Jackson, MS, United States
Jackson, MS, United States

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Revellame E.,Mississippi State University | Hernandez R.,Mississippi State University | French W.,Mississippi State University | Holmes W.,Mississippi State Chemical Laboratory | And 2 more authors.
Journal of Chemical Technology and Biotechnology | Year: 2011

Background: The production of biodiesel from activated sludge obtained from Tuscaloosa, AL was optimized based on the yield of fatty acid methyl esters (FAMEs) using an in situ transesterification process. An orthogonal central composite response surface design was considered to investigate the main and interaction effects of temperature, methanol to sludge ratio, and catalyst concentration. RESULTS: The biodiesel yield can be satisfactorily described by the quadratic response surface model with R 2 of 0.836 and a statistically not significant lack of fit (p = 0.254). Coded regression coefficients, main effect plots and surface plots indicated that maximum biodiesel yield may be obtained at 75 °C, 30 mL g -1 (methanol/sludge) and 10% volume (catalyst concentration). Numerical optimization showed that at this reaction condition, a biodiesel yield of 3.78% (weight) can be obtained. Experimental verification gave a biodiesel yield of 3.93 ± 0.15% (weight) giving a model error of 7.35%. This indicates high reliability of the model. CONCLUSIONS: The economic analysis showed that the in situ transesterification of wet activated sludge (84.5% weight moisture) is less economical than the in situ transesterification of dried sludge (5% weight moisture). However, sensitivity analysis indicated that the process can be made more economical by reduction of water to 50% (weight). At this level of moisture, a biodiesel break-even price of around $7.00 per gallon is attainable, which is still more expensive than petroleum-based diesel (~$2.95 per gallon). For the biodiesel from activated sludge to be economically competitive, a biodiesel yield of at least 10% (weight) is necessary. © 2010 Society of Chemical Industry.

Taylor C.M.,Shimadzu | Raines J.M.,Mississippi State Chemical Laboratory | Rodriguez J.M.,Mississippi State Chemical Laboratory | Rodriguez J.M.,Mississippi State University
Food Analytical Methods | Year: 2013

The aim of this project is to determine polycyclic aromatic hydrocarbons (PAHs) in several seafood matrices, i.e., fish, and mussel, by the use of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GCXGC-MS). The procedure involves a simple extraction of PAHs, a filtration and concentration step followed by GCXGC-MS analysis. PAHs were determined in fish tissue samples by GCXGC-MS and by a standard high-pressure liquid chromatography fluorescence detector method. A Bland-Altman analysis of the two methods was performed. It indicated equivalence between the two methods. Analysis of mussel tissue (National Institute of Standards and Technology (NIST)-SRM 2974a) was performed. The results were in line with the official results of NIST. © 2012 Springer Science+Business Media New York.

Revellame E.,Mississippi State University | Hernandez R.,Mississippi State University | French W.,Mississippi State University | Holmes W.,Mississippi State Chemical Laboratory | Alley E.,Mississippi State Chemical Laboratory
Journal of Chemical Technology and Biotechnology | Year: 2010

BACKGROUND: The microbial biomass present in activated sludge contains lipidic compounds that can be used as biodiesel feedstock. In this study, the production of biodiesel from activated sludge from Tuscaloosa, AL was optimized based on the yield of fatty acid methyl esters (FAMEs). In situ transesterification was used with sulfuric acid as catalyst. A general factorial design of 4 × 6 × 5 for temperature, methanol to sludge ratio and catalyst concentration, respectively, was considered for optimization. RESULTS: Biodiesel yield can be adequately described by the quadratic response surfacemodel with R 2 of 0.843 and statistically insignificant lack of fit (p = 0.152).Numerical optimization showed that an optimum biodiesel yield of 4.88% can be obtained at 55 °C, 25 methanol to sludge ratio and4%volume sulfuric acid. The optimum experimental biodiesel yieldwas indeed obtained at that condition but with a value of 4.79 ± 0.02%. The highest error was 2.30% which indicates good agreement between the model and the experimental data. CONCLUSIONS: Acid-catalyzed polymerization of unsaturated fatty acids or their esters at temperature above 60° Csignificantly decreased biodiesel yield. The fatty acid profile of the biodiesel produced indicates that activated sludge may be used as biodiesel feedstock. © 2010 Society of Chemical Industry.

Bowling J.J.,University of Mississippi | Anderson J.B.,University of Mississippi | Armbrust K.L.,Mississippi State Chemical Laboratory | Hamann M.T.,University of Mississippi
Fuel | Year: 2014

Oil production from single cells has been in development since the 1980s primarily for the pharmaceutical and neutraceutical industries, but the technology for using microorganisms to convert plant cellular material directly into oil is still undeveloped. The unusual amount of oil extracted from the imported fire ant (Solenopsis sp.) may be an indication of the presence of oleaginous microorganisms or enzymes supporting the digestion of raw sugars. Yield of the ant oil is 16% dry weight and contains most of the fatty acids also found in other biomass resources. Heat of combustion of the ant oil was 133,000 BTU/gal, an amount within the range of reported values for vegetable oil and biodiesel. This investigation also explores the potential source of the oil through stable isotope labeling and offers a unique perspective of a potentially new source of microorganisms or enzymes useful for reducing the cost of producing an alternative fuel. © 2013 Elsevier Ltd. All rights reserved.

Xia K.,Mississippi State Chemical Laboratory | Atkins J.,Mississippi State Chemical Laboratory | Foster C.,Mississippi State Chemical Laboratory | Armbrust K.,Mississippi State Chemical Laboratory
Journal of Agricultural and Food Chemistry | Year: 2010

Cyromazine is used as an additive in poultry feed to inhibit the development of fly larvae in chicken manure. U.S. Environmental Protection Agency (EPA) method AG-555, modified from method AG-376, has been the standard method for cyromazine analysis in poultry feed. However, these methods are time-consuming (∼3 h) and require large volumes (200 mL) of solvent. This study developed an extraction procedure using the QuEChERS method that is faster (∼30 min) and uses 20 times less solvent than the AG-555 method. After extraction using the QuEChERS method, the extractant was subjected to cleanup using a C-18 solid phase extraction (SPE) followed by filtering through a 0.45 μm syringe Teflon filter before the liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Recovery of 75.0 ± 6.2% was achieved. The method detection limit (MDL) and the limit of quantitation (LOQ) were 0.028 and 0.094 ppm, respectively. Analyses of commercial poultry feed samples using the QuEChERS method yielded results similar to those obtained via EPA method AG-555. © 2010 American Chemical Society.

Gunatilake S.R.,Mississippi State University | Clark T.L.,Mississippi State University | Rodriguez J.M.,Mississippi State Chemical Laboratory | Mlsna T.E.,Mississippi State University
Analytical Methods | Year: 2014

Comprehensive two-dimensional gas chromatography (GC × GC) hyphenated with rapid quadrupole mass spectrometry was successfully used to develop a novel method for the determination of trace level estrogens in influent and effluent wastewater. Five estrogens used for the study were 17β-estradiol (βE2), 17α-estradiol (αE2), estrone (E1), 17α- ethynylestradiol (EE2) and estriol (E3). Two orthogonal columns and thermal modulation result in enhanced separation, while the rapid scanning quadrupole mass spectrometer gives high resolution peaks. Samples were extracted with Hydrophilic-Lipophilic Balance (HLB) cartridges and derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) prior to analysis. The method uses a single extraction step and ng L-1 method detection limits were achieved using a relatively low sample volume of 500 mL. Elimination of additional cleanup steps make the method time effective. Furthermore, the method has less initial cost as the instrument is far less expensive than a tandem mass spectrometer. A parallel conventional gas chromatographic-mass spectrometric (GC/MS) study was carried out to compare the results. Detection limits were 2 to 4 times improved with the GC × GC over the GC/MS. © 2014 The Royal Society of Chemistry.

Overmyer J.P.,University of Georgia | Smith P.F.,University of Georgia | Kellock K.A.,University of Georgia | Kwon J.-W.,Mississippi State Chemical Laboratory | Armbrust K.L.,Mississippi State Chemical Laboratory
Environmental Toxicology | Year: 2010

Sertraline is a selective serotonin reuptake inhibitor (SSRI) prescribed as an antidepressant. Although SSRIs are known to block serotonin reuptake sites on cell membranes, they also have been shown to inhibit acetylcholinesterase (AChE) activity. Thus, the interaction of these chemicals with other AChE inhibitors, namely, organophosphate and carbamate insecticides, is of interest. In addition, these insecticides have been shown to interact with serotonergic neuronal pathways creating questions as to how these chemicals might interact. In this study, the interactive effect of sertraline (SSRI) in binary combinations with carbaryl (carbamate insecticide) and diazinon (organophosphate insecticide) was assessed using a 48-h acute toxicity test with black fly larvae, Simulium vittatum IS-7. Results showed that observed mortality was bracketed by the independent action model and concentration addition model with the independent action model slightly underestimating mortality and the concentration addition model slightly overestimating mortality. Varying the concentration of the chemicals in the mixture did not indicate that sertraline was interacting with the insecticides to make them more toxic or vice versa. These results indicate that sertraline and the insecticides are likely eliciting toxicity at separate neuronal pathways since no interaction was observed. © 2009 Wiley Periodicals, Inc.

Maruya K.A.,Southern California Coastal Water Research Project | Vidal-Dorsch D.E.,Southern California Coastal Water Research Project | Bay S.M.,Southern California Coastal Water Research Project | Kwon J.W.,Mississippi State Chemical Laboratory | And 2 more authors.
Environmental Toxicology and Chemistry | Year: 2012

To investigate the occurrence and bioaccumulation of organic contaminants of emerging concern (CECs) near four major wastewater ocean outfalls in the Southern California Bight, more than 75 pharmaceutical and personal care products, current-use pesticides, and industrial/commercial chemicals were analyzed in sediment and liver tissues of hornyhead turbot (Pleuronichthys verticalis) using gas and liquid chromatography-mass spectrometry. Although most CECs targeted were infrequently detected or not detectable, triclosan, 4-nonylphenol (4-NP) and bis(2-ethylhexylphthalate) were detected in all sediments at median (maximum) concentrations of 5.1 (8.6), 30 (380), and 121 (470) μg/kg, respectively. In the liver, 4-NP and polybrominated diphenyl ether (PBDE) congeners 47 and 99 were detected in >90% of samples at median (maximum) concentrations of 85 (290) and 210 (480) μg/kg, respectively. The sedative diazepam was detected in all liver samples, but was infrequently detected in sediments. Sediment and liver concentrations across outfall locations ranged over several orders of magnitude and were elevated relative to a reference site. Relative to sediment, accumulation in liver of PBDEs 47 and 99 was comparable to that for legacy organochlorines, confirming their high bioaccumulation potential and suggesting their inclusion in future tissue monitoring studies. Mean tissue PBDE and diazepam concentrations were higher in livers from male versus female P. verticalis, suggesting that gender differences also be considered in designing such studies. © 2012 SETAC.

Xia K.,Mississippi State Chemical Laboratory | Hundal L.S.,Metropolitan Water Reclamation District of Greater Chicago | Kumar K.,Metropolitan Water Reclamation District of Greater Chicago | Armbrust K.,Mississippi State Chemical Laboratory | And 2 more authors.
Environmental Toxicology and Chemistry | Year: 2010

Land application of biosolids is a common practice throughout the world. However, concerns continue to be raised about the safety of this practice, because biosolids may contain trace levels of organic contaminants. The present study evaluated the levels of triclocarban (TCC), triclosan (TCS), 4-nonylphenol (4-NP), and polybrominated diphenyl ethers (PBDEs) in biosolids from 16 wastewater treatment plants and in soils from field plots receiving annual applications of biosolids for 33 years. All of the four contaminants evaluated were detected in most of the biosolids at concentrations ranging from hundreds of μg/kg to over 1,000 mg/kg (dry wt basis). They were detected at μg/kg levels in the biosolids-amended soil, but their concentrations decreased sharply with increasing soil depth for 4-NP, PBDEs, and TCC, indicating limited soil leaching of those compounds. However, potential leaching of TCS in the biosolids-amended soils was observed. The levels of all four compounds in the surface soil increased with increasing biosolids application rate. Compared with the estimated 33-year cumulative input to the soil during the 33-year consecutive biosolids application, most of the PBDEs and a small percentage of 4-NP, TCC, and TCS remained in the top 120-cm soil layer. These observations suggest slow degradation of PBDEs but rapid transformation of 4-NP, TCC, and TCS in the biosolids-amended soils. © 2009 SETAC.

Brown A.E.,Mississippi State Chemical Laboratory | Sparks D.L.,Mississippi State Chemical Laboratory
Journal of the Science of Food and Agriculture | Year: 2014

Aflatoxins are highly toxic, mutagenic, teratogenic and carcinogenic compounds produced predominantly as secondary metabolites by certain species of fungi belonging to the Aspergillus genus. Owing to the significant health risks and economic impacts associated with the presence of aflatoxins in agricultural commodities, a considerable amount of research has been directed at finding methods to prevent toxicity. This review compiles the recent literature of methods for the detoxification and management of aflatoxin in post-harvest agricultural crops using non-biological remediation. © 2013 Society of Chemical Industry.

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