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A review of polymer nanofibres by electrospinning and their application in oil–water separation for cleaning up marine oil spills
2016
Sarbatly, Rosalam | Krishnaiah, Duduku | Kamin, Zykamilia
The growths of oil and gas exploration and production activities have increased environmental problems, such as oil spillage and the resulting pollution. The study of the methods for cleaning up oil spills is a critical issue to protect the environment. Various techniques are available to contain oil spills, but they are typically time consuming, energy inefficient and create secondary pollution. The use of a sorbent, such as a nanofibre sorbent, is a technique for controlling oil spills because of its good physical and oil sorption properties. This review discusses about the application of nanofibre sorbent for oil removal from water and its current developments. With their unique physical and mechanical properties coupled with their very high surface area and small pore sizes, nanofibre sorbents are alternative materials for cleaning up oil spills.
Afficher plus [+] Moins [-]Design of a toxicity biosensor based on Aliivibrio fischeri entrapped in a disposable card
2016
Jouanneau, Sulivan | Durand-Thouand, Marie-José | Thouand, Gérald
The degradation of the marine environment is a subject of concern for the European authorities primarily because of its contamination by hydrocarbons. The traditional methods (ISO 11348 standard) of general toxicity assessment are unsuitable in a context of in situ monitoring, such as seaports or bathing zones. Consequently, to address this issue, bacterial biosensors appear to be pertinent tools. This article presents the design of an innovative bioluminescent biosensor dedicated to in situ toxicity monitoring. This biosensor is based on the entrapment of the wild marine bioluminescent bacterial strain Aliivibrio fischeri ATCC® 49387™ in an agarose matrix within a disposable card. A pre-study was needed to select the most biological parameters. In particular, the regenerating medium’s composition and the hydrogel concentration needed for the bacterial entrapment (mechanical resistance) were optimized. Based on these data, the ability of the bacterial reporter to assess the sample toxicity was demonstrated using naphthalene as a chemical model. The biosensor’s results show a lower sensitivity to naphthalene (EC₅₀ = 95 mg/L) compared with the results obtained using the reference method (EC₅₀ = 43 mg/L). With this architecture, the biosensor is an interesting compromise among low maintenance, ease of use, appropriate sensitivity, relatively low cost and the ability to control online toxicity.
Afficher plus [+] Moins [-]Volcano-related materials in concretes: a comprehensive review
2016
Cai, Gaochuang | Noguchi, Takafumi | Degée, Hervé | Zhao, Jun | Kitagaki, Ryoma
Massive volcano-related materials (VRMs) erupted from volcanoes bring the impacts to natural environment and humanity health worldwide, which include generally volcanic ash (VA), volcanic pumice (VP), volcanic tuff (VT), etc. Considering the pozzolanic activities and mechanical characters of these materials, civil engineers propose to use them in low carbon/cement and environment-friendly concrete industries as supplementary cementitious materials (SCMs) or artificial/natural aggregates. The utilization of VRMs in concretes has attracted increasing and pressing attentions from research community. Through a literature review, this paper presents comprehensively the properties of VRMs and VRM concretes (VRMCs), including the physical and chemical properties of raw VRMs and VRMCs, and the fresh, microstructural and mechanical properties of VRMCs. Besides, considering environmental impacts and the development of long-term properties, the durability and stability properties of VRMCs also are summarized in this paper. The former focuses on the resistance properties of VRMCs when subjected to aggressive environmental impacts such as chloride, sulfate, seawater, and freezing–thawing. The latter mainly includes the fatigue, creep, heat-insulating, and expansion properties of VRMCs. This study will be helpful to promote the sustainability in concrete industries, protect natural environment, and reduce the impacts of volcano disaster. Based on this review, some main conclusions are discussed and important recommendations regarding future research on the application of VRMs in concrete industries are provided.
Afficher plus [+] Moins [-]Risk assessment and technical feasibility of usage of paper mill sludge biochar-based exhausted adsorbent for geopolymeric brick formation
2016
Devi, Parmila | Saroha, Anil K.
Risk assessment and technical feasibility of brick formation from exhausted paper mill sludge derived biochar obtained after its use as an adsorbent for the treatment of effluent containing pentachlorophenol was studied. The bricks were prepared by geopolymerization mechanism in presence of sodium hydroxide, and the extent of geopolymerization was determined on the basis of crystal structure, surface functionalities, and surface morphology of the bricks. The preparation parameters (sodium hydroxide dosage, initial water and calcium carbonate content and curing temperature) were optimized and the results were analyzed in terms of compressive strength, water absorption, and abrasion index. Risk assessment of heavy metals was performed to determine the contamination level and overall hazard index of the biochar-based geopolymer bricks. Hazard quotient and hazard index were calculated to assess the overall non-carcinogenic risk posed by selected heavy metals via ingestion and dermal contact. The leaching potential of heavy metal and pentachlorophenol from the biochar-based geopolymer bricks was also determined. The results showed that the biochar-based geopolymer bricks showed good mechanical properties and the concentration of heavy metals in the leachate falls within the permissible limits prescribed by Indian Standards for Industrial and Sewage Effluents Discharge (inland surface water).
Afficher plus [+] Moins [-]Effect of clay nanoparticles on model lung surfactant: a potential marker of hazard from nanoaerosol inhalation
2016
Kondej, Dorota | Sosnowski, Tomasz R.
This work investigates influence of different aluminosillicate nanoparticles (NPs) which are found in air in selected workplaces on the properties of the phospholipid (DPPC) monolayer at air–saline interface considered as ex vivo model of the lung surfactant (LS). The measurements were done under physiological-like conditions (deformable liquid interface at 37 °C) for NP concentrations matching the calculated lung doses after exposure in the working environment. Measured surface pressure–area (π–A) isotherms and compressibility curves demonstrated NP-induced changes in the structure and mechanical properties of the lipid monolayer. It was shown that hydrophilic nanomaterials (halloysite and bentonite) induced concentration-dependent impairment of DPPC’s ability of attaining high surface pressures on interfacial compression, suggesting a possibility of reduction of physiological function of natural LS. Hydrophobic montmorillonites affected DPPC monolayer in the opposite way; however, they significantly changed the mechanical properties of the air–liquid interface during compression. The results support the hypothesis of possible reduction or even degradation of the natural function of the lung surfactant induced by particle–phospholipid interactions after inhalation of nanoclays. Presented data do not only supplement the earlier results obtained with another LS model (animal-derived surfactant in oscillating bubble experiments) but also offer an explanation of physicochemical mechanisms responsible for detrimental effects which arise after deposition of inhaled nanomaterials on the surface of the respiratory system.
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