Novel eco-friendly organic depressants with high selectivity are attracting ever-growing interests. The selective inhibition effect of pyrogallic acid (PA) on galena in chalcopyrite flotation was investigated in this study. Flotation trials showed that PA markedly depressed galena with only a small effect on chalcopyrite, which contributed to the separation of chalcopyrite and galena by flotation after adding a low dosage of PA. Surface hydrophobicity tests suggested that PA strongly adsorbed on galena but not on chalcopyrite, which attenuated the adsorption activity of collector on galena, thus rendering galena highly hydrophilic. Conversely, chalcopyrite still retained favorable floatability. These findings were corroborated by the results obtained from infrared and surface adsorption measurements. Results of time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy measurements also validated the strong adsorption of PA on galena. This behavior promoted the generation of other hydrophilic species on galena. In addition, molecular dynamic simulations demonstrated that PA tended to adsorb on galena, and water molecules accumulated on galena following PA adsorption, which would decrease the floatability of galena.
Qiyong Jiang,Meng Liu,Zhaosheng Wang,Rentang Zhang,Yuxiao Wang,Fengjun Guo,Qing Sun
Radical mediated reaction method was chosen to prepare ferulic acid grafted pectin (FA-P) to enhance the properties of the native pectin. HPLC and FTIR results presented that ferulic acid was successfully grafted onto the pectin molecule. Among them, FA-P conjugation with a mass ratio of 0.75:1 was the most effective with the highest grafting efficiency, emulsifying activity index and emulsifying stability index. Subsequently, FA-P (0.75:1) was used to emulsify resveratrol to prepare FA-P-R emulsion. Compared to the resveratrol emulsion emulsified with native pectin (P-R), FA-P-R had a lower ζ-potential and a 57.4% reduction in mean particle diameter. Scanning electron microscopy demonstrated that the particles of FA-P-R emulsion were more rounded, with flatter and smoother surfaces, suggesting the formation of a better emulsified morphology. In addition, the encapsulation efficiency, load capacity and light stability of FA-P-R increased by 31.6%, 31.5% and 28.0%, respectively, compared to P-R. The FA-P-R samples showed the best antioxidant properties among the four emulsions of FA-P-R, P-R, FA-P and pectin for the functional coatings prepared, with the highest DPPH and ABTS + radical scavenging activity. Finally, the FA-P-R functional coating for wrapping frozen limes was able to significantly inhibit the yellowing of frozen limes during freezing storage. The results highlight that the prepared FA-P-R functional coating can be used to inhibit the quality deterioration of frozen fruits and extend the freezing period.
危险品化学品经营许可证（带存储）