Engelli Karıştırmalı Tanklarda Karıştırıcı Hızı Değişiminin Pickering Emülsiyonlarının Damlacık Boyut Dağılımı Üzerine Etkisi

Year 2020, Volume: 8 Issue: 1, 181 - 192, 28.01.2020

Usman Kayode Abdulrasaq İnci Ayranci

https://doi.org/10.21541/apjes.542644

Abstract

Pickering emülsiyonları, katı
parçacıklar ile stabilize edilmiş emülsiyonlardır. Sürfaktan bazlı
emülsiyonlara potansiyel bir alternatiftirler. Pickering emülsiyonunun
kararlığı, dağılmış faz damlacıklarının büyüklüğü ile ilişkilidir. Küçük
damlacıklar daha kararlıdır. Pickering emülsiyonlarının kararlığı,
emülsiyonları üretmek için kullanılan partiküllerin özelliklerine ve üretim
işleminde sağlanan karıştırmaya bağlıdır. Bu araştırma, karıştırıcı hızının
değişiminin, karıştırılmalı tankta üretilen Pickering emülsiyonlarının damlacık
boyutuna etkisini incelemektedir. Silikon yağı saf su içinde dağıtılmış ve su
içinde yağ türü emülsiyonlar oluşturmak için hidrofilik cam parçacıklarla
stabilize edilmiştir. İki farklı boyutta farklı makaslama kapasitesine sahip
iki farklı karıştırıcı kullanılmıştır: Rushton türbini ve eğimli bıçaklı
türbin. Elde edilen damlacık boyut dağılımı Malvern Mastersizer 3000® ile
belirlenmiştir. Yeterli akış sağlayabilen karıştırıcılar için, karıştırıcı
hızının arttırılmasının emülsiyonun damlacık boyutunu azalttığı görülmüştür.
Hızı azaltmanın, mevcut stabilize bir emülsiyonun damlacık boyutunu arttırdığı
görülmüştür. Emülsiyon oluşumunda bir hız histerezisi gözlenmiştir. Karıştırma
süresi analizi, damlacıkların tankın bazı bölgelerinde kalma süresinin, artan
hızla damlacık büyüklüğünün azalmasının nedeni olduğunu doğrulamıştır.

Keywords

Pickering emülsiyonu, sıvı-sıvı karıştırma, karıştırmalı tank, damlacık birleşimi, emülsifikasyon

The Effect of the Change of Impeller Speed on the Droplet Size Distribution of Pickering Emulsions in a Baffled Stirred Tank

Abstract

Pickering emulsions are
emulsions stabilized by solid particles. They are a potential alternative to
surfactant-based emulsions. The stability of a Pickering emulsion is related to
the size of the dispersed phase droplets. Smaller droplets are more
stable.  The stability of Pickering
emulsions depends on the properties of the particles used to produce the
emulsions and the agitation provided in the production process. This paper investigates
the effect of the change of impeller speed on the droplet size of Pickering
emulsions produced in a baffled stirred tank. Silicon oil was dispersed into
distilled water and stabilized with hydrophilic glass beads to form oil in
water Pickering emulsions. Two different impellers with different shearing
capacities at two different sizes were used: the Rushton turbine and the
pitched blade turbine. The resulting droplet size distribution was determined
with Malvern Mastersizer 3000®. For impellers with adequate flow, increasing
the impeller speed decreases the droplet size of the emulsion. Decreasing the
speed increases the droplet size of the emulsion. A speed hysteresis was
observed in the emulsion formation. Mixing time analysis confirmed that the
residence time of droplets in parts of the tank was the reason of the droplet
size decrease with increasing speed.

Keywords

Pickering emulsions, liquid-liquid mixing, stirred tank, droplet coalescence, emulsification

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