Interaction characteristics between diesel and coal with different hydrophilicity: Kinetic and force effects

Energy Feature of Air Bubble Detachment from a Low-Rank Coal Surface in the Presence of a Dodecane-Oleic Acid Collector Mixture

It has been generally proved that mixed collectors can enhance the flotation of low-rank coal (LRC). However, the inhibition effect of mixed collectors on the detachment between particles and bubbles is still unclear. In this paper, the energy feature of air bubble detachment from the LRC surface in the presence of dodecane (D), oleic acid (OA), and the mixture of dodecane and oleic acid (OA-D) was studied. The effect of collectors on the LRC surface property was analyzed using contact angle measurement, X-ray photoelectron spectroscopy, and wetting heat measurement. The force and displacement during the detachment process were measured synchronously using microforce balance. The results showed that the collector treatment increased the C-C/C-H content and decreased the content of oxygen-containing groups on the LRC surface. The synergistic effect between OA and D enabled the mixed collector to exhibit higher contact angle and wetting heat. Bubble detachment from the LRC surface can be divided into two stages: bubble stretching and bubble sliding, which corresponded to activation energy and detachment work, respectively. The activation energy and detachment work decreased in the same order of OA-D > OA > D, indicating that the mixed collector OA-D increased the energy of bubble detachment from the LRC surface and enhanced the adhesion strength. The theoretical detachment work was calculated, and the calculated results were in agreement with the measured results. This research provides a new perspective on the mechanism of LRC flotation being improved by mixed collectors.

BiOI-on-SiO2 microspheres: A floating photocatalyst for degradation of diesel oil and dye wastewater

The powder-based photocatalytic material is often difficult on wide application and then loaded on a matrix for separating conveniently from the liquid. Submerged photocatalysts may not take advantage of the light energy adequately. Thus, this boundedness may reduce their utilization and potentially cause the secondary pollution on the environment. In this paper, the micron-sized silica sphere is used as a floating substrate, and the visible-light-driven photocatalytic material iodine oxygen bismuth is prepared onto the hollow silica microspheres. The composite spheres as the visible-light-driven photocatalytic material have been characterized by XPS, XRD, SEM, EDX, PL, etc. It confirmed that BiOI combined on the SiO₂ microsphere (mSiO₂) by Bi-O-Si. The photogenerated electrons of the composite have a low probability of recombination and have a narrow band energy (1.82 eV). The composite was used to photodegrade diesel-containing wastewater and rhodamine B, and the superoxide group (·O₂^-) was found to be the main degradation active factor. And by GC-MS test, it is known that the superoxide group (·O₂^-) can degrade long-chain alkanes into short chains or form branches. Detailed studies on the acute exposure experiments of Vibrio qinghaiensis sp.-Q67 and zebrafish embryos showed that the composites can effectively reduce the toxicity of BiOI and mSiO₂.