Reducing Free Fatty Acids in Crude Palm Oil Using Diethylene Glycol and Zinc(II) Chloride Based Deep Eutectic Solvent

Lieli Suriyanti(1), Thamrin Usman(2*), Winda Rahmalia(3)

(1) Department of Chemistry, Faculty of Mathematics and Natural Sciences, Tanjungpura University, Jl. Prof. Dr. H. Hadari Nawawi, Pontianak 78124, Indonesia
(2) Department of Chemistry, Faculty of Mathematics and Natural Sciences, Tanjungpura University, Jl. Prof. Dr. H. Hadari Nawawi, Pontianak 78124, Indonesia
(3) Department of Chemistry, Faculty of Mathematics and Natural Sciences, Tanjungpura University, Jl. Prof. Dr. H. Hadari Nawawi, Pontianak 78124, Indonesia
(*) Corresponding Author


Deep eutectic solvents (DES) were prepared by precise combinations of mol fractions of chemical compounds, resulting in a lowered melting point due to hydrogen bonding. This research aimed to elucidate the physicochemical attributes of DES and its effectiveness in mitigating free fatty acid (FFA) levels in crude palm oil (CPO). Zinc(II) chloride (ZnCl2) served as the hydrogen bond acceptor (HBA) while diethylene glycol (DEG) as the hydrogen bond donor (HBD). Characterization included freezing point, density, viscosity, conductivity, and pH determination. At a ZnCl2 mol fraction of 0.30, the resulting DES exhibited homogeneity with transparent liquid properties, featuring a freezing point below −10 °C, density of 1.42 g/mL, viscosity of 1933.40 cP, conductivity of 66.13 µS/cm, and pH 3.42. FTIR spectra confirmed hydrogen bond interactions between HBA and HBD. Applied to CPO at a 1:1 volumetric ratio (DES:CPO), with 2 h of stirring time at 50 °C, FFA content decreased from 4.11 to 0.86%. This research highlights DES as an environmentally sustainable purification agent, significantly reducing FFA levels in unrefined palm oil.


free fatty acids; CPO; diethylene glycol; deep eutectic solvent; hydrogen bond

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[1] Saputro, E.A., Rizaldi, A., Simamora, T., Erliyanti, N.K., and Yogaswara, R.R., 2022, A biodiesel production technology from used cooking oil: A review, IPTEK J. Technol. Sci., 33 (1), 59–71.

[2] Husin, S., Wijaya, C., Ghafur, A.H.S., Machmud, T.M.Z., and Mardunugraha, E., 2023, Trade policies support for palm oil downstreaming in Indonesia, JEJAK: Jurnal Ekonomi dan Kebijakan, 16 (2), 302–322.

[3] Ruswanto, A., Ramelan, A.H., Praseptiangga, D., and Partha, I.B.B., 2019, Palm oil yield potency on different level of ripening and storage time based on fruits percentage and fresh fruit bunches, IOP Conf. Ser.: Earth Environ. Sci., 443 (1), 012005.

[4] Ishola, F., Adelekan, D., Mamudu, A., Abodunrin, T., Aworinde, A., Olatunji, O., and Akinlabi, S., 2020, Biodiesel production from palm olein: A sustainable bioresource for Nigeria, Heliyon, 6 (4), e03725.

[5] Tan, B.A., Nair, A., Zakaria, M.I.S., Low, J.Y.S., Kua, S.F., Koo, K.L., Wong, Y.C., Neoh, B.K., Lim, C.M., and Appleton, D.R., 2023, Free fatty acid formation points in palm oil processing and the impact on oil quality, Agriculture, 13 (5), 957.

[6] Japir, A.A., Salimon, J., Derawi, D., Bahadi, M., Al-Shuja’a, S., and Yusop, M.R., 2017, Physicochemical characteristics of high free fatty acid crude palm oil, OCL, 24 (5), D506.

[7] Abdullah, M.H., Riyanto, O.A.W., and Wulan, D.P.I.B.S., 2021, Optimization of esterification and transesterification process for biodiesel production from used cooking oil, J. Res. Technol., 7 (2), 207–216.

[8] Tang, B., Zhang, H., and Row, K.H., 2015, Application of deep eutectic solvents in the extraction and separation of target compounds from various samples, J. Sep. Sci., 38 (6), 1053–1064.

[9] Li, L., Liu, Y., Wang, Z., Yang, L., and Liu, H., 2021, Development and applications of deep eutectic solvents derived functional materials in chromatographic separation, J. Sep. Sci., 44 (6), 1098–1121.

[10] Freitas, R.H.C.N., 2015, Zinc chloride, Rev. Virtual Quim., 7 (6), 2641–2646.

[11] Marraffa, J.M., 2014, “Diethylene glycol” in Encyclopedia of Toxicology (Third Edition), Eds. Wexler P., Academic Press, Oxford, UK, 140–142.

[12] Adhitya, A., Rahmalia, W., Syahbanu, I., Gusrizal, G., and Adhitiyawarman, A., 2023, Deep eutectic solvents (DES) based on choline chloride and mono-, di-, poly-ethylene glycol as KI/I2 electrolyte solvents on DSSC devices, Indones. J. Chem., 23 (5), 1294–1303.

[13] Rahmalia, W., Shofiyani, A., Dewi, Y.S.K., and Septiani, S., 2022, Simple green routes for metal-bixin complexes synthesis using glycerol-based deep eutectic solvent, Indones. J. Chem., 22 (6), 1759–1767.

[14] Anis, U., Milati, R., and Hidayat, C., 2022, Optimization of crude palm (Elaeis guineensis) oil bleaching using zeolite-Fe by response surface methodology, AgriTECH, 42 (1), 23–29.

[15] Mulia, K., Adam, D., Zahrina, I., and Krisanti, E.A., 2018, Green extraction of palmitic acid from oil using betaine-based natural deep eutectic solvents, Int. J. Technol., 9 (2), 335–344.

[16] American Oil Chemists’ Society, 1989, Official Methods and Recommended Practices of the American Oil Chemists’ Society, Champaign, USA, Ca 5a-40.

[17] Cox, H.E., and Pearson, D., 1962, The Chemical Analysis of Foods, Chemical Publishing Co Inc, New York, USA.

[18] American Oil Chemists’ Society, 1989, Official Methods and Recommended Practices of the American Oil Chemists’ Society, Champaign, USA, Ca 2c-25.

[19] Kivelä, H., Salomäki, M., Vainikka, P., Mäkilä, E., Poletti, F. Ruggeri, S., Terzi, F., and Lukkari, J., 2022, Effect of water on a hydrophobic deep eutectic solvent, J. Phys. Chem. B, 126 (2), 513–527.

[20] Hayyan, A., Hizaddin, H.F., Abed, K.M., Mjalli, F.S., Hashim, M.A., Abo-Hamad, A., Saleh, J., Aljohani, A.S.M., Alharbi, Y.M., Alhumaydhi, F.A., Ahmad, A.A., Yeow, A.T.H., Aldeehani, A.K., Alajmi, F.D.H., and Al Nashef, I., 2022, Encapsulated deep eutectic solvent for esterification of free fatty acid, Biomass Convers. Biorefin., 12 (9), 3725–3735.

[21] Smith, E.L., Abbott, A.P., and Ryder, K.S., 2014, Deep eutectic solvents (DESs) and their applications, Chem. Rev., 114 (21), 11060–11082.

[22] Schep, L.J., Slaughter, R.J., Temple, W.A., and Beasley, D.M.G., 2009, Diethylene glycol poisoning, Clin. Toxicol., 47 (6), 525-535.

[23] Naser, J., Mjalli, F., Jibril, B., Al-Hatmi, S., and Gano, Z., 2013, Potassium carbonate as a salt for deep eutectic solvents, Int. J. Chem. Eng. Appl., 4 (3), 114–118.

[24] Ma, W., and Row, K.H., 2021, pH-Induced deep eutectic solvents based homogeneous liquid-liquid microextraction for the extraction of two antibiotics from environmental water, Microchem. J., 160, 105642.

[25] Trivedi, M.K., Sethi, K.K., Panda, P., and Jana, S., 2017, A comprehensive physicochemical, thermal, and spectroscopic characterization of zinc(II) chloride using X-ray diffraction, particle size distribution, differential scanning calorimetry, thermogravimetric analysis/differential thermogravimetric analysis ultraviolet-visible, and Fourier transform-infrared spectroscopy, Int. J. Pharm. Invest., 7 (1), 33–40.

[26] Sethu Raman, M., Kesavan, M., Senthilkumar, K., and Ponnuswamy, V., 2015, Ultrasonic, DFT and FT-IR studies on hydrogen bonding interactions in aqueous solutions of diethylene glycol, J. Mol. Liq., 202, 115–124.

[27] Ahmed, M.K., McLeod, M.P., Nézivar, J., and Giuliani, A.W., 2010, Fourier transform infrared and near-infrared spectroscopic methods for the detection of toxic diethylene glycol (DEG) contaminant in glycerin based cough syrup, Spectroscopy, 24, 608749.

[28] Hammoudeh, A.Y., Obeidat, S.M., Abboushi, E.K., and Mahmoud, A.M., 2020, FT-IR spectroscopy for the detection of diethylene glycol (DEG) contaminant in glycerin-based pharmaceutical products and food supplements, Acta Chim. Slov., 67 (2), 530–536.

[29] Ellerbrock, R.H., and Gerke, H.H., 2021, FTIR spectral band shifts explained by OM-cation interactions, J. Plant Nutr. Soil Sci., 184 (3), 388–397.

[30] Shahbaz, K., Mjalli, F.S., Hashim, M.A., and AlNashef, I.M., 2011, Using deep eutectic solvents based on methyl triphenyl phosphunium bromide for the removal of glycerol from palm-oil-based biodiesel, Energy Fuels, 25 (6), 2671–2678.

[31] Ashaari, A., Ahmad, T., Awang, S.R., and Abd Shukor, N., 2021, A graph-based dynamic modeling for palm oil refining process, Processes, 9 (3), 523.

[32] Manurung, R., and Siregar, A.G.A., 2020, Performance of menthol based deep eutectic solvents in the extraction of carotenoids from crude palm oil, Int. J. Geomate, 19 (74), 131–137.

[33] Niawanti, H., Zullaikah, S., and Rachimoellah, M., 2017, Purification of biodiesel by choline chloride based deep eutectic solvent, AIP Conf. Proc., 1840 (1), 050006.

[34] Effensi, S., Syarif, A., and Irawan, I., 2022, Purification of raw material and biodiesel products from waste oil with deep eutectic solvent (DES), Proceedings of the 5th FIRST T1 T2 2021 International Conference (FIRST-T1-T2 2021), Atlantis Press, Amsterdam, Netherlands, 158–161.

[35] Wang, X., Lu, J., Liu, H., Jin, Q., and Wang, X., 2016, Improved deacidification of high-acid rice bran oil by enzymatic esterification with phytosterol, Process Biochem., 51 (10), 1496–1502.

[36] Putri, M., Kalsum, L., and Syarif, A., 2021, Waste cooking oil free fatty acid reduction using deep eutectic solvent as raw material of biodiesel, Indones. J. Fundam. Appl. Chem., 6 (2), 40–45.

[37] Ifa, L., Wiyani, L., Nurdjannah, N., Ghalib, A.M.T., Ramadhaniar, S., and Kusuma, H.S., 2021, Analysis of bentonite performance on the quality of refined crude palm oil`s color, free fatty acid and carotene: The effect of bentonite concentration and contact time, Heliyon, 7 (6), e07230.

[38] Ali, A.S.M., and Abdurrahman, A.M., 2013, Determination of free fatty acids in palm oil samples by non-aqueous flow injection using salicyaldehyde-2,4-dinitrophenylhydrazone as colorimetric reagent, Chem. Mater. Eng., 1 (3), 96–103.

[39] Rahayu, S., Supriyatin, S., and Fauziah, T.R., 2019, Lime (Citrus aurantifolia) peel effect on peroxide value of cooking oil, IOP Conf. Ser.: Earth Environ. Sci., 391 (1), 012045.


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