Synthesis of biodiesel from waste cooking oil using a pulsed high-intensity ultrasound method

ABSTRACT

Biodiesel is widely recognized as an environmentally friendly biofuel. The key to the industrial production of biodiesel is the cost of components, especially that of the feedstock. In this study, a green pulsed ultrasound-assisted synthesis method for biodiesel production is reported. The biodiesel was prepared from waste cooking oil by transesterification in the presence of KOH, a homogeneous catalyst, under pulsed high-intensity ultrasonic treatment. The effects of various experimental parameters such as catalyst type, catalyst dosage, molar ratio of oil to methanol, temperature, ultrasonic power, and ultrasonic pulse mode were investigated. The results demonstrated that KOH had high catalytic performance compared to a heterogeneous K₃PO₄ catalyst for the transesterification of waste cooking oil. The yield of biodiesel reached up to 91.5% in 120 min of reaction time under the most optimal reaction conditions. The reaction conditions included a catalyst dose of 3% KOH, oil to methanol molar ratio of 1:6, temperature of 55°C, ultrasonic intensity of 260 W, and pulse mode of 9 s on/1 s off. Kinetic studies were conducted to obtain the rate constants at various reaction temperatures. The kinetic rate constant was observed to increase with increasing temperatures, and the activation energy for the ultrasonic method was calculated to be 35.9 kJ/mol. Hence, this green method shows great potential for applications in biodiesel production.

KEYWORDS:

• Biodiesel
• homogeneous catalyst
• green
• pulse mode
• kinetics

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grant No. [21767028] and The Undergraduate Innovation Training Program National Project in 2017 under Grant No. [201710755015].

Notes on contributors

Abulikemu Abulizi

Abulikemu Abulizi, Ph. D., Professor, Research areas are Photoelectric function nanomaterials, Clean energy conversion and storage materials, Application of ultrasonic chemistry in material synthesis and photocatalysis, Pollution control and waste resource utilization.

Haifeng Bai

Haifeng Bai, Postgraduate, Key Laboratory of Coal Conversion & Chemical Engineering Process (Xinjiang Uyghur Autonomous Region), School of Chemical Engineering and Technology, Xinjiang University, Urumqi, PR China.

Nawuersihan Saierkejiang

Nawuersihan Saierkejiang, Postgraduate, affiliated to Key Laboratory of Coal Conversion & Chemical Engineering Process (Xinjiang Uyghur Autonomous Region), School of Chemical Engineering and Technology, Xinjiang University, Urumqi, PR China.

Kenji Okitsu

Kenji Okitsu, Professor, Research areas are Analysis of physicochemical properties of acoustic cavitation bubbles, Synthesis of functional nanoparticles and their application, Sono chemical degradation of pollutants in water.

Mailikezhati Maihemuti

Mailikezhati Maihemuti, Senior engineer, affiliated to Key Laboratory of Coal Conversion & Chemical Engineering Process (Xinjiang Uyghur Autonomous Region), School of Chemical Engineering and Technology, Xinjiang University, Urumqi, PR China.

Dilinuer Talifu

Dilinuer Talifu, Master, Professor, Research area is Atmospheric aerosol and Preparation of activated carbon research.