Volume 2 Issue 4
Authors: B. Bhuvaneshwari; Nagesh R. Iyer; Saptarshi Sasmal
Abstract: Nanoscience and nanotechnology provide enormous opportunities to engineers the properties of materials by working in atomic or molecular level. It has not only facilitated to overcome many limitations of conventional materials, but also tremendously improved the mechanical, physical and chemical properties of the materials as well. To develop high performance, multifunctional, ideal (high strength, ductile, crack free, durable) construction material, carbon nanotubes (CNTs) show promising role to modify/enhance the characteristics of the conventional construction materials such as concrete and steel. In the paper, a brief on geometry and mechanical properties, synthesis processes, possibilities and findings of different researchers on CNT reinforced composites is presented. It is also brought out that a crack free durable concrete is possible if certain issues such as uniform distribution of CNT in composite and bond behavior of CNT modified concrete can be addressed. Finally, few pre-proof of concepts are mentioned where CNTs can play the pivotal role to redefine the scope and ability of civil engineering, in general, and structural engineering, in particular.
Keywords: Carbon Nanotubes; Concrete Composite; Durability; High Strength; Synthesis; Challenges
Authors: Smaail RADI; Nouraddine BASBAS; Said TIGHADOUINI; Maryse BACQUET; Stéphanie DEGOUTIN; Francine CAZIER
Abstract: Porous silica has been chemically modified with conjugated phenylamine and phenyldiamine moieties using the homogeneous route. This synthetic route involved the reaction of carbaldehyde derivatives with 3-aminopropyltrimethoxysilane prior to immobilization on the support. The resulting materials have been characterized by elemental analysis, FT–IR, 13C NMR of the solid state, nitrogen adsorption-desorption isotherm, BET surface area, B.J.H. Pore sizes, thermogravimetry analyser (TGA) curves, X-ray diffraction (XRD) and scanning electron microscope (SEM). The new chelating surfaces exhibit good chemical and thermal stability. The solids were employed as Cu(II) adsorbents from aqueous solutions at room temperature. The effects of pH and adsorption kinetics have been studied using the batch technique. Flame atomic absorption spectrometry was used to determine the Cu(II) concentration in the filtrate after the adsorption process. The results indicate that under the optimum conditions, the maximum adsorption value for Cu(II) was 24.5 mg Cu(II) g−1 modified silica, whereas the adsorption capacity of the unmodified silica was only 1 mg Cu(II) g−1 silica. On the basis of these results, it can be concluded that it is possible to modify chemically silica with amine derivatives and to use the resulting modified porous silica as an effective adsorbent for Cu(II) in aqueous media.
Keywords: Modified SiO2; Sorbent; Phenylamine; Adsorption; Cu(II).
Authors: Mário R. Góngora-Rubio; Silas Derenzo; Adriano M. de Oliveira; Juliana N. Schianti; Natália N. P. Cerize
Abstract: Microfluidic devices have become an important tool to produce micro and nanoparticles. However, the operation ranges of these systems are still a challenge when we think of large scale industrial applications. In this work we present two microfluidic devices for scaling up a nanoprecipitation process. The microfluidic systems are microfabricated in glass substrates and the flow distribution are done through reservoirs and a branching system, with four outputs in each device. In these systems we can operate in mL/min range and it is possible to have a yield up to ten times higher than a single channel system. We use the devices in a rifampicin nanoprecipitation process, obtaining nanoparticles in a range of 250 nm. As expected, parameters such as total flow rate and ratio between phases are determinant in the final mean particle size. Each output of our devices produces homogenous results and we can see that these results can be improved to obtain nanoparticles in larger volumes.
Keywords: Nanoprecipitation; Microfluidic Device; Scale up; Rifampicin; Flow Focusing; Parallel Microchannels