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Entropy decreas in adsorption?

Pulmonary surfactant

Entropy (energy dispersal)

Standard molar entropy

Carbon nanotube

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Entropy changes during adsorption processes vary based on the system studied. In the case of nanorods adsorbed onto smooth walls, the loss of translational and rotational entropy is observed, but the strong adsorption of long nanorods is attributed to the entropy gain related to increased solvent free volume . Similarly, for mixed surfactants at the air/water interface, a negative partial molar entropy change is noted upon adsorption, decreasing with increasing adsorption before abruptly increasing, possibly due to strong repulsion between adsorbed molecules . Furthermore, adsorption of hydrogen on carbon nanotubes results in a significant decline in entropy due to steric considerations, leading to close packing at low temperatures . These examples highlight the complex interplay between adsorption and entropy changes in various systems.

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Journal Article•DOI Enthalpy and entropy effects in hydrogen adsorption on carbon nanotubes. Irena Efremenko, Moshe Sheintuch - Show less +1 more 04 Jun 2005-Langmuir 28 Citations	Entropy decreases during hydrogen adsorption on carbon nanotubes due to steric constraints, leading to close packing at low temperatures, as indicated by the study's analysis.
Journal Article•DOI Entropy of adsorption of mixed surfactants from solutions onto the air/water interface Long-Wu Chen, Jian-Hai Chen, Nai Fu Zhou - Show less +2 more 01 Jan 1995-Journal of the Chemical Society, Faraday Transactions 16 Citations	The entropy decrease in adsorption of mixed surfactants is attributed to adsorption-orientation of molecules in the monolayer, while an abrupt increase near maximum adsorption is due to strong repulsion.
Journal Article•DOI Non-affinity adsorption of nanorods onto smooth walls via an entropy driven mechanism. Yi Ting Cheng, Heng Kwong Tsao, Yu Jane Sheng - Show less +2 more 16 Jun 2021-Soft Matter 1 Citations	Adsorption of nanorods onto smooth walls leads to reduced translational and rotational entropy, with entropy-driven attraction increasing for longer rods due to solvent free volume gain.
Journal Article•DOI Calculation of Entropy of Adsorption for Small Molecules on Mineral Surfaces Akin Budi, Susan L. S. Stipp, Martin Andersson - Show less +2 more 21 Mar 2018-Journal of Physical Chemistry C 37 Citations	Entropy decreases upon adsorption of small molecules on mineral surfaces, with the loss mainly influenced by surface coverage, molecule characteristics, and degrees of freedom, as indicated by DFT calculations.

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What is entropy in chemistry?5 answersEntropy in chemistry is a crucial thermodynamic function that quantifies the disorder and randomness of molecules within a system or process. It is determined by the number of possible configurations accessible to the molecules, reflecting their level of disorder. This concept finds extensive applications in various fields such as biology, chemical graph theory, and both organic and inorganic chemistry. Entropy plays a significant role in chemical and biochemical reactions, influencing their directionality and spontaneity. The relationship between entropy and potential energy is vital, where high potential energy signifies order, while entropy represents disorder, with an inverse relationship between the two. Understanding entropy aids in grasping the structural, functional, and informational changes that occur in molecules over time, impacting their behavior and properties.

What is the chemical adsorption?4 answersChemical adsorption is a process in which molecules distribute themselves between a solid phase and a liquid or gas phase. It is a widely used unit operation in chemical engineering for the separation and purification of fluid streams. Over the last four decades, adsorption has developed into a major industrial separation technique. The properties of most admixtures, such as water reducers and superplasticizers, are derived from their ability to adsorb on the surface of particles or on the liquid-vapor interface. Adsorption behavior depends on various factors, including the chemical composition and dosage of the adsorbate, characteristics of the adsorbent surface, and composition of the liquid phase. Adsorption isotherms are commonly used to model experimental equilibrium data and quantify the amount of adsorbed molecules. Chemical adsorption can also be utilized in cooling apparatus and adsorbing materials for emergent adsorption treatment.

What are the characteristics of Adsorption?3 answersAdsorption is a physical-chemical process where molecules distribute themselves between a solid phase and a liquid or gas phase. It is a major industrial separation technique that has been used for many years. The process of adsorption involves the removal of gaseous pollutants or the collection of valuable materials from a gas stream by adhering to the surface of a solid. Adsorption can be influenced by various factors such as pH, kinetics, temperature, and the presence of mesoporosity in the adsorbent material. The adsorption capacity can be affected by the initial pH, adsorbent dosage, contact time, and the initial concentration of the adsorbate. The adsorption process can be described by the pseudo-second-order kinetic model and the Langmuir isotherm model, indicating that it is a chemical and spontaneous process involving physical absorption, ion exchange, surface complex formation, and chemical reactions.

Does temperature have a significant influence on the adsorption equilibrium, with distinct effects on gaseous and liquid systems?2 answersTemperature has a significant influence on the adsorption equilibrium, with distinct effects on gaseous and liquid systems. For liquids, temperature-dependent viscosity leads to a decrease in mean velocity profile and enhancement in mean temperature profile. On the other hand, for gases, temperature-dependent viscosity shows the reverse effect, resulting in an increase in the velocity profile. Additionally, the thermo-physical properties, such as conductivity and mass diffusivity, also affect the flow phenomena, causing changes in the temperature and concentration profiles. In the case of adsorption in the liquid phase, kinetic and equilibrium aspects, as well as thermodynamic properties, play a role in the adsorption mechanism and operation characteristics. Overall, temperature plays a crucial role in determining the equilibrium behavior of adsorption processes in both gaseous and liquid systems.

When does chemical adsorption occur?3 answersChemical adsorption occurs when molecules or atoms bind to a surface through chemical bonds. It involves the formation of new chemical species on the surface. Chemical adsorption is influenced by factors such as thermodynamics, energetics, and surface phenomena. It is an important process in various fields, including environmental technology and soil contamination. Understanding and handling chemical adsorption is crucial in these areas. Adsorption models and studies provide insights into diverse phenomena, such as oxygen binding to hemoglobin and vapor-liquid phase coexistence. The coexistence of different pollutants, such as cadmium and arsenate, can affect the adsorption behavior of heavy metals and anions in biochar-engineered environments. Overall, chemical adsorption plays a significant role in various natural and technological processes, and its study helps in developing effective separation methods and understanding environmental contamination.

What happens during physical adsorption?5 answersDuring physical adsorption, gases or gas and liquid mixtures are attracted to and accumulate on the surface of a solid material. This process is characterized by the interaction between the adsorbate (gas or liquid) and the adsorbent (solid surface). The adsorption can be either physisorption, which involves weak van der Waals forces, or chemisorption, which involves stronger chemical bonds. The amount of adsorbate that is adsorbed, the kinetics of adsorption and desorption, and electron transfer during adsorption are important factors in this process. Physical adsorption on heterogeneous solids at fluid-solid interfaces is a complex phenomenon that requires a unified description and a standard method for evaluating the energy distribution function.

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