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Most TCF pulp is produced in Sweden and Finland for sale in Germany, [31] all markets with a high level of environmental awareness. In 1999, TCF pulp represented 25% of the European market. [32] TCF bleaching, by removing chlorine from the process, reduces chlorinated organic compounds to background levels in pulp-mill effluent. [33]
Sodium hypochlorite is most often encountered as a pale greenish-yellow dilute solution referred to as chlorine bleach, which is a household chemical widely used (since the 18th century) as a disinfectant and bleaching agent.
Elemental chlorine free (ECF) is a technique that uses chlorine dioxide for the bleaching of wood pulp.It does not use elemental chlorine gas during the bleaching process and prevents the formation of dioxins and dioxin-like compounds, carcinogens.
A sample of fuller's earth in its raw state from Pakistan. Fuller's earth is a term for various clays used as an absorbent, filter, or bleaching agent. Products labeled fuller's earth typically consist of palygorskite (also known as attapulgite) or bentonite. [1]
This bond is easily broken, giving rise to very reactive oxygen species, which are the active agents of this type of bleach. The main products in this class are: Hydrogen peroxide (H 2 O 2). It is used, for example, to bleach wood pulp and hair or to prepare other bleaching agents like perborates, percarbonates, peracids, etc. Sodium ...
Hydrogen peroxide is by itself a strong bleaching agent and should be used only in diluted form, such as a 3% solution in water. Hypochlorite plus peroxide releases triplet oxygen, which is itself a bleaching agent, but is short-lived in water solution. Reacting large amounts of peroxide can release enough oxygen to create a fire or explosion ...
When bleaching action carries out with oxygen, it removes the chromophoric sites and makes the cloths whiter. Oxygen is a degrading bleaching agent. Its bleaching action is based on ''destroying the phenolic groups and the carbon–carbon double bonds.''. [30] The major source of chemical bleaching is Hydrogen peroxide H 2 O
A Retention agent is added to bind fillers to the paper. Fillers, such as calcium carbonate, usually have a weak surface charge. The retention agent is a polymer with high cationic, positively charged groups. An additional feature of a retention agent is to accelerate the dewatering in the wire section of the paper machine.