commonly found herbicides in surface and groundwaters of the United States and Europe, and it contaminates these environments even when it is used according to the manufacturer's instructions for conventional formulations. To determine how its persistence in soil is affected by herbicide formulation and soil type, alachlor was applied to several soils in different formulations: technical grade (AT), a commercial formulation (CF), and different ethylcellulose microencapsulated formulations (MEFs). The results show that MEFs provided a prolonged release of the herbicide into the soil solution and protected against its dissipation in soil more than AT or the CE The half-life in soil (t(1/2)) for the AT, CF, and MEFs was up to 2.7, 6.4, and 32.54 d, respectively. The lowest herbicide loss was observed in MEFs prepared using a lower stirring speed or a higher ethylcellulose viscosity during the microencapsulation process. As with AT and the CF, the microencapsulated alachlor persisted longer in the soils with low pH and high clay content. In the soil where alachlor showed the least persistence, MEFs reduced the herbicide loss by 54% compared with the CF. The use of MEFs extended the alachlor concentration in the soil, thereby avoiding the need for using high herbicide application rates and decreasing the risk of environmental contamination.
Research Interests:
Research Interests:
Research Interests:
The development of controlled-release formulations of alachlor to extend the period of weed control was studied. This extended duration reduces the need for high herbicide application rates that could lead to environmental contamination.... more
The development of controlled-release formulations of alachlor to extend the period of weed control was studied. This extended duration reduces the need for high herbicide application rates that could lead to environmental contamination. For this purpose, the influence of formulation, as well as the influence of soil characteristics, on alachlor efficacy and persistence in soil of a commercial formulation (CF) and different ethylcellulose microencapsulated formulations (MEFs) was evaluated. Higher alachlor rates yielded an enhanced initial herbicidal activity. The prolonged release of alachlor provided by the MEFs resulted in a higher herbicidal efficacy and a longer period of weed control compared with the effects of CF in the two soils tested (at 40 days after treatment, oat growth inhibition for CF and MEFs was 1.96% and 93.5% respectively). Soil characteristics strongly influenced alachlor efficacy and weed control by MEFs. The highest alachlor efficacy and persistence were observed in the soil with lowest microbial activity and clay and organic matter content. The use of MEFs can be advantageous because they permit the maintenance of the desired concentration of the herbicide in the soil for longer periods of weed control.
Research Interests:
Research Interests:
ABSTRACT The aqueous solubility of the pesticide 2,4-D was improved by inclusion complexation with α-CD. The formation of such inclusion compounds was studied via the phase-solubility diagram (solution state) and by DSC and HSM (solid... more
ABSTRACT The aqueous solubility of the pesticide 2,4-D was improved by inclusion complexation with α-CD. The formation of such inclusion compounds was studied via the phase-solubility diagram (solution state) and by DSC and HSM (solid state). 2,4-D presented a typical Bs Higuchi solubility curve, coprecipitating a 1:2 pesticide-α-CD complex. In order to obtain solid complexes, three processing methods were checked: kneading, coprecipitation and spray-drying. DSC and HSM showed that only the last two of these yielded true inclusion compounds. Chemical analysis also revealed that the stoichiometry of such solid complexes corresponds to a 2,4-D-α-CD ratio of 1:2.
Research Interests:
Research Interests:
The effect of one organic amendment consisting of an urban waste compost (UWC) was assessed on the sorption properties of the herbicide 2,4-D on four soils of different physicochemical characteristics. The soils chosen were a Typic... more
The effect of one organic amendment consisting of an urban waste compost (UWC) was assessed on the sorption properties of the herbicide 2,4-D on four soils of different physicochemical characteristics. The soils chosen were a Typic Haphorthod (ST), a Typic Endoaquept (SR), an Entic Pelloxerert (TO), and a Typic Eutrochrept (AL). Adsorption experiments were performed on the original soils, and on mixtures of these soils with UWC at a rate of 6.25% (w/w). These mixtures were used just after preparation, and after aging for 8 and 25 weeks. 2,4-D adsorption was the highest on ST soil, whereas the lowest adsorption was for SR soil. This behavior is related to the high amount of organic matter (OM) and amorphous iron and aluminum oxides content on soil ST, whereas soil SR had the lowest OM content and specific surface area of the soils of this study. Addition of exogenous OM to soils caused an increase in the 2,4-D adsorption by three of the soils treated with UWC, with the only exception being ST soil, due to an observed decrease in its specific surface area. The adsorbed amounts of the herbicide on aged organic fertilized soils diminished in three of the amended soils, but was still greater than on unammended soils. In contrast, the ST soil showed the largest adsorption for unammended soil.
Research Interests:
Research Interests:
Adsorption-desorption studies of norflurazon on 17 soils of very different characteristics have been performed using a batch equilibration method and correlated to its mobility, activity, and persistence in soils. The influence of... more
Adsorption-desorption studies of norflurazon on 17 soils of very different characteristics have been performed using a batch equilibration method and correlated to its mobility, activity, and persistence in soils. The influence of different soil properties and components on norflurazon adsorption was determined. The significant variables were organic matter (OM) content and iron and aluminum oxides, which accounted for 85 and 11% of the variability, respectively. Norflurazon desorption from soils was hysteretic in all cases, being more irreversible at the lowest herbicide concentrations adsorbed. The percentage of norflurazon eluted from columns of selected soils reached almost 100% in soils with sand content >80% and OM <1%, but in the soil which gave the highest sorption, herbicide residues were not detected at depths >16 cm. The herbicidal activity of norflurazon was followed by measuring its bleaching effect on soybean plants, and the herbicide concentration required to give 50% chlorophyll inhibition (CI(50)) was calculated. CI(50) was achieved on a sandy soil with 0.08 mg x kg(-)(1), whereas 1.98 mg x kg(-)(1) was necessary for the soil that presented maximum norflurazon adsorption.
Research Interests:
Research Interests:
The development of controlled-release formulations of alachlor to diminish its leaching in sandy soils, avoiding groundwater contamination and maintaining its efficacy, was studied. For this purpose, ethylcellulose (EC) microencapsulated... more
The development of controlled-release formulations of alachlor to diminish its leaching in sandy soils, avoiding groundwater contamination and maintaining its efficacy, was studied. For this purpose, ethylcellulose (EC) microencapsulated formulations (MEFs) of alachlor were prepared under different conditions and applied to soil columns to study their mobility. The results show that in all cases the release into water of alachlor from MEFs was retarded when compared with commercial formulation. Total leaching losses in soil columns were reduced to 59% from 98%. The mobility of alachlor from EC microspheres into soil columns has been greatly diminished in comparison with its current commercial formulation (CF), above all with increasing EC/herbicide ratios. Distribution of alachlor applied as MEFs at different depths in the soil was higher in the soil surface (66.3-81.3% of herbicide applied at the first 12 cm). In contrast, the residues from CF along the complete soil column were only 20.4%. From the results of bioassays, MEFs showed a higher efficacy than CF at 30 days after the treatment. The use of ME formulations could provide an advantage in minimizing the risk of groundwater contamination by alachlor and reducing the application rates, as a result of maintaining the desired concentration of the herbicide in the top soil layer, obtaining longer periods of weed control.
Research Interests:
Research Interests:
ABSTRACT Different extraction techniques are presented here to determine whether their extraction abilities correlate with the bioaccessible diuron fraction in an aged contaminated soil. Diuron bioaccessibility was tested establishing... more
ABSTRACT Different extraction techniques are presented here to determine whether their extraction abilities correlate with the bioaccessible diuron fraction in an aged contaminated soil. Diuron bioaccessibility was tested establishing correlations between the amount of diuron biodegraded after different aging periods, using a specific diuron biodegrader microorganism consortium, and the amount of diuron extracted by 50 mM hydroxypropyl-β-cyclodextrin (HPBCD), 10 mM CaCl2, hexane, or butanol. HPBCD extraction procedure correlated better than the other extraction techniques tested with diuron measured microbial biodegradation for all aging times (1, 30, 60, 90, and 120 days). The results obtained with this soil indicate that the aqueous HPBCD extraction technique has potential to become a valuable tool for estimating the bioaccessible fraction of soil-associated diuron at different aging times, and it could be applicable in the assessment of risk and contaminated land bioremediation potential.
Research Interests:
Research Interests:
Research Interests:
Research Interests: Geology and Clay Minerals
Research Interests: Geology and Clay Minerals
The interaction of norflurazon with alpha- and gamma-cyclodextrins (CDs) yielded the formation of inclusion complexes at a 1:1 stoichiometric ratio in solution and in the solid state. Apparent stability constants of 50.7+/-1.6 and... more
The interaction of norflurazon with alpha- and gamma-cyclodextrins (CDs) yielded the formation of inclusion complexes at a 1:1 stoichiometric ratio in solution and in the solid state. Apparent stability constants of 50.7+/-1.6 and 37+/-1.7 M(-1) and an increase in herbicide solubility by up to five and fourfold for alpha- and gamma-CD, respectively, were determined from the phase solubility diagrams at 25 degrees C in water. Three processing methods (kneading, spray-drying and vacuum evaporation) were used to prepare norflurazon-CD solid inclusion complexes, which were characterised by infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy. A high increase in the norflurazon dissolution rate was obtained with all the solid complexes with gamma-CD, but when alpha-CD was used, only the solid system obtained after the vacuum evaporation process showed a higher dissolution rate. This finding is a first step in the development of new, environmentally sound formulations of norflurazon (NFL), due to the capacity for increasing its dissolution rate and hydrosolubility, and thus diminishing the use of organic solvents. On the other hand, the effect of alpha- and gamma-cyclodextrin on the solubility of norflurazon in solution was also considered as a way of modifying its behaviour in the soil environment. Desorption studies of NFL from soils in the presence of alpha- and gamma-cyclodextrin were carried out using a batch equilibration method. The results obtained showed that alpha- and gamma-cyclodextrin greatly increased the removal of norflurazon previously adsorbed, proving the potential use of these CDs for in situ remediation of pesticide-contaminated soils.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
... T. UNDABEYTIA ∗ , E. MORILLO, AB RAMOS and C. MAQUEDA Instituto de Recursos Naturales y Agrobiología (CSIC), 41080 Sevilla, Spain (∗ author ... analyzed for pH in saturated paste (Hesse, 1971), and size particle distribution by the... more
... T. UNDABEYTIA ∗ , E. MORILLO, AB RAMOS and C. MAQUEDA Instituto de Recursos Naturales y Agrobiología (CSIC), 41080 Sevilla, Spain (∗ author ... analyzed for pH in saturated paste (Hesse, 1971), and size particle distribution by the hydrometer method (Gee and Bauder ...
Research Interests:
Page 1. Research Article Theme: Advanced Technologies for Oral Controlled Release Guest Editors: Michael Repka, Joseph Reo, Linda Felton, and Stephen Howard Preparation and Characterization of Inclusion Complexes ...
Research Interests:
ABSTRACT
Research Interests:
Journal of Agriculture and Natural Resources, ISSN 0718-3267. ...
Research Interests:
Research Interests:
Research Interests: Engineering, Analytical Chemistry, Biomedical Engineering, Water, Kinetics, and 31 moreNuclear Magnetic Resonance, Magnetic Resonance Spectroscopy, Pharmaceutical Chemistry, Molecular modeling, Pharmaceutics, Polymer, Differential scanning calorimetry, Absorption spectroscopy, Ultrasonics, Temperature, Macromolecules, Household Production, High Temperature, Solubility, Herbicides, CHEMICAL SCIENCES, Spectrum, X ray diffraction, Thermal Stability, Fourier transform infrared spectroscopy, Time Factors, Solutions, Solid State, Stoichiometry, Cyclodextrins, Agricultural and Food Chemistry, AAPS PharmSciTech, Water soluble polymers, Structure activity Relationship, Furosemide, and Nuclear Magnetic Resonance Spectroscopy
ABSTRACT Inclusion complex formation of 2,4-dichlorophenoxyacetic acid (2,4-D) with hydroxypropyl-β-cyclodextrin (HP-β-CD) has been proposed as a way of modifying the behaviour of the pesticide in the soil environment. The present study... more
ABSTRACT Inclusion complex formation of 2,4-dichlorophenoxyacetic acid (2,4-D) with hydroxypropyl-β-cyclodextrin (HP-β-CD) has been proposed as a way of modifying the behaviour of the pesticide in the soil environment. The present study assesses the effect of complex formation on 2,4-D physicochemical properties (aqueous solubility, crystallinity and dissolution rate) and its behaviour on soils.The solid complexes were prepared using different methods (spray drying, kneading and heating in a sealed container). To confirm the complex formation in the solid state differential scanning calorimetry, hot stage microscopy and x-ray diffraction techniques were employed. Complex formation in solution was studied by phase solubility. The presence of HP-β-CD increased the 2,4-D solubility nine times approximately. The apparent stability constant was determined as 98.6 M−1. The dissolution rates of the 2,4-D/HP-β-CD complexes were examined and compared with that of the pure pesticide. The results indicated that the complex may have great utility as a rapid way of dissolving the pesticide. Batch experiments were performed to study the adsorption–desorption of 2,4-D on soils and the influence of the HP-β-CD over these processes. The results showed that HP-β-CD could increase the desorption of 2,4-D previously adsorbed on soils.© 2000 Society of Chemical Industry