Download - Evonik Industries

More documents

Recommendations

Info

Still common practice in developing countries: washing by hand. But growing prosperity is making washing machines and automatic laundry detergents more affordable United States, the activator of choice is nonanoyloxybenzolsulfonate, NOBS, which forms pernonanic acid with hydrogen peroxide. TAED and NOBS are only partially effective below 30° C because the corresponding peracids are not as reactive under these conditions. As a result, countries that have traditionally used primarily cold water to do laundry, such as the United States, Japan and a few countries in Southern Europe, tend to use hypochlorite as their bleaching agent. This is why the chlorine released as a byproduct is also associated with hygiene and cleanliness in the United States. Laundry detergent markets in flux The laundry detergent market is subject to continual change. While the environmental movement of the 1980s, for example, spurred a trend toward compact laundry detergents and concentrates, as well as a ban on phosphate-based detergents in Europe, today’s changing demographics are lowering sales figures and increasing competition in Europe’s all-purpose laundry detergent market. With the number of households of individuals and households made up of senior citizens being on the rise and the number of households with children being on the drop, a clear trend toward more synthetic fibers and delicate clothing but less stained and dirty laundry is seen. Over the past ten years, this trend has resulted in a significant shift in market shares in favor of liquid laundry detergent over conventional powdered laundry detergents. This trend appears to have stopped, however, since liquid laundry detergents are reaching their limits (see info box on liquid laundry detergents). To offset the limited cleaning power of liquid laundry detergents, detergent manufacturers have now brought an array of bleaches and stain removers onto the market. Traditional laundry habits are changing, however—not just in Europe but worldwide. Unlike Europe, the developing countries are faster-growing markets, since greater prosperity and purchasing power also means closets filled with more clothes. And more clothes means increased sales of washing machines and automatic laundry detergents. In developed countries like the United States and Japan, growing environmental awareness is increasing consumers’ willingness to buy European washing machines (front loaders), which are more energy-efficient and watersav ing than the technically and mechanically less complex Amer i - can washing machines (top load ers). At the same time, demand for low-foaming European all-purpose laundry detergents designed specifically for these machines is also on the rise. 32 elements32 evonik science newsletter
Perborate – a star fades Perborate was the bleaching component of Eu - ro pe‘s all-purpose laundry detergents for nearly 100 years, and has been gradually replaced by percarbonate only in the last decade. In countries with high humidity and dramatic temperature fluctuations, perborate is still used in laundry detergents because of its chemical stability. Uncoated and thus less stable percarbonate was historically used mainly as a stain remover for pretreatment purposes or an additive for the main wash cycle. Changes in the raw materials market and more recent eco-toxicological evaluations, however, have resulted in increased use of percarbonate as a replacement for perborate in the laundry detergents of regions with difficult climates. Because Borax is mined only in China, Turkey and the United States, the construction boom in China and the Middle East has led to a severe shortage of the raw material. Limited supply and a sharp rise in demand have pushed the price of borates so high that perborates are now significantly more expensive than percarbonate. Percarbonate – an unstable powerhouse In Europe, laundry detergent manufacturers successfully completed the gradual transition to percarbonate about ten years ago. Demanding climates, such as those in Central and South America, Africa and the Middle East, however, can quickly diminish the bleaching power of laundry detergents formulated with percarbonate. Moreover, percarbonate‘s greater sensitivity to humidity raises its risk potential, which is further exacer bated by the heightened safety requirements dur ing both transport and production. Percarbonate is less stable than perborate primarily because of its molecular and crystalline structures. Characteristic for both is that they release hydrogen peroxide very easily in contact with water or humidity. Unlike percarbonates, perborates are true peroxygen compounds, in which the oxygen is bound to the boron atom in the presence of a peroxo group. The boron and oxygen atoms in these compounds form a six-membered ring system with highly stable energy. Percarbonate, on the other hand, is an addition compound. The hydrogen peroxide molecules in the crystal lattice are bound relatively loosely by hydrogen bridges, similar to crystal water molecules. In the presence of atmospheric humidity, water molecules from the air can diffuse into the crystals and force the hydrogen peroxide molecules out of their positions in the crys- elements32 evonik science newsletter c o A t i n G & B o n D i n G t e c H n o l o G i e S Liquid laundry detergent liquid laundry detergents contain—besides lots of water— surfactants and organic solvents but no bleaching agent. As the consumer test foundation Stiftung warentest so impressively confirms time and again, their cleaning efficiency is poor. this is why laundry detergent manufacturers advise consumers to use bleaching salts or bleach boosters in addition to liquid detergents—additives that are quite expensive but contain the same percarbonate and activator found in every allpurpose laundry detergent. liquid laundry detergents do contain optical brightening agents as whiteners— Uvactive organic substances or titanium dioxide—that lay on the fibers and thereby generate a certain whitening effect. But they do not kill germs on laundry. on the contrary: detergent residues collect on the plastic parts of the washing machine‘s interior, such as the detergent compartment, the plastic hose or the rubber seals, and provide a breeding ground for bacteria and fungi. A „biofilm“ forms, and in the worst case scenario, these bacteria and fungi can migrate to the laundry then easily degrades to water and oxygen under increased heat. The water and the increased temperature, in turn, accelerate the degradation process until the percarbonate is completely converted (autocatalytic degradation process). <strong>Evonik</strong> tames percarbonate There are essentially two processes available for the production of percarbonate: the crystalliza tion process and the granulation process. Pro duced by the classical wet process, in which sodium carbonate solution is mixed with hydrogen peroxide and cooled, percarbonate has open-pored crystals with a large surface area that is hard to coat. In the 1990s, <strong>Evonik</strong> developed a spray granulation process for creating sodium percarbonate crystals as round particles with a small, smooth surface. In a second process step, the coating step, this surface is covered in an extremely dense, homogeneous coating made of inorganic salts such as sodium sulfate. This coat ing acts as a diffusion barrier and prevents water molecules on the outside from diffusing inside, and hydrogen peroxide molecules on the inside from diffusing outside. tal lattice. The hydrogen peroxide that is released >>> 33
Page 1 and 2: elements32 S c i e n c e n e w S l
Page 3 and 4: +++ Evonik Industries to expand its
Page 5 and 6: +++ Catalysis: Evonik expands its p
Page 7 and 8: In October 2008, Evonik established
Page 9 and 10: Fiber-reinforced composites reduce
Page 11 and 12: The energy of the future has many s
Page 13 and 14: Success project needed a business p
Page 15 and 16: The Projects Barrier films for flex
Page 17 and 18: +++ nano+art competition - day and
Page 19 and 20: elements32 evonik science newslette
Page 21 and 22: grippers can easily adapt to object
Page 23 and 24: this transition from prototype prod
Page 25 and 26: University FH Aachen University of
Page 27 and 28: Hot stamping involves a process in
Page 29 and 30: Markets elements32 evonik science n
Page 31: sive advanced all-purpose laundry d
Page 35 and 36: Big bags of sodium percarbonate rea

Download - Evonik Industries

Create successful ePaper yourself

Delete template?

Save as template?