Pretreatment of landfill leachate by chemical oxidation processes

Kinetics and efficiency of Fenton’s and ozonation processes for the pretreatment of two landfill leachates (fresh and mature) resulting from municipal waste disposal were studied. Both samples presented high organic load, high toxicity and low biodegradability. These were the reasons why oxidative treatment was proposed. Fresh and mature leachate showed different behaviors in the oxidation experiments. The final extents of removal were attained in comparable time intervals in both oxidation systems. Maximal removal of organics by the Fenton’s oxidation reached more than 50 % according to COD. Zero or first order kinetics were found the best to describe the organic components (in terms of COD and DOC) removal by the Fenton’s oxidation for both landfill leachates. Higher reaction rate values of the Fenton’s oxidation were achieved with fresh leachate samples. The efficiency of initial organics removal with ozone was about 70 % for mature leachate, while in case of the fresh one only 41 % of COD were removed. The best fits of COD and DOC experimental data from oxidation of fresh and mature leachates were obtained by a combined kinetic model. No significant improvement of the biodegradability of landfill leachates was achieved using these treatment procedures. Regarding toxicity, ozonation showed to be more effective than the Fenton’s oxidation. Advanced oxidation experiments confirmed that the Fenton’s oxidation and ozonation are comparable oxidative treatment techniques for the reduction of organic pollution in the investigated municipal landfill leachates. However, neither of them is effective enough to be used as a pretreatment method followed by biological treatment.     

Relation between kinetic parameters for reactions of organic matter degradation in waste environmental matrix

The organic fraction of urban solid residues disposed of in sanitary landfills during the decomposition yields biogas and leachate, which are sources of pollution. Leachate is a resultant liquid from the decomposition of substances contained in solid residues and it contains in its composition organic and inorganic substances. Literature shows an increase in the use of thermoanalytical techniques to study the samples with environmental interest, this way thermogravimetry is used in this research. Thermogravimetric studies (TG curves) carried out on leachate and residues shows similarities in the thermal behavior, although presenting complex composition. Residue samples were collected from landfills, composting plants, sewage treatment stations, leachate, which after treatment, were submitted for thermal analysis. Kinetic parameters were determined using the Flynn–Wall–Ozawa method. In this case they show little divergence between the kinetic parameter that can be attributed to different decomposition reaction and presence of organic compounds in different phases of the decomposition with structures modified during degradation process and also due to experimental conditions of analysis.     

Methylmercury determination in biological samples using electrothermal atomic absorption spectrometry after acid leaching extraction

An efficient and sensitive method for the determination of methylmercury in biological samples was developed based on acid leaching extraction of methylmercury into toluene. Methylmercury in the organic phase was determined by electrothermal atomic absorption spectrometry (ETAAS). The methylmercury signal was enhanced and the reproducibility increased by formation of certain complexes and addition of Pd-DDC modifier. The complex of methylmercury with DDC produced the optimum analytical signal in terms of sensitivity and reproducibility compared to complexes with dithizone, cysteine, 1,10-phenanthroline, and diethyldithiocarbamate. Method performance was optimized by modifying parameters such as temperature of mineralization, atomization, and gas flow rate. The limit of detection for methylmercury determination was 0.015 μg g⁻¹ and the RSD of the whole procedure was 12% for human teeth samples (n=5) and 15.8% for hair samples (n=5). The method’s accuracy was investigated by using NIES-13 and by spiking the samples with different amounts of methylmercury. The results were in good agreement with the certified values and the recoveries were 88–95%.     

High-performance liquid chromatographic determination of colouring matters in historical garments from the Holy Mountain of Athos

This work is probably the first attempt to identify the organic colouring materials contained in post-Byzantine textiles, from the Holy Mountain of Athos. Samples extracted from seven ecclesiastical garments (15th–19th century) are investigated by high performance liquid chromatography with UV-Vis diode array detection. The detection limits for alizarin, purpurin, carminic acid, laccaic acid A, luteolin, apigenin, genistein, fisetin, sulfuretin, ellagic acid, indigotin and indirubin are found to be within 0.002–0.029 μg mL⁻¹. The following organic dyes are identified in the extracts: dyer’s broom (Genista tinctoria L.), young fustic (Cotinus coggygria Scop.), an indigoid dye source either indigo (Indigofera species) or woad (Isatis tinctoria L.), madder, cochineal and lac dye (Kerria lacca Kerr). Furthermore, the identification of a brazilein derivative indicates the presence of a Caesalpinia dye source in the samples. Correspondence: Ioannis Karapanagiotis, Ormylia Art Diagnosis Center, Sacred Convent of the Annunciation, Ormylia, GR-63071 Chalkidiki, Greece     

Application of scanning calorimetry to estimate soil organic matter loss after fires

The severe heating of soil during wildfires and prescribed burns may result in adverse effects on soil fertility due to organic matter loss. No rapid and reliable procedure exists to evaluate soil organic matter (SOM) losses due to heating. Enthalpy of SOM combustion correlates with organic matter content. Quartz is a ubiquitous mineral in soils and has a remarkably constant composition and reversible α–β phase transition at 575 °C. We suggest that SOM content in heated and unheated soils can be compared using the ratio of SOM combustion enthalpy on heating to the β–α quartz transition enthalpy measured on cooling of the same sample. This eliminates the need to dry and weigh the samples, making possible field applications of the proposed method. The feasibility of using the (ΔH _{comb SOM})/(ΔH _β–α Qz) ratio was established with experiments on soil samples heated in the laboratory and the method was then used for evaluation of SOM loss on two pile burn sites at UC Berkeley’s Blodgett Forest Research Station in Georgetown, California.     

Analytical strategy based on the use of liquid chromatography and gas chromatography with triple-quadrupole and time-of-flight MS analyzers for investigating organic contaminants in wastewater

The presence of a wide variety of organic pollutants with different physicochemical characteristics has been investigated in wastewater samples from a municipal solid-waste-treatment plant in Castellón, Spain. An advanced analytical strategy was applied—combined used of two powerful and complementary techniques, GC and LC, both hyphenated with tandem mass spectrometry with triple-quadrupole analyzers. The GC–MS–MS method was based on sample extraction using C₁₈ SPE cartridges and enabled the determination of approximately 60 compounds from different chemical families, for example PAHs, octyl/nonylphenols, PCBs, organochlorine compounds, insecticides, herbicides, and PBDEs. Most of the compounds selected are included as priority contaminants in the European Union (EU) Water Directive. The UHPLC–MS–MS method, which provided high chromatographic resolution and sensitivity and short analysis time, used sample extraction with Oasis HLB SPE cartridges and enabled the determination of 37 (more polar) pesticides. The methodology developed was applied to the analysis of 41 water samples (20 untreated raw leachates and 21 treated samples) collected between March 2007 and February 2009. Amounts of the contaminants investigated rarely exceeded 0.5 μg L⁻¹ in the treated (reverse osmosis) water samples analyzed. As expected, in untreated leachates the number of compounds detected and the concentrations found were notably higher than in treated waters. The most commonly detected pollutants were herbicides (simazine, terbuthylazine, terbutryn, terbumeton, terbacil, and diuron), fungicides (thiabendazole and carbendazim), and 4-t-octylphenol. The results obtained proved that use of reverse osmosis for water treatment was efficient and notably reduced the amounts of organic contaminants found in raw leachate samples. In order to investigate the presence of other non-target contaminants, water samples were also analyzed by using GC–TOF MS and LC–QTOF MS. Several organic pollutants that did not form a part of the previous list of target contaminants were identified in the samples, because of the high sensitivity of TOF MS in full-spectrum acquisition mode and the valuable accurate-mass information provided by these instruments. The insecticide diazinon, the fungicide diphenylamide, the UV filter benzophenone, N-butylbenzenesulfonamide (N-BBSA), the insect repellent diethyltoluamide, caffeine, and the pharmaceuticals erythromycin, benzenesulfonanilide, ibuprofen, atenolol, and paracetamol were some of the compounds identified in the water samples analyzed.     

Bentonite stability,speciation and migration behaviour of some critical radionuclides

The contribution is focused on chemical, geochemical and mineralogical research of bentonite stability with the aim to determine the effect of saturation medium composition and loading by heat on bentonite stability. The main part of the research is directed to the experimental results of bentonite and bentonite leachate samples obtained for the bentonite interaction under laboratory experiments. Computer-modeling methods were used to calculate equilibrium thermodynamic principles, the distributions of predominant aqueous species, and potential solubility controls for the environmentally important oxidation states of each investigated radioactive contaminants. The Eh–pH diagrams of individual chemical species of the tested radionuclides were calculated by the geochemical software tool Geochemist’s Workbench that included the actual chemical compositions of the solid–liquid systems under the given experimental conditions. It was confirmed that smectites are transformed to more stable silicate phases, such as illite/smectite mixed layers, illite. The data obtained from the model calculations conform with experimental results. The effect of the variable aqueous phase composition on bentonite stability using Ca–Mg and Na–Ca bentonites for the experiments was studied. The synthetic granitic waters with the higher concentration of the K⁺ and Mg²⁺ cations were applied for the study of bentonite stability.     

Performance of commercial soil laboratories in a proficiency test program in Brazil

A soil proficiency test (PT) was administered to 50 participant laboratories in which two sets of samples, consisting of 20 yearly PT samples and 5 ‘blind’ samples in clients’ names were analyzed for pH, organic matter, total acidity, extractable calcium, magnesium, potassium and phosphorus by the laboratories. Our objective was to determine whether laboratories take extra care to analyze clients’ samples as they do with regular PT samples. The analytical data were evaluated essentially by the procedure described in the international harmonized protocol for proficiency testing of analytical chemistry laboratories. Performance of participant laboratories was assessed by z-scores and summary z-scores statistics involving sum of squared z-scores interpreted as chi-square ( c_n² ) \left( {\chi_{n}^{2} } \right) distribution for zero-centered z-scores with unit variance. From 8 750 determinations, outliers and stragglers accounted for less than 2% of the entire data. Over 93% of the data were satisfactory, whereas between 2 and 4% were either unsatisfactory or questionable in both the PT and ‘blind’ tests. On the basis of sum of squared z-scores interpreted from c_n² \chi_{n}^{2} distribution table, between 30 and 40% of the laboratories had more than 90% probability of having their measurement data within the robust mean and standard deviation for each soil parameter, while another 30–42% of the laboratories had less than 50% probability of having measurement data within the robust mean and standard deviation. Overall, 21 laboratories (42%) were ranked in Class A either in the PT or ‘blind’ tests out of which 12 of them (57%) retained this ranking in both tests. Fourteen laboratories (28%) were ranked in Class C in either the PT or ‘blind’ tests with only 5 of them (36%) consistently ranking in this class in both tests.     

Post-Extraction Losses of Volatile Aromatic Hydrocarbons During Capillary Extraction–HRGC Analysis: A Quantitative Assessment

Benzene, toluene, ethylbenzene and o-, m-, and p-xylenes (BTEX), were extracted from aqueous samples by capillary extraction (CEx), a manual form of in-tube microextraction inherently compatible with capillary GC, and analyzed by HRGC analysis in order to quantify the post-extraction losses of these volatile organic compounds. Accuracy of the VOC determination by CEx–HRGC is dependent on these losses. The used active extraction devices were fused silica open-tubular capillaries of 0.25 mm i.d., with lengths in the range of 3–15 cm, coated with a 0.25 μm film of PTE-5 (5% phenyl methylpolysiloxane) stationary phase. The losses decreased remarkably when the extractor lengths were increased. In particular, the losses were modest or negligible for capillary extractors of usual length, though the losses increased with rising solute volatility and ‘lag time’ (the length of time required to connect in-line the laden capillary extractors with the HRGC column). BTEX losses between 2% (benzene) and 0.5% (o-xylene) resulted from CEx conducted under very usual conditions, independently from sample concentration. The short-term precision of the CE–HRGC experiments, expressed as relative standard deviation, was 0.8–4.9% (n = 5).     

Mesophilic Digestion Kinetics of Manure Slurry

Anaerobic digestion kinetics study of cow manure was performed at 35°C in bench-scale gas-lift digesters (3.78 l working volume) at eight different volatile solids (VS) loading rates in the range of 1.11–5.87 g l⁻¹ day⁻¹. The digesters produced methane at the rates of 0.44–1.18 l l⁻¹ day⁻¹, and the methane content of the biogas was found to increase with longer hydraulic retention time (HRT). Based on the experimental observations, the ultimate methane yield and the specific methane productivity were estimated to be 0.42 l CH₄ (g VS loaded)^–1 and 0.45 l CH₄ (g VS consumed)^–1, respectively. Total and dissolved chemical oxygen demand (COD) consumptions were calculated to be 59–17% and 78–43% at 24.4–4.6 days HRTs, respectively. Maximum concentration of volatile fatty acids in the effluent was observed as 0.7 g l^–1 at 4.6 days HRT, while it was below detection limit at HRTs longer than 11 days. The observed methane production rate did not compare well with the predictions of Chen and Hashimoto’s [1] and Hill’s [2] models using their recommended kinetic parameters. However, under the studied experimental conditions, the predictions of Chen and Hashimoto’s [1] model compared better to the observed data than that of Hill’s [2] model. The nonlinear regression analysis of the experimental data was performed using a derived methane production rate model, for a completely mixed anaerobic digester, involving Contois kinetics [3] with endogenous decay. The best fit values for the maximum specific growth rate (μ _m) and dimensionless kinetic parameter (K) were estimated as 0.43 day^–1 and 0.89, respectively. The experimental data were found to be within 95% confidence interval of the prediction of the derived methane production rate model with the sum of residual squared error as 0.02.     

HPLC–DAD–MS analysis of dyes identified in textiles from Mount Athos

Organic colorants contained in 30 textiles (16th to early 20th century) from the monastery of Simonos Petra (Mount Athos) have been investigated using high-performance liquid chromatography equipped with diode-array detection and mass spectrometry (HPLC–DAD–MS). The components of natural dyes identified in samples treated by the standard HCl dyestuff extraction method were: alizarin, apigenin, butein, carminic acid, chrysoeriol, dcII, dcIV, dcVII, ellagic acid, emodin, fisetin, flavokermesic acid, fustin, genistein, haematein derivative (Hae′), indigotin, indirubin, isoliquiritigenin, isorhamnetin, kaempferide, kaempferol, kermesic acid, luteolin, naringenin, purpurin, quercetin, rhamnazin, rhamnetin, sulfuretin, and type B and type C compounds (last two are markers for Caesalpinia trees). Early, semi-synthetic dyes, for example indigo carmine, fuchsin components, and rhodamine B were identified in objects dated late 19th to early 20th century. A dyestuff extraction method which involves use of TFA, instead of HCl, was applied to selected historical samples, showing that the mild method enables efficient extraction of weld (Reseda luteola L.) and dyer’s broom (Genista tinctoria L.) glycosides. The marker compound (Hae′) for logwood (Haematoxylum campechianum L.) identification after treatment with HCl was investigated by liquid chromatography coupled to mass spectrometry (LC–MS) in negative electrospray ionization (LC–MS-ESI⁻) mode. LC–MS in negative atmospheric pressure chemical ionization (LC–MS-APCI⁻) mode was used, probably for the first time, to investigate cochineal (Dactylopius coccus Costa) samples. Positive electrospray ionization (LC–MS-ESI⁺) mode was used for identification of fuchsin components. Detailed HPLC–DAD studies were performed on young fustic (Cotinus coggygria Scop.) and Persian berries (Rhamnus trees).     

Interlaboratory comparisons – demonstrating degree of equivalence

 The role of matrix reference materials in the process of demonstrating the degree of equivalence of measurement results obtained from intercomparisons is outlined, reviewing exemplary selected experience gained at BAM regarding the determination of organic contaminants in environmental matrices. The specific characteristics of reference materials employed in the process of demonstrating equivalence between laboratories in the course of proficiency testing as well as the development, comparison and validation of methods are elaborated. The demand is for series of appropriately characterised samples which are fit for the purpose and it is seen from representative examples that the utilisation of such tailor-made RM designed to tackle the specific need of an analytical problem dominates over certified matrix reference materials in this context. Concluding, the role of certified matrix reference materials in quality assurance is briefly looked at both from the user’s and providers’ points of view. Received: 9 September 2002 Accepted: 16 December 2002 Presented at CERMM-3, Central European Reference Materials and Measurements Conference: The function of reference materials in the measurement process, May 30–June 1, 2002, Rogaška Slatina, Slovenia Correspondence to R. Becker     

Thermal stability and degradation of Co(II), Cd(II), and Zn(II) complexes with <Emphasis Type="Italic">N</Emphasis>-benzyloxycarbonylglycinato ligand

Thermal behavior of Co(II), Cd(II), and Zn(II) complexes with N-benzyloxycarbonylglycinato ligand was investigated using the results of TG, DSC and DTG analysis obtained at different heating rates (2.5 to 30 °C min⁻¹), from room temperature to about 900 °C. Mechanisms of complex degradation, as well as enthalpies of the degradation processes were determined. It is shown that thermal stability of investigated complexes correlates with their crystal structures, especially with the presence of crystallization and coordinated water molecules. The values of dehydration enthalpies are discussed and correlated with composition of the complexes. Kissinger’s, Ozawa’s, and Friedman’s isoconversion methods were used for the determination of kinetic parameters: the pre-exponential factor A and the apparent activation energy E _a. For all three complexes and all steps of degradation, the values of kinetics parameters obtained by Kissinger’s and Ozawa’s methods are in good agreement. The results obtained by Friedman’s method showed that some decomposition steps are simple and some others are complex ones.     

Thermal,physicochemical and microstructural studies of binary organic eutectic systems

Solid–liquid phase equilibrium data of three binary organic systems, namely, 3-hydroxybenzaldehyde (HB)—4-bromo-2-nitroanilne (BNA), benzoin (BN)—resorcinol (RC) and urea (U)—1,3-dinitrobenzene (DNB), were studied by the thaw–melt method. While the former two systems show the formation of simple eutectic, the third system shows the formation of a monotectic and a eutectic with a large immiscibility region where two immiscible liquid phases are in equilibrium with a liquid of single phase. Growth kinetics of the pure components, the monotectic and the eutectics, studied by measuring the rate of movement (v) of solid–liquid interface in a thin U-tube at different undercoolings (ΔT) suggests the applicability of the Hillig–Turnbull’s equation: v = u (ΔT) ⁿ , where v and n are the constants depending on the nature of the materials involved. The thermal properties of materials such as heat of mixing, entropy of fusion, roughness parameter, interfacial energy, and excess thermodynamic functions were computed from the enthalpy of fusion values, determined by differential scanning calorimeter (Mettler DSC-4000) system. The role of solid–liquid interfacial energy on morphologic change of monotectic growth has also been discussed. The microstructures of monotectic and eutectics were taken which showed lamellar and federal features.     

Synthesis and physicochemical study of ZSM-5 high-silica zeolite from natural raw materials

ZSM-5 high-silica zeolite was obtained from metakaolinite, Dzhenranchel’sk volcanic ash, and silica gel at T = 150–220°C, pH 9–13, and τ = 48–240 h with the use of an organic structure-forming additive, butanediol-1,4, in an alkaline solution. Optimum conditions for the synthesis of ZSM-5 zeolite were found (T = 200°C, pH 10, τ = 144 h). The catalytic properties of its H-form in vapor-phase esterification of acetic acid (I) with ethanol (II) were studied at 140–180°C and a I: II molar ratio from 1 to 2. Synthesized HZSM-5 showed high activity and selectivity in this reaction.     

A high performance method for thermodynamic study on the binding of copper ion and glycine with Alzheimer’s amyloid β peptide

The interaction of Cu²⁺ to the first 16 residues of the Alzheimer’s amyloid β peptide, Aβ(1–16) was studied by isothermal titration calorimetry at pH 7.2 and 37°C in aqueous solution. The Gholamreza Rezaei Behbehani (GRB) solvation model was used to reproduce the enthalpies of interactions of Aβ(1–16) with glycine, Gly+Aβ(1–16), and Cu²⁺ ions, Cu²⁺ +Aβ(1–16), over the whole range of Cu2+ concentrations. The binding parameters recovered from the solvation model were attributed to the structural change of Aβ(1–16) due to the glycine and Cu²⁺ interactions. It was found that there is a set of two identical binding sites for Cu²⁺ ions. p=2 indicates that the binding has positive cooperativity in the two binding sites. Aβ(1–16) structure is destabilized greatly as a result of binding to Cu²⁺ ions.     

Study of exciton transport in luminescent molecular nanoclusters using energy traps

We used a squarylium dye SQ as a specific exciton trap for J aggregates of the amphiphilic cyanine dye amphi-PIC. The exciton transport parameters in amphi-PIC J aggregates were estimated using a modified Stern–Volmer equation. We found that SQ quenches 50% of the luminescence of amphi-PIC J aggregates for a ratio of 1 SQ molecule per 80 amphi-PIC molecules. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 1, pp. 50–53, January–February, 2009.     

Determination of organophosphorus pesticides in environmental water samples by dispersive liquid–liquid microextraction with solidification of floating organic droplet followed by high-performance liquid chromatography

A simple dispersive liquid–liquid microextraction based on solidification of floating organic droplet coupled with high-performance liquid chromatography–diode array detection was developed for the determination of five organophosphorus pesticides (OPs) in water samples. In this method, the extraction solvent used is of low density, low toxicity, and proper melting point near room temperature. The extractant droplet could be collected easily by solidifying it in the lower temperature. Some important experimental parameters that affect the extraction efficiencies were optimized. Under the optimum conditions, the calibration curve was linear in the concentration range from 1 to 200 ng mL⁻¹ for the five OPs (triazophos, parathion, diazinon, phoxim, and parathion-methyl), with the correlation coefficients (r) varying from 0.9991 to 0.9998. High enrichment factors were achieved ranging from 215 to 557. The limits of detection were in the range between 0.1 and 0.3 ng mL⁻¹. The recoveries of the target analytes from water samples at spiking levels of 5.0 and 50.0 ng mL⁻¹ were 82.2–98.8% and 83.6–104.0%, respectively. The relative standard deviations fell in the range of 4.4% to 6.3%. The method was suitable for the determination of the OPs in real water samples.