Malaysian Journal of Analytical Sciences Vol 23 No 1 (2019): 124 - 130

DOI: 10.17576/mjas-2019-2301-15

 

 

 

DEHYDRATING ETHANOL USING A TERNARY SOLUTE AND EXTRACTIVE BATCH DISTILLATION

 

(Pengeringan Etanol Menggunakan Zat Larut Ternari dan Penyulingan Kelompok Hasil Ekstrak)

 

Tjukup Marnoto¹, I Gusti Suinarcana Budiaman¹, Chintya Rizki Hapsari¹, Risqi Angga Y. Prakosa¹, Khuzaimah Arifin²*

 

¹Chemical Engineering Department, Industrial Engineering Faculty

Universitas Pembangunan Nasional “Veteran” Yogyakarta, Indonesia 55283

²Fuel Cell Institute,

 Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

 

*Corresponding author:  khuzaim@ukm.edu.my

 

 

Received: 13 April 2017; Accepted: 17 April 2018

 

 

Abstract

Anhydrous bioethanol is a material used in many applications including biofuel.  Commonly, bioethanol is produced through sugar fermentation which results in a low concentration of ethanol. For utilization as biofuel, the lowest ethanol concentration should be 99.5%. Distillation is common technique to dry a mixture solution, however, the mixture of bioethanol and water is forming an azeotrope that limit the concentration of 96% ethanol. This paper discusses ethanol dehydration through extractive batch distillation by the addition of a ternary solute sodium hydroxide, citric acid, sulfuric acid, glycerol or ethylene glycol to ethanol. The initial concentration of ethanol used was 86% v/v, and the amount of ternary solute added was selected based on the colligative properties of the solution, which included a boiling point elevation (ΔT_B) that ranged from 5 to 25 °C. All the ternary solutes could break or shift the ethanol-water azeotrope. The highest concentration of ethanol was 99.91% v/v at ΔT_B = 25 °C with sulfuric acid as the ternary component. The resulted ethanol concentration exhibited a linear relationship with ΔT_B, which was also affected by the boiling point of the ternary solute. This study successfully produced anhydrous bioethanol by low cost and simple distillation process.

 

Keywords:  bioethanol, azeotrope, colligative properties, ternary solute

 

Abstrak

Bioetanol anhidrat adalah bahan yang diperlukan dalam pelbagai aplikasi termasuk biofuel. Biasanya, bioetanol dihasilkan melalui penapaian gula, yang menghasilkan kepekatan etanol yang rendah. Supaya boleh digunakan dalam aplikasi biofuel, diperlukan kepekatan etanol sekurang-kurangnya 99.5%. Distilasi adalah kaedah yang umum digunakan untuk mengeringkan larutan, namun campuran bioetanol dan air membentuk azeotrop yang membatasi kepekatan 96% etanol. Kajian ini membincangkan pengeringan etanol dengan penambahan zat larut ternari: natrium hidroksida, asid sitrik, asid sulfurik, gliserol atau etilena glikol. Kepekatan awal etanol yang digunakan adalah 86% v/v. Jumlah zat larut yang ditambahkan dipilih berdasarkan sifat koligatif pelarut, termasuk ketinggian titik didih (ΔT_B) yang berkisar antara 5 hingga 25 °C. Semua bahan terner didapati boleh memecahkan atau mengalihkan azeotrop air etanol; kepekatan tertinggi etanol yang diperoleh ialah 99.91% pada ΔT_B = 25 °C dengan asid sulfurik sebagai komponen ternari. Kepekatan etanol yang dihasilkan memperlihatkan hubungan linear dengan ΔT_B, yang juga dipengaruhi oleh titik didih zat larut ternari. Kajian ini telah berjaya menghasilkan bioethanol kering melalui kaedah penyulingan yang murah dan sederhana.

 

Kata kunci:  bioetanol, azeotrop, sifat koligatif, zat larut ternar

 

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