Xi Zhang,Mingzhu Huangfu,Jiushuai Deng,Yu Wang,Bozeng Wu,Mingzhen Hu,Honghui Zhao,Suozhi Wu
Specularite is generally recovered by flotation, but its floatability is relatively weak. Activation is an effective method to improve the floatability of minerals. Therefore, finding an economic and effective activator to improve the recovery of specularite is an important research direction. In this study, lead nitrate as an activator was found and confirmed to improve the floatability of specularite. Its activation mechanism was further investigated by various analytical methods. The micro-flotation tests results showed that the recovery of specularite increased from 69.57% to 92.47% at a Pb 2+ concentration of 3 × 10 -5 mol/L, an approximately 23% increase, indicating that Pb 2+ could obviously activate specularite. The SEM-EDS results illustrated that the content of Pb on the specularite surface apparently increased after specularite treatment with lead nitrate, which confirmed the adsorption of Pb species on the surface of specularite. Zeta potential results showed that the zeta potential positively shifted within the pH range from 3 to 11, which was beneficial to the occurrence of electrostatic adsorption and chemisorption between negatively charged oleate species and specularite. XPS results revealed that lead species mainly adsorbed on the O atoms of Fe-O and Fe-OH at the specularite surface, and Pb atoms became new sites to interact with sodium oleate. In addition, Pb 2+ and Pb(OH) + were the predominant components that interacted with the specularite surface and formed -O-Pb and Fe-O-Pb complexes, which considerably increased the number of reactive sites on the specularite surface. After oleate components interacted with Pb-modified specularite, a denser hydrophobic layer was generated on the surface of specularite, which intensified the floatability of specularite.
We developed paper-based powder X-ray diffraction (PP-XRD) to implement phase identification and/or crystal structure determination on paper-based platforms. These aims are not possible with other paper-based detectors, such as Raman spectroscopy and mass spectrometry. PP-XRD overcomes these limitations. Here we reported the simple and low-cost in situ PP-XRD protocol for phase identifications of inorganic and organic materials. We demonstrated that sample amounts of lead nitrate on paper substrate can be reduced into 1/30 of conventional ones by using the standard glass substrate at the same signal-to-noise ratio (S/N) of the X-ray diffraction (XRD) pattern. The paper-based method was comparable in sample quantity and intensity with zero background holder method, even though single crystal Si(100) substrate as zero background holder was used for the specimen preparation of CTAB (C 19 H 42 BrN). More importantly, paper substrates helped reduce preferred orientation that was generally present in routine powder XRD. Also, combined with paper chromatography , overlap peaks were eliminated in the XRD detection patterns of lead nitrate and cobalt nitrate hexahydrate. This new PP-XRD protocol may accelerate the process to identify phase or determine the molecular structures of new materials using trace sample directly. It also includes a hyphenated technique of powder XRD with a simple paper-based microfluidic separation of chemical solutions .
危险品化学品经营许可证（带存储）