Müfit Bahadir

Removal efficiency of a calix(4)arene-based polymer for water-soluble carcinogenic direct azo dyes and aromatic amines

A Mannich base derivative of 5,11,17,23-tetrakis-[(1,4-dioxa-8-azaspiro-[4.5]decanyl)methyl]-25,26,27,28-tetrahydroxy calix[4]arene 3 was synthesized by the treatment of calix[4]arene with a cyclic secondary amine (1,4-dioxa-8-azaspiro-[4.5]decane) and formaldehyde. The compound 3 was treated with dibromoxylene to obtain a calix[4]arene-based copolymer 4. In batch sorption experiments of selected carcinogenic azo dyes and aromatic amines, the compounds 3 and 4 were found to be a better sorbent for azo dyes than for the aromatic amines. It was observed that the percentage of azo dye removal was 95-99% for compound 3 and 83-97% for 4 when the pH of the dye solution was in the range of 2.0-8.0. The sorption of azo dyes and aromatic amines by calix[4]arenes-based compounds indicates that amino groups play the major role for the formation of hydrogen bonds and electrostatic interactions.

Risk assessment of polycyclic aromatic hydrocarbons in a Mediterranean semi-enclosed basin affected by human activities (Abu Qir Bay, Egypt).

The contamination of sediments and mussels sampled from Abu Qir Bay by polycyclic aromatic hydrocarbons (PAHs) was investigated. Concentrations of PAHs recorded in the bay sediments ranged from less than MDL to 2660 microg/kg dw. In general, concentrations of PAHs in mussels were higher than their corresponding sediment concentrations reflecting their great bioavailability (242-3880 microg/kg dw). The highest concentration was observed in the western part of the bay, a location affected by intensive shipping activities. The distribution pattern of PAHs was similar for mussels and sediments, particularly for sediments characterized by high contamination level, and they were dominated by the high molecular weight PAHs (4-6-rings). Applying different PAHs ratios, it was found that PAHs originated predominantly from the pyrogenic source either from the combustion of grass, wood and coal (majority of the samples) or from petroleum combustion (harbour area). The output of a Screening Level Ecological Risk Assessment (SLERA) on the bay sediments revealed that adverse ecological effects to benthic organisms are expected to occur in only one sample, and thus PAHs are not considered as contaminants of concern in Abu Qir Bay. Also adverse health effects are not expected to occur from the consumption of the investigated mussels with respect to PAHs in Abu Qir Bay.

Degradation of eight highly condensed polycyclic aromatic hydrocarbons by Pleurotus sp. Florida in solid wheat straw substrate

Abstract The degradation of eight unlabeled highly condensed polycyclic aromatic hydrocarbons (PAH) and the mineralization of three 14C-labeled PAH by the white-rot fungus Pleurotus sp. Florida was investigated. Three concentrations containing 50, 250 or 1250 μg each unlabeled PAH/5 g straw were added to sterile sea sand. Selected treatments were added subsequently with 14C-labeled pyrene, benzo[a]anthracene or benzo[a]pyrene. The PAH-loaded sea sand was then mixed into straw substrate and incubated. The disappearance of the unlabeled four-to six-ring PAH: pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene and benzo[ghi]perylene, was determined by high-performance liquid chromatography. After 15 weeks of incubation, the recoveries were less than 25% for initial amounts of 50 μg (controls above 85%). The recoveries of unlabeled PAH increased in the inoculated samples with increasing concentrations applied. No correlation could be determined between the number of condensed rings of the PAH and the recoveries of added PAH. Pleurotus sp. Florida mineralized 53% [14C]pyrene, 25% [14C]benzo[a]anthracene and 39% [14C]benzo[a]pyrene to 14CO2 in the presence of eight unlabeled PAH (50 μg applied) within 15 weeks. During the course of cultivation, Pleurotus sp. Florida degraded more than 40% of the wheat straw substrate. Variation of the initial concentration of PAH did not influence the extent of degradation of the organic matter.

Biological monitoring of landfill leachate using plants and luminescent bacteria

Abstract Landfill leachates were evaluated using assays with plants and luminescent bacteria as indicators of toxicity. Four tests were conducted with several dilutions of untreated leachate samples from two landfills (Braunschweig and Hannover), and untreated and treated samples from a third landfill (Schwicheldt). The experimental variables were growth rate of the aquatic plant Lemna minor , root lengths of the terrestrial plants Brassica rapa and Lepidium sativum after a 72 hour germination period, root elongation of Lepidium sativum over 8 days, and light emission by Photobacterium phosphoreum . Chemical analyses of the leachates were also made. At concentrations of 100 ml/L and higher, all untreated leachate samples exhibited severe toxicity, resulting in plant death or substantially poorer root growth compared to controls. EC 50 values obtained from the bacterial toxicity test were 350 and 180 ml/L for the Braunschweig and Hannover samples respectively. Plants grown in treated samples from the Schwicheldt landfill demonstrated negative responses only with undiluted leachate, indicating that this sample was less toxic than the untreated one. Chemical analysis showed substantial differences between untreated and treated samples, which may explain the decreased toxicity observed in biological tests with the treated sample. Results of the different tests were similar for all the leachates evaluated, increasing the reliability of these assays. Analytical techniques can elucidate the chemical characteristics of an environmental sample, but give little information regarding its potential ecological effects. In contrast, the bacterial and phytotoxicity assays used in this study provided inexpensive and consistent, ecologically relevant information on the toxicity of landfill leachates.

Thermal formation of PBDD/F from tetrabromobisphenol A--a comparison of polymer linked TBBP A with its additive incorporation in thermoplastics.

For a long period, polybrominated flame retardants are under discussion because of the formation of polybrominated dibenzo-p-dioxins (PBDD)/dibenzofurans (PBDF) (PBDD/F) in case of thermal stress. Concerning polymer linked tetrabromobisphenol A (TBBP A), formation of PBDD/F was commonly presumed to be sterically hindered because of the covalent fixation into the polymer backbone. Combustion experiments with additively incorporated TBBP A compared with its polymer linkage revealed, that this assumption is incorrect and has to be revised. Under same conditions, similar PBDD/F concentrations in the range of 17.5-19.6 mg PBBD/F per kg TBBP A applied were analyzed. PBDD/F homologue distribution patterns were almost identical predominated by low brominated PBDF. These findings for PBDD/F formation have to be considered in future discussions regarding thermal stress caused by combustion or recycling processes, including other flame retardants bound in polymer matrix, e.g. polybrominated polystyrene (PS), or those with molecular structures showing less analogy to PBDD/F, like hexabromocyclododecane. The second aspect introduced, is the influence of different plastics on the formation rates of PBDD/F. In this context, combustion experiments were performed in an atmosphere consisting of synthetic air and HBr. PBDD/F concentrations were 8.47 mg/kg polyethylene, 1.67 mg/kg PS, 3.92 mg/kg phenolic resin and 18.1 mg/kg epoxy resin. Distribution patterns of PBDD/F homologues could partly be correlated with the occurrence of the precursors polybrominated benzenes and phenols.

Sugarcane bagasse treated with hydrous ferric oxide as a potential adsorbent for the removal of As(V) from aqueous solutions.

The mechanism of As(V) removal from aqueous solutions by means of hydrated ferric oxide (HFO)-treated sugarcane bagasse (SCB-HFO) (Saccharum officinarum L.) was investigated. Effects of different parameters, such as pH value, initial arsenic concentration, adsorbent dosage, contact time and ionic strength, on the As(V) adsorption were studied. The adsorption capacity of SCB-HFO for As(V) was found to be 22.1 mg/g under optimum conditions of pH 4, contact time 3h and temperature 22 °C. Initial As(V) concentration influenced the removal efficiency of SCB-HFO. The desorption of As(V) from the adsorbent was 17% when using 30% HCl and 85% with 1M NaOH solution. FTIR analyses evidenced two potential binding sites associated with carboxyl and hydroxyl groups which are responsible for As(V) removal. Adsorption, surface precipitation, ion exchange and complexation can be suggested as mechanisms for the As(V) removal from the solution phase onto the surface of SCB-HFO.

Use of modified wheat bran for the removal of chromium(VI) from aqueous solutions

Novel adsorbents, wheat bran (WB) and modified wheat bran (M-WB) with tartaric acid were developed and Cr(VI) adsorption was investigated by changing various parameters. The adsorption increased with contact time and become optimum at 180 min for WB and 200 min for M-WB. When the pH of the solution phase increased, some of toxic Cr(VI) reduced into less toxic Cr(III) on the WB surface. The maximum removal of Cr(VI) from the solution having an initial Cr(VI) concentration of 200 mg L(-1) was obtained at pH 2.0 as 51.0% and 90.0% for WB and M-WB, respectively. Isotherm data of Cr(VI) adsorption on WB and M-WB was described by the Freundlich adsorption model. The adsorption capacity of 4.53 mg of Cr(VI)/g for WB and 5.28 mg of Cr(VI)/g for M-WB was obtained at pH 2 and 2.2 respectively.

Effects of modifiers, adsorbents and eluents in supercritical fluid extraction of selected pesticides in soil

Abstract The applicability of supercritcal fluid extraction (SFE) in pesticide residue analysis of fenpropimorph, pirimicarb, parathion-ethyl, triallate and fenvalerate in soil was investigated. Fortification experiments were conducted to optimize the extraction procedure by varying modifiers, trap adsorbents and eluents. Best efficiency was achieved at 60°C extraction temperature and CO 2 pressure of 3.8·10 7 Pa by the use of 5% methanol as modifer, a diol-modified silica gel trap and ethyl acetate as eluent. Recoveries of the target compounds ranged from 93–104%. Additionally, real soil samples taken 3 and 31 days after application under field conditions were analyzed for fenpropimorph, primicarb and parathion-ethyl residues by SFE and slurry as well as Soxhlet extraction technique. For all extraction methods investigated comparably high extraction efficiency was achieved. SFE is the most rapid procedure considering especially that no time-consuming clean-up steps are necessary. However, the little sample size applicable in the instrument specific extraction thimbles is the limiting factor in the detection of pesticides at low concentrations. Therefore, SFE extracts of replicates have to be pooled and concentrated in order to yield detection limits as low as those of conventional extraction procedures.

Use of supercritical fluid extraction in the analysis of pesticides in soil

The applicability of supercritical fluid extraction (SFE) in pesticide residue analysis in soil was investigated by analysing real soil samples from field experiments. Additionally, radiotracer batch experiments were performed to study the release of non-extractable residues. High repeatability, accuracy and high selectivity were the most important advantages of SFE in residue analysis. Extracts with low amounts of coextractants from the soil matrix were achieved, allowing extracts to be pooled and concentrated without further clean up steps. Thus, the limited volume of extraction thimbles of the SFE apparatus used could be compensated and insufficiently high limits of determination could be improved. Although the application of methanol-modified supercritical CO(2) was a time-saving extraction procedure which reduced solvent usage and solvent waste, SFE efficiency proved only competitive to conventional slurry and Soxhlet extraction. No exhaustive release of non-extractable residues was achieved in radiotracer batch experiments.

Brominated flame retardants and resulting PBDD/F in accidental fire residues from private residences

Abstract Fire residues of three different accidental fires in private residences were investigated for PBDD/F and brominated flame retardants. In most samples brominated substances could be detected, especially PBDPE, in a concentration range from 1 to 100 mg/kg. One sample, a plastic TV-case, however, contained 5 % PBDPE. The concentrations of PBDD/F were in the range from 1 to 173 μg/kg with the exception of another TV-case, which contained 14,910 μg/kg PBDD/F. That TV-case which was probably equipped with brominated flame retardants represented a source for PBDD/F-contamination of other objects in the room. During this investigation we found that brominated dioxins and furans were generated by defined sources containing precursor substances, and were then transported to other objects of different surface structures. Objects far away from the source of PBDD/F and with a smooth surface contained less PBDD/F than those near to the source or with a raw and well adsorbing surface.