Explore the vast range of titles available.

We focused on preparing cellulose nanofibrils by purification, separation, and mechanical treatment of Kombucha membranes (KM) resulted as secondary product from beverage production by fermentation of tea broth with symbiotic culture of bacteria and yeast (SCOBY). We purified KM using two alkaline solutions, 1 and 4 M NaOH, which afterwards were subjected to various mechanical treatments. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) were employed to evaluate the purification degree, the size and aspect of cellulose fibrils after each treatment step, the physical-chemical properties of intermediary and final product, and for comparison with micro-crystalline cellulose from wooden sources. We determined that 1 M NaOH solution leads to approx. 85% purification, while a higher concentration assures almost 97% impurities removal. XRD analysis evidenced an increase in crystallinity from 37% to 87% after purification, the characteristic diffractograms of Iα and Iβ cellulose allomorphs, and a further decrease in crystallinity to 46% after microfluidization, fact correlated with a drastically decrease in fibrils’ size. FTIR analysis evidenced the appearance of new chain ends by specific transmission bands at 2941 and 2843cm−1.

In this work, Sb (III) adsorption on oxidized exfoliated graphite nanoplatelets (ox-xGnP) was evaluated for the first time, to the best of our knowledge. The ox-xGnP were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), Brunauer–Emmet–Teller (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy-dispersive X-ray spectroscopy (EDX), and Zeta potential analysis. The adsorption parameters, such as pH and contact time, were optimized, and the best adsorption capacity obtained was 8.91 mg g−1 at pH = 7.0, 1.0 mg ox-xGnP/100 mL solution, T = 293 K, 1.0 mg L−1, Sb (III), 25 min contact time. The best correlation of the kinetic data was described by a pseudo-first-order kinetic model, with R2 = 0.999. The adsorption isotherms of Sb (III) onto ox-xGnP were best described by the Langmuir isotherm model. The thermodynamic parameters showed that the adsorption process was exothermic and spontaneous.

The paper proves that the miscibility of some blends based on starch can be improved by finding for each of them the melt resistance to flow at which the nonstationary flow and the melt degradation are avoided and the developed shear rate homogenizes optimally the material composition. The obtained results show that, for process sensitive materials like starches, the border between good and less miscibility is so narrow that the window of melt processing conditions and the best formulation must be found for each of them. The improving of miscibility by controlling the melt resistance to flow proves to be a good method to prevent retrogradation and plasticizer leaching and so to handle the new compounds behavior during usage.

CO₂ emissions represent an actual problem for the environment. Additionally, the new demands for all chemical and physical processes request to be more eco-friendly. In this work, deep eutectic solvents (DESs), a relatively new class of solvents, were used for CO₂ capture and desorption. DESs are more environmentally friendly than classical solvents. Two choline chloride-based DES – ethaline (ChCl:EG, 1:2 molar ratio) and reline (ChCl:U, 1:2 molar ratio) were prepared and characterized before studying their CO2 absorption – desorption capacity. The formation of eutectics was confirmed by FT-IR analysis and DESs were characterized in terms of pH, density, viscosity, refractive index, and electrical conductivity. The tests showed that ethaline had better CO₂ absorption and desorption capacity than reline, which could be explained by several parameters.

Methylene blue is generally used as dyeing agent in textile, printing and pharmaceutical industries, which leads to the obtaining of large amounts of wastewater. The purpose of this study is to remove methylene blue dye from aqueous solutions using fir wood sawdust waste as low cost biosorbent material. In order to evaluate the adsorption process, analyses for determination of micrometric properties, infrared spectroscopy, optical microscopy and colorimetry were performed. To increase the efficiency of the process and the adsorption surface, the fir wood sawdust was grinded and sieved. Some specific parameters were varied in the experimental part in order to study the influence of the adsorbent support dose, concentration, temperature, contact time, volume and stirring rate. The removal efficiency of methylene blue dye was further studied for evaluating the adsorption capacity of the fir wood sawdust.

In this paper the adsorption of pyridine, a toxic pollutant, on naturally occurring clay, namely bentonite? was studied at a basic pH and room temperature. Sodium saturated bentonite as well as modified with a cationic surfactant were used and the results compared. The influence of contact time and of the initial pollutant concentration on the pyridine uptake was determined by GC-MS. The adsorbents were characterized before and after being in contact with the pyridine solution by BET specific surface area and porosity, XRD and FTIR analysis. The hydroxyl groups of bentonite in contact with pyridine solution led to protonated pyridine forms which can be responsible for hydrogen bonds formation and electrostatic interactions with the clay and for surfactant removal. Chemical adsorption prevailed over the partition/physical adsorption in both cases and the process followed the pseudo-second-order kinetics with the Freundlich isotherm model representing well the equilibrium adsorption data. The equilibrium adsorptive efficiency was 82.88% for the surfactant modified bentonite and 97.82%o for sodium bentonite, the latter being a better alternative for sequestering pyridine from solution.

In this paper we present the synthesis of bolaform gluconolactone-based surfactants with C8 and C12 hydrocarbon chains, in mild reaction conditions and the influence of hydrocarbon chain length on the surface properties of synthesized surfactants. The structural characterization of 1,12-digluconamidododecane and 1,8-digluconamidooctane was made by Fourier transform infrared spectroscopy. The visualization of aggregates was performed by optic microscopy in the case of 1,12-digluconamidododecane and transmission electron microscopy for 1,8-digluconamidooctane. It was found that 1,12-digluconamidododecane undergoes a crystallization process, hexagonal crystals being visualized by optic microscopy. We note the vesicular aggregates formed in the 1,8 - digluconamidooctane solution with dimensions between 200-300 nm, visualized by transmission electron microscopy. The surface activity of surfactants was evaluated with a KSV Sigma 700 automated tensiometer, using DuNouy Ring technique. 1,12-digluconamidododecane solutions present a moderate efficiency in reducing the surface tension of water, while 1,8-digluconamidooctane is more efficient in reducing the surface tension of water at low concentrations.