Chemical Engineering

In recent years, many pharmaceutical drugs and hormones have been consumed in too much quantity. [1-3]. After the use of these drugs, negative effects on the environment and human health occur. Many unused, expired, and residual drugs are released into the environment during and after treatment. These pharmaceutical drugs are mixed with human urine and manure and wastewater after metabolism in the human body [4]. As a result of studies, pharmaceutical drugs have been detected in sewage, surface water, and groundwater in many countries [5-7]. Paracetamol (also known as acetaminophen or APAP) is an analgesic and antipyretic drug widely used all over the world [8,9]. It is also used as an intermediate in the production of azodies and photographic chemicals. The presence of trace amounts of paracetamol (PAR) and other xenobiotic compounds in drinking water is also a public health problem. Because these compounds are taken through drinking water for a long time, chronic health effects occur [10]. Some physicochemical and biodegradation methods are used to prevent contaminations and to reduce their concentration [11-13]. These methods have disadvantages such as being less effective and needing long reaction times. It has been reported that some techniques such as activated carbon adsorption [14,15] ultrasound [16], Fenton oxidation [17,18] and ozonation [19,20] are frequently used in the removal of PAR in wastewater. However, it is noteworthy that there are few studies on the use of photocatalysts in the removal of pharmaceutical chemicals. Advanced oxidation process (AOP) is an important technique known as photocatalytic oxidation of organic materials. After the photolysis reaction with UV light, the surface of the pollutants react with the catalyst and the electrons move from the valence band to the conduction band. Reactive species (e− and h+) initiate oxidation and reduction reactions. As a result of the redox reactions occurring with these active species, the mineralization of organic compounds takes place. Oxidation to strong oxidizing species such as OH• occurs by the reaction of light-formed cavities in the valence band with OHor H 2 O. Since the hydroxyl radical has an oxidation potential of 2.80 eV, it can react with organic compounds 1012 times faster than other oxidants [21]. Laboratory-scale studies and reports from treatment plants prove that paracetamol PAR shows very low or no biodegradability [22,23]. When an additional treatment such as chlorination is applied, very toxic by-products are formed [24,25]. Therefore, there is a need to investigate highly efficient, economical, and environmentally friendly processes such as AOPs. It is important to develop harmless, highly effective alternative methods using nanocatalysts with low toxicity, low cost, and high performance, especially in the degradation of resistant hazardous chemicals.

The separation processes of the phenolic compounds from solid plant matrixes are of great importance. In the scope of developing more efficient methods to separate olive leaf extract, dried and ground olive tree leaves from Aegean region of Turkey were extracted by means of Soxhlet and supercritical fluid extraction (SFE) methods. In the Soxhlet method, different types of solvents (hexane, water, ethanol, methanol, and methanol/hexane (3:2, v/v) mixture) were used to determine the effect of the solvent type on the extraction performance. In the SFE method, the effect of pressure (100-300 bar), temperature (50 and 100 C), and type of co-solvent on the amount of both extract and oleuropein were investigated. Ethanol, methanol and water were selected as co-solvent in 20% (v/v) amount. Quantitative analysis was performed by using a liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) technique. The results of SFE were compared with those obtained by the Soxhlet method. Whereas the highest oleuropein yield was achieved via the Soxhlet method through methanol with the value of 37.84 mg/g dried leaf, the best oleuropein yield was achieved with the value of 14.26 mg/g dried leaf by using CO 2 modified by methanol at 300 bar and 100 C in the SFE method.

Liquid + liquid) equilibrium (LLE) data for the solubility curves and tie-line compositions were examined for mixtures of {water (1) + propionic acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3)} at T = 298.15 K and atmospheric pressure, (101.3 ± 0.7) kPa. The relative mutual solubility of the propionic acid is higher in the dibasic esters phases than in the aqueous phase. The reliability of the experimental tie-line data were confirmed by using the Othmer-Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC and modified UNIFAC methods. Distribution coefficients and separation factors were evaluated for the immiscibility region.

Liquid-liquid equilibrium (LLE) data including solubility curves and tie-line compositions were measured for mixtures of water (1) + formic acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3) at T ) 298.2 K and atmospheric pressure, p ) (101.3 ( 0.7) kPa. The relative mutual solubility of the formic acid is higher in the aqueous phase than in the dibasic ester phases. The reliability of the experimental tie-line data was confirmed by using the Othmer-Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC and modified UNIFAC methods. Distribution coefficients and separation factors were evaluated for the immiscibility region.

Liquid + liquid) equilibrium (LLE) data for the solubility curves and tie-line compositions were examined for mixtures of {water (1) + propionic acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3)} at T = 298.15 K and atmospheric pressure, (101.3 ± 0.7) kPa. The relative mutual solubility of the propionic acid is higher in the dibasic esters phases than in the aqueous phase. The reliability of the experimental tie-line data were confirmed by using the Othmer-Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC and modified UNIFAC methods. Distribution coefficients and separation factors were evaluated for the immiscibility region.

Liquid-liquid equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {(water (1) + butyric acid (2) + diethyl succinate or diethyl glutarate or diethyl adipate (3)} at 298.2 K and 101.3 ± 0.7 kPa. The relative mutual solubility of butyric acid is higher in the diethyl succinate or diethyl glutarate or diethyl adipate layers than water layers. The consistency of the experimental tie-lines was determined through the Othmer-Tobias correlation equation. The LLE data were correlated with NRTL model, indicating the reliability of the NRTL equations for these ternary systems. The best results were achieved with the NRTL equation, using non-randomness parameter (˛= 0.3) for the correlation. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the solvents.

The present study focuses on developing methods for olive leaf extraction and deals with obtaining extract, rich in oleuropein, which is the most abundant phenolic compound in olive leaves. Supercritical fluid extraction (SFE) was applied to the dried and ground olive leaves by using CO 2 as supercritical (SC) fluid in the presence of water and ethanol as co-solvent. The influences of operating parameters by means of co-solvent content (0-1 mL/ min), temperature (50 and 100 C) and pressure (100-300 bar) on both extract and oleuropein yields were investigated. Quantitative analysis was performed by using a liquid chromatographyelectrospray ionization-tandem mass spectrometry (LC-ESI-MS/ MS) technique. The experimental results obtained by using SC-CO 2 alone were not satisfactory, and it was seen that addition of a polar modifier is necessary in order to improve yield and selectivity of the process. It was observed that CO 2 modified by water and ethanol showed nearly the same extract performance, where CO 2 modified by water is better for high oleuropein yield.

Liquid + liquid) equilibrium (LLE) data for the solubility curves and tie-line compositions were examined for mixtures of {water (1) + propionic acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3)} at T = 298.15 K and atmospheric pressure, (101.3 ± 0.7) kPa. The relative mutual solubility of the propionic acid is higher in the dibasic esters phases than in the aqueous phase. The reliability of the experimental tie-line data were confirmed by using the Othmer-Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC and modified UNIFAC methods. Distribution coefficients and separation factors were evaluated for the immiscibility region.

Liquid-liquid equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {(water (1) + butyric acid (2) + diethyl succinate or diethyl glutarate or diethyl adipate (3)} at 298.2 K and 101.3 ± 0.7 kPa. The relative mutual solubility of butyric acid is higher in the diethyl succinate or diethyl glutarate or diethyl adipate layers than water layers. The consistency of the experimental tie-lines was determined through the Othmer-Tobias correlation equation. The LLE data were correlated with NRTL model, indicating the reliability of the NRTL equations for these ternary systems. The best results were achieved with the NRTL equation, using non-randomness parameter (˛= 0.3) for the correlation. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the solvents.

Large-conductance Ca2+-activated K+ channels (BKCa or maxiK channels) are expressed in different cell types. They play an essential role in the regulation of various cell functions. In particular, BKCa channels have been extensively studied in vascular smooth muscle cells, where they contribute to the control of vascular tone. They facilitate the feedback regulation against the rise of intracellular Ca2+, membrane depolarization and vasoconstriction. BKCa channels promote a K+ outward current and lead to membrane hyperpolarization. In endothelial cells expression and function of BKCa channels play an important role in the regulation of the vascular smooth muscle activity. Endothelial BKCa channels modulate the biosyntheses and release of various vasoactive modulators and regulate the membrane potential. Because of their regulatory role in vascular tone, endothelial BKCa channels have been suggested as therapeutic targets for the treatment of cardiovascular diseases. Hypertension, atherosclerosis, and diabetes are associated with altered current amplitude, open probability, and Ca2+-sensing of BKCa channels. The properties of BKCa channels and their role in endothelial and vascular smooth muscle cells would address them as potential therapeutic targets. Further studies are necessary to identify the detailed molecular mechanisms of action and to investigate selective BKCa channels openers as possible therapeutic agents for clinical use.

The paper is concerned with the investigation of oxygen transport in layer-by-layer (LbL) self assembly of polystyrene sulfonic acid sodium salt (PSS) and polyallylamine hydrochloride (PAH) on Nafion membrane depending on the number of deposited bilayers, ion type within the multilayers and temperature. It is observed from SEM analysis that the polyelectrolyte layers growth on each side of Nafion membrane regularly. The oxygen permeability (P O 2 ) of (PAH-PSS) 20 is 691 cm 3 /(m 2 day bar) at 25 • C while P O 2 of pristine Nafion is 2329 cm 3 /(m 2 day bar) at the same temperature. This significant reduction (70.3%) in gas permeability can be explained by the formation of LbL multilayers which both restrict the mobility of gas through the polymer matrix and adjust gas solubility properties in conjunction with ion-dipole interaction between the polar phase of Nafion and the secondary ammonium groups of PAH. (PAH/PSS) 20 -Na + and (PAH/PSS) 20 -H + exhibit 64.4% and 52.3% reduction in oxygen permittivity at 25 • C in comparison with the pristine Nafion ® 117, respectively, while the proton conductivities of these membranes are 106.9 and 136.9 mS/cm. Promisingly, it is found that the membrane selectivity values (˚) of all multilayered membranes in both H + and Na + form are much higher than that of perfluorosulfonated ionomer. The thickness of deposited bilayers dominates the diffusion and solubility properties of oxygen through the composite membrane while the major effect of surface hydrophilicity is not observed on oxygen permeability.

The development of composite membranes and catalyst containing membranes (CCMs) with low methanol permittivity attracts a great deal of research attention for achieving higher performance in direct methanol fuel cells (DMFCs). Here, the fabrication and DMFC performance of composite and catalyst containing membranes (CCM) via layer-by-layer (lbl) technique are demonstrated. lbl composite and catalyst containing membrane based membrane-electrode assemblies (MEAs) show quite impressive cell performance. While the single cell performances of lbl composite membrane based MEAs are found to be in the range of 19.5 and 22 mW cm −2 , DMFC performance of MEA obtained from Pt containing self-assembled 10 bilayer of polyallylamine hydrochloride and polyvinylsulfonic acid, (PAH/PVS-H + ) 10-Pt , is found to be 24 mW cm −2 . This performance is nearly 65.5% higher compared to pure Nafion ® 112 based MEA. Inductive coupling plasma-mass spectroscopy (ICP-MS) result shows that Pt particles incorporate inside lbl multilayers with a loading of 0.28 g cm −2 . From the analyses of the performance evaluations, it is emphasized that the use of thin lbl catalyst containing membranes can be possible and quite promising in DMFC applications instead of thicker membranes due to their improved methanol barrier properties as well as proton conductivity.

The paper is concerned with the deposition of self-assembled polyelectrolyte multilayer on Nafion membrane by layer-by-layer (LbL) technique with lowered methanol cross-over for direct methanol fuel cell (DMFC) applications. The formation of self-assembled multilayered film on Nafion was characterized by UV–vis spectroscopy and it was found that the polyelectrolyte layers growth on the Nafion surface regularly. Furthermore, the proton conductivity and methanol cross-over measurements were carried out for characterization of the LbL self-assembled composite membranes. The results showed that the concentration and pH of the polyelectrolytes significantly affect the proton conductivity and methanol barrier properties of the composite membranes. 10−1 monomol polyelectrolyte concentration and pH 1.8 was found to be optimum deposition conditions considering proton conductivity and methanol permeation properties of the LbL self-assembled composite membranes. The methanol permeability of the 10 bi-layers of PAH1.8/PSS1.8 deposited LbL self-assembly composite membrane was significantly suppressed and found to be 4.41 × 10−7 cm2/s while the proton conductivity value is in acceptable range for fuel cell applications.