Activated carbon adsorption
Basics
Carbon-containing materials such as wood, peat, coconut, brown coal, hard coal, etc. are used as the raw material for activated carbon. However, petroleum-containing raw materials such as plastic waste can also be processed into activated carbon.
The activation, i.e., the production of activated carbon from a raw material, is basically about selectively degrading part of the carbon under suitable conditions. As a result of this degradation, volatile substances escape, and many pores, crevices, and cracks form in the activated carbon obtained. The most diverse chemical elements and molecules can then attach to these surfaces, i.e., adsorb.
Two different production processes, the chemical activation and the gas activation, are distinguished. During the chemical activation, non–carbonated raw materials such as peat are mixed with dehydrating agents such as phosphoric acid and then activated at 400 - 600 ° C. The resulting activated carbons, which are typically coarse-pored, are widely used in industry. Due to possible residues, it is usually not used in water treatment.
In the gas activation, already-charred raw materials (charcoal, hard coal, etc.) are used, which are oxidatively activated with water vapor and carbon dioxide at 700–1000 °C. Due to the partial oxidation of the carbon, especially the non-crystalline carbon, the activated carbon gets its very porous structure and enormously large inner surface. Tar-like products that "clog" the pores before activation are expelled by activation. What remains is a largely exposed carbon skeleton with just that enormous surface area.
Application
ROWAcarbon+ is our special activated carbon for the field of aquaristics. An extruded, pelleted form of activated carbon from ROWA, made of hard coal. Activated by water vapor. Made in Germany.
The balanced pore structure with a BET surface area of 1000 m2/g is characterized by very high mechanical stability and very good hardening properties. A low abrasion is just as important to us as a low phosphate release and a high adsorption capacity, even for substances in low concentrations.
ROWAcarbon+ not only provides you with crystal clear water and removes drug residues and ozone residues; it has also been proven to protect you from nettle poisons (Tartaglione et al., 2016, An aquarium hobbyist poisoning: Identification of new palytoxins in Palythoa cf. toxica and complete detoxification of the aquarium water by activated carbon). Toxicon 121. 41–50.)
Activated carbon pre-filters in extruded (KF10 combifilter) or sintered form (KF10-S combifilter) are also frequently used in reverse osmosis systems (RO systems). This is primarily about the removal of chlorine residues from drinking water. Of course, smaller particles, organic odorants and flavors, plant protection products, drug residues, etc. are also removed from the raw water by these activated carbon pre-filters and thus relieve the downstream reverse osmosis membrane. When using a sediment prefilter (e.g., the Sediment Filter SF10), only particle filtration takes place.
Our colleagues at WEIL Wasseraufbereitung GmbH use activated carbon pre-filters for their industrial RO systems. Also applicable to larger pet stores. They use our ROWAcarbon+ in various small-house installations for drinking water treatment as well.
In drinking water RO systems with a storage tank (membrane pressure tank), an activated carbon post filter is often used to neutralize the taste of the water. In the case of drinking water systems of the latest generation, a storage container is deliberately omitted. The flow rates are so high that the water can always be tapped freshly.
Our sister company, Harbauer GmbH, uses tons of activated carbon in many rehabilitation projects. Of course, it is environmentally friendly because the activated carbon used there can often be reactivated and reused.
The fields of application for activated carbon are very diverse and are not limited to water filtration, exhaust air purification, and other areas of the chemical industry. It is also used in the food industry as a dye, E153 (biochar), and is used, for example, in fruit juices, jellies, jams, confectionery, toothpaste, and as a black wax coating for cheese. And thanks to activated carbon inserts, some sneakers are significantly less smelly.