Effect of amide group on the flotation performance of lauric acid

Abstract

To investigate the effect of amide group at the α-C position of lauric acid on quartz flotation, a novel surfactant 2-(carbamoylamino) lauric acid (2-CLA) was synthesized and used as the flotation collector. The 2-CLA was characterized by element analysis, 1H NMR, and FT-IR. Quartz flotation tests showed that the 2-CLA was an anionic collector and flotation recovery was above 98% when the slurry temperature was as low as 10 °C. Zeta potential analysis combined with solution chemistry calculations and contact angle measurements indicated that electrostatic adsorption didn’t occur between collector 2-CLA and activated quartz. Computational simulation based on DFT showed that the adsorption probability of the main species in the pulp on quartz surface was in the order of Ca2+ > Ca(OH)+ > OH− > H2O > 2-CLA−, namely, activator was preferentially adsorbed. Also, it revealed that the strong chemisorption occurred between collector 2-CLA and activated quartz because 3s and 3d orbitals of the Ca2+ gained electrons from 2p orbital of the O atoms in 2-CLA. The CONH2 group containing special O and N atoms could strengthen the chemical bonding adsorption and hydrogen bonding synergy, which lead to the excellent flotation performance of collector 2-CLA even at 10 °C.