Understanding the Droplet Diffusion in Ionic Liquid Microemulsions.

Ionic liquids (ILs) as polar components in nonaqueous microemulsions are complex formulations that have interesting transport and structural properties, and offer broader applicability of ILs in areas such as drug delivery and cleaning technology. The phase behavior, electrical conductivity, and nanostructures of these formulations have been investigated for quite some time, but the characteristics of the diffusion of nanodroplets were rarely explored─ and hence little understood. This work investigates the droplet diffusion processes in a series of IL-microemulsions containing 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim]BF4) by means of viscosity and depolarized dynamic light scattering (DDLS) measurements. The intensity correlation functions are strikingly similar to polymeric solutions in nonaqueous media and aqueous microemulsions containing block copolymers─having bimodal relaxations that are separated by three to four decades of correlation delay times. The "faster" diffusion process is likely a collective process characterizing the correlated motions of droplets in droplet clusters. The collective diffusion coefficient Dcol values are quite comparable to aqueous microemulsions. The "slower" diffusion is likely due to the "caging" effect caused by nearby clusters and/or bulk solvent─this mode may be linked to the microemulsion bulk viscosity. Interestingly, the Dcol variations on increasing [C4mim]BF4 concentration are strongly correlated to the microemulsion viscosity changes as well as locations of these compositions on the microemulsion phase diagram.

Effect of successive recycling and reuse of acid liquor for the synthesis of graphene oxides with higher oxygen-to-carbon ratios.

Graphene has recently drawn exponential attention due to its surprising physicochemical properties and diversified field of applications. Although graphene oxides (GOs), itself is an exclusive material, it is also an intermediate product for the production of reduced graphene oxides (rGOs), graphene and their derivatives, which are other more superficial materials. In this study, GOs with higher oxygen to carbon ratios were synthesized following the Tour method, where the excess feed acid liquor (FAL) of mixed concentrated sulfuric and orthophosphoric acids at a ratio of 90:10 was recovered from the reaction slurries by applying the centrifugation technique. About 80-90 % of the FAL was recycled and reused as feed for the subsequent batches. The changes in the properties of FAL for the five consecutive recycling and reuse were studied. The properties of recycled FALs were investigated by measuring density, moisture content, pH, and ion concentration. The consecutive recycling of FALs tends to increase the moisture content about 0.5% in each recycles. Ion-chromatography (IC) was used to measure the variation in SO42- and PO43- ions in the FALs. The H2SO4 reacts with KMnO4 and crystalized out from the recovered FAL faster than the phosphoric acid. So, sulfuric acid content in the makeover FALs must be greater than primary FAL. The product GOs were characterized using FT-IR, FT-Raman, UVVis, STA, SEM, XPS, Zeta-potential, and particle size analyzers. The variation of the properties of GOs with the changes in the reaction parameters such as temperature and time were investigated and correlated with the product yield. It was observed that the effect of temperature on the reaction rate was found to be negatively and positive with the reaction time. The oxygen-to-carbon atomic ratio from XPS analysis was found 66.7%, which supported the increase in product yields 66.9% in the experimental results. The effect of acid concentration, reaction temperature, and time on the GOs properties were satisfactory, correlated, and easily controllable with the reaction conditions. A higher extent of oxidation and enhanced product yields 65-70% were observed at 60-70 °C and 14-18 h. A mixture of nano- and macro-molecular GOs was obtained, and their compositions were easily controllable and separable by controlling the reaction conditions. A correlation was made among the properties of synthesized GOs, FAL, and recycled FAL and reaction conditions.

Exploring the biomedical competency of gamma-radiation aided hydroxyapatite and its composite fabricated with nano-cellulose and chitosan.

The well-known biomaterial Ca-hydroxyapatite (Hap) in its pristine form holds the top ranking position in the field of biomedical research and extensive investigation is continuing across the globe to enhance its competency. Hence, having the intention to introduce superior physiognomies (e.g. cytotoxicity, haemocompatibility, and bioactivity coupled with antimicrobial and antioxidant activity) in Hap, in this research work, we exposed Hap to 200 kGy γ-radiation. As a result, γ-radiated Hap exhibited extreme antimicrobial (more than 98%) and moderate (∼34%) antioxidant properties. On the other hand, cytotoxicity and haemocompatibility of γ-radiated Hap were in good agreement with the ISO 10993-5 and ISO 10993-4 standards respectively. Since, bone and joint infections as well as degenerative disorders e.g. osteoarthritis, osteomyelitis, bone injury, and spinal problems have emerged as serious issues and urge a remedial way out, application of γ-radiated Hap could be a promising solution in this regard.

Development of ceramic grade red iron oxide pigment from waste iron source.

Ceramic grade red iron oxide (α-Fe2O3) nanoparticles pigments have been synthesized from waste condensed milk containers which contain a prominent amount of iron (93.2%). The synthesis method comprised of two steps: in the first step ferrous sulfate was prepared following an acid leaching method; while the second step was oxidation and calcination of ferrous sulfate to produce desired α-Fe2O3 in nano form. The structure, functional groups, chemical state, morphology, particle size, surface area, elemental, thermal analysis and magnetic properties of the samples were investigated using XRD, FTIR, XPS, SEM, BET, EDS, TG-DT and VSM respectively. Pure hematite (α-Fe2O3) phase was confirmed by XRD and the average crystal sizes were in the range 34-126 nm have been performed by Debye-Scherer's formula, which are consistent with the results as achieved from SEM images. Agglomerated irregular spherical nanoparticles (45-149 nm) were found in SEM image. The surface chemistry and the chemical state (Fe3+) of the hematite nanoparticles was also confirmed by XPS. The mesoporous nature of the nanoparticles with high surface area were measured by BET and it has been revealed that the BET specific surface area (33.55 m2/g) was marginally higher than the commercial one. The magnetic nature of the nanoparticles was portrayed by VSM and the nanoparticles showed the ferromagnetic behavior. Moreover, particle size distributions and zeta potential values have been also measured by DLS.

Synthesis and characterization of nano crystallite plaster of Paris prepared from waste eggshells and exploration of cytotoxicity, hemolysis and antimicrobial properties.

Plaster of Paris, a well-known biomaterial, was synthesized from waste eggshells, which were chosen as an available bio-source of calcium. The produced plaster of Paris was characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Raman spectroscopy, UV-Vis spectroscopy, and SEM images along with a few crystallographic parameters such as crystallite size (Scherrer equation and different model equations), lattice parameters, crystallinity index, the volume of the unit cell, microstrain, dislocation density, growth preference, and residual stress from the XRD-sin2 Ψ technique. The biomedical competency of the prepared plaster of Paris was evaluated utilizing the cytotoxicity, hemolysis, and antimicrobial activity of E. coli and S. aureus. The cytotoxicity assessment has revealed that the percentages of viable cells were 93-98% and a highly hemocompatible nature (<5%) was exerted by the sample. The plaster of Paris only revealed antimicrobial properties against Gram-positive bacteria (S. aureus), and no effect was noticed for Gram-negative bacteria (E. coli).