A highly efficient method with low energy and water consumption in biodegradation of total petroleum hydrocarbons of oily sludge.

The hydrocarbons in petroleum sludge are environmental pollutants. It is crucial to eliminate this type of pollution. In this study, a comprehensive and operational study has been conducted on the total petroleum hydrocarbons (TPH) biodegradation in oily sludge. The experiments were performed in a semi-solid phase by two degrader bacterium, Arthrobacter citreus and Rhodococcus jostii, and they were compared with the slurry phase. Solid samples were prepared in three mixing modes of oily sludge with clay. Experiments were conducted by semi-solid bioreactors and other methods on samples contaminated with petroleum hydrocarbons. The performance of the semi-solid bioreactor for the removal of clay-free oily sludge samples showed the best results, in which biodegradation of TPH was 90.33%. GC analyses were conducted on samples before and after biodegradation. It was observed that the contaminants were decomposed uniformly by the microorganisms, except for a combination with a large peak in 12 min. For the best case, the GC-MS test was performed before and after biodegradation. Compounds with a high concentration in the sludge were significantly reduced. Only one heavy aromatic compound was detected in 51.628 min, which decomposed quite slowly and produced a large peak. It was found that 78.2% of the compounds were removed completely.

A simple, fast and low-cost method for the efficient separation of hydrocarbons from oily sludge.

Since a large amount of sediment organic matter and hydrophobic organic compounds presented in oily sludge sediments in petroleum storage tanks, separation or degradation of these compounds are environmentally important. Therefore, the effect of four solvents and their combinations on the extraction of hydrocarbons in oily sludge from the dredging of petroleum storage tanks in Iran was investigated in this study. Besides, the number of extraction steps and the temperature were also investigated, and the mechanical shaking method was introduced and compared with that of mixing and Soxhlet. The results showed that chloroform held the best solvent, and the combination of solvents showed better extraction than the pure solvents individually. Furthermore, hydrocarbon extraction increased as temperature and extraction steps raised. According to gas chromatography tests, all the solvents revealed acceptable extraction scales. Moreover, the amounts of extracted hydrocarbons by the mechanical shaking method had better results than that of mixer and Soxhlet. The highest percentage of that belonged to mechanical shaking method by 82.8%. It seems that the mechanical shaking method is a simple, fast, low-cost, and suitable alternative to the Soxhlet method for hydrocarbon extraction in oily sludge and petroleum sludge-contaminated soil.

Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Drop with Central Composite Design for the Spectrofluorometric Determination of Naproxen.

A quick, simple and efficient method for extraction, preconcentration, and determination of naproxen in water and plasma specimens with acceptable recovery by dispersive liquid-liquid microextraction based on solidified floating organic drop with spectrofluorimetry is presented. Various parameters affecting the extraction efficiency are optimized by the Central Composite Design. Moreover, under optimal conditions (120 µL 1-Undecanol with 1 mL Ethanol, pH = 3.5, 2 mL KCl 10% solution), the calibration curve was linear in the range 10.0-120.0 ng/mL. Finally, for naproxen, the detection limit was 2.4 ng/mL.

Carbon Dots Green Synthesis for Ultra-Trace Determination of Ceftriaxone Using Response Surface Methodology.

The present study sought to develop a facile and green synthetic approach for producing fluorescent carbon dots (CDs) from a natural biomass using aqueous extraction of carbonized blue crab shell. Spherical carbon dots (6.00 ± 3.0 nm) exhibited an extended emission range with excellent quantum yield (14.5 ± 3.5%). In order to measure ceftriaxone, we offered a simple and sensitive method, based on fluorescence quenching of carbon dots in plasma and water with recovery values of 94.5-104.1%. Furthermore, with usage of central composite design (CCD) based response surface methodology (RSM); we optimized the effect of different factors. In addition, ANOVA evaluated the accuracy and suitability of quadratic model. Under optimal conditions, fluorescence quenching revealed a sensitive response in the concentration range of 20-1000 nM with the limit of detection 9.0 nM for ceftriaxone. Finally, carbon dots-based fluorescence quenching procedure was able to quantify ceftriaxone in plasma, as well as mineral and tap water. Spiked samples achieved satisfactory efficiencies.

Immobilization of hexavalent chromium in cement mortar: leaching properties and microstructures.

Stabilization and solidification (s/s) of heavy metals by cementitious materials are one of the effective methods in hazardous waste management. In cement alkaline environment, Cr(VI) compounds appear in the form of chromate anion (CrO4-2), which is highly soluble; it makes the implication of the s/s method challenging. Therefore, it is important to study the amount of chromium leaching from cementitious materials. The effects of Cr(VI) concentration and water-to-cement (w/c) ratio on the level of leaching of chromium from cement mortar (CM) were investigated in this study. Results indicated w/c not significantly affect the leaching of chromium in the age of 28-day but in the 90-day-old samples indicated a reduction in leaching of chromium from mortar with increasing w/c. Results from toxicity characteristic leaching procedure (TCLP) tests indicated that the efficiency of Cr(VI) stabilization was reduced with greater chromium content but was enhanced with increased w/c. In detail, results showed that only about 0.21% and 0.26% cement weight in TCLP and tank test of Cr(VI) was stabilized in CM, respectively. The results of X-ray diffraction (XRD) and scanning electron microscope (SEM/EDS) tests indicated that increasing the Cr(VI) content leads to changes in the formation of the cement main phases and microstructure of CM.

Corrigendum to "Polythiophene-Chitosan Magnetic Nanocomposite as a Highly Efficient Medium for Isolation of Fluoxetine from Aqueous and Biological Samples".

[This corrects the article DOI: 10.1155/2016/2921706.].

Polythiophene-Chitosan Magnetic Nanocomposite as a Highly Efficient Medium for Isolation of Fluoxetine from Aqueous and Biological Samples.

Polythiophene/chitosan magnetic nanocomposite as an adsorbent of magnetic solid phase extraction was proposed for the isolation of fluoxetine in aqueous and biological samples prior to fluorescence detection at 246 nm. The synthesized nanoparticles, chitosan and polythiophene magnetic nanocomposite, were characterized by scanning electron microscopy, FT-IR, TGA, and EDAX. The separation of the target analyte from the aqueous solution containing the fluoxetine and polythiophene/chitosan magnetic nanocomposite was simply achieved by applying external magnetic field. The main factors affecting the extraction efficiency including desorption conditions, extraction time, ionic strength, and sample solution pH were optimized. The optimum extraction conditions were obtained as 10 min for extraction time, 25 mg for sorbent amount, 50 mL for initial sample volume, methanol as desorption solvent, 1.5 mL for desorption solvent volume, 3 min for desorption time, and being without salt addition. Under the optimum conditions, good linearity was obtained within the range of 15-1000 µg L(-1) for fluoxetine, with correlation coefficients 0.9994. Furthermore, the method was successfully applied to the determination of fluoxetine in urine and human blood plasma samples. Compared with other methods, the current method is characterized with highly easy, fast separation and low detection limits.

Study of kinetic and fixed bed operation of removal of sulfate anions from an industrial wastewater by an anion exchange resin.

Sulfate anions represent very important wastewater pollutants, which appear in the effluents discharged from copper mines. In this study, for the first time, an attempt has been made on the removal of sulfate anions by an ion exchange resin. This work is focused on the removal of sulfate anions from the Sarcheshmeh copper complex (Kerman province, Southeast of Iran) wastewater by an anion exchange resin. Batch experiments of sulfate anions adsorption on Lewatit K6362 resin were carried out to determine the adsorption equilibrium data and the relation of adsorption isotherms. Isothermal data can be fitted with Freundlich adsorption isotherms better than Langmuir equation. The results show that maximum removal of sulfate anions take places in the resin dosage of 1000 mg/100ml and the adsorption of sulfate anions on the resin follows reversible first-order kinetics. The overall adsorption rate constants were compared for different initial concentrations. Finally, the effects of parameters such as the flow rate, bed height and inlet adsorbate concentration on the breakthrough curve in a fixed bed column were studied in detail.