The United Nations’ Sustainable Development Goals have sparked growing interest in biosurfactants from many surfactant-loaded industries including those utilizing froth flotation for mineral separation. However, the interaction of biosurfactants with mineral surfaces is currently poorly understood. We bridge this gap by studying adsorption of a yeast-derived bola acidic sophorolipid (ASL) biosurfactant on djurleite (Cu_1.94S). The methods used include Hallimond flotation, contact angle, adsorption isotherm, zeta potential, leaching measurements, and X-ray photoelectron spectroscopy (XPS). To facilitate the interpretation of the adsorption results, we characterize the activity of ASL at the air-water interface and measure its critical micelle concentration (CMC) at different pH using static surface tension. We find ASL to be a multifunctional surfactant with an unusual, pH-sensitive interfacial behavior. At the air-water interface, ASL is most active at pH 8, while its CMC goes through minimum as low as 40 μM at pH 7. The surfactant adsorption at the djurleite-water interface makes the sulfide surface hydrophilic at acidic pH and hydrophobic at neutral and basic pH. In addition, ASL has strong affinity to copper sulfide and demonstrates metal leaching properties. Finally, ASL demonstrates detergency properties. We offer a mechanistic interpretation of these findings. Our results provide a basis for the application of acidic glycolipids in froth flotation and have implications for their application in ion separation using hydrometallurgical routes, as well as for the chemical stability of metal sulfides in environmental systems.

联合国的可持续发展目标引起了许多表面活性剂负载行业对生物表面活性剂的兴趣，这些行业包括利用泡沫浮选进行矿物分离的行业。然而，目前对生物表面活性剂与矿物表面的相互作用了解甚少。我们通过研究酵母衍生的硼酸酸性槐糖脂（ASL）生物表面活性剂在绿榴石上的吸附（Cu _1.94S）。所使用的方法包括Hallimond浮选，接触角，吸附等温线，ζ电位，浸出测量和X射线光电子能谱（XPS）。为便于解释吸附结果，我们表征了ASL在空气-水界面的活性，并使用静态表面张力在不同pH下测量了其临界胶束浓度（CMC）。我们发现ASL是一种多功能的表面活性剂，具有不寻常的，pH敏感的界面行为。在空气-水界面处，ASL在pH值为8时最活跃，而其CMC在pH值为7时最小经过40μM。表面活性剂在菱锰矿-水界面的吸附使硫化物表面在酸性pH值下具有亲水性，而在酸性pH下则具有疏水性。中性和碱性pH。此外，ASL对硫化铜具有很强的亲和力，并显示出金属浸出性能。最后，ASL展示了去污性能。我们对这些发现提供了机械的解释。我们的研究结果为酸性糖脂在泡沫浮选中的应用提供了基础，并对它们在使用湿法冶金法进行离子分离中的应用以及在环境系统中金属硫化物的化学稳定性具有影响。