Study of selective enhancement of surface hydrophobicity on magnesite and quartz by N, N-Dimethyloctadecylamine: Separation test, adsorption mechanism, and adsorption model

• Published in: Applied surface science 2022-05, Vol.583, p.152482, Article 152482
• Main Authors: Sun, Haoran, Yin, Wanzhong, Yao, Jin
• Format: Article
• Language: English
• Subjects: Adsorption mechanism; Adsorption model; Magnesite; NDOA; Quartz
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2022.152482

[Display omitted] •NDOA has a higher quartz selectivity and collecting ability than magnesite.•NDOA showed selectively enhancement in the hydrophobicity of quartz.•NDOA adsorption on the quartz surface via hydrogen bonding and electrostatic contact.•NDOA onto quartz could be attributed to selective interactions with the O sites of quartz. The separation of magnesite and quartz using flotation is complicated because of their hydrophilicity. In this study, N, N-Dimethyloctadecylamine (NDOA) was used as a collector for the first time to selective enhance the magnesite and quartz surfaces' hydrophobicity and efficiently separate magnesite from quartz. The micro-flotation study showed that NDOA had a selective-collection influence on quartz and that magnesite separation from quartz could be accomplished at pH 5.0 and 60 mg/L NDOA. In contact-angle tests, NDOA showed selectively enhancement in the contact angle of quartz, leading to enhanced surface hydrophobicity of the quartz, but not magnesite. As revealed by field emission scanning electron microscopy (FESEM) with an energy dispersive X-ray spectrometer (EDS) detecting, NDOA predominantly adsorbed onto quartz surface and transformed its surface from smooth to rough and oily, rather than magnesite. NDOA adsorption on the quartz surface through hydrogen bonding and electrostatic interaction was identified through FTIR spectroscopy. According to X-ray photoelectron spectroscopy (XPS), the preferential adsorption of NDOA on the surface of quartz is due to NDOA's interaction with the O sites of quartz. On the basis of these findings, a potential model for the flotation separation process was suggested.