Sodium Chloride interaction with solvated and crystalline cellulose : sodium ion affects the tetramer and fibril in aqueous solution

TL;DR

This study investigates how aqueous sodium chloride influences cellulose structure at the molecular level, revealing sodium ion interactions that disrupt hydrogen bonding and affect cellulose's thermodynamic stability.

Contribution

It provides detailed molecular insights into sodium chloride's effects on cellulose tetramers and fibrils, a novel focus in understanding biomass processing.

Findings

Na+ forms specific contacts with cellulose molecules

Sodium ions disrupt hydrogen bonding networks in cellulose

Na+ affects the conformational states of cellulose hydroxymethyl groups

Abstract

Inorganic salts are a natural component of biomass which have a significant effect on the product yields from a variety of biomass conversion processes. Understanding their effect on biomass at the microscopic level can help discover their mechanistic role. We present a study of the effect of aqueous sodium chloride (NaCl) on the largest component of biomass, cellulose, focused on the thermodynamic and structural effect of a sodium ion on the cellulose tetramer, and fibril. Replica exchange molecular dynamics simulations of a cellulose tetramer reveal a number of preferred cellulose-Na contacts and bridging positions. Large scale MD simulations on a model cellulose fibril find that Na+ perturbs the hydroxymethyl rotational state population and consequently disrupts the "native" hydrogen bonding network.