Interaction of amino acid functional group with water molecule on methane hydrate growth

Abstract

Kinetic inhibitor-amino acid exhibits a promising advantage in preventing the hydrate formation. In this work, adsorption behaviors of amino acid including glycine, serine and valine on methane hydrate surface are investigated by the density functional theory (DFT). It is found that the nitrogen/oxygen and hydrogen atoms in hydrophilic groups of amino acid prefer to attach the hydrogen and oxygen atoms of water molecules in hydrate simultaneously to achieve a more stable adsorption mode. The adsorption energy of hydrophobic groups is lower than that of hydrophilic groups. Meanwhile, molecular dynamics (MD) simulations are carried out to analyze the inhibition effect of glycine, serine and valine. It is observed that the strongest interaction appears between the hydrophilic groups of serine and methane hydrate surface. The hydrophobic group-methyl of valine weakens the interaction of amino and carboxyl groups with water molecules, whereas increases the disturbance of water molecules.