Department of Chemical Engineering, Indian Institute of Technology (Indian School of Mines) Dhanbad, Dhanbad, 826004, Jharkhand, India.
Environ Sci Pollut Res Int. 2023 Apr;30(19):55596-55614. doi: 10.1007/s11356-023-26177-0. Epub 2023 Mar 10.
Biodiesel is considered the prospective substitute for non-renewable fossil fuel-derived sources of energy. However, the high costs of feedstocks and catalysts inhibit its large-scale industrial implementation. From this perspective, the utilization of waste as the source for both catalyst synthesis and feedstock for biodiesel is a rare attempt. Waste rice husk was explored as a precursor to prepare rice husk char (RHC). Sulfonated RHC was employed as a bifunctional catalyst for the simultaneous esterification and transesterification of highly acidic waste cooking oil (WCO) to produce biodiesel. The sulfonation process coupled with ultrasonic irradiation proved to be an efficient technique to induce high acid density in the sulfonated catalyst. The prepared catalyst possessed a sulfonic density and total acid density of 4.18 and 7.58 mmol/g, respectively, and a surface area of 144 m/g. A parametric optimization was conducted for the conversion of WCO into biodiesel using the response surface methodology. An optimal biodiesel yield of 96% was obtained under the conditions of methanol to oil ratio (13:1), reaction time (50 min), catalyst loading (3.5 wt%), and ultrasonic amplitude (56%). The prepared catalyst showed higher stability up to five cycles with biodiesel yield greater than 80%.
生物柴油被认为是可再生能源替代不可再生化石燃料的有前景的选择。然而，原料和催化剂的高成本阻碍了其大规模的工业应用。从这个角度来看，利用废物作为催化剂合成和生物柴油原料的来源是一种罕见的尝试。废稻壳被探索用作制备稻壳炭（RHC）的前体。磺化的 RHC 被用作一种双功能催化剂，用于同时酯化和酯交换高酸性废食用油（WCO）以生产生物柴油。磺化过程与超声辐射相结合被证明是一种有效的技术，可以在磺化催化剂中诱导高酸度。所制备的催化剂具有 4.18 mmol/g 的磺酸密度和 7.58 mmol/g 的总酸密度，以及 144 m²/g 的表面积。使用响应面法对 WCO 转化为生物柴油进行了参数优化。在甲醇与油的比例（13:1）、反应时间（50 分钟）、催化剂负载量（3.5 重量%）和超声幅度（56%）的条件下，获得了 96%的最佳生物柴油产率。所制备的催化剂在五个循环中表现出更高的稳定性，生物柴油产率大于 80%。
