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24 issues per year
Current Issue: Issue 17, 2017
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Transactions of the Chinese Society of Agricultural Engineering, the 1st in Agricultural Engineering, is supervised by China Association for Science and Technology, and sponsored by Chinese Society of Agricultural Engineering. It aims to introduce the latest scientific achievements and developing trends of Agricultural Engineering and provides the academic developments abroad and domestic of the discipline. The scope covers agricultural water-soil engineering, agricultural information and electrical technology, agricultural products processing engineering. The journal is included in EI, JST, Pж(AJ), CA and CSCD.
Preparation of biodiesel from microalgae by direct transesterification under ultrasonic-assisted ionic liquid composite conditions
Transactions of the Chinese Society of Agricultural Engineering,2017,Vol 33,No. 17
Microalgae biodiesel can solve these problems of plants materials, such as shortage of arable land, impact of climate change on production and high crop prices. But the production of microalgae biodiesel traditionally involves multiple stages, including oil extraction, purification and subsequent esterification or transesterification, which cost large quantities of energy and chemicals. The extraction of microalgae oil and the grease ester exchange in the preparation of biodiesel were coupled to a single unit, which was a biodiesel preparation method with great application potential. In this paper, the biodiesel from Chlorella was prepared via in-situ ultrasonic assisted transesterification method using ionic liquids as extraction agent and catalyst. The effects of mass ratio of methanol to microalgae powder, reaction temperature, reaction time, ionic liquid type, ionic liquid dosage, ultrasonic power and frequency on the transesterification were investigated, and at the same time, this method was compared with traditional water bath heating mechanical agitation method. The results showed that ultrasonic wave and ionic liquid had synergetic effects on transesterification. Ionic liquid had the effects of catalysis, extraction and solubilization, which could eliminate the interface of methanol and oil, and also could reduce the saponification. The introduction of ultrasound enhanced the transfer process of mass transfer, which could shorten the time of the reaction of esters, decrease the reaction temperature and the dosage of ionic liquid and methanol. When the extractant was ionic liquid [BMIM][HCOO], the extraction rate of microalgae was the highest. The catalytic effect of acidic ionic liquid was significantly higher than that of alkaline ionic liquids. When the catalyst was ionic liquid [SO 3H-BMIM][HSO 4], the conversion rate of microalgae was the highest. Under the conditions of mass ratio of methanol to microalgae powder of 6:1, mass ratio of ionic liquid to microalgae powder of 4:1, ultrasonic power of 240 W, ultrasonic frequency of 28 kHz, reaction temperature of 50 °C and reaction time of 50 min, the yield of fatty aid methyl ester reached 69.6%. Preparation of biodiesel from microalgae by direct transesterification under ultrasonic assisted ionic liquid conditions does not need to extract oil from microalgae powder, thus reducing the process cost, and shortening the process, which can make oil-containing microalgae transformed into biodiesel directly by esterification.