ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Liquid–liquid extractive de-sulfurization of diesel oil by using five deep eutectic solvents (DES) in 1 mm circular T and Y junction geometries

Vikas Kumar Choudhary, Bushra Khatoon, Sadhana Sachan, and M. Siraj Alam

Department of Chemical Engineering, MNNIT Allahabad, Pryagraj, India

E-mail: msalam@mnnit.ac.in

Received: 17 July 2025  Accepted: 31 December 2025

Abstract:

In the present study, the extractive de-sulphurization of diesel oil was investigated using deep eutectic solvents (DESs) in a 1 mm diameter T and Y junction microchannel. Five different DESs were synthesized by combining ethylene glycol, triethylene glycol, and propionic acid as hydrogen bond donors (HBD) in combination with choline chloride, methyl triphenyl phosphonium bromide (MTPB), and tetrabutylammonium bromide (TBAB) as hydrogen bond acceptors (HBA). The effects of flow rate and temperature variation on slug flow in both microchannels were examined. The percentage removal of sulfur content, slug length, specific interfacial area, and volumetric mass transfer coefficient were evaluated for the five synthesized DESs. Increasing the flow rate in the microchannels resulted in longer slugs and larger interfacial areas, which enhanced the mass transfer coefficient and extraction efficiency of the liquid–liquid system. However, experimental results indicated that at very high flow rates, the slugs formed were less suitable for efficient mass transfer. The highest mass transfer was achieved at a flow rate of 6 mL/min in the T-junction and 8 mL/min in the Y-junction microchannel. The extraction efficiency ranged from 28.03 to 76.42% for DES-2 at 6 mL/min in the 1 mm T-junction and from 34.26 to 73.61% for DES-1 at 8 mL/min in the 1 mm Y-junction microchannel. Liquid–liquid mass transfer between the two phases was also studied under varying ambient temperatures, as the properties of DESs depend on temperature. Under these conditions, DES-2 performed comparatively better in both microchannels, achieving an extraction efficiency of 75.31% in the T-junction and 72.31% for DES-1 in the Y-junction microchannel.

Keywords: Microchannel; De-sulfurization; Deep eutectic solvent; Slug flow; Extraction efficiency

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04642-7

Chemical Papers 80 (4) 3693–3708 (2026)