Total chlorine free bleaching

Totally chlorine free bleaching (TCF) technologies, 10 304-305 Totally chlorine-free (TCF) bleaching processes, 21 44... 

Why are solid, unmodified alumina, silicas, and zeolites able to be used as catalysts (77) Are lanthanide catalysts really environmentally friendly 18) What are solid acids and solid bases and how can they be used for catalysis 19) Why is catalysis a foundational pillar of green chemistry 20) What are the advantages of a totally chlorine free bleaching process (27)... 

S Origgi, V Trichet, A Castellan, and RS Davidson. The Action of Phloroglucinol in the Presence of Hydrochloric Acid on Photoaged, Totally-Chlorine-Free, Bleached Chemical Pulps. J. Photochem. Photobiol. A Chem. 103 159-162, 1997. 

G Gellerstedt, L Heuts, D Robert. Structural changes in lignin during a totally chlorine free bleaching sequence. Part II An NMR study. J Pulp Pap Sci 25 111-117, 1999. 

Both the demand for increased brightness and the technology trend to elemental chlorine-free and total chlorine-free bleached pulps has led to an increased use of chelating agents today, dominated by DTPA and EDTA. 

Continued promotion of eco-white kraftliner, based on a new process for significantly more efficient wood and fiber utilization plus totally chlorine-free bleaching. Thanks to the improved environmental profile, it has been possible to speed up the market introduction, resulting in additional revenues of several tens of millions of Swedish kronor. 

Chemical pulp bleaching has undergone significant process changes since around 1990. Until that time, nearly every chemical pulp mill that had used bleaching had incorporated elemental chlorine (Clj) into some of its processes. Because of environmental and health concerns about dioxins, U.S. pulp mills now use elemental chlorine free (ECF) and total chlorine free (TCF) bleaching technologies. The most common types of ECF and TCF are shown in Table 21.5. The difference... 

Common Chemicals Used in Elemental Chlorine Free (ECF) and Total Chlorine Free (TCF) Bleaching Processes... 

Elemental chlorine free (ECF) bleaching with low AOX or totally chlorine free (TCF) bleaching... 

TCF [Totally Chlorine-Free] A generic term for pulp-bleaching processes which do not use chlorine in any form. Oxidants and enzymes are used. See also ECF. 

Today, the pulp and paper industry operates with two main pulping processes and three bleaching processes. The latter are the chlorine bleaching process, the elementary chlorine-free (ECF) process, and the totally chlorine-free (TCF) process they are compared in Table 6.4. 

Totally chlorine-free (TCF) process. The TCF process uses hydrogen peroxide in the bleaching process. As a drawback, about 10% more wood has to be used for the... 

Nelson, P., Elemental Chlorine Free (ECF) and Totally Chlorine Free (TCF) Bleaching of Pulps, in Environmentally Friendly Technologies for the Pulp and Paper Industry, R. A. Young and M. Akhtar (Eds.), John Wiley Sons, New York, 1998. 

Since it became clear that the direct use of chlorine in the bleaching of pulp and paper leads to highly poisonous chlorinated organic species in the waste water, chlorine dioxide is used instead in the so-called ECF (Elemental Chlorine Free) process. The competing process is the TCF (Total Chlorine Free) process, which uses peroxides [11],... 

Molecular chlorine, CI2, is an ideal chemical for delignification as it is cost-efficient and has reasonable selectivity, well capable of removing 75-90% of the residual lignin in a single stage. However its undesirable effects - waste water with chlorides that is corrosive, and a tiny by-product of chlorinated organic compounds -means that molecular chlorine has been abandoned entirely in some countries and where it is still used this is often in conjunction with chlorine dioxide (D) whose environmental footprint is some 2.6 times smaller. Today, more than 75% of pulps are bleached without any molecular chlorine. These are described as elemental chlorine-free (ECF). Only c. 6% of bleached pulps are total chlorine-free (TCF),... 

In paper industry jargon, chlorine dioxide bleaching is ECF bleaching (elemental-chlorine-free) and bleaching with oxygen species TCF bleaching (totally-chlorine-free). 

Chemical pulps bleached using CI2 and CIO2 show very little light-induced yellowing because of their extremely low lignin contents. However, so-called ECF and totally chlorine-free (TCP) pulps contain somewhat more lignin, and are more sensitive to light. Research in this area is in its infancy, and only a few spectroscopic studies have appeared. 

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