Synthesis of bio-base oil from catfish fat

Master. TRAN THI HONG (Industrial University of HCMC; University of Technology, HCMC National University), Master. NGUYEN KIMTRUNG, PhD. DAO THỊ KIM THOA, Assoc. Prof. Ph.D. PHAN MINH TAN (University of Technology, HCMC National University)


This paper presents the chemical conversion of Catfish fat into bio-base oil. The raw Catfish fat is filtered preliminarily to capture the refined Catfish oil. Next, the refined Catfish oil is metabolized chemically by the epoxydation reaction and the opening reaction of oxirane ring. The result of these reactions is the Catfish ester oil. The results of the analysis the Catfish ester oil’s properties according to mineral base oil quality standards show that the Catfish ester oil can be used as a type of bio-based oil. The blending bio-lubricant from mineral oil (SN150 & SN500), bio-based oil and additives was studied. The results show that if the blending ratio (wt/wt) of bio-based oil and mineral-based oil is 25/75, it can meet the quality standards of SAE 20W40 engine lubricant. The results also indicate that the synthesis process of bio-based oil from the Catfish fat can be developed sustainably.

Keywords: Catfish fat, epoxidation, opening - oxirane ring, bio-base oil, bio-lubricant.

1. Introduction

Nowaday, the demand for lubricants in Vietnam and Asian countries increases. The waste lubricants is also problem for environment. This prompted scientists to consider for the alternative, renewable and environmentally friendly materials. Vegetable oils and animal fats is one of the source of renewable and biodegradable materials. However, they need to be treated to enhance some properties. In recent years, many studies used vegetable oils directly for bio-lubrication such as bio-lubricant was blended by soybean oil and olive oil [1]. However, the oxidative stability and its ability to work at low temperatures is not high because of the double bonded in Catfish fat structure and some of the impurities contained in it [2]. For the purpose of enhancing the features of bio-lubricant, many researchs metabolized the double bonds of Catfish fat by chemical method. 2015, Rajesh V. Sharma et al was metabolized the unsaturated composition of Canola oil by epoxydation reaction, openning epoxy ring reaction and esterification reaction. Esterified product can made a biolubricant because it has high thermal oxidation stability and high lubricity [3]

Jumat Salimon and partners spent a great deal of time researching the synthesis of bio-lubricant from vegetable oils. In the author's studies, oleic acid, linoleic acid (the major constituent in vegetable oils) was metabolized in two steps, that is epoxydation reaction and opening oxirane ring reaction. Properties such as lubricity, oxidation stability of the products improved significantly and they can meet the quality requirements of commercial lubricants [4]. Phan Hong Phuong and his colleagues converted vegetable oil into bio-base oil. The chemical process consists of two steps, that is the epoxidation of the vegetable oil and the opening of the epoxy ring with butanol [5]. In 2017, Ebtisam K. Heikal and partners synthesized biolubricant from palm oil and Jatropha oil by two esterification reactions. The ester products had high viscosity indices, high thermal stabilities and low pour point temperature and it can meet the technical requirements of commercial ISO-VG-46 lubricant [6]. So it can say clearly that, After chemical processes, properties of vegetable oils improved significantly and they can meet the quality requirements of mineral base oils. However, demand use of vegetable oils such as soybean oil, sunflower oil as cooking oil increasing. Therefore, finding other raw materials is interested. Vietnam is one of the world's leading exporter of fillet Catfish. The process of Catfisf in Viet Nam get the fillet portion, it accounts 30 % (wt) of Catfish. So 70% (wt) of fat, skin, head, bone are the by-products of Catfish processing and fats accounts for the largest share [7]. In Vietnam, only Sao Mai company produces cooking oil from Catfish fat in limited scale. So the Catfish fats is an abundant and available resources in Viet Nam. Generally, the process of synthesizing bio-base oil from Catfish fat can be developed sustainably.

2. Method

2.1. Materials           

Catfish fat (CFF) was bought from) is bought by Phuoc Thanh Agricultural Import Export Company Limited, 12F2 Truong Chinh, My Phuoc Ward, Long Xuyen City, An Giang province, Viet Nam. Mineral base oil SN150, SN500 and some additives were provided from Đai Lam Son Lubricant Company in Dong Nai province, Viet Nam. Sodium of H2O2 (30% wt), CH3COOH (99%wt) and H2SO4 (99% wt) was purchased from Chemsol company, Viet Nam.  2-propanol, assay ≥99.5% was from Merck and Chemicals and solvents in analysis the physico-chemical properties were analytical pure standard and they were procured from Merck.  The mechanical stirrer IKA RW16 basic (Germany).

2.2. Experiment

2.2.1. Refining of Catfish fat

Raw Catfish fat was pre-treated by filtration to remove sediments. The process can be described as follows: raw Catfish fat was added to the bucket, fitted with a mechanical stirrer, lightly stirred, lightly heated (30-35 oC) and fed Catfish fat through a screen filter with a 30 μm diameter filter cloth. The product obtained after pre-filtration exists in liquid form and it is called refined Catfish oil (RCFO). Some properties of RCFO are determinated to calculated the data for the epoxidized reaction of RCFO.

2.2.2. Chemical processes of refined Catfish oil

First, RCFO epoxidized reaction with peracetic acid, H2SO4 catalyst created epoxidized refined Catfish oil (ERCFO). The epoxy reaction was carried out at optimum conditions, temperture of 55 oC, molar ratio of H2O2/CH3COOH/double bond of 3/1/1 and time reaction of 3 hours. The reaction mixtures were washed several times with distilled water to remove the acid catalyst and dry to remove the water in a vacuum drying system. Products of RCFO epoxidized reaction was tested the epoxy content (ASTM D1652) to determinated the performance reaction and calculated the data for the opening reaction of ERCFO. Next, the opening reaction of ERCFO with 2-propanol, H2SO4 catalyst formed opening epoxidized refined Catfish oil (OERCFO). The opening reaction of ERCFO was carried out at optimum conditions, temperture of 90 oC, molar ratio of  epoxy/2-propanol  of 1/2 and time reaction of 5 hours. The mixtures reaction were washed by distilled water, dried by vacuum drying and anhydrous mangenium sulfate. The Products of opening reaction of ERCFO was tested the epoxy content (ASTM D1652) and the hydroxyl number (ASTM D4274) to determinated the conversion and performance of reaction. Final, the properties of OERCFO was were analyzed according to SN 500 mineral base oil quality standards. It then evaluates OERCFO's ability to use bio-based oils.

2.2.3. Blending bio-lubricant

Firstly, the engine lubricant SAE 20W-40 was blended from the mineral oils (SN150, SN500) and additives. From the 20W-40 formular, the mineral base oil (MBO) was replaced by bio-base oil (OERCFO) in ratio of OERCFO/MBO of 25/75, 50/50 and 75/25 and bio-lubricant blends was coded 25Bio, 50Bio and 75Bio respectively. Finally, the alternatives of bio-base oil for mineral base oil was evaluated base on the results of their properties analysis.

2.3. Analysis

TGA test was carried out in LINSEIS STA-PT 1600, under nitrogen, temperature in range of (25-800 oC), heating rate at 10 oC/minute in Biomass laboratory of Research Institute for Sustainable Energy, HCMC National University. Rancimat test was carried out in Rancimat 743. Temperature was set up at 110 oC with an airflow of 10 l/h. Properties of samples were testes in the Laboratory of Petroleum Products of Quality Testing Center Standard 3, Viet Nam. Biodegradability of samples were analyzed by biochemical oxygen demand test (BOD) and chemical oxygen demand test (COD). Sample of biolubricant was diluted 10 times and mineral lubricant was diluted 100 times in distillated water. The properties of materials and products were determined according to the TCVN and ASTM standard in Petroleum Laboratory of HCMC University of Technology (HCMUT), HCMC National University and Industry University HCMC (IUH).

3. Results and discussion

3.1. Refining of Catfish fat

Refined Catfish oil (RCFO) obtained from pre-filtration and it was a yellow liquid oil.  Propeties and fatty acid composition contained in RCFO (GC-ISO / CD 5509: 94) shows in table 3.1 and table 3.2 respectively.

The data in Table 3.1 and Table 3.2 shows that, unsaturated fatty acid content in RCFO is range of  (52.8 % ÷ -54.2 %). Beside it, Iod value and acid value of RCFO was 68 (gIod/100g) and 2.9 (mgKOH/g). So RCFO's oxidation stability is not high. Therefore, it is necessary to perform the chemical double bonding of RCFO to increase its oxidation stability [8]. 

3.2. Chemical processes of rifined Catfish oil

3.2.1. Epoxidation reaction

          RCFO epoxidized reaction, product is a colorless liquid and iod value of it was 4. The conversion epoxidized reaction reached at 97.21%. The products was titrated according to ASTM D1652 to determine epoxy content (E) and E reached at 10.11% (wt), the yield reached at 91.48%.

The results on epoxydation reaction of other studies were similar to those of Catfish oil epoxydation reaction. The epoxydation reaction of refined soybean oil in the research of Ju Wang and colleagues. Authors used peracid formic as epoxidizing agent. The tempreratures reaction of 50 oC and time reacrion of 6 hours was the optimum conditions of reaction [9]. The epoxidized canola reaction was studied by Chandu S. Madankar and partners.  Hydrogen peroxide was used as epoxidizing agent, Amberlite IR-120H catalys. The temperature of 65 oC and time of 7 h for optimum results [10]. Castor oil methylester was used as material, peracid acetic was used as epoxidizing agent,  ion exchange resin was used as a catalyst in the reaesrch of Venu Babu Borugadda and colleagues, temperature of 60 oC, time reaction of 10 hours, used catalyst of 15 %(wt) of Castor oil methylester, molar ratio of H2O2/CH3COOH/double bond of 1.5/0.5/1 were the optimum conditions of this reaction [11]. Phan Hong Phuong and colleagues was studied the synthesis of bio-base oil from soybean oil and sunflower oil through epoxidation reaction and openning reaction of oxirane ring. The optimum condition of the epoxidation reaction was the temperature of 60 °C, molar ratio of H2O2 / CH3COOH / = of 3/1/1 and time of 7 hours [5].

3.2.2. Oxirane ring opening reaction

The OERCFO product was determined epoxy content (E) according to ASTM D1652 and E is 1.2% (wt), so the conversion of CFO opening reaction reached at 88.13%. The products was titrated according to ASTM D4274 to determine hydroxyl number (H) and H reached at 121.24, the yield reached at 91.92%.

The results of this study are consistent with the results of other studies. The results of study of Zuleica Lozada et al on the synthesis of soybean polyol compounds by epoxy ring-opening reaction with ethylene glycol and methanol. High-performance reaction at 150°C and time is in the range of (4 ÷ 11) hours [12]. 2015, Jing Zhang et al, synthesized polyol compound from opening reaction oxirane of soybean oil with castor oil-based fatty diol. The influence of factors on the reaction performance includes the reaction rate, reaction time and reaction temperature was similar to the effect of the parameters on the opening reaction of oxirane ring of refined Catfish oil in this study [13].

3.3. Blending bio-lubricant

3.3.1. Determination of properties of refined Catfish oil (RCFO), opening epoxidized refined Catfish oil (OERCFO) and mineral base oil (SN500)

The physicochemical properties of RCFO, OERCFO and SN10,
The physicochemical properties of RCFO, OERCFO and SN10, SN 500

The data in Table 3.3 indicates that, OECFO can be used as a bio-base oil because most of its properties can meet the quality requirements of mineral oil base (SN150, SN500). The pour point of OECFO is higher than that of mineral base oil but this is not worrisome because the average temperature in winter Vietnam and Asian  countries is over 10 oC. In addition, in the blending of OECFO's bio-lubricant, an amount of freezing point additive can be added to improve the performance of the low temperature of the bio-lubricant. SO it can say that, using OECFO as biological base oil is entirely possible. The characteristics of base oil of OECFO bio-base oil were similar to those of other bio-base oils. The kinematic viscosity viscosity (at 40oC,  100oC), viscosity index, flash point, density of the synthetic ester from the original oleic acid and original linoleic acid, product of opening reaction of epoxide linoleic acid with oleic acid and synthetic ester of original canola oil were equal to those of bio-base oil in this research [4].

3.3.2. Blending bio-lubricant

The 20W-40 engine lubricant formular can be described in table 3.4 [14]. Bio-lubricants were blended base on the formular of 20W-40 engine lubricant, the bio-lubricant blends are prepared with the replacing mineral base oil (SN150, SN500) as bio-base oil (OERCFO). The properties of bio-lubricant blends and the 20W-40 engine lubricant showed in tables 3.5 and figure 3.1

The formular of 20W-40 engine lubricant

The physicochemical properties of 20W-40 engine lubricant and bio-lubricant blends

The data in Table 3.5 shows that, bio-lubricant blends can meet the required quality of 20W40 mineral lubricant. Bio-lubricant samples have a higher lubricity and lower foaming ability than that of mineral lubricants 20W40. TBN values are reduced from 25Bio sample to 75Bio sample and lower than that of mineral lubricant 20W40 and the difference between 25Bio and 20W40 models is negligible. The difference of TBN of samples can be explained by the amount of acid contained in the OECFO. Thus, TBN of blend of bio-lubricant is decreased as increasing amount of OECFO in blending bio-lubricant [15]. TGA results on the thermal oxidation stability of the samples also tended to be similar to the results of the TB analysis. The stable temperature and decomposition temperatures of 25Bio, 50Bio, 75Bio at 5 %wt, 50 %wt, 95 %wt and 99 %wt are lower than those of 20W40. This may be explained by the presence of oxygen atoms in the OECFO structure, it cause the oxidation of bio-lubricant. However, these temperature values for the 25Bio sample are approximately equal to the 20W40 sample

From the above analysis and reasoning, the 25Bio blend was chosen as a bio-lubricant formulation from mineral oil, bio-base oil and additives. When comparing with orther biolubricants, the difference of the properties of  them is not so much. The onset temperature, flash point and viscosity index of polyesters bio-lubricant from original linoleic acid was 215 oC, 264 oC and 192 respectively [16]. Viscosity index of canola biolubricant was 184.84 and TGA thermogram of it was similar to that of bio-lubricant in this study [17].

The curves TGA of bio-lubricant blends and mineral lubricant (20W40)4. Inclusion

Refined Catfish oil was metabolized by epoxidation reactions and opening reaction of oxirane ring of Refined Catfish oil. Properties such as kinematic viscosity (40 oC, 100 oC), viscosity index and flash point were improved significantly, 250.8 cst, 31.15 cst, 165.9 and 254 oC. So product of opening reaction of oxirane ring of Refined Catfish oil can be used as bio-base oil. Bio-lubricants were blended in ratio (wt/wt) of bio-base oil/mineral base oil of 25/75, 50/50 and 75/25.   The analysis results show that, bio-lubricant blends of 25/75 meets the quality standards of 20W40 engine lubricant. It can say that, the process of synthesis of bio-base oil from Catfish fat is sustainable


The authors wish to thank the Faculty of Chemical Engineering, Industrial University of HCMC for their support and their financial support.  The authors also wish to thank the Unit Petroleum Engineering, Faculty of Chemical Engineering, University of Technology, HCMC National University (HCMUT) and Biomass laboratory of Research Institiute for Sustainable Energy, HCMC National University for their support.


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 ThS. Trần Thị Hồng

 Trường Đại học Công nghiệp Thành phố Hồ Chí Minh và Trường Đại học Kỹ thuật, Đại học Quốc gia Thành phố Hồ Chí Minh

TS. Đào Thị Kim Thoa - TS. Nguyễn Kim Trung - PGS.TS. Phan Minh Tân

Khoa Kỹ thuật Hóa học, Trường Đại học Kỹ thuật, Đại học Quốc gia Thành phố Hồ Chí Minh


Bài báo trình bày về quá trình tổng hợp dầu gốc sinh học từ mỡ cá Tra. Mỡ cá Tra thô được lọc sơ bộ thu dầu cá Tra tinh chế. Tiếp theo, dầu cá Tra tinh chế được chuyển hóa hóa học qua 2 phản ứng liên tiếp là phản ứng epoxy hóa, phản ứng mở vòng dầu epoxy và sản phẩm cuối cùng là dầu ester. Từ các kết quả phân tích các tính chất của dầu ester này cho thấy rằng, sản phẩm dầu este nhận từ quá trình chuyển hóa hóa học dầu cá Tra tinh chế hoàn toàn có thể sử dụng làm dầu gốc sinh học. Sau đó, tiến hành pha chế dầu nhờn sinh học từ dầu gốc sinh học, dầu gốc khoáng và phụ gia. Hỗn hợp pha chế dầu nhờn sinh học tại tỉ lệ (khối lượng/khối lượng) dầu gốc sinh học/dầu gốc khoáng là 25/75 có thể đáp ứng theo yêu cầu kĩ thuật của dầu nhờn động cơ 20W40. Các kết quả của nghiên cứu này cho thấy, quá trình tổng hợp dầu gốc sinh học từ mỡ cá Tra mang tính phát triển bền vững.

 Từ khóa: Mỡ cá Tra, phản ứng epoxy hóa, phản ứng mở vòng epoxy, dầu gốc sinh học, dầu nhờn sinh học.