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Open access

Salima Chebbi, Atmane Allouche, Marian Schwarz, Souhila Rabhi, Hayet Belkacemi and Djoudi Merabet

Abstract

The present study investigates the application of induced air flotation (IAF) technique on PAHs (PAHs) removal performance from a real oilfield produced water of a separator cell. The quantification of total PAHs (PAHtot) was done using ultraviolet-visible spectrometry (UV-Vis) according to the naphthalene calibration curve. The UV-Vis spectra of naphthalene dissolved in a mixture of the binary solvent (water-ethanol) and the Tween 80 showed stability in the molecular orbital of C10H8. The use of small concentration of Tween 80 was revealed to be discrete in the quantification of PAHtot. The flotation process was improved at the critical micelle concentration of Tween 80 (CMC) of 2 % and the critical coalescence concentration of ethanol (CCC) of 0.5 mL/L for the PAHtot recovery of 49.76 % and the PAHtot content in the pulp of 50.24 %. At these concentrations, half of PAHtot was removed from produced water PW. Above the CMC and the CCC, the PAHtot recovery decreased and the PAHtot content in the pulp increased. It was found that there is a collector concentration at which the amount of water carrying from the pulp to the concentrate was increased and in parallel, the PAHtot recovery increased and the PAHtot content in the pulp decreased. Both of the CMC and the CCC have promoted the decrease on the conditioning time from 30 to 10 min and the flotation time from 20 to 6 min. Since the impeller speed and air flow rate were constant, the flotation of PAHs was limited. The flotation kinetics of PAHtot was described by the Higuchi model.

Open access

Dalila Ksouri, Hafit Khireddine, Ali Aksas, Tiago Valente, Fatima Bir, Nadir Slimani, Belén Cabal, Ramón Torrecillas and José Domingos Santos

Abstract

In this work ternary bioactive glasses with the molar composition 63 % SiO2, 28 % CaO, and 9 % P2O5 have been prepared via sol-gel processing route leading to xerogel or aerogel glasses, depending on the drying conditions. Two types of drying methods were used: atmospheric pressure drying (evaporative), to produce xerogels, and supercritical fluids drying, to obtain aerogels. Both dried gels were subjected to heat-treatment at three different temperatures: 400, 600 and 800 ºC in order to the removal of synthesis byproducts and structural modifications. The resulting materials were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA), and by in vitro bioactivity tests in simulated body fluid. The influence of the drying and the sintering temperature of their structure, morphology, and bioactivity of the final products were evaluated. The results show a good bioactivity of xerogel and aerogel bioactive glass powders with the formation of an apatite layer after one day of immersion in SBF solution for aerogel bioactive glass powders and a particle size less than 10 nm. An apatite layer formed after 3 days in the case of xerogel bioactive glass powders and a particle size around 100 nm.

Open access

Zita Tokárová and Anna Biathová

Abstract

Substituted thiophene-2-carbaldehydes 1a-dwere utilized in the synthesis of symmetrically substituted thiazolo[5,4-d]thiazoles 3a-d. Bis(5,4-d)thiazoles with thiophene core at the termini are the most employed in the chemistry of materials but exhibit insufficient solubility in majority of organic solvents with notable impact on the low yields of products. Accordingly, the synthetic approach towards 2,5-dithiophen- 2-yl-thiazolo[5,4-d]thiazole (3a) and its substituted derivatives 3b-d is discussed under the various reaction conditions. Appropriate structural characterisations are included with emphasis on relationship between structure and physicochemical properties highlighting the UV-Vis and fluorescence.

Open access

Ogofure G. Abraham, Bello-Osagie O. Idowu, Aduba U. Barbara, Ighodaro E. Veadams and Emoghene O. Alexander

Abstract

The qualitative assessment of putative bacterial pathogens on the surfaces of canned drinks sold in Benin metropolis was evaluated in this study. Standard bacteriological culture-based techniques employing the use of selective and differential media (Oxoid) such as Bacillus cereus agar, mannitol Salt agar, Pseudomonas cetrimide agar, bile esculin agar and MacConkey agar were used for isolation and identification of bacteria from swabbed surfaces of canned drinks. Kirby-Bauer disc diffusion technique was used for antibacterial susceptibility testing. The multiple antibiotic resistance (MAR) index was deduced from the antibiogram characterization to evaluate the public health importance of the bacterial isolates. Refrigerated samples had 25% contamination while 75% were not contaminated and about 15.39% contamination was observed for non-refrigerated samples (stored in crates or cartons) compared to the counterpart 84.61%. The bacterial species include Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus, Bacillus sp. and Enterococcus sp. The bacteria were found to be sensitive to ciprofloxacin (92.5%) and gentamicin (90.1%) and least susceptible to cefixime (23.1%) and vancomycin (26.4%). They were found to be multi-resistant because they have an MAR index above the tolerable permissible limit (0.2) for common antibiotics usually used for their eradication. It is important to ensure that the surfaces of canned drinks must be rinsed with water before consumption.

Open access

Peter Pristas, Jana Kiskova, Ivana Timkova, Lenka Malinicova, Alena Luptakova, Maria Kusnierova and Jana Sedlakova-Kadukova

Abstract

The genus Acidithiobacillus comprises 7 species of Gram-negative obligatory acidophilic chemolithotrophic bacteria that derive energy mainly from the oxidation of reduced sulphur compounds. Four of the species also catalyse the dissimilatory oxidation of ferrous iron while three (A. thiooxidans, A. albertensis, and A. caldus) do not. Bacteria from the genus Acidithiobacillus are often associated with mineral biotechnologies (biomining) and acid mine drainage. While acceleration of mineral solubilisation is a positive aspect in environmental biotechnologies, it is undesirable in acid mine drainage with strong negative ecological impact and there is profound interest in genetics and genomics of these bacteria. Representatives of Acidithiobacillus genus occur world-wide, however there are limited data on Acidithiobacillus spp. variability from Slovakia. In our work the variability of Acidithiobacillus spp., from Slovakia was analysed and the presence of A ferrooxidans was detected. In addition, for the first time we report here on the occurrence of A. albertensis as well. Comparative analyses confirmed pronounced genetic and genomic diversity within the genus, especially within A. ferrooxidans and A. thioxidans complexes. Based on data presented, several Acidithiobacillus species could be considered as a complex species and the description of several new species is very probable in the near future.

Open access

Nabila Boucherit, Mahmoud Abouseoud and Lydia Adour

Abstract

The removal of direct yellow 106 (DY106, C.I.40300) by a combined process of Fenton oxidation and enzymatic degradation in a sequential or mixed batch reactor is discussed. Experiments were first conducted with the enzymatic and chemical oxidation processes separately in order to determine the effects of various parameters such as pH, ferrous ion, hydrogen peroxide, dye and enzyme concentrations on the overall yield and kinetics of both processes. Decolourization was followed by UV-visible spectroscopy and high performance liquid chromatography (HPLC). Results showed that 89.5 % of DY106 were removed by enzymatic treatment after only 2 min, while 10 min of contact time were necessary to eliminate more than 98 % of 50 mg/L by Fenton’s process. A high performance was achieved under optimized conditions by the mixed combined process with time reduction down to 5 min. The study was also conducted to evaluate the efficiency of combined Fenton’s reaction as a pre-treatment and post treatment process combined with C-peroxidase at different ferrous ions concentrations. The optimal doses of Fe2+ were 2.5 mM, 1m M and 0.8 mM for Fenton, Fenton-enzymatic sequential and mixed processes. Intermediate products absorbing in UV range were detected for single Fenton or enzymatic treatment but were eliminated in all combined enzymatic-Fenton processes. Phytotoxicity tests showed that no toxicity was detected after treatment by combined process.

Open access

Katarína Kulichová, Mária Maliarová, Jozef Sokol, Katarína Lašáková and Michaela Havrlentová

Abstract

Oats are important cereals. Oats are a good source of protein and lipids, polyphenolics, phenolic acids, flavonoids and avenanthramides. Avenanthramides is phenolic group, which is unique in oats and have antioxidant activity, anti-inflammatory, anti-atherogenic and anti-proliferative effect. The aim of study is determination of the majoritarian avenanthramides (2c, 2p and 2f) and phenolic acids (p-coumaric and ferulic) in selected varieties of oat (Avena sativa L.) grown in two consecutive years using the HPLC method. The oats were exposed to ultrasound supported extraction (two 15 min cycles).The simultaneous separation was performed using C18 type of stationary phase. The method showed a good linearity in the concentration range 0.04 - 5.24 μg/mL for p-coumaric acid, 0.04 - 5.13 μg/mL for ferulic acid, 0.19 - 24.5 μg/mL for avenanthramide 2c, 0.53 - 17.1 μg/mL for avenanthramide 2p, 0.8 - 25.6 μg/mL for avenanthramide 2f. Correlation coefficients were higher than 0.9997. Detector operated at a wavelength 320 nm. The repeatability of the method was evaluated in three concentration levels with satisfactory results for each analyte. The content of both phenolic acids is significantly lower (50- - 100-times) compared to the total content of avenanthramides in both years’ harvests for all analyzed varieties. Content of total avenanthramides was the highest in varieties Racoon (723.28 mg/kg) followed by Oliver (578.59 mg/kg) and Kamil (384.17 mg/kg).

Open access

Pranjal Bharali, Salam Pradeep Singh, Yasir Bashir, Nipu Dutta, Bolin Kumar Konwar and Chingakham Brajakishor Singh

Abstract

Petroleum and hydrocarbons contamination can be remediated by physical, chemical or biological methods. Among these, in situ bioremediation is considered to be environmentally friendly because it restores the soil structure, requires less energy input and involves the notable removal after degradation of biosurfactant. The present study involves the characterization and assessment of biosurfactant producing indigenous hydrocarbonoclastic bacteria and their potential application in bioremediation processes. Three bacterial strains were isolated from various crude oil contaminated environments and characterized using standard identification techniques. The results clearly demonstrate the capability of utilizing hydrocarbon and biosurfactant produced by the bacterial strains. 16S rDNA sequencing followed by BLAST analysis revealed their similarity to Pseudomonas aeruginosa. The physico-chemical characterization of the biosurfactants revealed significant surface properties with stability at extreme temperature conditions (up to 121˚C), pH (5 - 8) and salinity (up to 4 %). Further, the mass spectrometry confirmed predominance of di-rhamnolipids in biosurfactant mixtures. The biosurfactants were found to be efficient in the removal of crude oil from the contaminated sand suggesting its applicability in bioremediation technology. Further, improved discharge of crude oil at elevated temperatures also confirms their thermo-stability which, could be exploited in microbial enhanced oil recovery processes. Thus, the applications of biosurfactants produced by the indigenous hydrocarbonoclastic strains appeared to be advantageous for bioremediation of petroleum-contaminated environments.

Open access

Gamal H. Ragab and Eman A. Bahgat

Abstract

This study reports about simple, robust and reproducible method for simultaneous bioanalytical determination of Valsartan (VAL) and co-administered Clopidogrel bisulfate (CGB) and Fenofibrate (FEN) in raw materials, spiked human plasma and tablets using isocratic RP-HPLC method. The chromatographic separation is carried out using isocratic binary mobile phase consisting of 80 mM phosphate buffer pH 3: Acetonitrile (30: 70 %; v/v) at the flow rate of 1.1 mL/min and 33 °C. A Diode array detector at wavelength 214 nm was used. Retention times for VAL, CGB and FEN were 3.1, 5.1 and 6.4 min, respectively. The calibration curves obtained were linear over the concentration ranges of 2.5 - 100 μg/mL for both VAL and CGB and 5 -100 μg/mL for FEN. The mean extraction recoveries of VAL, CGB and FEN from spiked plasma were 75.38±1.34 %, 89.91±2.17 % and 96.92±6.02 %, respectively. The limits of detection and quantification were 0.86, 0.67, 1.11 μg/mL and 2.60, 2.03, 3.36 μg/mL for VAL, CGB and FEN, respectively. The method was applied to the analysis of these drugs in spiked human plasma and in tablets as they are commonly used as a combination for prevention of stroke. Results obtained show good accuracy, precision and acceptable recoveries from plasma samples.

Open access

Barbora Legerská, Daniela Chmelová and Miroslav Ondrejovič

Abstract

The aim of the present study was to investigate the dye decolorization ability of laccase from Trametes versicolor. Five azonaphthalene dyes (Acid Violet 7, Acid Red 1, Allura Red AC, Orange G and Sunset Yellow FCF) were used to evaluate dye decolorization. Laccase from T. versicolor is capable of decolorizing dyes, namely Acid Violet 7 (53.7±2.3 %) and Orange G (46.0±2.2 %). The less effective ability of laccase was observed at the decolorization of other selected dyes (6.9 - 18.6 %). The presence of redox mediator (1-hydroxybenzotriazole) increased decolorization percentage for all tested dyes (≥ 90.5 %). Toxic effect of azo dyes and their degradation products after laccase treatment was observed on the growth of selected bacteria (Micrococcus luteus, Bacillus subtilis, Pseudomonas syringae and Escherichia coli), yeasts (Candida parapsilosis and Saccharomyces cerevisiae) and algae (Chlorella vulgaris and Microcystis aeruginosa). It was confirmed that degradation products showed lower inhibition effect compared to initial dyes. These findings suggest that laccase from T. versicolor are able to decolorize and detoxify selected azonaphthalene dyes.