Lewatit-immobilized lipase from Bacillus pumilus as a new catalyst for biodiesel production from tallow: Response surface optimization, fuel properties and exhaust emissions

Authors: SHABBIR, AROOSH - Government College University; MUKHTAR, HAMID - Government College University; WASEEM MUMTAZ, MUHAMMAD - University Of Gujrat; RASHID, UMER - Universiti Putra Malaysia; ABBAS, GHULAM - University Of Gujrat; Moser, Bryan; ALSALME, ALI - King Saud University; TOUQEER, TOOBA - University Of Gujrat; NGAMCHARUSSRIVICHAI, CHAWALIT - Chulalongkorn University

Submitted to: Process Safety and Environmental Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2022
Publication Date: 2/15/2022
Citation: Shabbir, A., Mukhtar, H., Waseem Mumtaz, M., Rashid, U., Abbas, G., Moser, B.R., Alsalme, A., Touqeer, T., Ngamcharussrivichai, C. 2022. Lewatit-immobilized lipase from Bacillus pumilus as a new catalyst for biodiesel production from tallow: Response surface optimization, fuel properties and exhaust emissions. Process Safety and Environmental Protection. 160:286-296. https://doi.org/10.1016/j.psep.2022.02.032.
DOI: https://doi.org/10.1016/j.psep.2022.02.032

Interpretive Summary: Disadvantages of biodiesel include utilization of edible oils for fuel production, generation of wastewater, and inability to recycle catalysts from the production process. The objective of this study was to utilize low-cost, inedible waste animal fat (tallow) to produce biodiesel using a new catalyst that can be recovered and reused. This research revealed that the biodiesel produced from tallow was acceptable as an alternative, low-cost, non-food alternative to conventional diesel fuel. This research also revealed that a new catalyst, Lewatit-immobilized lipase, has important advantages over currently used catalysts for commercial production of biodiesel, which are the ability to recover the catalyst and use it again and less wastewater generation. Overall, the properties of the resulting biodiesel were comparable to that of soybean-based biodiesel, thus indicating its acceptability as a new source of biodiesel fuel. These results will be important to biodiesel producers, distributors, and end-users (customers) because a new biodiesel fuel and a new catalyst were described that have favorable properties. This research may ultimately improve market penetration, availability, and public perception of renewable agricultural fuels such as biodiesel, thus enhancing rural economies while affording greater national independence from petroleum-based fuels.

Technical Abstract: Biodiesel is currently regarded as a sustainable and renewable alternative to depleting fossil fuels such as petro-diesel. Biodiesel production on a large scale could have a positive impact on the energy sector and the environment by lowering greenhouse gas emissions. Disadvantages of biodiesel include utilization of high-cost edible oils for production of biofuels, generation of wastewater and inability to recycle catalysts after alkaline-catalyzed methanolysis. The objectives of the current study were to utilize low-cost, inedible tallow to produce biodiesel from Lewatit-immobilized lipase produced from Bacillus pumilus and to measure the fuel properties and exhaust emissions of the resulting fatty acid methyl esters. Response surface methodology was used to optimize reaction conditions and alkaline (potassium hydroxide; KOH) catalysis was performed for comparison. A conversion of 96% was achieved by two step chemical-mediated transesterification, whereas conversion was 67% for the single step lipase-mediated method. Acid pre-treatment was needed in the case of KOH-catalyzed transesterification to reduce the acid value of tallow from 17.6 to 1.3 mg KOH/g, whereas the Lewatit-immobilized lipase was able to efficiently catalyse both transesterification of glycerides and esterification of free fatty acids. To the best of our knowledge, the lipase from B. pumilus has not yet been studied for biodiesel production from tallow. Fuel properties of the resulting optimized biodiesel were within the limits prescribed in ASTM D6751 and EN 14214. In addition, exhaust emissions studies revealed reduced CO and PM relative to petro-diesel. In both cases, reductions were greater as the percentage of biodiesel increased in blends with petro-diesel. However, NOx emissions were elevated versus petrodiesel in blends that contained 50% or more of biodiesel. This research reveals new ways for utilization of waste animal fats for biodiesel production as well as a new efficient lipase source that yields more products and provides environmental and economic security.