Search results
Results from the WOW.Com Content Network
Chemical pulping involves dissolving lignin in order to extract the cellulose from the wood fiber. The different processes of chemical pulping include the Kraft process, which uses caustic soda and sodium sulfide and is the most common; alternatively, the use of sulfurous acid is known as the sulfite process, the neutral sulfite semichemical is treated as a third process separate from sulfite ...
The pulp produced up to this point in the process can be bleached to produce a white paper product. The chemicals used to bleach pulp have been a source of environmental concern, and recently the pulp industry has been using alternatives to chlorine, such as chlorine dioxide, oxygen, ozone and hydrogen peroxide.
All bleaching agents used to delignify chemical pulp, with the exception of sodium dithionite, break lignin down into smaller, oxygen-containing molecules. These breakdown products are generally soluble in water, especially if the pH is greater than 7 (many of the products are carboxylic acids). These materials must be removed between bleaching ...
The kraft process involves treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na 2 S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper.
It is used in topical medications for acne [19] and to bleach flour. [22] Ozone (O 3). While not properly a peroxide, its mechanism of action is similar. It is used in the manufacture of paper products, especially newsprint and white kraft paper. [23] Potassium persulfate (K 2 S 2 O 8) and other persulfate salts. It, alongside ammonium and ...
The researchers sampled 39 brands of straws made of paper, bamboo, glass, stainless steel and plastic. Of those, 27 were found to contain PFAS, though the concentrations were low.
As Food & Wine previously reported, PFAS chemicals, which number in the thousands, have been used in consumer products since the '50s. The Regulatory Council of Interstate Technology noted that ...
Stainless steels is used extensively in the pulp and paper industry [12] for two primary reasons, to avoid iron contamination of the product and their corrosion resistance to the various chemicals used in the papermaking process. [12] A wide range of stainless steels are used throughout the pulp making process.