Band 234, Heft 10

Over the last two centuries, thermodynamics has contributed significantly to technical and industrial progress. According to phenomenological thermodynamics developed by Rudolf Clausius and Josiah Willard Gibbs, properties such as volume or interface represent energetic qualities of a real body. In the present work, the energy concepts of thermodynamics and special relativity are connected with each other. The plausibility of complete mass-energy equivalence is evaluated within the thermodynamic context. Einstein’s interpretation of the well-known equation E = mc 2 as complete mass-energy equivalence results as a special case for idealized moving point masses – according to the assumptions of the theory of special relativity. It is shown that mass is one energy-equivalent property of matter, but not the only one, because complete mass-energy equivalence contradicts the principle of conservation of energy. Thermodynamics suggests matter-energy equivalence. In accordance with the two main laws of thermodynamics and corresponding with experimental facts, it forms the basis of an in-depth understanding of nature and provides impetus for the research in quantum physics, thermodynamics and astrophysics.

Ionic liquids (ILs) give a wide scope of favorable applications due to their much-upgraded properties. The strong electrostatic interactions between the cationic moiety of IL and the anionic surfactant play a very important role in the assembly of the large aggregates. We have investigated the aggregation behavior of anionic surfactants and IL in aqueous solution. Different temperatures and concentrations of IL have been taken to study the effect on critical micelles concentrations of surfactant. The critical micelle concentration values obtained by conductivity measurements are further confirmed by the fluorescence studies. The method is based on the fit of the experimental obtained raw data of fluorescence spectroscopy to a simple nonlinear category of a Boltzmann type sigmoidal function. Thermodynamical parameters of micellization ΔHm0$\Delta H_{m}^{0}$, ΔGm0$\Delta G_{m}^{0}$ and ΔSm0$\Delta S_{m}^{0}$ have been considered to study the effect of aqueous IL 1-butyl-3-methylimidazolium bromide concentration and temperature on aggregation behavior of surfactant sodium dodecyl sulfate. FT-IR spectra have been studies to verify the structural changes arise in the aqueous IL and surfactant system.

This research work is based on the preparation and physicochemical characterization of Poly(N-isopropylacrylamide)–Cellulose–Poly(Acrylic acid) [PNIPAAm–Cellulose–PAAc] based terpolymer hydrogels. The free radical polymerization reaction was initiated by the presence of ammonium persulphate (APS) and crosslinking between different monomers was occurring through N,N l - Methylene bis-acrylamide (MBA). Confirmation of polymerization process was done by FT-IR and UV-visible spectroscopy. The prepared hydrogels were further characterized by different physicochemical techniques like rheology, Ostwald viscometry and dynamic light scattering (DLS). The effect of external stimuli like temperature, pH and composition of the samples on the physicochemical behavior was also carried out by dynamic rheology, swelling measurement and DLS. Various other properties like elasticity, shear stress, shear strain, loss modulus, storage modulus and complex viscosity was investigated by rheology. DLS was used to trace the size and swelling behavior of the samples. From the results obtained it was found that all the microgel samples are stimuli responsive and most of their physicochemical properties were prominently varying while changing the internal as well as the external experimental variable. These changes in physicochemical behavior of the gel can be attributed to two possibilities; the change in the hydrophobic character of gel (PNIPAAm) with temperature and also to the weakening of intermolecular hydrogen bonds with increase in temperature. As a result of this the PAA chains may undergo a transition from a compact conformation to an expanded coil conformation, resulting in the swelling of the hydrogels.

Highly dispersed CuNi nanoparticles (NPs) immobilized on reduced graphene oxide (RGO) were synthesized via the simple in situ co-reduction of an aqueous solution of Copper(II) sulfate pentahydrate, nickel chloride hexahydrate, and graphene oxide (GO) by the reduction of ammonia borane (AB) at room temperature. The powder XRD, FTIR, EDS, and TEM techniques were used to charaterize the structure, size, and composition of the CuNi/RGO catalysts. The as-prepared CuNi/RGO catalysts showed excellent catalytic performance toward the hydrolysis of AB at room temperature. Compared to Cu/RGO, Ni/RGO, and the RGO-free Cu 0.6 Ni 0.4 counterpart, the as-prepared Cu 0.6 Ni 0.4 /RGO catalysts showed much better catalytic activity. Furthermore, kinetic studies showed that the catalytic hydrolysis of AB by Cu 0.6 Ni 0.4 /RGO has zero order dependence on the AB concentration, but first order dependence on the catalyst concentration. The turnover frequency (TOF) of Cu 0.6 Ni 0.4 /RGO catalyst for the hydrolytic dehydrogenation of AB was determined to be about 20.2 mol H 2 (mol Cu 0.6 Ni 0.4 /RGO) −1 min −1 at 25 °C. In addition, the activation energy ( E a ) of Cu 0.6 Ni 0.4 /RGO was determined to be around 17.7 kJ mol −1 , which is one of the lowest activation energy’s of the reported metal-based catalysts.

This study investigated the removal of phenol from steel industry wastewater by three dimensional electrochemical (TDE) process using CoFe 2 O 4 nanobiocomposite based activated carbon in the presence of H 2 O 2 (EC-CoFe 2 O 4 @AC-H 2 O 2 ). In this study, CoFe 2 O 4 nanobiocomposite-foundation activated carbon (CoFe 2 O 4 @AC) was used as microelectrode, adsorbent, and activator for peroxide hydrogen. The removal efficiency of phenol and COD was investigated through the parameters of pH, contact time, CoFe 2 O 4 @AC dosage, current density, and H 2 O 2 concentration. The highest removal rates of phenol and COD were >99% and 98%, respectively. Also, steel plant wastewater under the optimal conditions of pH = 6.5, current density = 15 mA cm −2 , contact time = 25 min, H 2 O 2 concentration of 1.0 mM, and CoFe 2 O 4 @AC dose = 0.3 g L −1 . Kinetic analysis revealed that the adsorption experimental data was best fitted by the pseudo-first-order model.

One-pot synthesis of Co 3 O 4 nanocrystals on reduced graphene oxide (rGO) was carried out by reacting cobalt nitrate, L-arginine, extract of Laportae aestuans as oxidant, fuel and reducing agent, respectively, in a domestic microwave. Morphologies of Co 3 O 4 –rGo (RGCO) composite was elucidated using UV-Vis, FT-IR, TEM, SEM, EDX, XRD and photoluminescence spectroscopies. The synthesized RGCO composite was applied as heterogeneous photocatalyst in the activation of Na 2 SO 3 (sulfite) as sacrificial agent to degrade cationic dyes: rhodamine B (RhB) and methylene blue (MB), under visible light, at neutral pH 7.0. Photocatalytic performance of as-prepared RGCO was significantly enhanced in the presence of Na 2 SO 3 . Enhanced photocatalytic activity of RGCO was attributed to the synergistic effects between sulfite radicals generated in situ , and reduced graphene oxide, in which rGO served as electron sink to suppress recombination of photogenerated charge carriers. Plausible mechanistic pathways responsible for the activation of sulfite anions in situ are presented in this paper.

A novel hydrogen bonded liquid crystal (HBLC) complexes are obtained from the non-mesogenic (benzylmalonic acid) and mesogenic (p-n-alkyloxybenzoic acid, where n = 6, 7 and 8) compound via intermolecular hydrogen bonds (H-bond). H-bonds are experimentally confirmed by the Fourier transform infrared spectroscopic (FT-IR) studies and the same is validated using density functional theory (DFT). Induced thermochromism is observed by the polarizing optical microscope (POM) and its possible applications are reported. Phase transition temperature and their analogous enthalpy values, stability factor and span width are determined by the differential scanning calorimetry (DSC) studies. Band gap energy is calculated using UV-visible and photoluminescence spectrum. Hyper conjugative stabilization energy and atomic charge distribution is studied by the natural bond orbital (NBO) studies. Mulliken analysis clearly reveals the intermolecular interaction and steric effect of the HBLC complexes. An interesting phenomenon is that the observation of luminescence and thermochromism in the highly fluidity nematic phase. This peculiar behavior is attributed due to the intermolecular H-bonding interaction between the BMA and nOBA compounds and the effect of rotatory motion of the molecules in nematic phase. Luminescence increases when the spacer moiety decreases in the present complexes is also reported. In nematic phase, the molecules are in different degrees of the excited state which is correlated with the hyper conjugative energy through NBO studies.