Kinetic modeling and half life study on bioremediation of crude oil dispersed by Corexit 9500

Hydrocarbon pollution in marine ecosystems occurs mainly by accidental oil spills, deliberate discharge of ballast waters from oil tankers and bilge waste discharges; causing site pollution and serious adverse effects on aquatic environments as well as human health. A large number of petroleum hydrocarbons are biodegradable, thus bioremediation has become an important method for the restoration of oil polluted areas. In this research, a series of natural attenuation, crude oil (CO) and dispersed crude oil (DCO) bioremediation experiments of artificially crude oil contaminated seawater was carried out. Bacterial consortiums were identified as Acinetobacter, Alcaligenes, Bacillus, Pseudomonas and Vibrio. First order kinetics described the biodegradation of crude oil. Under abiotic conditions, oil removal was 19.9% while a maximum of 31.8% total petroleum hydrocarbons (TPH) removal was obtained in natural attenuation experiment. All DCO bioreactors demonstrated higher and faster removal than CO bioreactors. Half life times were 28, 32, 38 and 58 days for DCO and 31, 40, 50 and 75 days for CO with oil concentrations of 100, 500, 1000 and 2000 mg/L, respectively. The effectiveness of Corexit 9500 dispersant was monitored in the 45 day study; the results indicated that it improved the crude oil biodegradation rate.     

Solubilization of multi walled carbon nanotubes under a facile and mild condition

Multi-walled carbon nanotubes (MWCNTs) functionalized with amino groups was prepared via chemical modification of carboxyl groups introduced on the carbon nanotube surfaces. Oxidation of MWCNTs was performed with ozone in aqueous phase and amidation of generated carboxylic groups, was occurred with amines in the presence of HATU as a coupling agent. Obtained functionalized MWCNTs are soluble in many common organic solvents. The functionalized MWCNTs were characterized in detail using FTIR-ATR, Raman CHN and SEM methods.     

Single Chirality (6,4) Single‐Walled Carbon Nanotubes for Fluorescence Imaging with Silicon Detectors

Postsynthetic single‐walled carbon nanotube (SWCNT) sorting methods such as density gradient ultracentrifugation, gel chromatography, and electrophoresis have all been inspired by established biochemistry separation techniques designed to separate subcellular components. Biochemistry separation techniques have been refined to the degree that parameters such as pH, salt concentration, and temperature are necessary for a successful separation, yet these conditions are only now being applied to SWCNT separation methodologies. Slight changes in pH produce radically different behaviors of SWCNTs inside a density gradient, allowing for the facile separation of ultrahigh purity (6,4) SWCNTs from as‐synthesized carbon nanotubes. The (6,4) SWCNTs are novel fluorophores emitting below ≈900 nm and can be easily detected with conventional silicon‐based charge‐coupled device detectors without the need for specialized InGaAs cameras. The (6,4) SWCNTs are used to demonstrate their potential as a clinically relevant NIR‐I fluorescence stain for the immunohistochemical staining of cells and cancer tissue sections displaying high endothelial growth factor receptor levels.     

Escherichia coli of poultry food origin as reservoir of sulphonamide resistance genes and integrons

The antimicrobial resistance phenotype and genotype, the flanking regions of sulphonamide resistance genes and the integrons were analyzed in 166 Escherichia coli isolates recovered from poultry meat in Tunisia. High percentages of resistance were detected to ampicillin, streptomycin, nalidixic acid, sulphonamide and tetracycline (66-95%), and lower percentages to gentamicin, amoxicillin-clavulanic acid and cefoxitin (1-4%). The bla_TEM, tet(A)/tet(B), aph(3′)-Ia, aac(6′)-Ib-cr, aac(3)-II and cmlA genes were identified in 92, 82, 29, 2, 2 and 7 isolates, respectively. Class 1 and/or class 2 integrons were detected in 52% of E. coli isolates and five different gene cassette arrangements were identified in the variable regions of class 1 integrons, which included antimicrobial resistance determinants. Sixty-eight isolates contained the sul1 gene and 37 of them presented this gene into a class 1 integron structure. The sul3 gene was detected associated with non-classic class 1 integrons in 4 out of 46 sul3-positive isolates. The sul2 gene was detected in 66 isolates, 51 of them were linked to strA/B genes in seven different genetic structures. Seventy-three-per-cent of integron-positive isolates presented resistance to at least five different antimicrobial families versus 38.7% of integron-negative isolates. Our study highlights the role of commensal E. coli isolates from poultry meat as an important reservoir for sulphonamide resistance genes and integrons carrying antimicrobial resistance genes.     

Porous nitrogen-doped graphene prepared through pyrolysis of ammonium acetate as an efficient ORR nanocatalyst

In the work presented here, a facile approach for the preparation of nitrogen-doped porous graphene was applied for the first time using ammonium acetate as a nitrogen rich precursor via pyrolysis at 900 °C for 2 h.The physicochemical properties of the prepared samples were determined using Field Emission Scanning Electron Microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS) mapping, Raman spectroscopy and X–ray photoelectron spectroscopy (XPS). The prepared samples were further applied for the oxygen reduction reaction (ORR) in alkaline solution, and the electrochemical performance was investigated and compared with porous graphene and Pt/C 20 wt.%. The results revealed that introducing nitrogen to the graphene structure leads to improvement in catalytic activity, enhanced catalytic current as well as more positive potential. Furthermore, N-doped graphene prepared using ammonium acetate exhibited excellent methanol tolerance and long-term stability. Finally, it was shown that the optimal pyrolysis temperature was obtained at 900 °C. Therefore, it is concluded that ammonium acetate could be used as an effective precursor for the ORR.     

Colonization of Bacteria on the Surfaces of Cold-Sprayed Copper Coatings Alters Their Electrochemical Behaviors

Copper coatings were fabricated on stainless steel plates by cold spraying. Attachment and colonization of Bacillus sp. on their surfaces in artificial seawater were characterized, and their effects on anticorrosion performances of the coatings were examined. Attached bacteria were observed using field emission scanning electron microscopy. Electrochemical behaviors including potentiodynamic polarization and electrochemical impedance spectroscopy with/without bacterial attachment were evaluated using commercial electrochemical analysis station Modulab. Results show that Bacillus sp. opt to settle on low-lying spots of the coating surfaces in early stage, followed by recruitment and attachment of extracellular polymeric substances (EPS) secreted through metabolism of Bacillus sp. The bacteria survive with the protection of EPS. An attachment model is proposed to illustrate the bacterial behaviors on the surfaces of the coatings. Electrochemical data show that current density under Bacillus sp. environment decreases compared to that without the bacteria. Charge-transfer resistance increases markedly in bacteria-containing seawater, suggesting that corrosion resistance increases and corrosion rate decreases. The influencing mechanism of bacteria settlement on corrosion resistance of the cold-sprayed copper coatings was discussed and elucidated.     

Effect of high-pressure homogenisation on metabolic potential of Lacticaseibacillus paracasei 90: in vitro and in situ studies in fermented milk and semihard cheese

The influence of high-pressure homogenisation (HPH) at 100 MPa on Lacticaseibacillus paracasei 90 (L90) was studied in vitro and in situ (fermented milk and cheese). Lysis and injury signs were observed in cells treated with HPH, which were linked to the release of intracellular enzymes and changes in the metabolic activity of L90. HPH treatment led to a higher lactic acid content and lower pH and pyruvic acid levels in fermented milk. The microbiological and peptide profiles of cheeses were modified by using cells or cell-free extracts of L90. Finally, this study suggests that L90 could release bioactive peptides.     

High removal of chlorinated solvents by reusable polydimethylsiloxane based absorbents

The objective of this work is to prepare absorbent materials based on polydimethylsiloxane (PDMS) for the absorption of organic solvents by a relative simple method, with large absorption capacities and reusability. Different particles (ZnO, MgSO₄, ZnCl₂, and NaHCO₃) were first incorporated in PDMS and then removed by immersion in HCl (c) or water. The absorbent materials were characterized by TGA, mercury porosimetry, stress–strain curves, SEM, EDS, XPS, FTIR, and water contact angle. The materials can absorb polar organic chlorinated solvents (carbon tetrachloride, dichloroethene, dichloromethane, and chloroform) more than four times its own weight. Other solvents were also tested showing 2–3 times its own weight. Additionally, these materials show demulsification properties and absorption of oleophilic compounds. The reusability of the material makes them good candidates for remediation of polluted water.     

Response surface methodology (RMS) modelling to improve n-dodecane degradation using Debaryomyces hansenii LAF-3 in a simulated desalter effluent

The effluent from a petroleum desalting unit contains salts, emulsifiers, hydrocarbons (mainly n-dodecane), and other contaminants. Conventional wastewater treatment cannot be used to treat this salt-containing effluent; thus, alternative approaches must be explored. In this study, a halo-tolerant yeast, Debaryomyces hansenii, was investigated for the removal of varying concentrations of n-dodecane in a simulated desalter effluent (SDE). Then, the removal of n-dodecane was optimized using response surface methodology (RSM). The effects of pH, salt, temperature, and n-dodecane concentration were evaluated, and a mathematical model was developed and verified. The results showed that complete removal of n-dodecane was achieved at 20°C and a salt concentration of 1–5 g L⁻¹. The main factors in COD removal are temperature, n-dodecane concentration, pH, and the interaction between n-dodecane and temperature. Salt concentration does not affect COD removal or the growth rate of D. hansenii in a SDE. Applying RSM suggested that interactional effects among the operational variables include temperature, n-dodecane concentration, and pH on the yeast's removal rate. Overall, it can be concluded that the use of D. hansenii could be a viable solution at a wide range of salt concentrations (1–5 g L⁻¹) for desalter wastewater treatment in petroleum refining.     

Joint power distribution and charging network design for electrified mobility with user equilibrium decisions

Rapid adoption of electric vehicles (EVs) requires the development of a highly flexible charging network. The design and management of the charging infrastructure for EV-dominated transportation systems are intertwined with power grid operations both economically and technically. High penetration of EVs in the future can increase the charging loads and cause a wide range of operational issues in power distribution networks (PDNs). This paper aims to design an EV charging network with an embedded PDN layout to account for energy dispatch and underlying traffic flows in urban transportation networks supporting electric mobility in the near future. A mixed-integer bilevel model is proposed with the EV charging facility location and PDN energy decisions in the upper level and user equilibrium traffic assignment in the lower level considering an uncertain charging demand. The objective is to minimize the cost of PDN operations, charging facility deployments, and transportation. The proposed problem is solved using a column and constraint generation (C&CG ) algorithm, while a macroscopic fundamental diagram concept is implemented to estimate the arc travel times. The methodology is applied to a hypothetical and two real-world case study networks, and the solutions are compared to a Benders decomposition benchmark. The east-coast analysis results indicate a 77.3% reduction in the computational time. Additionally, the benchmark technique obtains an optimality gap of 1.15%, while the C&CG algorithm yields a 0.61% gap. The numerical experiments show the robustness of the proposed methodology. Besides, a series of sensitivity analyses has been conducted to study the impact of input parameters on the proposed methodology and draw managerial insights.