Recent Advances in Poly (Amide-B-Ethylene) Based Membranes for Carbon Dioxide (CO2) Capture: A Review

Polyamide-b-ethylene (Pebax) is a promising material for membrane-based gas separation application with excellent CO₂ capturing potential. Pebax is a rubbery elastomer which offers good mechanical support with its hard crystalline phase and excellent gas transport through its amorphous polyether phase. This review article includes recent advances in Pebax based membrane synthesis, solvent selection for membrane synthesis, compatible fillers with Pebax matrix and the improved gas separation performance of the prepared membranes. The literature review shows that Pebax based membranes are a good candidate for separation of CO₂ from flue gases and can be used for commercial applications.     

A New Method for Siting Hazardous Units in Chemical Process Facilities Which Minimizes Risk at Least Cost: RIDIMPUS

A new method, RIsk and DIstance Minimization in Process Units Siting (RIDIMPUS), is presented with which hazardous units can be sited in a chemical process facility in a manner that the risk of accidents involving the hazardous units as also the cost of spacing the units is minimized. To achieve this, safety and cost factors were modeled using various governing parameters and then expressions were designed to integrate the safety and the economic concerns to form model equations, inequalities and disjunctions. The resulting nonlinear programming model is solvable by using algorithms and solvers on any common desktop computer, thereby providing an optimal and prompt solution.     

Monitoring of Corrosion in Structural Reinforcing Bars: Performance Comparison Using In Situ Fiber-Optic and Electric Wire Strain Gauge Systems

This work addresses the problems of effective in situ measurement of the initiation or the rate of steel corrosion in reinforced concrete structures through the use of optical fiber sensor systems. By undertaking a series of tests over prolonged periods, coupled with acceleration of corrosion, the performance of fiber Bragg grating-based sensor systems attached to high-tensile steel reinforcement bars (ldquorebarsrdquo), and cast into concrete blocks was determined, and the results compared with those from conventional strain gauges where appropriate. The results show the benefits in the use of optical fiber networks under these circumstances and their ability to deliver data when conventional sensors failed.     

In situ ultrasound enhancement of octanoic acid directional solvent extraction for seawater desalination

The low yield and high salinity of the water product have limited the use of directional solvent extraction desalination method to the treatment of only low salinity water. In this research, in situ ultrasound enhancement of octanoic acid solvent extraction desalination is reported. The pre-prepared 3.5% (w/w) of saltwater solution and octanoic acid were mixed at five different temperatures which resulted in two phases. The performance of extraction for each set was evaluated based on salinity, yield of the recovered water, and solvent residual in the product water. The calculated yield of pure water under the ultrasound effects was higher than that without the ultrasound. This is due to the role of ultrasound in weakening the intermolecular interaction to dissociate water from salt, increasing the solvent efficiency in extracting water. The recovered water salinity was lower by using the ultrasound which can be explained as result of increasing the water yield.     

Protection provided by surface treatments against chloride induced corrosion

Corrosion of reinforcement bars due to chloride ingress is a well known problem in reinforced concrete. Several methods have been adopted to protect reinforced concretc, and one of them is to provide added protection to the concrete surface in the form of surface treatments such as silanes and siloxanes. They react with the cement matrix and form a hydrophobic layer on the walls of the pores within the concrete. This protects the concrete from the ingress of water and water-born salts. Moisture is required for reaction of silanes and siloxanes with the hydrated cement matrix. However, too much water in the pores of concrete will prevent the treatments from penetrating deeper into the pores. A study has been carried out to investigate the variation, due to the presence of moisture, on the effectiveness of the protection. It has been found that irrespective of the moisture content at the time of application of treatment, silanes and siloxanes provided good protection against chloride ingress and corrosion of reinforcement bars. However, the depth of penetration and therefore the durability of the treatment is adversely affected when the concrete is near saturation.

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Résumé Dans le béton armé, la corrosion des armatures de renforcement due à la pénétration du chlorure est un problème bien connu. Plusieurs méthodes ont été adoptées pour protéger le béton armé, dont la protection supplémentaire au revêtement du béton sous forme de traitement à la surface par des silanes et des siloxanes. Ces produits réagissent avec la matrice cimentaire et forment une couche hydrophobe sur les parois des pores à l'intérieur du béton, empêchant la pénétration de l'eau et des sels véhiculés par l'eau. L'humidité est nécessaire pour obtenir la réaction des silanes et des siloxanes avec la matrice cimentaire hydratée. Cependant, trop d'eau dans les pores du béton empêche les traitements de pénétrer plus profondément dans les pores. Une étude a été menée sur l'efficacité de la protection en fonction des variations de la présence de l'humidité. On a constaté que, quelle que soit la teneur en humidité au moment de l'application du traitement, les silanes et les siloxanes fournissent une bonne protection contre l'entrée du chlorure et la corrosion des armatures. Néanmoins, la profondeur de la pénétration, et donc la résistance du traitement, sont défavorablement modifiées lorsque le béton est près de la saturation.

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Editorial note Prof. David J. Cleland is a RILEM Senior Member and the Secretary of TC 145-WSM (Workability of Special Concrete Mixes). Prof. A. E. Long is a RILEM Senior Member and a member of TCs 126-IPT (In-place Testing of Hardened Concrete) and 163-TPZ (Interfacial Transition Zone and Properties of Transfer).     

Status of biodiesel research and development in Pakistan

Performance of biodiesel in engines is well established and biodiesel is currently adjudged as a low carbon fuel with the most potential of replacing fossil fuels. The fossil fuel sources are dwindling in Pakistan resulting in importation of about 8.1 million tonnes at approximately US$ 9.4 billion per annum. In the ambit of this justification, augmenting the energy scarce resources in Pakistan through intense harnessing of the varied biodiesel sources can adequately address the deficiency and can ensure energy security. Towards this end, the progress attained in biodiesel related researches in Pakistan are evaluated and presented with the view of highlighting ways of achieving the target set by the Government. A feedstock that drew less attention is spent triglycerides, and the little work reported by some organizations appeared promising. Now the onus is upon organizations such as the Alternative Energy Development Board and Pakistan State Oil to harness the research results from several indigenous Universities and develop a full-scale biodiesel economy in Pakistan.     

Mitigation of connector damage during disengaging DC loads using polymeric arc suppressor

Although connectors are generally not designed to disconnect electrical loads under power, in some circumstances they are mated and unmated under load. For instance, during repairs, diagnostic procedures, or when blown fuses are replaced under short circuit conditions. At dc system voltage levels significantly higher than the minimum arc voltage of metals such hot-disconnections may impact the reliability of the connection, the electrical distribution system, and automotive safety. Gassing polymers mounted onto connector terminals may reduce the damage resulting from disconnections under dc loads, and therefore enable connector designs with occasionally (forward running) arcing terminals. The authors discuss the effects of different types of gassing polymers on arc extinction and connector damage of standard automotive connectors.