Application of agro-waste derived materials as heterogeneous base catalysts for biodiesel synthesis

Abstract

Agro-wastes are the post-harvest products or agricultural residues generated through various agricultural activities which have diverse scopes for various applications. Reutilization of agro-waste is an environmentally safe and cost-effective process of waste management. Proper and optimal utilization of these waste by-products is one of the major challenges for the human society nowadays. The recent trend around the globe is to transform waste into different products useful for various applications. Agro-waste derived ashes have recently been extensively studied as the heterogeneous base catalysts in biodiesel synthesis which is attracting increasing attention worldwide. Agro-waste derived catalysts are easily available, simple to prepare, easy to handle, biodegradable, non-toxic, more environmentally benign, and more cost-effective. In this study, an attempt has been made to review the utilization of agro-waste derived ashes as heterogeneous catalysts and metal loaded ash catalysts in synthesis of biodiesel through transesterification reaction of various oil feedstocks. Several parameters like the calcination temperature, catalyst amount, ratio of methanol to oil, reaction times, and temperatures which affect the transesterification reaction were also briefly discussed herein. The agro-waste derived heterogeneous base catalysts are highly active for catalysing transesterification of oil to biodiesel with a shorter reaction time and higher conversion up to 100% as compared to commercial catalysts and other catalysts derived from other renewable biomasses such as egg shells, fish scales, and bones. Further, the performance of agro-waste derived heterogeneous base catalysts is better and more efficient than that of the metal source loaded ash catalysts. The high activities of these catalysts are due to the higher potassium content which is accrediting their high basicity. Moreover, efficient utilization of waste materials will help to reduce global warming and enhance the clean and clear environment in the society.