Thermodynamic Research Articles

Methylene Blue Adsorption by Magnesium Oxide Nanoparticles Immobilized with Chitosan (CS-MgONP): Response Surface Methodology, Isotherm, Kinetics and Thermodynamic Studies

In this research, a chitosan-immobilized magnesium oxide nanoparticle (CS-MgONP) was synthesized to evaluate it as a prospective adsorbent for a cationic Methylene Blue (MB) dye. For the synthesized adsorbent, functional groups were analyzed through Fourier transform InfraRed (FT-IR) spectroscopy. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to identify the structural and morphological observations. The evaluation of process parameters such as pH (5-9), CS-MgONP dosage (0.2-0.6g/L), initial MB concentration (10-30mg/L), and temperature (283-323K) on MB adsorption was done at an equilibrium agitation time of 70 min using Central Composite Design (CCD) of Response Surface Methodology (RSM). MB removal percentage of 94.51% (desirability=0.829) was obtained under the optimal conditions of pH=7.28, dosage=0.47g/L, initial MB concentration= 19.37mg/L and temperature =309.76K. The adsorption onto CS-MgONP fits well with pseudo-second-order kinetics equation and equilibrium data made the best fit with Langmuir isotherm with maximum MB uptake capacity of 163.87mg/g.

팬데믹에서 살아남기 위한 열역학 정치 －마가렛 애트우드의 『홍수의 해』－

팬데믹에서 살아남기 위한 열역학 정치 －마가렛 애트우드의 『홍수의 해』－

Computational and Experimental Study on the Interaction of Terbium(III) and Ytterbium(III) Complexes Containing 1,10-phenanthroline with Bovine Serum Albumin

In this work, the interaction of two synthesized complexes [Tb(phen)2Cl3.OH2] and [Yb(phen)2Cl3.OH2] (phen is 1,10-phenanthroline) with bovine serum albumin (BSA) were studied by UV-Vis, fluorescence, and molecular docking examinations. The experimental data indicated that these lanthanide complexes have a high binding affinity with BSA by effectively quenched the fluorescence of BSA via the static mechanism. The binding parameters, the type of interaction, the value of resonance energy transfer, and the binding distance between complexes and BSA were estimated from the analysis of fluorescence measurements and Forster theory. The thermodynamic parameters suggested that van der Waals interactions and hydrogen bonds play an important role in the binding mechanism. While the energy transfer from BSA molecules to these complexes occurs with high probability, the binding constants showed that the binding affinity ranked in the order Tb-complex > Yb-complex that has been related to the radius of Ln3+ ion. Also, the results of competitive experiments and molecular docking calculations assessed the microenvironment residues around the bound mentioned complexes and represent site 3 of BSA, located in subdomain IB, as the most probable binding site for these complexes. The computational results kept in good agreement with experimental data.

Precipitation Modeling via the Synergy of Thermodynamics and Kinetics

Precipitation Modeling via the Synergy of Thermodynamics and Kinetics

Removal of acid black 1 by Acacia Concinna; adsorption kinetics, isotherm and thermodynamic study

In the present research, batch adsorption of anionic dye such as Acid Black 1 (AB1) in aqueous solution onto biosorbent Acacia concinna was investigated at room temperature. The effect of various physico-chemical parameters such as contact time, adsorbent dosage, initial dye concentration and temperature on the percentage removal of dye were investigated. Adsorption kinetics was investigated using linear and nonlinear form of pseudo first-order and pseudo-second-order kinetic models but experimental data for adsorption of AB1 dye in aqueous mixture onto biosorbent Acacia concinna was fitted well to pseudo-second order model with maximum value of regression coefficient (0.9995). Linear and nonlinear forms of Langmuir, Freundlich, Tempkin, and Dubinin– Radushkevich (D–R) were used to reveal experimental data but experimental data for adsorption of AB1 dye in aqueous mixture onto biosorbent Acacia concinna fitted well to the Langmuir isotherm model with adsorption capacity 3.21✕10-4 Adsorption thermodynamic study showed that adsorption of AB1 dye onto adsorbent Acacia concinna was endothermic and spontaneous process. This study revealed that biosorbent Acacia concinna was good biosorbent for removal of dyes from aqueous solution.

Synthesis of new Organo-Inorgano-Clay materials based on metal ions, CTMAB and Bentonite. Application for removal of Acid dye

The present study focuses on the synthesis of pillared bentonites materials prepared by intercalating solutions of aluminum, chromium and iron and cetyltrimethylammonium bromide (CTMAB) into natural bentonite. Six solids were obtained and applied as adsorbents to remove acid yellow E-4G dye from aqueous solutions. Different characterization methods, such as chemical composition, X-ray diffraction and specific surface area, were used for that purpose. The efficiency of dye removal was studied as a function of pH, initial dye concentrations, contact time and temperature. The efficiency of dye removal by CTMA-Al intercalated bentonite was found higher than that of inorgano-bent, under similar conditions. The results obtained showed that the maximum adsorption capacity for dye by modified bentonite was reached within the pH range from 1 to 2. Indeed, the maximum adsorption capacity was estimated to be 385 mg/g at room temperature. The results of kinetics study regarding the removal of E-4G dye by modified bentonites was found to fit the pseudo-second-order model. Moreover, it turned out that the adsorption isotherm data obtained fit well the Freundlich model, which is not the case for the Langmuir and D-R models tested. Calculated thermodynamic parameters indicated that the adsorption process is spontaneous and endothermic with bentonite intercalated by aluminum and iron (B-AlFe) and is exothermic in the case of inserted bentonite by cetyltrimethylammonium and chromium (B-C-AlCr).

Background field method in thermo field dynamics for wave propagation in unmagnetized spinor QED plasmas

In this paper, we propose a relativistic quantum many-body theory for the collective modes in spinor quantum electrodynamic plasma. Different from the usual quantization scheme, we use the self-consistency nontrivial background field method in the framework of thermo field dynamics, in which the resulting quanta are temperature-dependent particles instead of the observable ones such as electrons, positrons, and photons. The theory provides a general scheme for many-body physics, which overcomes the disadvantages of random phase, Hartree–Fock, or other equivalent mean-field approximations. The essential point for our theory is to exactly evaluate the background fields. In this paper, we propose a general and efficient method to determine them, which we name as the “classical limit method” for convenience. To demonstrate how to apply the theory, we discuss the collective modes in unmagnetized electron–positron plasma, in both the low-energy and high-energy limits. It yields the well-known dispersion relations of longitudinal and transverse modes for non-relativistic degenerate plasmas, at zero and nonzero temperature. Furthermore, it gives the additional relativistic and vacuum fluctuation corrections, including increasing mass, decreasing effective charge, finite light velocity influence on the dispersion relation, and virtual charge redistribution. The last effect is reported for the first time.

A Protocol Triumvirate - Risk Assessment and Risk Reduction

Scientific laws are introduced to engineering students in the various disciplines, for example, Ohm’s law in electrical engineering; Newton’s law in mechanical engineering; Boyle’s law in fluid mechanics; Entropy in thermodynamics; Avogadro’s constant in chemical engineering; and the Mass - Energy Equivalence (E = mc2) in physics. Ask someone to cite some of the laws in safety engineering! Indeed, ask a safety practitioner to define safety. Will he explain that the technical definition of safety is the reciprocal of Risk which is defined almost everywhere as a combination of hazard severity and hazard exposure? This challenged definition of safety is really a description that has been replaced by the safety community with Risk Matrices developed through consensus not research. It has, nevertheless, been incorporated into guidelines for conducting Risk Assessment and Risk Reduction which is the subject of this paper. Generally, if we characterize a contrivance, the protocols for its risk assessment and risk reduction include five building blocks: Hazard Identification, Definition of Risk, Risk Acceptance Criteria, Hierarchies of Control, and Control Management. The value of these protocols for defining safety and improving safety, derives from the fact that the combination of building elements includes the concepts of Design and Safeguards which are supported by the classical engineering disciplines. In addition, users of the protocols are introduced to the full safety toolbox together with an enlightened presentation covering most of the significant historical safety observations. On the other hand, these building blocks have never been validated by research and the protocols have not been compared to risks computed from actual statistical data. The protocols are critiqued in this paper primarily through the lens of their authors. With time, the risk protocol that was originally presented as a guideline has undergone a metamorphosis into a faux-safety theorem by virtue of its introduction into a variety of consensus standards and safety reference books. It has achieved ubiquity and currently carries the mantle of a gold standard for determining Tolerable Risk. Notwithstanding its value, it remains an art form that does not contribute to the basic underpinnings of safety technology. Protocols present in three different forms. The most advanced are directed toward products that reflect critical mishaps such as aircraft design and weapon design; these protocols contain an extra building block, Validation and Documentation, together with Risk Acceptance Criteria that include independent authority outside the purview of the design team. An intermediate level protocol that is championed by ISO/IEC deals with non-critical mishaps that also include the extra building block, Validation and Documentation, without the requirement that Risk Acceptance Criteria embrace independent scrutiny. Finally, a very popular protocol of a type recommended by ANSI for non-critical mishaps, has no validation requirements and uses Risk Acceptance Criteria for the determination of tolerable risk that reside in the discretion of the designers.

Optimal synthesis of a community-based off-grid polygeneration plant using fuzzy mixed integer linear programming model

Polygeneration provides an alternative approach for producing clean energy with enhanced overall thermodynamic efficiency, thus reducing environmental emissions and wastes. The growth of energy demand can be attributed to population growth together with the economic progress of developing countries. Such countries need to map out carbon-constrained growth trajectories that make intensive use of clean energy. In developing countries, there are still sites found in remote rural areas or islands which are still off-grid. Provision of electricity to such isolated communities is often problematic due to lack of economies of scale. Most of the livelihood of citizens in these areas is mainly based on agriculture and fisheries, which requires basic utilities such as electricity, clean drinking water, and cooling or refrigeration to preserve the agricultural produce and fishery catch. Polygeneration systems offer an efficient means of satisfying the utility needs of such remote communities. Hence, this study is focused on the development of a model for the optimal synthesis of community-based off-grid polygeneration plants needed to supply the basic needs of electricity, potable water, and cooling. The proposed approach uses a fuzzy mixed integer linear programming (FMILP) formulation. A hypothetical but realistic case study of a community-based off-grid is used to demonstrate the model.

The importance of thermodynamic insight in Work and Heat Exchange Network Design

Work and Heat Exchange Network (WHEN) design has been an emerging topic in the area of Process Synthesis and has attracted increasing research interest in the past few years. Not only temperature changes but also pressure changes of process streams have been taken into consideration in WHEN design. As a result, pressure changing equipment such as compressors, expanders, pumps, valves, etc., as well as traditional heat exchange equipment is included in WHEN design. Similar to HEN design problems, both graphical and mathematical optimization approaches have been under development for WHEN design. The graphical approaches utilize fundamental thermodynamic insight while mathematical optimization approaches enable dealing with large size problems. This paper focuses on a comparison between the graphical and mathematical optimization approaches for WHEN design. A case study is used to illustrate the importance of thermodynamic insight in WHEN design even in the case of using mathematical optimization approaches.

A combined numerical approach for the thermal analysis of a piston water pump

Abstract The paper proposes a numerical model for the investigation of a piston water pump under different operating conditions. In particular, the lubricating system is analysed and modelled. The study accounts for the lubrication and friction phenomena, heat transfer, multiphase fluid approach and motion simulation. A computational thermo fluid dynamics approach has been adopted to develop a numerical tool able to simulate the behaviour of the oil during the machine working phases. The CFD approach simulates the moving metal components by means of moving meshes techniques; the friction phenomenon is estimated on the basis of formulations available in literature. The numerical model evaluates the heat transfer between moving metal parts and oil during the operating phases of the system. Furthermore, the heat transfer between oil and environment is calculated, accounting for conduction through the metal crankcase walls. A multiphase fluid approach is used for the simulation of the oil and air mixing during the crank rotation. The heat transfer coefficient predicted by the CFD approach are employed in a lumped and distributed numerical model; the reliability and accuracy of the proposed numerical approach is addressed and validated against experimental results. Experimental data have been collected by means of a thermographic camera and thermocouples. Finally, the tool's predictive capabilities are addressed by simulating different working conditions.

The living state: How cellular excitability is controlled by the thermodynamic state of the membrane

The thermodynamic (TD) properties of biological membranes play a central role for living systems. It has been suggested, for instance, that nonlinear pulses such as action potentials (APs) can only exist if the membrane state is in vicinity of a TD transition.Herein, two membrane properties in living systems – excitability and velocity – are analyzed for a broad spectrum of conditions (temperature (T), 3D-pressure (p) and pH-dependence). Based on experimental data from Characean cells and a review of literature we predict parameter ranges in which a transition of the membrane is located (15-35°C below growth temperature; 1−3pH units below pH7; at ∼800atm) and propose the corresponding phase diagrams. The latter explain: (i) changes of AP velocity with T,p and pH.(ii) The existence and origin of two qualitatively different forms of loss of nonlinear excitability (“nerve block”, anesthesia). (iii) The type and quantity of parameter changes that trigger APs. Finally, a quantitative comparison between the TD behavior of 2D-lipid model membranes with living systems is attempted. The typical shifts in transition temperature with pH and p of model membranes agree with values obtained from cell physiological measurements. Taken together, these results suggest that it is not specific molecules that control the excitability of living systems but rather the TD properties of the membrane interface. The approach as proposed herein can be extended to other quantities (membrane potential, calcium concentration, etc.) and makes falsifiable predictions, for example, that a transition exists within the specified parameter ranges in excitable cells.

Removal of methyl green dye from aqueous solutions using activated carbon derived from cryogenic crushed waste tires

Activated carbon obtained from cryogenic crushing of used tire prepared and characterized previously was used as an adsorbent for the removal of cationic dye “methyl green dye MG” from an aqueous solution. Batch adsorption studies were carried as a function of varying parameters of the system such as initial solution pH, adsorbent dosage, initial dye concentration, and temperature. The experimental data were fitted using Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherm models. The Langmuir isotherm model fitted well the obtained experimental data. The maximum adsorption capacity of methyl green dye at pH 7 was found to be 71.43 mg/g. The results of kinetics study indicated that the experimental data are fitted to Pseudo-first order model. The thermodynamic properties like ∆G, ∆H, and ∆S were estimated for the adsorption processes and indicated that this latter was exothermic, spontaneous, and favorable. The developed activated carbon might be used in a favorably manner for removing methyl green from aqueous solution.

Термодинамическое исследование системы Bi2Se3–Bi2Te3 методом ЭДС

Термодинамическое исследование системы Bi2Se3–Bi2Te3 методом ЭДС

First‐principles spectroscopic screening of hybrid perovskite ( CH 3 CH 2 NH 3 PbI 3 ) with fundamental physical properties: A potential photovoltaic absorber

Herein, we have discussed the ethyl-ammonium based hybrid perovskite (viz. CH3CH2NH3PbI3 or EAPbI3) as the potential candidate material for the development of photovoltaic devices having low processing cost and high power conversion efficiency (PCE). To address the stability and environmental issues due to leaching of lead from MAPbI3, we urge to replace cation CH3NH3+ (MA+) with an appropriate cation CH3CH2NH3+ (EA+) and hope that the EAPbI3 perovskite would prove to be a stable and eco-friendly photovoltaic absorber (PVA) material yielding high PCE. We have investigated physical properties like energy bandgap, electron density distribution and optical coefficients by FP-LAPW+lo and density functional theory (DFT). The present study reveals that EAPbI3 has a direct energy bandgap of 1.55 eV with absorption coefficient exceeding 2 × 104 per cm, which confirms its suitability as PVA material. The dependence of thermoelectric (TE) coefficients on chemical potential and carrier concentration at various temperatures has also been discussed. We have also carried out the calculations of spectroscopic limited maximum efficiency (SLME) parameter (30.5%), and the thermodynamic (TD) properties in the realm of quasi-harmonic approximation. A detailed investigation on some of the properties of EAPbI3 perovskite relevant to PVA material is being done for the first time, the present study may motivate researchers for more comprehensive theoretical and experimental investigations in search of stable and economically and environmentally viable PVA materials.

Uraren azidotasunari buruzko ikerketa Bizkaiko hiru estuarioetan: Urdaibai, Plentzia eta Nerbioi-Ibaizabal

Lurraren % 70 estaltzen dutelarik, ozeanoek zeresan handia dute planetaren prozesu gehienetan. Azken 200 urteetan CO2-aren emisioak gorakada handia izan du gizakien jarduera dela eta. Horren ondorioz, atmosferako CO2-aren kontzentrazioa 280 ppm-tik 415 ppm ingurura igo da garai aurreindustrialetik gaur egunera bitartean. Zenbait ikerketaren arabera, 2100. urterako kontzentrazioak 936 ppm-ko mailara irits daitezke, isuriek orain arte bezala jarraituz gero. CO2-aren hazkundeak bi efektu nagusi ditu: alde batetik, tenperatura globalaren igoera, hau da, berotegi efektuaren areagotzea; eta bestetik, ozeanoen azidotasuna. Ozeanoek CO2-a absorbatzen dute, eta, ondorioz, atmosferan dagoen kontzentrazioa murrizten da, baina horrek uraren pH-a jaitsiarazten du. Itsasoko uraz gain, bereziak diren hainbat gune ikertzearen beharra ere agertu da, hala nola estuarioak. CO2-aren hazkundeak ur-sistema horietan izan dituen efektuak ez dira gehiegi aztertu, eta oso garrantzitsuak dira, zeren eta animalia- eta landare-espezie askoren bizileku baitira. Azidotasuna aztertzeko, lau parametro erabiltzen dira: alkalinitate totala, disolbatutako karbono ezorganikoa, pH-a eta iheskortasuna. Haien arteko erlazio termodinamikoa dela eta, esperimentalki soilik bi neurtu behar dira beste biak kalkulatu ahal izateko. Lan honetan, alkalinitate totala eta disolbatutako karbono ezorganikoa neurtu dira. Lau parametro horien azterketa egin da Bizkaiko hiru estuariotan: Urdaibai, Plentzia eta Nerbioi-Ibaizabal. Laginketak hiru urtez egin ziren, urtaro guztietan, estuarioen arteko berdintasunak eta ezberdintasunak ikusi nahian, bai eta denborarekiko erlazioak aztertu nahian ere.

Moisture sorption behavior and thermodynamic properties of dry‐crystallizedPalada payasam(rice flakes milk pudding) mix determined using the dynamic vapor sorption method

Moisture sorption behavior and thermodynamic properties of dry‐crystallized<i>Palada payasam</i>(rice flakes milk pudding) mix determined using the dynamic vapor sorption method

Study of the Kinetics and Thermodynamics of Adsorption of Hexavalent Chromium on the Luffa Cylindrica Cords

In the present work, the objective is to determine the potential use of natural materials, Luffa cylindrica cords for the removal of Chrome (VI) through the adsorption batch process under different experimental conditions. The determination of the concentrations of Chrome (VI) has been performed using a UV - visible spectrophotometer. Adsorption studies were carried out under various parameters such as contact time, pH, initial concentration, and temperature. The results obtained show that Luffa cylindrica cords/Chrome (VI) have an adsorption capacity of 29.98 mg/g. The adsorption process was rapid and reached equilibrium in 60 min of contact at 343K and pH 7.7. The different adsorption models Langmuir, Freundlich, Temkin, and Elovich were used for the mathematical description of the adsorption equilibrium, and it was found that the very well - equipped experimental data for the Langmuir model (R2=0.9700), the pseudo-first-order and pseudo-second-order kinetic models were applied to the experimental data. The experimental data fitted very well the pseudo-second-order kinetic model (R2= 0.982) and also followed the model of intraparticle diffusion (Kdif vary from 0.687 to 4.040 mg/(g min1/2) for concentrations between 25 and 150 mg/L), whereas diffusion is not the only rate - control step. The thermodynamic parameters study shows that the negative value of ΔH° (-11.49 kJ/mol) indicated that the adsorption of Chrome (VI) on Luffa Cylindrica cords was exothermic, the reaction was accompanied by a decrease in entropy (- 0.033 kJ/K. mol). The Gibbs free energy increased from -0.171 to -1.722 kJ/mol, respectively for Chrome (VI) when the temperature was increased from 296 to 343 K. The studied system shows that the adsorption process is spontaneous. The physical properties of the biosorbent were determined by FT-IR analysis and X-RD.

Optimization of Cascade Cooling System with Absorption Refrigeration Cycle Using Thermodynamic Models

Cooling systems have been widely studied over the past few years, but there are little researches on cascade cooling system containing different cooling methods. Cascade cooling system is suitable for the hot stream cooling process with large temperature variation. A new cascade cooling system containing waste heat recovery, air cooling, water cooling, absorption refrigeration and compression refrigeration is proposed. In this system, hot water is used to recycle waste heat from the hot stream, then drive the absorption refrigeration cycle (ARC), providing refrigerant water for hot stream cooling process. The mass flowrate of hot water determines the amount of waste heat recovered, and the final hot water temperature affects the thermal efficiency of ARC. Both the flowrate and the final temperature of hot water influence the cooling capacity generated by ARC, and further affect the heat load distribution of cascade cooling system. The hot water mass flowrate is a critical decision variable for the optimal design of the system. This study develops a model for the techno-economic optimization of cascade cooling system with ARC. ARC is modelled using thermodynamics with the concept of state points. The proposed model determines the optimal heat load distribution of cascade cooling system and the optimal design of ARC, with the minimum total annual cost (TAC) simultaneously. The effectiveness of this method is demonstrated with a case study in a polysilicon enterprise.

Optimal Design and Sizing of Solar-assisted CHP System Based on Thermodynamic and Economic Analysis

This work develops a method for the optimal design of a solar-assisted combined heat and power (CHP) system, in which the solar thermal central receiver subsystem and the steam power cycle subsystem are integrated to meet the real-time requirements of steam and power from production process. A mathematical model with the objectives of minimum total annual cost (TAC) and environmental impact (EI) is formulated to optimize the configuration and the size of the major equipment units, and schedule the dynamic operation of entire system. This model accounts for the hourly variability of Direct Normal Irradiance (DNI) and the electricity load in a typical day, as well as the power losses caused by the partial load operation of steam turbines. Based on the presented model, the optimum level of solar capacity is determined through a comprehensive analysis considering the trade-off between TAC and EI of the system. At last, a case study is illustrated and the results are elaborated to demonstrate that the desired system configuration can be obtained by application of the proposed model.