Toward Sustainable Production of Sugar-Based Alkyl Polyglycoside Surfactant─A Comprehensive Review on Synthesis Route and Downstream Processing

This review aims to identify the challenges and opportunities in sustainable production of sugar-based alkyl polyglycoside, s-APG, by first assessing and subsequently comparing the production route and downstream processing for both the chemically and biologically catalyzed synthesis process, from the perspective of critical operating parameters, type of reactor technologies, and downstream processing strategies. From a sustainability point-view, the acidic homogeneous catalyst in chemically catalyzed s-APG production should be substituted by a practically active, stable, and recyclable heterogeneous catalyst. Alternatively, the green solvent could be used to increase the interaction between sugar and fatty alcohol, resulting in high yield s-APG without using a catalyst. To make the process employing biocatalyst more economically competitive, the free enzyme must be reused through the immobilization method, reactor intensified with membrane or other appropriate downstream processes. A less energy-intensive extraction process to replace the existing evaporative method to separate fatty alcohol from s-APG also deserves an intensive investigation.