Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman Synthesis of Na + trapped bentonite/zeolite-P composite as a novel catalyst for effective production of biodiesel from palm oil; Effect of ultrasonic irradiation and mechanism Mostafa R. Abukhadra a,b, ⁎ , Sherouk M. Ibrahim a,c , Sobhy M. Yakout d,e , Mohamed E. El-Zaidy f , Ahmed A. Abdeltawab g a Materials Technologies and Their Applications Lab, Geology Department, Faculty of Science, Beni-Suef University, Beni-Suef City, Egypt b Geology Department, Faculty of Science, Beni-Suef University, Beni-Suef City, Egypt c Chemistry Department, Faculty of Science, Beni-Suef University, Beni-Suef City, Egypt d Department of Biochemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia e Department of Analytical Chemistry and Control, Hot Laboratories and Waste Management Center, Atomic Energy Authority, Cairo 13759, Egypt f Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia g Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia ARTICLE INFO Keywords: Bentonite Zeolite Heterogeneous catalyst Palm oil Biodiesel Ultrasonic ABSTRACT Bentonite/zeolite-P composite (B/ZP) was synthesized by simple alkaline hydrothermal treatment at 150 °C for 4 h and characterized by different analytical techniques. The composite was introduced as a low-cost catalyst of enhanced physiochemical properties and catalytic activity in the transesterification of palm oil into biodiesel. The catalytic activity of B/ZP catalyst was inspected by normal stirring mixing and under ultrasonic irradiation of different powers (20–60%). The best biodiesel yield by normal stirring (96.2%) was achieved at operating conditions of 210 min as conversion time, 20:1 as a methanol-to-oil molar ratio, 5 wt% as a catalyst loading, 90 °C as temperature and 900 rpm as stirring speed. The conversion reaction under the ultrasonic irradiation (power 60%) gives biodiesel yield of 98.8% after 120 min as reaction time using 5 wt% as catalyst loading, 20:1 as a methanol-to-oil ratio, and 90 °C as temperature. The ultrasonic irradiation is of positive impacts in reducing the conversion time interval, reaction temperature, catalyst loading, and methanol-to-oil molar ratio with bio- diesel yield similar to that obtained by normal stirring at its best conditions. The catalyst is of higher activities than several homogenous and heterogeneous catalysts and can be reused several times with high catalytic ac- tivity especially using an organic solvent either by normal stirring or under the ultrasonic irradiation. The physicochemical specification of the obtained biodiesel by both methods matches the requirements of STM D- 6571 and EN 14214 international standards. 1. Introduction The renewable and clean energy resource attracted the considera- tions of the responsible energy and environmental organizations as a potential solution for the future energy shortage problems and the as- sociated hazardous emissions of traditional fuels [1–4]. In the later years, biodiesel and biofuels were suggested as an effective and eco- friendly alternative for traditional fuels [6,7]. It was reported that the produced biodiesel from the transesterification of vegetable oil and animal fats is of biodegradable properties, no toxic emissions and ex- cellent diesel technical properties [8–11]. This qualifies it to be used directly in the engines or integrated into a blend with petroleum diesel [11–14]. The transesterification reaction for oil into biodiesel performed mainly in the existence of a potential catalyst either homogenous cat- alyst or heterogeneous catalyst to accelerate the process [14,15,3]. The previous literature reported that the applying of homogenous catalysts is of high catalytic activities but they suffer from non-reusability, high separation costs, high corrosion properties, and of toxic residuals [5,16]. However the heterogeneous catalysts are of lower catalytic ac- tivities than homogenous catalysts, they are environmental materials of low fabrication cost and can be reused several times with simple se- paration and recovery techniques [1,14]. The recorded low catalytic activities of heterogeneous catalysts https://doi.org/10.1016/j.enconman.2019.06.027 Received 1 April 2019; Received in revised form 31 May 2019; Accepted 14 June 2019 ⁎ Corresponding author. E-mail address: Abukhadra89@Science.bsu.edu.eg (M.R. Abukhadra). Energy Conversion and Management 196 (2019) 739–750 0196-8904/ © 2019 Elsevier Ltd. All rights reserved. T