Variation of pH and Electrical Conductivity Values of Different Deep Eutectic Solvents with Temperature

Öz

In this study, the variation of pH and electrical conductivity values of 6 different deep eutectic solvents (choline chloride-acetic acid, choline chloride-urea, choline chloride-citric acid, choline chloride-glycerol, choline chloride-lactic acid, and glycerol-citric acid) most likely to be used in food processes with temperature (25 °C, 50 °C and 75 °C) were investigated. The molar ratio was used as 1:1 for the glycerol-citric acid combination, and the molar ratio was applied as 1:2 for other solvents. Besides, 30% water by mass was added to all solvents. As a result, it was observed that the variation of pH values with temperature changed depending on the hydrogen bond donor type, while the electrical conductivity values increased in direct proportion to the increase in temperature. It was seen that linear model compatibility was high for both values. When the relations between pH and electrical conductivity values were examined, it was seen that deep eutectic solvent combinations formed with acid-based hydrogen bond donors showed a positive correlation, while other combinations showed a negative correlation. Finally, when the activation energies are examined, the combinations using citric acid as hydrogen bond donor for pH and urea for electrical conductivity have the highest value

Anahtar Kelimeler

• Deep eutectic solvents
• pH
• Electrical conductivity
• Temperature

Farklı Derin Ötektik Çözücülerin pH ve Elektriksel İletkenlik Değerlerinin Sıcaklık ile Değişimi

Öz

Bu çalışmada, gıda proseslerinde kullanılması en muhtemel 6 farklı derin ötektik çözücünün (kolin klorür-asetik asit, kolin klorür-üre, kolin klorür-sitrik asit, kolin klorür-gliserol, kolin klorür-laktik asit ve gliserol-sitrik asit) pH ve elektriksel iletkenlik değerlerinin sıcaklık (25 °C, 50 °C ve 75 °C) ile değişimi araştırılmıştır. Gliserol-sitrik asit kombinasyonu için molar oran 1:1 olarak kullanılmış olup, diğer çözücüler için molar oran 1:2 olarak uygulanmıştır. Ayrıca tüm çözücülere kütlece %30 oranında su eklenmiştir. Sonuç olarak, pH değerlerinin sıcaklık ile değişiminin hidrojen bağı donörü türüne bağlı olarak değiştiği, elektriksel iletkenlik değerlerinin ise sıcaklık artışı ile doğru orantılı olarak arttığı görülmüştür. Her iki değer için de doğrusal model uyumluluğunun yüksek olduğu görülmüştür. pH ve elektriksel iletkenlik değerlerinin de birbirleri ile ilişkileri incelendiğinde ise asit bazlı hidrojen bağ donörleri ile oluşturulan derin ötektik çözücü kombinasyonlarının pozitif, diğer kombinasyonların ise negatif bir korelasyon gösterdiği görülmüştür. Son olarak, aktivasyon enerjileri incelendiğinde ise pH için hidrojen bağ donörü olarak sitrik asit, elektriksel iletkenlik için ise ürenin kullanıldığı kombinasyonlar en yüksek değer almıştır.

Anahtar Kelimeler

• Derin ötektik çözücüler
• pH
• Elektriksel iletkenlik
• Sıcaklık

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