Langmuir adsorption model (original) (raw)
The Langmuir adsorption model explains adsorption by assuming an adsorbate behaves as an ideal gas at isothermal conditions. According to the model, adsorption and desorption are reversible processes. This model even explains the effect of pressure i.e at these conditions the adsorbate's partial pressure, , is related to the volume of it, V, adsorbed onto a solid adsorbent. The adsorbent, as indicated in the figure, is assumed to be an ideal solid surface composed of a series of distinct sites capable of binding the adsorbate. The adsorbate binding is treated as a chemical reaction between the adsorbate gaseous molecule and an empty sorption site, S. This reaction yields an adsorbed species with an associated equilibrium constant :
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| dbo:abstract | The Langmuir adsorption model explains adsorption by assuming an adsorbate behaves as an ideal gas at isothermal conditions. According to the model, adsorption and desorption are reversible processes. This model even explains the effect of pressure i.e at these conditions the adsorbate's partial pressure, , is related to the volume of it, V, adsorbed onto a solid adsorbent. The adsorbent, as indicated in the figure, is assumed to be an ideal solid surface composed of a series of distinct sites capable of binding the adsorbate. The adsorbate binding is treated as a chemical reaction between the adsorbate gaseous molecule and an empty sorption site, S. This reaction yields an adsorbed species with an associated equilibrium constant : From these basic hypotheses the mathematical formulation of the Langmuir adsorption isotherm can be derived in various independent and complementary ways: by the kinetics, the thermodynamics, and the statistical mechanics approaches respectively (see below for the different demonstrations). The Langmuir adsorption equation is the following: where is the fractional occupancy of the adsorption sites, i.e., the ratio of V, the volume of gas adsorbed onto the solid, to , the volume of a gas molecules monolayer covering the whole surface of the solid and completely occupied by the adsorbate. A continuous monolayer of adsorbate molecules covering a homogeneous flat solid surface is the conceptual basis for this adsorption model. (en) O modelo de adsorção de Langmuir explica assumindo que um adsorbato comporta-se como um gás ideal em condições isotérmica. Nessas condições, a pressão parcial do adsorvato, , é relacionada ao seu volume , adsorvido em um adsorvente sólido. O adsorvente, como indicado na Figura 1, é assumido como uma superfície sólida ideal composta de sítios distintos capazes de ligarem o adsorbato. A ligação do adsorvato é tratada como uma reação química entre a molécula de adsorvato e um sítio vazio, . Essa reação rende um complexo adsorvido com uma constante de equilíbrio associada Desse pressuposto, a isoterma de Langmuir pode ser derivada, que afirma que: onde é a fração de ocupação dos sítios de adsorção e é o volume da monocamada. Uma monocamada de moléculas de gás em torno de um sólido é a base conceitual para esse modelo de adsorção. A isoterma de Langmuir é formalmente equivalente a em bioquímica. (pt) Langmuirs adsorptionsisoterm är ett uttryck som beskriver, vid konstant temperatur och jämvikt, sambandet mellan täckningen av ett adsorbat på en yta som funktion av partialtrycket av densamma. Modellen bygger på antagandena att adsorbatet har samma bindningsenergi till adsorptionssätena oavsett hur stor täckningen är, att adsorption och desorption är i jämvikt och att adsorbatet inte bildar mer än ett lager. Uttrycket härleddes av Irving Langmuir, som senare fick Nobelpriset för sitt arbete med ytkemi. Isotermen lyder, för adsorbat , , där är täckningen av adsorbatet, är volymen adsorbat, är volymen av ett lager adsorbat, är en jämviktskonstant beroende på adsorption och desorption och är partialtrycket. För låga tryck är täckningen proportionell mot trycket, medan den för höga tryck är så gott som konstant. (sv) |
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| rdfs:comment | The Langmuir adsorption model explains adsorption by assuming an adsorbate behaves as an ideal gas at isothermal conditions. According to the model, adsorption and desorption are reversible processes. This model even explains the effect of pressure i.e at these conditions the adsorbate's partial pressure, , is related to the volume of it, V, adsorbed onto a solid adsorbent. The adsorbent, as indicated in the figure, is assumed to be an ideal solid surface composed of a series of distinct sites capable of binding the adsorbate. The adsorbate binding is treated as a chemical reaction between the adsorbate gaseous molecule and an empty sorption site, S. This reaction yields an adsorbed species with an associated equilibrium constant : (en) O modelo de adsorção de Langmuir explica assumindo que um adsorbato comporta-se como um gás ideal em condições isotérmica. Nessas condições, a pressão parcial do adsorvato, , é relacionada ao seu volume , adsorvido em um adsorvente sólido. O adsorvente, como indicado na Figura 1, é assumido como uma superfície sólida ideal composta de sítios distintos capazes de ligarem o adsorbato. A ligação do adsorvato é tratada como uma reação química entre a molécula de adsorvato e um sítio vazio, . Essa reação rende um complexo adsorvido com uma constante de equilíbrio associada (pt) Langmuirs adsorptionsisoterm är ett uttryck som beskriver, vid konstant temperatur och jämvikt, sambandet mellan täckningen av ett adsorbat på en yta som funktion av partialtrycket av densamma. Modellen bygger på antagandena att adsorbatet har samma bindningsenergi till adsorptionssätena oavsett hur stor täckningen är, att adsorption och desorption är i jämvikt och att adsorbatet inte bildar mer än ett lager. Uttrycket härleddes av Irving Langmuir, som senare fick Nobelpriset för sitt arbete med ytkemi. Isotermen lyder, för adsorbat , , (sv) |
| rdfs:label | Langmuir adsorption model (en) Modelo de adsorção de Langmuir (pt) Langmuirs adsorptionsisoterm (sv) |
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