Water-stable, strong, biodegradable lignocellulose straws replacement for plastic straws

Abstract

The mechanical properties and uncontrollable deformation of paper straws in water limit their potential to replace plastic straws. In this study, a simple and effective approach was developed for processing biomass and making water-stable, strong, biodegradable lignose cellulose straws (LCSs). Chemical pretreatment in an aqueous solution of nitric acid and hydrogen peroxide was used to activate residual lignin and increase the levels of phenolic hydroxyl (0.79 mmol/g) and carboxyl groups (0.54 mmol/g) in the biomass to enhance adhesion between fibers. A mechanical treatment was used to refine and branch the fibers, so that the fibers resembled thick trunks with thin branches. LCSs were made by rolling wet paper made from the fibers that contained thick trunk fibers, thin branched fibers and activated residual lignin. The residual lignin and thin branched fibers filled the voids between adjacent thick trunk fibers to form a dense structure. In the subsequent heat treatment process, residual lignin softened and penetrated the gaps between adjacent fibers, and acted as a polyphenol binder to enhance the mechanical strength and water resistance of the LCSs. The LCSs exhibited outstanding tensile strength (127 MPa), flexural strength (62 MPa) and durable water stability for more than 150 d. The LCSs were safe and fully biodegradable, and they are a sustainable alternative to plastic straws.