{"id":14234,"date":"2024-01-31T08:11:03","date_gmt":"2024-01-31T07:11:03","guid":{"rendered":"https:\/\/www.rct-online.de\/magazin\/?p=14234"},"modified":"2025-07-11T16:10:48","modified_gmt":"2025-07-11T14:10:48","slug":"adsorption-absorption-the-difference-rct-magazine","status":"publish","type":"post","link":"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/","title":{"rendered":"The Difference Between Adsorption and Absorption"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_73 ez-toc-wrap-center counter-hierarchy ez-toc-counter ez-toc-white ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/#What_Does_Adsorption_Mean\" title=\"What Does Adsorption Mean?\">What Does Adsorption Mean?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/#What_Is_Physisorption\" title=\"What Is Physisorption?\">What Is Physisorption?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/#What_Is_Chemisorption\" title=\"What Is Chemisorption?\">What Is Chemisorption?<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/#What_Does_Absorption_Mean\" title=\"What Does Absorption Mean?\">What Does Absorption Mean?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/#Absorption_in_Physics\" title=\"Absorption in Physics\">Absorption in Physics<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/#Absorption_in_Chemistry\" title=\"Absorption in Chemistry\">Absorption in Chemistry<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/#Adsorption_and_Absorption_in_Purification_Processes\" title=\"Adsorption and Absorption in Purification Processes\">Adsorption and Absorption in Purification Processes<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/#Adsorption_as_a_Drying_Process\" title=\"Adsorption as a Drying Process\">Adsorption as a Drying Process<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/#Adsorption_in_Heterogeneous_Catalysis\" title=\"Adsorption in Heterogeneous Catalysis\">Adsorption in Heterogeneous Catalysis<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/adsorption-absorption-the-difference-rct-magazine\/#Adsorption_and_Absorption_in_Refrigeration_Systems\" title=\"Adsorption and Absorption in Refrigeration Systems\">Adsorption and Absorption in Refrigeration Systems<\/a><\/li><\/ul><\/nav><\/div>\n<p style=\"text-align: justify;\"><strong>The two terms adsorption and absorption describe processes that take place at the interface between two phases. In adsorption, gases or liquids\u2014known as adsorbates\u2014adhere to the surface of a solid material called the adsorbent. In absorption, by contrast, atoms, molecules, or ions from a gas or liquid are taken up into the bulk of a liquid or solid material\u2014called the absorbent.<\/strong><\/p>\n<h2><span class=\"ez-toc-section\" id=\"What_Does_Adsorption_Mean\"><\/span>What Does Adsorption Mean?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">The term adsorption derives from the Latin word &#8220;adsorbere,&#8221; which means &#8220;to draw to oneself.&#8221; The atoms or molecules inside a solid are held together by bonding forces that act between them in all three spatial directions.<\/p>\n<div class=\"box info  \"><div class=\"box-inner-block\"><i class=\"fa tie-shortcode-boxicon\"><\/i>\n\t\t\t\n<p>However, atoms or molecules at the surface have unbound valences that allow them to attract or bind gases and dissolved substances. Depending on the type of binding of the adsorbates to the adsorbing surface, a distinction is made between physical adsorption, physisorption, and chemical adsorption, chemisorption.<\/p>\n\n\t\t\t<\/div><\/div>\n<h3><span class=\"ez-toc-section\" id=\"What_Is_Physisorption\"><\/span>What Is Physisorption?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">Physical adsorption relies on weak, long-range interactions\u2014such as van der Waals forces, hydrogen bonds, or dipole-dipole interactions\u2014between the adsorbate and the surface. Chemical bonds of the adsorbate molecules are preserved in the process. Due to the longer range of the weak bonding forces, several adsorption layers can form.<\/p>\n<p style=\"text-align: justify;\">The binding energy in physisorption is relatively low, less than 100 kJ\/mol. When atoms or molecules encounter a solid surface, they may either be reflected or become adsorbed. If the particles are adsorbed, they release kinetic energy in the form of heat. This is an exothermic reaction.<\/p>\n<p style=\"text-align: justify;\">Physical adsorption is reversible; an equilibrium forms between adsorbing and desorbing particles. This equilibrium depends on the size of the adsorbing surface, temperature, and the concentration of the adsorbate or, in the case of gases, the partial pressure of the gas. Initially, the adsorption rate is relatively high, but decreases with increasing surface coverage until equilibrium is reached. Desorption can occur by increasing the temperature or lowering the pressure.<\/p>\n<p style=\"text-align: justify;\">Due to their large surface area, materials such as <a href=\"https:\/\/www.rct-online.de\/en\/filtration\/granulars-and-sorbent-material\/31201\/activated-carbon-granular-sorbent-material-based-on-cocnut\">activated carbon<\/a>, activated coke, silica gel or <a href=\"https:\/\/www.rct-online.de\/en\/filtration\/granulars-and-sorbent-material\/30877\/molecular-sieve-sorbent-material-4-aa\">molecular sieve sorbents<\/a> are frequently used as adsorbents.<\/p>\n<p><a href=\"https:\/\/www.rct-online.de\/en\/filtration\/granulars-and-sorbent-material\/30881\/high-tech-adsorber-filter-unit-for-gas-purification\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-9474 size-medium\" title=\"High-Tech Adsorber Filter Unit for Gas Purification\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/adsorber-filterbehaelter-zur-gasreinigung-300x300.jpg\" alt=\"High-Tech Adsorber Filter Unit for Gas Purification\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/adsorber-filterbehaelter-zur-gasreinigung-300x300.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/adsorber-filterbehaelter-zur-gasreinigung-150x150.jpg 150w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/adsorber-filterbehaelter-zur-gasreinigung.jpg 500w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a> <a href=\"https:\/\/www.rct-online.de\/en\/filtration\/granulars-and-sorbent-material\/31201\/activated-carbon-granular-sorbent-material-based-on-cocnut\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-9475 size-medium\" title=\"Activated Carbon Granular Sorbent Material based on coccnut\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/aktivkohle-granulat-sorbens-auf-kokosnuss-basis-300x300.jpg\" alt=\"Activated Carbon Granular Sorbent Material based on coccnut\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/aktivkohle-granulat-sorbens-auf-kokosnuss-basis-300x300.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/aktivkohle-granulat-sorbens-auf-kokosnuss-basis-150x150.jpg 150w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/aktivkohle-granulat-sorbens-auf-kokosnuss-basis.jpg 500w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">These <a href=\"https:\/\/www.rct-online.de\/en\/filtration\/granulars-and-sorbent-material\">granules and sorbents<\/a> are used in filtration systems within <a href=\"https:\/\/www.rct-online.de\/en\/filtration\/filter-housings-filterelements-and-filtermodules\">filter housings<\/a>, for example for gas purification.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"What_Is_Chemisorption\"><\/span>What Is Chemisorption?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">In chemisorption, chemical bonds are formed between adsorbate and adsorbent molecules or atoms. As a result, both the adsorbate and the adsorbent can be chemically altered. The binding energies here are around 800 kJ\/mol.<\/p>\n<p style=\"text-align: justify;\">Chemisorption is usually irreversible, i.e., not an equilibrium reaction; desorption can often only take place at higher temperatures. The chemically bound layer typically consists of just a single monolayer. Many processes in heterogeneous catalysis are based on chemical adsorption. Reactants adsorb onto a catalyst and are thereby transferred to an activated state. Chemical reactions with other reaction partners can thus proceed more easily.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"What_Does_Absorption_Mean\"><\/span>What Does Absorption Mean?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>The term absorption derives from the Latin &#8220;absorbere&#8221; and means &#8220;to devour&#8221; or &#8220;to swallow.&#8221;<\/p>\n<div class=\"box note  \"><div class=\"box-inner-block\"><i class=\"fa tie-shortcode-boxicon\"><\/i>\n\t\t\tIn physics, absorption is the reduction of electromagnetic radiation or sound waves when passing through a material. Absorption in chemistry means the uniform distribution of one substance in another, such as the dissolution of solids or gases in liquids.\n\t\t\t<\/div><\/div>\n<h3><span class=\"ez-toc-section\" id=\"Absorption_in_Physics\"><\/span>Absorption in Physics<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">When electromagnetic radiation such as light strikes a medium, energy is absorbed. The electrons in the absorbing medium are excited to a higher energy level. The absorbed energy can subsequently be released in another form, such as heat.<\/p>\n<div class=\"box success  \"><div class=\"box-inner-block\"><i class=\"fa tie-shortcode-boxicon\"><\/i>\n\t\t\t\n<p>If not all wavelengths are absorbed uniformly, the medium appears colored. For example, chlorophyll, a natural pigment, mainly absorbs violet, orange, blue and yellow light; green light is reflected. This is why plant leaves appear green to us.<\/p>\n\n\t\t\t<\/div><\/div>\n<p style=\"text-align: justify;\">The absorbed energy is taken up by chlorophyll molecules and serves to produce sugar and oxygen through photosynthesis.<\/p>\n<p><a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/laboratory-containers\/test-tubes-centrifuge-tubes-and-cuvettes\/29860\/macro-cuvette-made-of-ps-crystal-clear\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-9477 size-medium\" title=\"Macro Cuvette made of PS - crystal-clear\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/makro-kuevette-aus-ps-glasklar-300x300.jpg\" alt=\"Macro Cuvette made of PS - crystal-clear\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/makro-kuevette-aus-ps-glasklar-300x300.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/makro-kuevette-aus-ps-glasklar-150x150.jpg 150w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/makro-kuevette-aus-ps-glasklar.jpg 500w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a> <a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/laboratory-containers\/test-tubes-centrifuge-tubes-and-cuvettes\/29861\/rct-accessories-cuvette-stopper-made-of-ldpe\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-9478 size-medium\" title=\"RCT\u00ae-Accessories: Cuvette Stopper made of LDPE\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/kuevettenstopfen-aus-ldpe-300x300.jpg\" alt=\"RCT\u00ae-Accessories: Cuvette Stopper made of LDPE\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/kuevettenstopfen-aus-ldpe-300x300.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/kuevettenstopfen-aus-ldpe-150x150.jpg 150w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/kuevettenstopfen-aus-ldpe.jpg 500w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">In spectroscopy using <a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/laboratory-containers\/test-tubes-centrifuge-tubes-and-cuvettes\">cuvettes<\/a>, the absorption of radiation as a function of wavelength is used to identify gases, liquids or solids based on their absorption spectra. In photovoltaics, absorbed sunlight is converted into electrical energy. In photochemical reactions, absorbed light acts as an initiator. Sunscreens contain various components that reflect, scatter or absorb UV light.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Absorption_in_Chemistry\"><\/span>Absorption in Chemistry<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">As with adsorption, a distinction is made in chemistry between chemical and physical absorption. In physical absorption, for example, water is absorbed in a sponge or carbon dioxide in hexane, without forming chemical bonds. In chemical absorption, the dissolution of the absorbate in the solvent occurs through chemical reactions. Examples of chemical absorption are the reactions of ammonia in water to form ammonium hydroxide, and hydrogen chloride with water to form hydrochloric acid.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Adsorption_and_Absorption_in_Purification_Processes\"><\/span>Adsorption and Absorption in Purification Processes<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">In water treatment, activated carbon <a href=\"https:\/\/www.rct-online.de\/en\/filtration\">filters<\/a> remove dyes and adsorbable halogenated hydrocarbons (abbreviated AOX, where X stands for a halogen) through adsorption. Enrichment of water with atmospheric oxygen, chlorine or ozone occurs through absorption.<\/p>\n<p style=\"text-align: justify;\">Both processes are also used in flue gas desulfurization. In regenerative flue gas desulfurization, sulfur oxides adsorb onto activated coke. The flue gas passes upward through the adsorber, while the activated coke flows downward in a countercurrent direction. The loaded activated coke is subsequently regenerated in a thermal process. The sulfur dioxide released in this process can be used for sulfuric acid production.<\/p>\n<figure id=\"attachment_9471\" aria-describedby=\"caption-attachment-9471\" style=\"width: 450px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-9471 size-full\" title=\"Activated carbon is particularly well-suited as an adsorbent due to its high porosity and large surface area\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/aktivkohle-als-adsorbens.jpg\" alt=\"Activated carbon is particularly well-suited as an adsorbent due to its high porosity and large surface area\" width=\"450\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/aktivkohle-als-adsorbens.jpg 450w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/aktivkohle-als-adsorbens-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption id=\"caption-attachment-9471\" class=\"wp-caption-text\"><center>Activated carbon is particularly well-suited as an adsorbent due to its high porosity and large surface area<\/center><\/figcaption><\/figure>\n<p style=\"text-align: justify;\">In non-regenerative processes, the flue gas is passed through a <a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/stirring-and-mixing\/drying-tubes-gas-sampling-bulbs-and-gas-wash-bottle\">gas wash bottle<\/a> or absorber containing calcium carbonate and calcium oxide, usually in countercurrent flow. The sulfur oxides form calcium sulfite with the calcium ions, which is oxidized to calcium sulfate by adding oxygen. The difference between adsorption and absorption in flue gas desulfurization is that adsorbed sulfur oxides are recycled, while gypsum is produced as a waste product.<\/p>\n<p style=\"text-align: justify;\">In the purification of raw biogas, hydrogen sulfide is removed by adsorption onto activated carbon or iron-containing filter material. In pressure water washing, the raw biogas is cleaned in an absorber under pressure in water, whereby carbon dioxide and other interfering gases dissolve in the water.<\/p>\n<p style=\"text-align: justify;\">In semiconductor technology, corrosive and toxic gases such as trichlorosilane, hydrogen bromide, boron trichloride and volatile organic compounds are produced. The exhaust gases can be cleaned using dry bed absorption or adsorption, which contain activated carbon or specially developed granules.<\/p>\n<p style=\"text-align: justify;\">In chemistry, adsorption chromatography has established itself as a valuable method for the separation, purification and analysis of mixtures.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Adsorption_as_a_Drying_Process\"><\/span>Adsorption as a Drying Process<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">In industry, desiccants such as silica gel, bentonite, or molecular sieves are used to protect products from moisture by adsorbing water molecules onto their surfaces.<\/p>\n<p><a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/laboratory-containers\/test-tube-racks-and-desiccators\/29875\/desiccator-made-of-pp\/pc\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-9479 size-medium\" title=\"Desiccator made of PP\/PC\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/exsikkator-aus-pp-pc-300x300.jpg\" alt=\"Desiccator made of PP\/PC\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/exsikkator-aus-pp-pc-300x300.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/exsikkator-aus-pp-pc-150x150.jpg 150w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/exsikkator-aus-pp-pc.jpg 500w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a> <a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/laboratory-containers\/test-tube-racks-and-desiccators\/29878\/silica-gel-desiccant-for-desiccators\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-9480 size-medium\" title=\"Silica-Gel-Desiccant for Desiccators\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/silica-gel-trocknungsmittel-fuer-exsikkatoren-300x300.jpg\" alt=\"Silica-Gel-Desiccant for Desiccators\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/silica-gel-trocknungsmittel-fuer-exsikkatoren-300x300.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/silica-gel-trocknungsmittel-fuer-exsikkatoren-150x150.jpg 150w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2025\/01\/silica-gel-trocknungsmittel-fuer-exsikkatoren.jpg 500w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Almost everyone should be familiar with small paper sachets filled with <a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/laboratory-containers\/test-tube-racks-and-desiccators\/29878\/silica-gel-desiccant-for-desiccators\">silica gel<\/a> that accompany shipments. Cat litter and <a href=\"https:\/\/www.rct-online.de\/en\/laboratory-equipment\/laboratory-containers\/test-tube-racks-and-desiccators\">desiccators<\/a> in chemistry also contain silica gel. Bentonite serves in construction for sealing, in the beverage industry for precipitating suspended particles and is a base material for many cosmetics. Molecular sieves are mainly used in chemistry for drying gases and many solvents.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Adsorption_in_Heterogeneous_Catalysis\"><\/span>Adsorption in Heterogeneous Catalysis<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">Many basic chemicals are produced through heterogeneously catalyzed processes. Examples include ammonia synthesis from hydrogen and nitrogen using iron\/aluminum oxide catalysts according to the Haber-Bosch process, sulfuric acid production from sulfur dioxide and oxygen using vanadium oxide catalysts according to the contact process, olefin polymerization using Ziegler-Natta catalysts, or nitric acid production from ammonia and oxygen using platinum\/rhodium meshes according to the Ostwald process.<\/p>\n<p style=\"text-align: justify;\">Automotive exhaust gas purification is also based on chemical adsorption. The catalyst consists of ceramic material coated with precious metals such as platinum or rhodium. Carbon monoxide and nitrogen oxides adsorb on the catalyst surface and react to form carbon dioxide and nitrogen.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Adsorption_and_Absorption_in_Refrigeration_Systems\"><\/span>Adsorption and Absorption in Refrigeration Systems<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">In conventional compression refrigeration systems, compression of the gaseous refrigerant is achieved by a compressor. In absorption refrigeration systems, a liquid solution absorbs the refrigerant. This mixture is then heated so that pressure and temperature rise. In adsorption refrigeration systems, the refrigerant attaches to a solid. The pressure and temperature increase here also occurs through heat. The acquisition costs of these two refrigeration systems are significantly higher than compression refrigeration systems, but they are more economical when waste heat from power plants, waste incineration plants or biogas plants is available.<\/p>\n<p style=\"text-align: justify;\">Adsorption plays a role in many everyday situations\u2014from range hoods and cigarette filters to carbonic acid bubbles. Absorption also simplifies daily life, whether in sponges and diapers, sweetening coffee and tea, or enhancing flavor through salt.<\/p>\n<pre><strong>Image sources: \r\n<\/strong>Title image | \u00a9 artemidovna \u2013 stock.adobe.com\r\nActivated carbon | \u00a9 eaumstocker \u2013 stock.adobe.com\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>The two terms adsorption and absorption describe processes that take place at the interface between two phases. In adsorption, gases or liquids\u2014known as adsorbates\u2014adhere to the surface of a solid material called the adsorbent. In absorption, by contrast, atoms, molecules, or ions from a gas or liquid are taken up into the bulk of a 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