The interaction between the 20 natural amino acids and the surfaces of sphalerite, pyrite, and chalcopyrite was examined in the light of density functional theory (DFT) simulations. The electronic properties of the active functional groups and the equilibrium geometries of the sorbed amino acid species were characterized as a function the 65 species resulting from their (de)protonations. Covalent bonds are predicted between the surface metallic atoms and the carboxyl groups and, though to a lesser extent, with the side and main amino groups. Chemisorption as a determining factor in the uptake of amino acid species was assessed in terms of sorption affinities for the mineral surfaces. The largest affinities result from the carboxyl groups of the deprotonated species at intermediate pH, whereas the fully protonated amino acids in acidic media predict the lowest affinities. Affinity of amino acids towards the mineral surfaces followed the trend: pyrite >> chalcopyrite > sphalerite with speciation-dependent decreasing sequence: ∼2.5 < pH < ∼9.5; pH > ∼9.5; pH < ∼2.5. By targeting the most suitable amino acid building blocks in bio-sourced collectors, either high collecting powers or superior selectivities can be aimed at depending on pH for improved separation of sulphidic minerals in flotation processes.

中文翻译：

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硫化物矿物表面上含水氨基酸物质的吸附——DFT 研究和对生物源试剂矿物浮选的见解

根据密度泛函理论 (DFT) 模拟，研究了 20 种天然氨基酸与闪锌矿、黄铁矿和黄铜矿表面之间的相互作用。活性官能团的电子特性和吸附的氨基酸种类的平衡几何形状被表征为 65 种由它们的（去）质子化产生的函数。预测表面金属原子和羧基之间的共价键，尽管在较小程度上，与侧氨基和主氨基之间存在共价键。根据对矿物表面的吸附亲和性来评估作为氨基酸种类吸收的决定因素的化学吸附。最大的亲和力来自中等 pH 值下去质子化物质的羧基，而酸性介质中完全质子化的氨基酸预测亲和力最低。氨基酸对矿物表面的亲和力遵循以下趋势：黄铁矿>>黄铜矿>闪锌矿，具有物种形成依赖性递减顺序：∼2.5 < pH < ∼9.5；pH＞～9.5；pH<～2.5。通过针对生物源捕收剂中最合适的氨基酸构建块，可以根据 pH 值实现高捕收能力或卓越的选择性，以改善浮选过程中硫化矿物的分离。