Challenges and Advances in Chemical Science Vol. 1

Although hysteresis in fluid adsorption in porous material has been known for over a century, the thermodynamic treatment of this phenomenon is still unspecified. We suggest recognising that thermodynamics is not designed to deal with constrained systems and creating a new set of rules to explain their behaviour. The basis for this suggestion is a significant number of simulation calculations. The simulation method used has been shown to describe both static and dynamic processes in this field [1]. The newly proposed theory takes into account the occurrence of hysteresis without inconsistencies Further, it will be shown, that the theory allows simulating diffusional and convectional transport (nanofluidics) by a unified ansatz without the need to introduce capillary forces (surface or interface tensions) by phenomenological parameters. The possibility for practical use is discussed in the second section of the study. It turns out that the new ideas pave the way for better applications by allowing for the use of unique states of matter observed in porous systems. We'll concentrate on the possibilities of driving a fluid in a pore into negative-pressure states under static and dynamic settings. It turns out that states with negative pressure can be reproducibly controlled. Negative pressure states have been understood in principle since Torricelli's time, and they have been explored as experimentally accessible conditions in the literature. Despite this, they have not been translated into functional utility, which is most likely due to the concept of their metastability in macroscopic systems. The topic of metastability has been discussed widely in the literature. Possible applications refer to controlling chemical reactions as well as new routes to efficient separation processes that are difficult to handle by conventional techniques.

The phenomenon of hysteresis occurs frequently when fluids adsorb in mesoporous material in contact with a vapour reservoir. It piques interest because it seems to go against thermodynamics, which states that a system's response to a collection of boundary conditions is unique, irrespective of the systems’s history. It is, on the other hand, reproducible in experiments and by all computer simulation approaches. Many authors have attempted to address this problem by postulating that either or both branches of a double valued adsorption isotherm must be metastable. A finite lifetime against decay into the ground state distinguishes a metastable condition. However, there is no experimental evidence that the adsorption isotherm within the hysteresis loop is time dependent, and we are ignorant of any attempt in the literature to use computer simulation to estimate the lifetime of either of the adsorption isotherm branches. In the present contribution we evaluate a reliable estimate for the lifetime of the states within the hysteresis loop. We find that even the shortest lived states display lifetimes that are several times the age of the universe and, thus, are practically to be considered as stable states. Accordingly, the concept of bistability (in some cases even multistability) appears appropriate to describe the hysteresis loop of adsorption isotherms. Clearly, certain thermodynamic laws do not apply to confined systems. The current work is the first to attempt to formulate a time dependent theory for confined thermodynamics, allowing access to the lifetime of states within the hysteresis loop for the first time.

Heterocyclic systems containing benzothiazoles, carbazole (and azacarbazole) moieties have attracted the attention of chemists owing to these nuclei having been identified in the literature as most promising pharmacophores in drug design and synthesis. Based on these observations, it could be anticipated that incorporation of the bioactive azepine moiety and quinoline moiety into the molecular framework of benzothiazoles fused to carbazole (and azacarbazoles) could produce interesting series of compounds 9-12 with enhanced biological activities, whose structure was unequivocally established from its micro analyses and spectral data.

Chitosan is interestingly thought to be used as raw material to make membrane for it has functional group of –NH₂ and –OH that is easy to modify. Chitosan membrane has weakness like low mechanical properties. To overcome those weaknesses, silica is added on chitosan membrane synthesis to improve chitosan membrane stability. In membrane synthesis process, plasticizer is used to improve mechanical properties, maintain integrality, and avoid holes and crackness. Polyethylene Glycol plasticizer addition is expected to increase physical and mechanical properties and hydrophilic properties on membrane surface significantly therefore metal ion solution can easily diffuse through chitosan-silica-PEG membrane. In this research, it is done chitosan-silica-PEG (Ch/Si/P) membrane synthesis with tetraethyl orthosilicate (TEOS) that is used as silica source then the membrane is used as adsorbent for ion Cu(II), Zn(II) and Cd(II) by batch method. Research shows that adsorption with batch method to all membranes is optimum pH for metal ions Cu(II) and Zn(II) = 6, Cd(II) = 5.5. Adsorption for ions Cu(II), Zn(II) and Cd(II) in membrane tends to follow Langmuir isotherm model. Generally, it can be said that Ch membrane ability on all adsorption metal ions increases with silica or PEG addition. Adsorption capacity value for Ch/Si/P membrane in \(\mu\)mol/g for ion Cu(II), Zn(II) and Cd(II) in order are 262, 183, and 107 \(\mu\)mol/g. Generally, in adsorption kinetic data there is a tendency of coefficient score of R² linearity that is higher in the second order of pseudo kinetic model.

Biodiesel has become more attractive as an alternative fuel for diesel engine because of its environmental benefits and the fact that it is made from renewable resources such as vegetable oil and animal fats by reacting them with short chain alcohols. The present research work focusses on optimization of water degummed Linseed biodiesel from transesterification process which involves the exchanging of organic group R” of an ester with the organic group of alcohol R’ often catalysed by the addition of an acid or base catalyst. It was found that the maximum recovery of bio- diesel yield was depicted at the optimum operation conditions (0.8% catalyst amount NaOH, reaction time 1 hour and reaction temperature 60°C). The comparison with the fuel properties of conventional diesel, especially with regards to kinematic viscosity and carbon residue, oil needs to purify through the degumming process to remove the gums before use in biodiesel production. The effect of degumming on fuel properties of water degummed Linseed methyl ester and their different diesel blends are discussed in this paper.

For the determination of anions, ion chromatography (IC) is a suitable analytical method. Bromine, fluorine, chlorine (Cl₂), and hydrogen chloride (HCl) are all included in JIS as analytical procedures for halogen compounds in flue gas. IC, with the exception of HCl and Cl₂, has not been adopted in JIS. Because the carbon dioxide in flue gas is absorbed in a 0.1 M sodium hydroxide solution as an absorber, it is interfered with the measurement of F^- and Cl^- ions. The development of IC's pretreatment equipment for flue gas analysis, as well as its applications to real flue gas analysis, are described in this study. Using the pretreatment apparatus, theF^-, Cl^-, Br^- and SO₄^2-  in the absorbing solution may be clearly separated by IC. IC can simultaneously determine halogen chemicals and sulphur oxides in real flue gas.  This method has been adopted to Japanese Industrial Standard (JIS K 0105, JIS K 0085).

A theoretical analysis of the stability of the non-equilibrium chemical engineering processes is presented. A unified approach is proposed for the creation of the mathematical models of the systems that allows the determination of the velocities at which the systems move to their thermodynamic equilibriums and their use for mathematical analysis of systems velocities stability. For this purpose, is used mathematical stability theory, evolution (autonomous) equations, bifurcation theory (stable focuses, stable cycles), parameter eigenvalues and eigenfunctions.

The internal structures of thin films, having nanoholes and densely branched morphologies and prepared from a long chain polystyrene-b-poly(ethylene oxide) (PS-b-PEO) diblock copolymer, were characterized. Using grazing-incidence small- and wide-angle X-ray scattering (GISAXS & GIWAXS), the thickness of the lamellar mesophase repeat unit and the orientation of the PEO crystalline chain stems within the thin film were determined. The dimensions of the internal structures and their orientations were linked to the surface morphologies measured by atomic force microscopy. For the nanoholes morphology, the film thicknesses were found to deviate from an integer multiple of the diblock copolymer lamellar units (~ 70 nm) promoting the hole textures. Dewetted architectures were obtained by annealing freshly prepared films under toluene/water vapour environment at an elevated temperature. After that, some PEO chains were able to crystallize within the dewetted large holes resulting in a densely branched morphology (DBM). The crystalline chain stems of the crystalline lamellar, within the dewetted large holes, were found to be roughly perpendicular to the film substrate with thicknesses of about 10 nm. This is in agreement with the diffusion-limited aggregated model.

The goal of this study was to valorize bovine and ovine cheese whey from small and medium cheese manufacturing plants by producing liquid and dry whey protein concentrates (LWPC and WPC). The flexibility provided by batch ultrafiltration (UF) and diafiltration (DF) enabled the production of liquid bovine WPC with protein contents ranging from 43 to 66% (dry basis) and ovine WPC with protein contents ranging from 61 to 87% (dry basis). Diafiltration, performed in sequential dilution mode (DFsdm) did not significantly improve the composition of WPC liquid products comparing to the results achieved by conventional UF. In comparison to traditional UF, using DF in volume reduction mode (DFvrm) enhanced protein content by more than 20%. Ovine products have greater protein content (62-84% on a dry basis), which makes them more appealing for manufacturing. Protein profiles varied with the whey origin and with the concentration process. By using batch DFvrm it was possible to obtain richer protein products free of low molecular weight compounds in comparison to the DFsdm mode. Finally, it can be concluded that use of membrane technology allows the recovery and direct valorization of the whey components in medium and small cheese companies, solving their environmental problems and contributing to the circular economy.

Water quality is a description of chemical, physical and biological characteristics of water in connection with intended use(s) and a set of standards. The quality of water sources has been deteriorated due to point source and non-point source pollution. Therefore, the water quality of any specific source can be investigated using physical, chemical and/or microbiological parameters. One of the most effective tools in communicating information on the quality of water is by using the term water quality index (WQI), which is a rating, reflecting the composite influence of different water quality parameters. WQI provides a single number that expresses the overall water quality at a certain location and time based on several water quality parameters. Hence, this study aimed to assess the quality  of  drinking  water  sources  in  Ado-Ekiti  and  environs,  Nigeria,  using Water Quality Index (WQI). This study was carried out using experimental study design at the Department of Microbiology, Ekiti State University, Ado-Ekiti, Ekiti State, Nigeria, between January 2014 and August 2014. Among several formulated water quality indices, the study adopted the  Weighted  Arithmetic  Water  Quality  Index  (WAWQI) method,  which  classifies water  quality  according  to  the  degree  of  purity. The  WAWQI  was determined on the basis of various physico-chemical parameters which included pH, total dissolved solids,  turbidity,  total  hardness,  calcium,  magnesium,  sulphate,  chloride  and  nitrate.  The parameters were determined using standard methods. The results of the study showed that the  mean  values  of  the  physico-chemical  parameters  of  majority  of  the samples  fell  below  the  WHO  maximum  permissible  limits  while  others  were  above  WHO specifications.  The  calculated  WAWQI  revealed  the  water  quality  level  of  the  different  water sources as follows; 54.16, 65.12, 67.46, 56.29, 46.08  and 49.59 for borehole, stream, pipe-borne, well, spring and packaged water samples, respectively. This result is an  indication  that  the  analyzed  water samples  from  different  sources were of poor water quality with the exception of spring and packaged water samples which are of good  quality in terms of physico-chemical qualities and thus safe for human consumption.