Influence of the Fabrication Conditions on the Physical Properties and Water Treatment Efficiency of Cellulose Acetate Porous Membranes

In membrane-based water purification technology, control of the membrane pore structure is fundamental to defining its performance. The present study investigates the effect of the preparation conditions on the final pore size distribution and on the dye removal efficiency of cellulose acetate membranes. The membranes were fabricated by means of phase inversion (using different speeds of film casting and different thicknesses of the casted solution) and introducing modifications in the preparation conditions, such as the use of a coagulation bath instead of pure water and the addition of a surfactant as a solution additive. Both isotropic and anisotropic membranes could be fabricated, and the membranes’ pore size, porosity, and water permeability were found to be greatly influenced by the fabrication conditions. The removal capacity towards different types of water contaminants was investigated, considering, as model dyes, Azure A and Methyl Orange. Azure A was removed with higher efficiency due to its better chemical affinity for cellulose acetate, and for both dyes the uptake could be fitted using a pseudo-second order model, evidencing that the rate-limiting step is chemisorption involving valency forces through the sharing or exchange of electrons between the dye and the membrane

Magnetite nanoparticles/polyvinyl pyrrolidone stabilized system for corrosion inhibition of carbon steel

The corrosion inhibitive effects of new polyvinylpyrrolidone stabilized crystalline super-paramagnetic nanoparticles (5–20 nm) were investigated. Several characterization techniques confirmed the high stability of the prepared stabilized nanoparticles in solution. The polarization and EIS measurements showed that the inhibition efficiency increased with increasing concentration of the magnetite nanoparticles. The results obtained from EIS and electrochemical polarization curves are in reasonably good agreement. The obtained results suggest that the prepared stabilized system is an excellent inhibitor for carbon steel corrosion in 1 M HCl solution. Keywords: Carbon steel, Magnetite nanoparticles, Stabilization, Potentiodynamic polarization, Impedance spectroscop

Attached to the submitted files in the name "Data" from Nanostructured mesoporous silica: influence of the preparation conditions on the physical-surface properties for organic dye uptake efficiency

A series of ordered mesoporous silica such as MCM-41, SBA-3 and SBA-15, in addition to silica micro- (SM) and nano- (SN) mesoporous particles, were prepared. The preparation conditions were found to greatly influence the physical-surface properties including morphological structure, porosity, particle size, aggregate average size, surface area, pore size, pore volume and zeta potential of the prepared silica, while the chemical structure, predicted from FT-IR spectra, and the diffraction patterns, predicted from wide-angle X-ray diffraction spectra, were identical. Surface areas of approximately 1500, 1027, 600, 552 and 317 m² g⁻¹, pore volumes of 0.93, 0.56, 0.82, 0.72 and 0.5 cm³ g⁻¹, radii of 2.48, 2.2, 5.66, 6.6 and 8.98 nm, average aggregate sizes of 56, 65.4, 220.9, 73, 61.1 and 261 nm and zeta potential values of −32.8, −46.1, −26.3, −31.4 and −25.9 mV were obtained for MCM-41, SBA-3, SBA-15, SN and SM, respectively. Methylene blue dye uptake capacity of the prepared silica types was investigated using the batch technique and in addition, the most effective material was further studied by the column flow system. The kinetics and isotherms of the uptake process were studied. The morphological structure, surface area, pore radius and zeta potential values were the most correlated factors

Cellulose Acetate Fabrics Loaded with Rhodamine B Hydrazide for Optical Detection of Cu(II)

In this work, different materials were fabricated from cellulose acetate, loaded with rhodamine B hydrazide and tested as Cu(II) optical sensor. We prepared membranes displaying a sub-micron porous structure using the phase inversion technique, clusters of fibers with varying diameter depending on the preparation procedure using electrospinning, and casted films presenting a smooth non porous structure. Loading of rhodamine B hydrazide on the fabrics after their production was found to be the best procedure to ensure the stability of the dye in the polymeric materials. Absorption and emission analysis of the solid substrates revealed the presence of the dye on the porous fabrics and allowed to choose the most suited materials and loading conditions to test their response towards Cu(II) ions. Reaction of the loaded rhodamine B hydrazide with Cu(II) was confirmed by absorption and emission spectroscopies and by confocal fluorescence imaging, through detection of the product rhodamine B. The results point to promising sensing applications of the prepared composite materials

Corrosion inhibition efficiency of some hydrophobically modified chitosan surfactants in relation to their surface active properties

This work deals with surface activity and corrosion inhibition efficiency of the natural polymer chitosan and its hydrophobically modified derivatives (eight polymeric compounds). Chitosan was found to be inactive at interfaces but the hydrophobic modification using different aliphatic and aromatic substituents renders the products surface active polymers. From the obtained data it was found that the surface active properties increased by increasing the hydrophobic character of these polymers. Chitosan and its based surfactants were investigated as corrosion inhibitors for carbon steel in 1 M HCl solution using the potentiodynamic polarization method. The resulted corrosion inhibition efficiency situated between 67.56% and 93.23% at 250 ppm and 25 °C. The inhibition efficiency was discussed on the light of surface active properties and the chemical structure of the used derivatives. The quantum chemical calculations were performed for some chitosan derivatives. The charge density distribution, highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and dipole moment were considered

Polythiophene modified chitosan/magnetite nanocomposites for heavy metals and selective mercury removal

Multi-functional nanocomposites were prepared based on magnetite nanoparticles, chitosan nanoparticles and polythiophene for efficient and selective mercury (II) removal from its aqueous solution. The prepared materials combine several functionalities; hydroxyl, amino, sulphur and phosphate groups in addition to the magnetite property of magnetite nanoparticles. The produced nanocomposites not only show a complete removal of mercury (II) ions but also a higher selectivity was recorded in presence of other metal ions over a wider pH range. Keywords: Chitosan, Magnetite nanoparticles, Polythiophene, Coating, Nanocomposites, Heavy metals uptake, Mercury uptake, Kinetics, Isotherm

Current advancements in chitosan-based film production for food technology; A review

Chitosan is obtained from chitin, which could be considered to be the most abundant polymer after cellulose. Owing to these properties, chitosan alone or chitosan-based composite film production is attaining huge attention in terms of applications from researchers and industrialists coming from divergent fields. To enhance the biological (mainly antimicrobial and antioxidant) and physiological (mainly mechanical, thermal and barrier) attributes of the chitosan-based films, a vast medley of plant extracts and supporting polymers has been blended into chitosan films. Considering the up to date literature reports based on chitosan film production and applications, it can be stated that still, the research ratio is low in this field. Chitosan blend/composite films with specific properties (superhydrophobicity, excellent mechanical strength, acceptable barrier properties) can be produced only for specific applications in food technology. In the current review, we tried to summarize the advancements made in the last 5–7 years in the field of chitosan film technology for its application in the food industry.</p