Unravelling the role of nanoparticles during bioethanol production: A review on pretreatment, hydrolysis and fermentation
Busiswa Ndaba, Haripriya Rama, Ndzondelelo Bingwa, Ashira Roopnarain
Abstract
• Role of nanoparticles during pretreatment, hydrolysis and fermentation are discussed. • Limiting factors associated with each stage are discussed. • Findings indicate extensive use of Iron oxide NPs towards bioethanol production. • Research gaps in mechanisms of action of NP at different stages were identified. Due to international legislation requiring the blend of bioethanol with gasoline, there is a growing demand for bioethanol worldwide. Renewable fuels such as bioethanol, are of great significance to circumvent the energy crisis through balancing the carbon footprint while meeting fuel energy demand. Bioethanol has unique characteristics including high octane number and contributes to less CO 2 emissions in comparison to gasoline, hence it is the ideal alternative fuel or fuel additive. This biofuel has been produced via biological and catalytic technologies whereby carbohydrate-rich biomass is utilized as feedstock. However, high operational costs with low production volume are the major limitations of these processes. Nanoparticles (NPs) have contributed significantly to bioethanol synthesis in terms of enhanced production. With increasing application of NPs for bioethanol production, due to their unique properties such as high catalytic activity, surface area to volume ratio and mechanical properties, their roles during different stages of bioethanol production needs to be explored. Therefore, this review elucidates the current factors that limit general bioethanol production followed by solutions to address these challenges through nanotechnology. These solutions require an understanding of the roles that NPs play as nanocatalysts, nanoadditives and/or nanocarriers. The key observations in the current review include the extensive use of Iron oxide NPs at different stages for enhancement of reducing sugar recovery as well as bioethanol production. Research gaps in understanding the mechanisms for each study remain a challenge. Nonetheless, the review taps into possible solutions to challenges of bioethanol production in the field of bioenergy.