Sains Malaysiana 49(1)(2020): 29-41

http://dx.doi.org/10.17576/jsm-2020-4901-04

Optimization of Response Surface Methodology by D-Optimal Design for Alkaline Hydrolysis of Crude Palm Kernel Oil

(Pengoptimuman Kaedah Gerak Balas Permukaan melalui Reka Bentuk D-Optimum untuk Hidrolisis Alkali Minyak Isirong Sawit Mentah)

MURAD BAHADI^1,2, MOHAMAD FIRDAUS YUSOFF¹, JUMAT SALIMON ¹& DARFIZZI DERAWI¹*

¹Laboratory for Biolubricant, Biofuels and Bioenergy Research, Department of Chemical Sciences, Faculty of Sciences and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

²Faculty of Education, Hadhramout University, Hadhramout, Yemen

Received: 20 March 2019/Accepted: 8 October 2019

ABSTRACT

Crude palm kernel oil (CPKO) was converted into its free fatty acids (FFAs) via alkaline hydrolysis. The reaction optimization was performed using Response Surface Methodology (RSM) through D-optimal design to optimize the conducted hydrolysis parameters. The optimization parameters were varied from 1.5 to 2.5 h of reaction time, 50-70°C of reaction temperature, and ethanolic KOH concentration 1-2 M. The highest percentage of free fatty acids was 98 ± 0.7 % with a percentage fatty acid yield of 84.7 ± 0.6 % under optimal conditions, which were 2.16 h of reaction time, 1.77 M ethanolic KOH concentration, and 70°C reaction temperature. High-temperature Capillary Column Gas Chromatography (GC-FID) and Nuclear Magnetic Resonance-Fourier Transform Infrared Spectroscopy (NMR-FTIR) were employed to characterize the product. The physicochemical properties of fatty acids were also tested. The acid value, iodine value, and hydroxyl value of the fatty acids obtained were 275.4 ± 0.7 mg NaOH/g, 21.8 ± 0.2 g I₂ / 100 g, and 168.2 ± 0.1 mg KOH/g, respectively.

Keywords: Crude palm kernel oil; fatty acids; hydrolysis; response surface methodology

ABSTRAK

Minyak isirong sawit mentah (CPKO) telah ditukar kepada asid lemak bebas (FFAs) melalui hidrolisis alkali. Pengoptimuman tindak balas dijalankan dengan menggunakan kaedah gerak balas permukaan (RSM) melalui reka bentuk D-optimum untuk mengoptimumkan parameter hidrolisis yang dijalankan. Parameter pengoptimuman telah berubah daripada 1.5 hingga 2.5 jam masa tindak balas, 50-70°C suhu tindak balas dan kepekatan etanolik KOH 1-2 M. Peratusan tertinggi asid lemak bebas adalah 98 ± 0.7% dengan peratus hasil asid lemak sebanyak 84.7 ± 0.6% di bawah keadaan optimum, iaitu 2.16 jam masa tindak balas, 1.77 M kepekatan etanolik KOH dan 70°C suhu tindak balas. Kromatografi Gas Kolum Kapilari Suhu tinggi (GC-FID) dan Resonans Magnet Nuklear- Spektroskopi Transformasi Fourier Inframerah (NMR-FTIR) telah digunakan untuk mencirikan produk. Sifat fizikokimia asid lemak juga telah diuji. Nilai asid, iodin dan hidroksil asid lemak yang diperoleh adalah 275.4 ± 0.7 mg NaOH/g, 21.8 ± 0.2 g I₂ / 100 g dan 168.2 ± 0.1 mg KOH/g.

Kata kunci: Asid lemak; hidrolisis; kaedah gerak balas permukaan; minyak isirong sawit mentah

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*Corresponding author; email: darfizzi@ukm.edu.my