Molecular simulations and critical pH studies for the interactions between 2-phosphonobutane-1,2,4-tricarboxylic acid and calcite surfaces in circular cooling water systems

The adsorption of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) on calcite surfaces ((Formula presented.)), (1 0 2), (1 0 4), (1 1 3), (2 0 2) was studied by molecular simulation. The phosphoric acid and carboxylic acid functional groups energetically interacted with the faces and preferentially occupied the carbonate ion sites by chemisorption, which is in agreement with the critical pH experiments. The strength of adsorption followed the order of ((Formula presented.)) > (1 1 3) > (1 0 2) > (2 0 2) > (1 0 4). The binding energy gradually decreased with increasing temperature. The relationship between the critical pH and the adsorbed PBTC²⁻configuration indicates that the adsorbed inhibitor configuration plays an important role in inhibitor efficiency.