Showing papers in "Environmental Chemistry Letters in 2010"

Heavy metals, occurrence and toxicity for plants: a review

Abstract: Metal contamination issues are becoming increasingly common in India and elsewhere, with many documented cases of metal toxicity in mining industries, foundries, smelters, coal-burning power plants and agriculture. Heavy metals, such as cadmium, copper, lead, chromium and mercury are major environmental pollutants, particularly in areas with high anthropogenic pressure. Heavy metal accumulation in soils is of concern in agricultural production due to the adverse effects on food safety and marketability, crop growth due to phytotoxicity, and environmental health of soil organisms. The influence of plants and their metabolic activities affects the geological and biological redistribution of heavy metals through pollution of the air, water and soil. This article details the range of heavy metals, their occurrence and toxicity for plants. Metal toxicity has high impact and relevance to plants and consequently it affects the ecosystem, where the plants form an integral component. Plants growing in metal-polluted sites exhibit altered metabolism, growth reduction, lower biomass production and metal accumulation. Various physiological and biochemical processes in plants are affected by metals. The contemporary investigations into toxicity and tolerance in metal-stressed plants are prompted by the growing metal pollution in the environment. A few metals, including copper, manganese, cobalt, zinc and chromium are, however, essential to plant metabolism in trace amounts. It is only when metals are present in bioavailable forms and at excessive levels, they have the potential to become toxic to plants. This review focuses mainly on zinc, cadmium, copper, mercury, chromium, lead, arsenic, cobalt, nickel, manganese and iron.

Field crops for phytoremediation of metal-contaminated land. A review

Abstract: The use of higher plants to remediate contaminated land is known as phytoremediation, a term coined 15 years ago Among green technologies addressed to metal pollution, phytoextraction has received increasing attention starting from the discovery of hyperaccumulator plants, which are able to concentrate high levels of specific metals in the above-ground harvestable biomass The small shoot and root growth of these plants and the absence of their commercially available seeds have stimulated study on biomass species, including herbaceous field crops We review here the results of a bibliographical survey from 1995 to 2009 in CAB abstracts on phytoremediation and heavy metals for crop species, citations of which have greatly increased, especially after 2001 Apart from the most frequently cited Brassica juncea (L) Czern, which is often referred to as an hyperaccumulator of various metals, studies mainly focus on Helianthus annuus L, Zea mays L and Brassica napus L, the last also having the greatest annual increase in number of citations Field crops may compensate their low metal concentration by a greater biomass yield, but available data from in situ experiments are currently very few The use of amendments or chelators is often tested in the field to improve metal recovery, allowing above-normal concentrations to be reached Values for Zn exceeding 1,000 mg kg−1 are found in Brassica spp, Phaseolus vulgaris L and Zea mays, and Cu higher than 500 mg kg−1 in Zea mays, Phaseolus vulgaris and Sorghum bicolor (L) Moench Lead greater than 1,000 mg kg−1 is measured in Festuca spp and various Fabaceae Arsenic has values higher than 200 mg kg−1 in sorghum and soybean, whereas Cd concentrations are generally lower than 50 mg kg−1 Assisted phytoextraction is currently facilitated by the availability of low-toxic and highly degradable chelators, such as EDDS and nitrilotriacetate Currently, several experimental attempts are being made to improve plant growth and metal uptake, and results are being achieved from the application of organic acids, auxins, humic acids and mycorrhization The phytoremediation efficiency of field crops is rarely high, but their greater growth potential compared with hyperaccumulators should be considered positively, in that they can establish a dense green canopy in polluted soil, improving the landscape and reducing the mobility of pollutants through water, wind erosion and water percolation

Preparation of CuO/SiO2 and photocatalytic activity by degradation of methylene blue

Abstract: A photocatalyst based on CuO/SiO2 was prepared, and evaluated for the degradation of methylene blue in aqueous medium. The photocatalyst was obtained by calcination method of copper salt, in the presence of silica. The characterization by XRD, FTIR, and TPR techniques confirmed the formation of CuO as active phase. SEM studies showed CuO deposited on the surface of SiO2. By ESI-MS, it was demonstrated that the degradation of methylene blue occurs through successive hydroxylations. Photodegradation assays showed that CuO/SiO2 was efficient for degradation, and that the material worked better in the presence of UV light.

Effects of gamma rays irradiation on seed germination and growth of hard wheat

Abstract: The effects of irradiation with low doses (0, 10, 20 and 30 Gy) of radioactive cobalt (60Co) γ rays on seed germination, shoot and epicotyl growth of hard wheat (Triticum durum Desf.) were investigated under laboratory and glasshouse conditions. Irradiated wheat seeds kept their germination speed and capacity levels compared to the control. However, improvements of +18 and +32% were, respectively obtained in root number and root length at the 20-Gy dose. Moreover, the 20-Gy-irradiation dose generated an increase of +33% in epicotyl length. The 20-Gy-irradiation dose improved the root length by +32% and root number by +75% in plants grown on liquid medium. A lower root length increase of +23% was obtained with the same treatment under glasshouse growing conditions. These results show that the in depth development stimulation of hard wheat roots following gamma ray treatment may be used for drought control.

Humic substances as surfactants

Abstract: Humic substances from soils and sediments can be defined as surface active substances based on the surface tension measurements. Although there are several micellar structural models of humic substances currently available, few studies evaluating humic substances as surfactants have been conducted to date. Therefore, we evaluated the ability of humic substances and their derivatives to influence surface tension. We found that the ability of a humic substance to influence the surface tension of a solution depends on its origin. Many industrially produced humic materials exerted little or no impact on surface tension, whereas humic substances isolated from natural environments (water, soil, peat, sediments, sludge from wastewater treatment facilities) exerted a large impact on surface tension. These findings indicate that the modification of humic substances can enable their use as surfactants. In addition, these findings indicate that solutions of humic substances and their derivatives can be used to increase the solubility of organic compounds.

Kinetic studies of the degradation of parabens in aqueous solution by ozone oxidation.

Abstract: Ozone degradation of a mixture containing methylparaben, ethylparaben, propylparaben, butylparaben and benzylparaben was carried out in aqueous solution. The degradation followed the pseudo-first-order kinetic model and occurs with two ozonation stages with the observed rate constants of second stage ozonation, k obs2, being higher than the observed rate constants in first stage, k obs1. The k obs1 of parabens was found to increase exponentially whilst k obs2 was found to maximize at 35°C. Both k obs1 and k obs2 were found to decrease exponentially with respect to the initial concentration of parabens. Both pH and ozone dose showed positive effects on the rate of degradation. It was also observed that an ozone dose of 0.67 g/h resulted in the removal of 99% of parabens in 12 min, and also the removal of 61 and 32% of chemical oxygen demand (COD) and total organic carbon (TOC), respectively, in 3 h of ozonation time for a 500 μM of solution of parabens.

Ethylenediamine-modified activated carbon for aqueous lead adsorption

Abstract: This study is to develop a carbon-based adsorbent containing multiple functional ligands for effective removal of lead ions from aqueous media. Activated carbon was oxidized by nitric acid, followed by chlorination with thionyl chloride and reaction with ethylenediamine. Modified activated carbon (MAC) was characterized using scanning electron microscopy in conjunction of energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FT-IR), and potentiometric titration. Surface characterizations confirmed that carboxyl, amine, and chlorine functional groups were effectively introduced onto the carbon surface by the treatments. The modifications lowered the pH at the point of zero charge (pHpzc) from 9.6 to 2.55 and resulted in more negatively charged surfaces. Adsorptive experiments showed that aqueous Pb removal by MAC was faster, with a 62% higher capacity than the original activated carbon (60.2 vs. 37.2 mg g−1).

Quantification of singlet oxygen and hydroxyl radicals upon UV irradiation of surface water

Abstract: We measured the formation rate and the steady-state concentration of hydroxyl radicals and of singlet oxygen upon irradiation of lake water. There is controversy about the importance of singlet oxygen in the environmental photochemistry, but here we show that the steady-state concentration of 1O2 under irradiation can be higher by about two orders of magnitude compared to the hydroxyl radical. The higher occurrence of singlet oxygen in surface waters is mainly due to a higher rate of formation, because the transformation rate constants of 1O2 (collision with the solvent) and of ·OH (reaction with dissolved compounds) are comparable.

A new environmentally friendly process for the recovery of gold from electronic waste

Abstract: A new method for the recovery of precious metals, in particular gold, from electronic waste is proposed. This work focused on the research of an easily renewable etching agent, in order to make an environmentally friendly process possible. Two well known hydrometallurgical etching agents, FeCl3 and CuCl2, were evaluated in terms of efficiency and kinetics, testing solutions with different concentration of etchant and hydrochloric acid. The recovery of spent etching solutions was evaluated: promising results were found in the case of CuCl2, which can be completely restored by oxidation of the cuprous chloride formed during the etching using atmospheric oxygen.

Influence of support on catalytic behavior of nickel catalysts in the steam reforming of ethanol for hydrogen production

Abstract: Al2O3, MgO, SiO2 and ZnO-supported nickel catalysts were prepared and evaluated in the ethanol steam reforming for hydrogen production. It is shown that the catalytic behavior can be influenced depending on the experimental conditions employed and chemical composition of the catalyst.

Hydrogen production by nitrogenase as a potential crop rotation benefit.

Abstract: Both climate change and the adverse effects of chemical use on human and environmental health are recognized as serious issues of global concern. Nowhere is this more apparent than in the agricultural sector where release of greenhouse gases such as carbon dioxide, nitrous oxide and methane continues to be problematic and where use of nitrogen fertilizer is responsible for negative impacts on both human populations and ecosystems. The manipulation of biological nitrogen fixation (BNF) could help alleviate part of the difficulty by decreasing the need for nitrogen fertilizers, which require huge quantities of fossil fuel to produce and contribute to the release of nitrous oxide from soil as well as being responsible for the contamination of drinking water systems and natural habitats. BNF is performed by a variety of microorganisms. One of the most studied examples is the BNF carried out by rhizobial bacteria in symbiosis with their plant hosts such as pea and soybean. Hydrogen gas is an energy-rich, obligate by-product of BNF. Legume symbioses with rhizobia lacking hydrogenase enzymes (which can recycle hydrogen) have traditionally been viewed as energetically inefficient. However, recent studies suggest hydrogen release to soil may be beneficial, increasing soil carbon sequestration and promoting growth of hydrogen-oxidizing bacteria beneficial to plant growth; the alleged superiority of symbiotic performance in rhizobia possessing functional hydrogenases (HUP+) over those rhizobia without functional hydrogenases (HUP−) has also not been conclusively shown. The structure of the iron-molybdenum cofactor or FeMo-co of nitrogenase (the active site of the enzyme) has been elucidated through X-ray crystallography but the mechanism of nitrogen fixation remains unknown. However, studies of effects of hydrogen production on BNF have revealed potential candidate intermediates involved in the nitrogenase reaction pathway and have also shown the role of hydrogen as a competitive inhibitor of N2, with hydrogen now considered to be the primary regulator of the nitrogenase electron allocation coefficient. The regulation of oxygen levels within legume root nodules is also being investigated; nitrogen fixation is energetically expensive, requiring a plentiful oxygen supply but too high an oxygen concentration can irreversibly damage nitrogenase, so some regulation is needed. There is evidence from gas diffusion studies suggesting the presence of a diffusion barrier in nodules; leghaemoglobin is another potential O2 regulator. Possible functions of hydrogenases include hydrogen recycling, protection of nitrogenase from damaging O2 levels and prevention of inhibitory H2 accumulation; there is evidence for H2 recycling only in studies where H2 uptake has been strongly coupled to ATP production and where this is not the case, it is believed that the hydrogenase acts as an O2 scavenger, lowering O2 concentrations. The distribution of hydrogenases in temperate legumes has been found to be narrow and root and shoot grafting experiments suggest the host plant may exert some influence on the expression of hydrogenase (HUP) genes in rhizobia that possess them. Many still believe that HUP+ rhizobia are superior in performance to HUP− species; to this end, many attempts to increase the relative efficiency of nitrogenase through the introduction of HUP genes into the plasmids or chromosomes of HUP− rhizobia have been carried out and some have met with success but many other studies have not revealed an increase in symbiotic performance after successful insertion of HUP genes so the role of HUP in increasing parameters such as N2 fixation and plant yield is still unclear. One advantage of the hydrogen production innate to BNF is that the H2 evolved can be used to measure N2 fixation using new open-flow gas chamber techniques seen as superior to the traditional acetylene reduction assay (ARA) conducted in closed chambers, although H2 cannot be used for field studies yet as the ARA can. However, the ARA is now believed to be unreliable in field studies and it is recommended that other measures such as dry weight, yield and total nitrogen content are more accurate, especially in determining real food production, particularly in the developing nations. Another potential benefit of H2 release from root nodules is that it stays in the soil and has been found to be consumed by H2-oxidizing bacteria, many of which show plant growth–promoting properties such as the inhibition of ethylene biosynthesis in the host plant, leading to root elongation and increased plant growth; they may well be promising as biofertilizers if they can be successfully developed into seed inoculants for non-leguminous crop species, decreasing the need for chemical fertilizers. It has been suggested that rhizobia can produce nitrous oxide through denitrification but this has never been shown; it is possible that hydrogen release may provide more ideal conditions for denitrifying, free-living bacteria and so increase production of nitrous oxide that way and this issue will require more study. However, it seems unlikely that a natural system would release nitrous oxide to the same degree that chemical fertilizers have been shown to do.

Characterization and source apportionment of polycyclic aromatic hydrocarbons in the ambient air (Tehran, Iran)

Abstract: Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the urban atmosphere and the atmospheric pollutants to be identified as the most suspected carcinogens. In early measurements of urban PAH concentrations in Tehran area, the correlation between concentrations of different species indicated that automobiles were the predominant source of emission of PAHs in this city. From the diagnostic ratios, the results indicated that PAHs in the ambient air in Tehran originate primarily from diesel and gasoline engines, but contribution of the related diesel emission is apparently higher, or dominant, at the sampling sites and therefore considered as the major emission of PAHs in the ambient air.

Degradation of Ni–EDTA complex by Fenton reaction and ultrasonic treatment for the removal of Ni2+ ions

Abstract: It is difficult to meet the increasingly stringent environmental regulations by the application of conventional precipitation processes treating complex heavy metal wastewaters. We studied the potential of a new method for removing heavy metals from metal–EDTA wastewater by Fenton reaction followed by hydroxide precipitation. This process is referred to as Fenton reaction-hydroxide precipitation (FR-HP) process. This study investigated the use of FR-HP and ultrasonic/FR-HP processes for the removal of Ni(II) from Ni–EDTA wastewater. The results indicate that ultrasonic/FR-HP process is more effective for the removal of nickel ions than FR-HP process.

Removal of chelated copper from wastewaters by Fe2+-based replacement–precipitation

Abstract: We studied the removal mechanism and affecting factors of Fe2+-based replacement–precipitation process for treating CuEDTA-containing wastewaters. Since Fe2+ was easily oxidized to Fe3+ in the presence of oxygen, the chelated copper was removed by the synergetic effect of Fe3+ replacement and NaOH precipitation. Our experiments showed that the copper removal efficiency was considerably dependant on pH conditions of the solution and molar ratio of Fe2+/Cu2+.

Comparison of different probe molecules for the quantification of hydroxyl radicals in aqueous solution

Abstract: We show that the transformation of benzene into phenol is a more selective probe for the hydroxyl radical than the transformation of nitrobenzene or the generation of 4-hydroxybenzoic acid from benzoic acid. The benzene to phenol system showed adequate performance as a probe upon irradiation of lake water samples and humic acids. We show that the use of nitrobenzene and benzoic acid as hydroxyl probes should be avoided because of poor selectivity. Moreover, all the tested probe molecules underwent important interference by irradiated antraquinone-2-sulphonate, and considerably overestimated the formation of the hydroxyl radicals.

Solid phase extraction and preconcentration of cobalt in mineral waters with PAR-loaded Amberlite XAD-7 and flame atomic absorption spectrometry

Abstract: A simple, sensitive, accurate, and selective method for determination of ultratrace levels of Co is modified. The method is based on preconcentration of Co on the PAR-loaded Amberlite XAD-7 at pH 2.0 ± 0.2 for contact time as low as 45 min. The adsorbed cobalt was eluted with concentrated nitric acid and measured by flame atomic absorption spectrometry. Recoveries up to 90% were achieved. The optimized preconcentration method was applied to cobalt determination in natural mineral waters. The detection limit was found to be 0.1 ng mL−1. The relative standard deviation was found to be 13% for 600 mL of 2.0 ng mL−1, for 10 replicate preconcentration procedures. Cobalt concentrations in the studied water samples were found to be in the ranges of 0.5–3.5 ng mL−1.

Adsorption of vanadate(V) on Fe(III)/Cr(III) hydroxide waste.

Abstract: Adsorption of vanadate(V) from aqueous solution onto industrial solid ‘waste’ Fe(III)/Cr(III) hydroxide was investigated. HCl treated Fe(III)/Cr(III) hydroxide was found to be more efficient for the removal of vanadate(V) compared to untreated adsorbent. The adsorption follows second-order kinetics. Langmuir and Freundlich isotherms have been studied. The Langmuir adsorption capacity (Q 0) of the treated and untreated adsorbents was found to be 11.43 and 4.67 mg g−1, respectively. Thermodynamic parameters showed that the adsorption process was spontaneous and endothermic in the temperature range 32–60°C. Maximum adsorption was found at system pH 4.0. The adsorption mechanism was predominantly ion exchange. Effect of other anions such as phosphate, selenite, molybdate, nitrate, chloride, and sulfate on adsorption of vanadium has been examined.

Effect of the nitrification inhibitor dicyandiamide on microbial communities and N2O from an arable soil fertilized with ammonium sulphate.

Abstract: Nitrous oxide (N2O) affects climate change as a greenhouse gas and indirectly contributes to stratospheric ozone depletion. The main source of N2O in soils is denitrification which requires high soil moisture, carbon and nitrate. Nitrification inhibitors can be used to mitigate emissions of N2O from soils. In Portugal, fertilisers are often applied when soils are still relatively warm and moist conditions conducive to denitrification. A Portuguese arable soil was inhibited with dicyandiamide, a nitrification inhibitor and the effect on soil microbiological activity and composition was determined after 46 days. Soils were then incubated and received carbon and ammonium under high soil water conditions and mineral N and N2O fluxes were measured during 22 days. We found that dicyandiamide decreased microbial populations and activity, but did not alter composition. Pre-conditioning of the soil with dicyandiamide was 80% more effective in reducing fluxes of N2O than simultaneous application with fertiliser.

Adsorption of nitrate on humic acids studied by flow-through coulometry

Abstract: Interactions of nitrates with humic acids are studied by means of flow-through coulometry. It was found that nitrates are adsorbed mainly by solid humic particles and a small amount is bonded to dissolved humic macromolecules or aggregates. Langmuir and Freundlich adsorption isotherms were tested for mathematical description. Two linear regions were observed in the case of both used models for normalized coordinates. The intersection is the same for both isotherms and corresponds with the measured adsorption maximum (>80% adsorbed). It indicates two principal sites for nitrate adsorption.

Photo-polymerization of triclosan in aqueous solution induced by ultraviolet radiation

Abstract: The formation of 2,8-dichlorodibenzo-p-dioxin and other harmful degradation products in the photo-degradation process of triclosan is of increasing concern. Here we worked on the identification of polymerized products at high triclosan concentration and on the mechanism of photoreaction. Five dimmers and two trimers of triclosan were detected by liquid chromatography-mass spectrum analysis. 2,8-dichlorodibenzo-p-dioxin was also identified by comparing with an authentic standard. Relatively low pH and high concentration favored the polymerization of triclosan. Three main routes of photoreaction were postulated, namely dechlorination, ring closure and polymerization.

Interferences of carbonate quantification in municipal solid waste incinerator bottom ash: evaluation of different methods

Abstract: Quantification of carbonate contents in fresh and weathered municipal solid waste incinerator (MSWI) bottom ash was performed using volumetric and gravimetric methods, Fourier Transform Infrared (FT-IR) spectroscopy and thermal analysis. Results differ considerably depending on the method applied. Volumetric measurement and thermogravimetry (TG) are based on the determination of CO2 release by acid or thermal treatment, respectively. Interactions of CO2 with the mineral matrix and de novo synthesis of carbonates during thermal analysis were observed. In order to find out the contribution of CO2 released from residual organic matter, an additional experiment was carried out to demonstrate how the material is affected by the heating process in the course of thermal analysis. FT-IR spectroscopy as a non-destructive method seems to provide the most reliable quantitative results.

Photocatalytic degradation of organic dyes by Er3+:YAlO3/TiO2 composite under solar light

Abstract: In this work, Er3+:YAlO3/TiO2 composite was synthesized by a ultrasonic dispersion and liquid boil method. The Er3+:YAlO3/TiO2 composite and pure TiO2 powder were characterized by XRD. The degradation of different organic dyes was used to evaluate the photocatalytic activity of the Er3+:YAlO3/TiO2 composite. It is found that the photocatalytic activity of Er3+:YAlO3/TiO2 composite is much higher than that for the similar system with only TiO2. Moreover, this Er3+:YAlO3/TiO2 composite provides a new way to take advantage of TiO2 in sewage treatment aspects using solar light.

Development of novel environmental friendly polyurethane foams

Abstract: To prepare materials with improved recycling capability, new flexible biodegradable polyurethane foams, in which non-degradable polyether polyol was partly substituted by the bio-polyols based on cellulose or starch derivatives were synthesized. The incorporation of bio-polyols into the foams’ structures as well as their influence on the foam thermal stability was assessed by Fourier-transformed infrared spectroscopy and thermogravimetric analysis analyses. The ecotoxicological aspects of the newly synthesized foams were investigated by extracting the samples using freshwater as a solvent followed by applying the microbiotest screening toxkit under trade name “Thamnotoxkit F™” with larvae of freshwater shrimps Thamnocephalus platyurus.

Stability studies of cholesterol lowering statin drugs in aqueous samples using HPLC and LC–MS

Abstract: In this study, stability of statin drugs in different conditions, such as various pH, diverse solvents ratio, presence of UV, and sunlight have been investigated. Results suggest strong dependence of statins upon pH, potential environmental persistence towards sun light, and UV light degradation via singlet excited state obtained by excitation into the π–π* band. In acidic conditions interconversion between lactone and hydroxy acid forms in aqueous solutions at room temperature is retarded, while for the same sun-exposed samples are accelerated. Longer exposures lead to the degradation processes. Statin interconversion in water is much lower than in acetonitrile.

Removal of malachite green from water samples by cloud point extraction using Triton X-100 as non-ionic surfactant

Abstract: A surfactant mediated cloud point extraction (CPE) procedure has been developed to remove color from wastewater containing malachite green using Triton X-100 as non-ionic surfactant. The effects of the concentration of the surfactant, temperature and salt concentration on the different concentrations of dye have been studied and optimum conditions were obtained for the removal of malachite green. The concentration of malachite green in the dilute phase was measured using UV–Vis spectrophotometer. It was found that the separation of phases was complete and the recovery of malachite green was very effective in the presence of NaCl as an electrolyte. The results showed that up to 500 ppm of malachite green can quantitatively be removed (>95%) by CPE procedure in a single extraction using optimum conditions.

Removal of metal ions from aqueous solution by chelating polymeric hydrogel

Abstract: Polysaccharide natural seed coat from the tree Magonia pubescens, in the form of hydrogel was used to remove metals in aqueous solution. Swelling tests indicate that seed coat presents hydrogel behavior, with maximum water absorption of 292 g water/g. Adsorption experiments performed using Na+, Mg2+, K+, Ca2+, Cr3+, Fe3+ and Zn2+ demonstrated that the polysaccharide structure has a high capacity to extract these ions from the aqueous solution. Scanning electron microscopy revealed significant morphological changes of the material before and after water contact. Differential scanning calorimetry measurements indicate a signal shift of the water evaporation temperature in the material with adsorbed zinc. X-ray photoelectron spectroscopy analysis combined with theoretical studies by the density functional theory and on Hartree–Fock (HF) level evidence that the metallic ions were adsorbed through coordination with hydroxyl groups of polysaccharide. In the case of Zn2+ the lowest HF energy was observed for the tetracoordination mode, where Zn2+ is coordinated by two hydroxyl groups and two water molecules.

Screening of phthalic acid esters in raw materials, premixes and feed additives

Abstract: Phthalates are animal carcinogens and may cause death or tissue deformities. Samples of feedstuffs collected in 2005 and 2006 from industrial feed manufacturers in the Czech Republic were analysed for contamination with phthalic acid esters (PAEs), specifically di-2-ethylhexyl phthalate (DEHP) and di-n-butyl phthalate (DBP). Samples of feed additives, premixes and raw materials were collected (year 2005, n = 26). For soybean oil, the total volume of phthalates measured (DBP + DEHP) reached a level of 131.42 mg kg−1; for rapeseed oil, fish meal and animal fats, the levels measured were 15.00, 7.96 and 58.87 mg kg−1, respectively. The lowest level of DBP + DEHP was found in corn (2.03 mg kg−1). Since phthalates were detected, samples of feed additives (n = 28) and raw materials (n = 28) were collected again in 2006. The highest levels of DBP + DEHP were found in raw materials containing fat. Phthalate levels in rapeseed oil samples ranged from 1.38 to 32.40 mg kg−1 DBP + DEHP. For feed additives, contamination levels in vitamins and amino acids ranged from 0.06 to 3.15 and 1.76 to 4.52 mg kg−1 DBP + DEHP, respectively. Here, we show that the levels of PAEs found in cereals such as wheat, barley and corn may be regarded as being alarmingly high, because cereals make up the largest proportion of compound feed of farm animals.

Photodegradation of fenamiphos on the surface of clays and soils

Abstract: The photodegradation of the organophosphorus fenamiphos was studied in various clay matrices: montmorillonite, kaolin and the mineral components of two soils collected from two different sites: Settat (S) and Berrechid (B). The degradation was shown to be mainly due to the direct excitation of fenamiphos and was similar for all the matrices with a two-step kinetics : a fast and a slower one. The first step rate obtained at the surface of montmorillonite was slightly lower than that determined at the surface of kaolin. The fenamiphos degradation process clearly depended on the amount of humic substances and iron(III). The latter component accelerated the disappearance of fenamiphos, while humic substances clearly inhibited the process. The degradation rate increased in the presence of water and was mainly due to the involvement of the photohydrolysis process leading to the scission of the P–O bond. The formation of the main by-products, sulfoxide, sulfone and phenol derivatives, were elucidated by HPLC/MS.

Photochemical reaction of nitro-polycyclic aromatic hydrocarbons: effect by solvent and structure

Abstract: Photochemical degradation of 1-nitropyrene, 2-nitrofluorene, 2,7-dinitrofluorene, 6-nitrochrysene, 3-nitrofluoranthene, 5-nitroacenaphthene, and 9-nitroanthracene were examined in CHCl(3), CH(2)Cl(2), DMF, DMF/H(2)O (80/20), CH(3)CN, or CH(3)CN/H(2)O (80/20). The degradation follows mostly the 1(st) order kinetics; but a few follow 2(nd) order kinetics or undergo self-catalysis. The photodegradation rates follow the order: CHCl(3) > CH(2)Cl(2) > DMF > DMF/H(2)O > CH(3)CN > CH(3)CN/H(2)O. DMF is an exceptional solvent because 3 of the 7 compounds undergo self-catalytic reaction. 9-Nitroanthracene, which has a perpendicular nitro group, is the fastest, while the more compact 1-nitropyrene and 3-nitrofluoranthene, are the slowest degrading compounds.

Removal of olive mill waste water phenolics using a crude peroxidase extract from onion by-products

Abstract: Olive mill waste water (OMWW) originating from a two-phase olive oil-producing plant was treated with a crude peroxidase extract prepared from onion solid by-products. The treatments were based on a 3 × 3 factorial design, employing a series of combinations of pH and H2O2, in order to identify optimal operational conditions. The treatment performance was assessed by estimating the removal percentage of total polyphenols. The model established produced a satisfactory fitting of the data (R2 = 0.94, p = 0.0158), while the second-order polynomial equation used to describe the process indicated that peroxidase-catalysed polyphenol removal in diluted OMWW is facilitated at relatively low pH and intermediate H2O2 values. A predicted value of 50.7 ± 9.5% removal was calculated under optimal operational conditions (pH 2.76, [H2O2] = 3.56 mM). Analysis of an untreated and an optimally treated sample by high performance liquid chromatography revealed that enzyme treatment brought about alteration in the original OMWW polyphenolic profile. The use of peroxidase from onion solid by-products is proposed as an alternative means that could have a prospect in bioremediation applications.