Microwave heating processing as alternative of pretreatment in second-generation biorefinery: An overview

Abstract

The development of a feasible biorefinery is in need of alternative technologies to improve lignocellulosic biomass conversion by the suitable use of energy. Microwave heating processing (MHP) is emerging as promising unconventional pretreatment of lignocellulosic materials (LCMs). MHP applied as pretreatment induces LCMs breakdown through the molecular collision caused by the dielectric polarization. Polar particles movement generates a quick heating consequently the temperatures and times of process are lower. In this way, MHP has positioned as green technology in comparison with other types of heating. Microwave technology represents an excellent option to obtain susceptible substrates to enzymatic saccharification and subsequently in the production of bioethanol and high-added compounds. However, it is still necessary to study the dielectric properties of materials, and conduct economic studies to achieve development in pilot and industrial scale. This work aims to provide an overview of recent progress and alternative configurations for combining the application of microwave technology on the pretreatment of LCMs in terms of biorefinery.

Pretreatment of Crop Residues by Application of Microwave Heating and Alkaline Solution for Biofuel Processing: A Review

“…In 1949, Spencer Percy discovered that electromagnetic frequency radiation could be used in dielectric heating via microwave for heating application in food and other process requiring the use of heat. Von Hippel in 1954 provided further elaboration based on understanding of theories on macroscopic interactions of microwave and matters explaining his theory with dissipated power, electric field intensity, and propagation constant [18]. MW heating is directly from inside the material-wave interactions, leading to heat transfer and basically has a higher energy yield in comparison with conventional oven techniques which transmit heat by conduction-convention mechanism [34].…”

“…Recently, many research works have described pretreatment as the most expensive stage in bioethanol production considering challenges faced during the conversion process [18]. Pretreatment accelerates lignocellulosic solubilization, thereby improving enzymatic reactions in the material [12,15,16].…”

“…For instance, there is growing interest in microwave heating as a pretreatment alternative to support secondgeneration lignocellulosic biorefineries. According to Aguilar-Reynosa et al [18], microwave heating process has attracted a series of experimental techniques because it satisfies green chemistry, reduction of time of processing by 10 times compared to other heating techniques, fast heat transfer, and essentially an alternative method to conventional heating [26][27][28].…”

Kinetics of Bioethanol Production from Waste Sorghum Leaves Using Saccharomyces cerevisiae BY4743

“…Several studies on the enhancement of fermentable sugar release from lignocellulosic substrates have been reported [3][4][5]. Microwave-assisted pre-treatment has received increased attention due to its lower energy demand and shorter process times [6]. Microwave radiation alters the structure of lignocellulose by emitting electromagnetic radiation, which results in the formation of thermal pockets.…”

“…Microwave radiation alters the structure of lignocellulose by emitting electromagnetic radiation, which results in the formation of thermal pockets. These pockets ultimately explode due to an increase in heat, leading to the relocation of crystalline structures within the lignocellulosic material [6]. Gabhane et al [7] studied the individual and interactive effects of acid and alkali pre-treatments using an autoclave, microwave, and ultrasonicator, and obtained a maximal reducing sugar yield of 36.84% from acid pre-treated banana waste by using microwave radiation.…”