Effect of mixed collector addition sequence on the adsorption behavior of low-rank coal surface: Experimental and molecular dynamics simulation study

The effect of addition sequence for mixed collectors comprising of dodecane(D) and n-valeric acid(A) on low rank coal flotation was explored by the following three sequences: D first and then A(D + A), A first and then D(A + D), D and A were added simultaneously(M). The total organic carbon, contact angle, zeta potential, and X-ray photoelectron spectroscopy results revealed that the coal had the highest adsorption capacity and the best hydrophobicity for the M, followed by A + D and D + A. The molecular dynamics simulation results indicated that for the M, the reagent molecules D and A worked together to facilitate the adsorption of the reagent molecules and solved some difficult-to-adsorb sites, not for the D + A and A + D. The M-type addition sequence would obtain the larger non-bonding interaction energy and more hydrogen bonds between collector molecules and the coal surface. Finally, the flotation experiments confirmed that the order of the flotation efficiency was M > A + D > D + A. (c) 2022 Elsevier B.V. All rights reserved.