Misel oluşumu ve deterjanlarda kritik misel konsantrasyonu belirlenmesi
Micelle formation and critical micelle concentration determination of detergents
Yazar: ÖZGE DEMİREL
Danışman: PROF. DR. HALE GÜRBÜZ
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Kimya Mühendisliği Ana Bilim Dalı / Kimya Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: Kimya Mühendisliği = Chemical Engineering

Özet:
Günümüzde deterjan kullanımının artması, deterjanların hem insan sağlığı hem ekoloji
üzerinde etkilerinin daha net görülmesine sebep olmuştur. Çamaşır, bulaşık
makinalarında, kişisel ve ev temizliğinde kullanılan deterjanların kalıntıları deri veya
solunum yoluyla bünyeye girebilmektedir. Bu kalıntıların insan sağlığı üzerindeki en
belirgin ve sık görülen etkisi deri üzerinde görülen alerjik reaksiyonlardır. Soluma ve
ya bulaşıklar üzerindeki kalıntılardan ağız yoluyla alınan deterjanlar ise solunum
yolları üzerinde yanma, tahriş gibi etkilere sebep olabilmektedir. Bunlar gibi temas
kesilince ortadan kalkabilecek zararlar dışında, deterjan kalıntılarının lenf, cilt veya
akciğer kanserleri gibi ölümcül hastalıklara da sebep olabileceği, hatta günümüzdeki
bu kanser türlerindeki artışın, temas edilen deterjanlardan kaynaklı olduğu
düşünülmektedir. Bunun dışında fazla deterjan kullanımının ekolojik etkileri de göz
ardı edilemeyecek seviyelerdedir. Denizlere atılan sentetik deterjan atıkları, aşırı
plankton üremelerine sebep olarak son zamanlarda Marmara denizinde gözlenmeye
başlanan kırmızı su (red-tide) olaylarının sebebi olduğu konusunda güçlü kanıtlar
vardır. Bu durumla Marmara denizinde son zamanlarda belirli yerlerde çok sık
karşılaşıldığı belirtilmektedir. Bunun dışında deterjanların zehirli etkileri sebebiyle,
sularda yaşayan canlı türleri ve sayısı azalmakta, besin zincirinin dengesi
bozulmaktadır.
Evlerde ve endüstride kullanılan çamaşır makinelerinin durulama sularının sınırlı
olması çamaşırlarda deterjan kalıntılarına sebep olmaktadır. Bu suların seviyesi
tasarımcı elinde olduğu için, kullanıcıların uygun miktarda deterjan kullanarak
kalıntıları en aza indirmesi, kalıntılardan gelecek zarara karşı alabileceği kişisel bir
önlemdir.
Deterjanın içeriğinde bulunan yüzey aktif maddeler, hidrofobik etkileşimler sonucu
kendi etraflarında veya ortamda bulunan diğer maddelerin etrafında toplanarak misel
denilen yapıları oluşturmaktadır. Misellerin oluşmaya başlaması temizlemenin
başladığını göstermektedir ve bu oluşumun başladığı yüzey aktif madde
konsantrasyonu kritik misel konsantrasyonu adını almaktadır.
Bu çalışmanın amacı çamaşır makineleri için kritik misel konsantrasyonunu ve
deterjanın belirli sıcaklıklarda maksimum çözünebilirliklerini hesaplayarak, gereksiz
deterjan kullanımının önüne geçerken uygun miktarda temizlenmenin sağlanmasıdır.
Bu sayede gereksiz su ve enerji kullanımının önüne geçilecek, çamaşır makinelerinin
enerji ve yıkama performansında iyileştirmeler yapılabilecektir. Ölçümler yapılırken
sıcaklık, kir tipi ve konsantrasyonu ve deterjan tipinin etkileri görülecek şekilde
deneyler planlanmıştır.
Kritik misel konsantrasyonu için absorbans ölçüm yöntemi kullanılmış, çeşitli
konsantrasyonlarda hazırlanan deterjan çözeltilerinin 223 nm'de absorbans değerleri 
alınarak grafik çizdirilmiş, eğimin değiştiği nokta kritik misel konsantrasyonu değerini
vermiştir. Bu ölçümler 25, 45 ve 55°C sıcaklıklarda, kir içermeyen, 10 g/L ve 20 g/L
kir içeren çözeltiler hazırlanarak yapılmıştır. Kullanılan kirler sebum ve şarap olarak
seçilmiştir.
Deterjanların maksimum çözünürlüğünü hesaplamak için ise aşırı miktarda toz
deterjan uzun süre karıştırılmış, daha sonra süzülüp kurutularak kalan katı kütlesinden
çözünürlük değeri elde edilmiştir. Sıvı deterjan için ise suya sürekli olarak deterjan
eklenmiş, ikinci bir fazın oluştuğu miktardan çözünürlük değeri belirlenmiştir.
Sonuç olarak kullanılması gereken deterjan miktarı hem sıvı hem toz deterjanlar için
6-40 g aralığında bulunmuştur.

Abstract:
Today, increase in the use of detergents has led to a clearer picture of the effects of
detergents on human health and ecology. Residuals of the detergents used in washing
machines, dishwashers or used for personal care and home care can enter human body
cutaneously or by inhaling. The most obvious and frequent effects of this residuals are
allergic reactions occur on skin. Detergents taken into body by inhaling may lead to
irritation on respiratory tract. Except these irreversible damages, it is concerned by the
authorities that, detergent residuals may lead to fatal diseases like lymphosarcomata,
skin and lung cancer. It is even thought that, being into contact with too many detergent
may lead to the increase of this diseases. Except health effects, ecological effects of
the excess detergent use can not be underestimated. There are strong evidences for the
cause of the red-tide situation which is seen in Marmara Sea in the last years is because
of the excess plancton reproduction which is caused by the synthetic detergent residues
drained to the sea. It is indicated that, this situation has been occuring for a couple of
decades frequently in some places in Marmara sea. Except this, type and quantity of
the living creatures in waters are diminishing, balance for the food chain is destroyed
because of the toxic effects of the detergents.
Limitation of the rinsing waters in household and industrial washing machines leads
to detergent residuals on laundries. Since these water amounts are decided by the
machine designer, users should use proper amounts of detergent to decrease the
residuals to a minimum level. This is a personal precaution that can be taken against
residuals. While determining this proper amount, washing performance should not be
decreased, because in that case, all the energy, water and chemicals used in that cycle
is wasted which causes ecological and economical demages.
Detergents are mixtures of a lot chemicals which is basically for cleaning and
protecting the soiled surface. For example if laundary detergents are examined,
surfactans, acid and bases, phospates, optical brighters, water softners and bleachers
can be found in their contents. The most important chemical for cleaning process is
surfactants. They are made of as combination of two parts, hydrophilic head and
hydrophobic tail. They can be divided into four groups by their electrical charges in
their hydrophilic head groups. The most common used one is anionic surfactants.
These are generally used in cleaining products and have an anionic head group. Second
group is cationic surfactans. They are not good cleaners but they are used in fabric
softners. Third group is amphotheric (zwitterionic) group which contains both anionic
and cationic electrical charges. According to washing medium conditions, they act as
anionic or cationic. Last group is non-ionic surfactants, which has no electrical charge.
They are good at cleaning oily dirts.
Washing process can be basically examined in three steps. Fisrt one is called wetting
step, which is caused by surfactants in detergents. Surfactants decreases the surface
tension of the water so water can be spread on surface better. This increases the
interaction between water/detergent and dirt. Second step is separating and keeping
the dirt suspending in washing environment. This occurs with the help of some
structures called micelles. These structures are created by surfactants contained in
detergents by gathering among each other and around other substances in the medium
because of the hydrophobic interactions. Because of the electrical charges of
surfactants, surface and outher part of the micelle is charged. Because of the electrical
repulses between the surface and micelle, dirt is separated and kept suspended. By the
help of this repulses, infinite growth of micelles is prevented. When micelles starts to
form, it is an evidence for the beginning of the cleaning and the surfactant
concentration for this is called critical micelle concentration. After this concentration,
adding surfactant to the system will not change the surface tension, it will only help
creating micelles. Last step of the washing process is discharging. Suspended soils are
discharged from medium in this step. In the end, washing process is finished and
rinsing process begin.
Purpose of this work is to determine the optimum detergent concentration for laundary
machines. To do that, critical micelle concentrations and maximum solubilities of
detergents at specific temperatures are determined. Optimum cleaning is achieved
while detergent concentration is 6-10 times of critical micelle concentration. So that
excess detergent use will be prevented while optimum amount of cleaning is achieved.
By this measurements, excess water and energy usage may be prevented so that energy
and cleaning performances of washing machines may be increased. In the end,
detergent amount drained to environment will be decreased and customers will spend
less money on detergents.
Experiments are designed to see the effects of temperature, soil type and concentration
and detergent type while measurements are conducting.
To determine critical micelle concentration, absorbance measuring method is used.
Two detergents are used, powder and liquid detergent.Detergent solutions with
different concentrations are prepared at various temperatures and their absorbance
spectrums are taken. The wavelength that gives the maximum absorbance for all
solutions is chosen to do critical micelle concentration determinations. This values is
measured as 223 nm. After some measurements it is seen that changing detergent type,
soil type, soil concentration and temperature is not affecting this value, so after a while,
absorbance values are measured at only 223 nm. Concentration-absorbance graphs
were drawn and the point where the slope changes, gives the critical micelle
concentration value for the detergent. This measurements were conducted at 25, 45
and 55°C temperatures, with the solutions that does not contain soil, contains 10 g/L
and 20 g/L soil. Used soils were sebum and wine. This parameters are based on
European Union's standart for determining the energy and performance for washing
machines. Powder detergent used in the tests is explained in this standard.
To determine the maximum solubility of the detergents, excess amunt of powder
detergent was stirred at constant temperatur for a long time which is enough to solve
every soluable chemical in it, filtered from a microfilter and 10 ml of it taken to be
dried in a stove at 100°C. Remaining soil mass gave the solubility of the detergent at 
that temparature. To determine the solubility of the liquid detergent, detergent is added
to water at constant temperature while stirring continously. The amount that second
liquid phase started to be seen is the solubility of the detergent in that temperature.
This experiments are conducted at 25, 45 and 55°C.
When the results are examined, it is seen that both powder and liquid detergents
solubility increases with increasing temperature as expected. Liquid detergent's
solubility values are higher than powder detergents'. This can be explained by
examining the contents of the detergents. Since liquid detergent contains water in it, it
is more soluable in water than powder detergent.
Critical micelle concentration values first decteases and then increases by temperature.
This can be explained by entrophy change. By temperature increases entrophy change
decreases until a spesific temperature. Increase in the entrophy chage lead to decrease
in the Gibbs free energy change which favors micellisation. After this specific
temperature, hyrdrophobic interactions are diminised and enthropy change value has
a negative sign which does not favor micellisation. This specific value is around 20-
25 °C for ionic surfactans and around 50-55 °C for non-ionic surfactants. In this work,
this value is 45°C for both liquid and powder detergents. Since detergents are mixtures
of both ionic and non-ionic surfactants, this outcome was expected.
Critical micelle concentration values of powder detergent is lower than the ones for
liquid detergent. This can be explained by their contents. Powder detergent has nearly
17% surfactant in it while liquid detergent has nearly 13%. So micelle formation for
powder detergent is easier and needs lower amounts of detergent.
Critical micelle concentration for the solutions containing sebum is decreased with
increasing dirt concentration for both detergent types. Since sebum is an oil based dirt
with hydrophobic branches, increasing sebum concentration increases hydrophobic
affects which favors micellisation. Critical micelle concentrations pattern with
temperature does not change at the sebum existence.
Critical micelle concentration for the solutions containing wine is increased with
increasing dirt concentration for both detergent types. Wine has ethyl alcohol in it and
short chained alcohols like it changes the structure of the water. By decreasing the
dielectrical constant of water, electrical repulses between surfactants are increased.
This lead to more energy need for micellisation. As a result of this, critical micelle
concentration increases by increasing wine concentration. Critical micelle
concentrations pattern with temperature does not change at the wine existence.
As a result of this work it is found that avarage detergent amount should be between
6-40 g for both liquid and powder detergent.