I will break this question down into two parts. First, the optical
I had a good place to start on the first part of your question, as I
had a recent chemistry lab that dealt with optical brighteners.
Basically, any cleaning product that claims to make "your whites
whiter and your colors brighter" uses a fluorescant material. Stated
from this site [ http://www.mayzo.com/OpticalBrightener.htm ],
"Optical brighteners create brilliance by absorbing UV light,
modifying the wavelength of the light and then emitting the light in a
fluorescent fashion." This property makes optical brighteners often
used in detergents, clothing, and paper products.
This project [ http://sylvain.genet.free.fr/projetindus.htm ] on
florescant whitening agents, provides a very thorough look at exactly
the topic you have described, from the physical properties of optical
brighteners [ http://sylvain.genet.free.fr/projetindus.htm#_Toc473542344
], to the chemical structure of different varieties of optical
brighteners [ http://sylvain.genet.free.fr/projetindus.htm#_Toc473542347
], to the reactions involved in the manufacture of the chemicals [
http://sylvain.genet.free.fr/projetindus.htm#_Toc473542351 ], to a
description of the various uses of optical brighteners [
http://sylvain.genet.free.fr/projetindus.htm#_Toc473542368 ], and much
I believe this website has everything you need, however, more sources
are listed below:
This page: [ http://www.cota.com.ar/productos-en.htm ] has some
information on the uses of specific optical brighteners, including
which types of products each one would be added to or used with.
One company, which manufactures the optical brightener Eastobrite [
http://www.mxsten.com/Online_Publications/ap27c/ap27c12.htm ], had
this to say about the uses of its particular optical brightener:
"Eastman Eastobrite optical brighteners are polymer additives that
increase the whiteness of synthetic textile fibers, plastics, and
recycled polymers....Eastobrite optical brighteners are normally used
in polyester staple and polyester filament. Markets where this
whiteness is important include white shirts, blouses, tablecloths,
drapes, handkerchiefs, bed sheets, medical uniforms, and any garment
that is typically white. Pastel and medium dyed shades are also
enhanced with the optical brighteners to give cleaner, brighter
The Merrimack Valley Planning Commission [
http://www.mvpc.org/services_sec/mass_bays/optical_handbook.htm ] has
this to say about optical brighteners: "The use of Optical Brightener
testing as an indicator in helping to identify: faulty septic systems,
sewage exfiltration, storm drain cross-connections, and human/animal
waste differentiation." Thus, optical brighteners can be used as a
chemical tracer in addition to making products more eye pleasing.
As for a possible disadvantage to use of optical brighteners, the
laundry alternative webpage "Are Leading Brand Laundry Detergents
Environmentally Friendly?" [
http://www.laundry-alternative.com/detergentsinfo.html ], they state
about optical brighteners "Optical brighteners do not readily
biodegrade. They are toxic to fish when washed into the general
environment and can create bacterial mutations. They can cause
allergic reaction when in contact with skin that is then exposed to
sunlight." Admittantly, they are likely a biased source since they
manufacture competing products which do not contain optical
brighteners, but I thought it relevant nonetheless.
According to another company that makes a brighener for polyester [
http://www.maxpages.com/saraf/Fluorescent_Brightening_Agent ], "SARAF
WHITE R LIQUID is Fluorescent Brightening Agent for polyester fibres.
It gives brilliant whitening effect which has good fastness to
sublimation, light and wet processing."
Applications (I assume you mean the process of applying an optical
brightener to a product) can vary depending on the particular
brightener and the product it is being added to. In the case SARAF
WHITE R LIQUID, the manufacturer can be quoted as saying "It can be
applied by high temperature exhaust or pad-thermosol method suitable
for whitening effect on texturised polyester and polyester/cotton. It
is available as nonionic fluid dispersion greenish yellow in colour.
The dispersion is miscible with water and can be diluted to any
desired concentration by adding water to it. It is recommended to
adjust the pH of the bath between 4.5 - 5.5 as whitening effect may be
reduce in extremely acidic or alkaline condition." More detailed
application instructions can be found at their website [
The project listed near the beginning of the answer has very thorough
information on the step by step process of creating optical
brighteners and including them in products such as paper [
According to the same paper, much of the mysteries of the manufacture
of optical brighteners are exactly that, [
http://sylvain.genet.free.fr/projetindus.htm#_Toc473542372 ] and I
quote "In spite of the large amount of FWA manufactured and new
technologies involved, data concerning the process of their production
are still under strong control of their owners. Nevertheless we have
tried our best to find technologies suitable in the manufacturing of
FWA. But the large amount of missing data was a very challenging but
insuperable problem. In order to achieve precise calculations physical
properties of reactants and products, kinetics data, and above all a
clear explanation of the real subject (I-e what are we suppose to
produce exactly) must be given."
Search strategy for optical brighteners:
I trust this informs you with all you needed to know about optical
brighteners. Please let me know if I left anything important out and I
will be happy to clarify my answer.
Now, on to Reverse Osmosis.
To quote this paper on "what is reverse osmosis" [
http://www.mizutec.com/images/techinfo/whatisro.pdf ], "Reverse
Osmosis (RO) is a modern process technology to purify water
for a wide range of applications, including semiconductors, food
processing, biotechnology, pharmaceuticals, power generation, seawater
desalting, and municipal drinking water. From initial experiments
conducted in the 1950's which produced a few drops per hour, the
reverse osmosis industry has today resulted in combined worldwide
production in excess of 1.7 billion gallons per day. With demand for
pure water ever-increasing, the growth of the reverse osmosis industry
poised to continue growing well into the next century."
They go on to provide a brief historical background on reverse
osmosis, explain what osmosis is, and describes how the reverse
process (reverse osmosis) works. In defining what a semi-permeable
membrane is, they pretty much describe the how reverse osmosis
functions: "Semi-permeable refers to a membrane that selectively
species to pass through it while retaining others. In actuality, many
species will pass through the membrane, but at significantly different
rates. In RO, the solvent (water) passes through the membrane at a
faster rate than the dissolved solids (salts). The net effect is that
solute-solvent separation occurs, with pure water being the product.
some cases, dewatering is desired to concentrate the salts)." If you
feel at ease with chemistry lingo, they provide a more in specific
definition of how reverse osmosis functions:
"With the tank in Figure 1a, the water moves to the salty side of the
membrane until equilibrium is achieved. Application of an external
pressure to the salt solution side equal to the osmotic pressure will
cause equilibrium (Figure 1b). Additional pressure will raise the
chemical potential of the water in the salt solution and cause a
flow to the pure water side, because it now has a lower chemical
potential. This phenomenon is called reverse osmosis. The driving
force of the reverse osmosis process is applied pressure.
The amount of energy required for osmotic separation is directly
to the salinity of the solution. Thus, more energy is required to
the same amount of water from solutions with higher concentrations of
The town of Jupiter, Florida, decided to implement a reverse osmosis
water treatment program [
] in order to preserve local freshwater supplies, by purifying less
desireable water with reverse osmosis. Therefore, one major use of
reverse osmosis is to satisfy demand for increasingly scare fresh
Whereas much reverse osmosis usage is to create fresh water, it is
sometimes the case that the dissolved solids in the water themselves
are what are valued and need to be extracted, such as with recycling.
One website I found [ http://www.krebs.com/i_indus.html ] outlined
this and many other uses and advantages to reverse osmosis. Such uses
are Salt Water Conversion, Metalworking Coolant Cleaning, and
Electronics Manufacturing, among others.
On a more personal note, my chemistry lab is equipped with reverse
osmosis water to ensure that our chemical reactions are not unduly
influenced by various chemicals that may be present in drinking water.
I imagine that this is even more important in industrial chemical
production than it is in lower division chemistry labs, and thus, this
is another important use of reverse osmosis water.
One website on "how does reverse osmosis work" [
has some good information on the speed you would expect reverse
osmosis systems to operate and the types of things you would expect
reverse osmosis to filter.
My search strategy for reverse osmosis:
I belive that this provides the kind of information you seek on
reverse osmosis and optical brighteners, as I want to satisfy your
query to the best of my ability. If you need additional information or
clarification, please request it, as I would be happy to provide it.