Sodium chloride interaction with solvated and crystalline cellulose: sodium ion affects the cellotetraose molecule and the cellulose fibril in aqueous solution

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 on the largest component of biomass, cellulose, focused on the thermodynamic and structural effect of a sodium ion on the cellotetraose molecule and the cellulose fibril. Replica exchange molecular dynamics simulations of a cellotetraose molecule 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.