Effect of Particle Size and Hydrophobicity on Bubble-Particle Collision Detachment at the Slurry-Foam Phase Interface.

The slurry phase, foam phase, and slurry-foam phase interfaces are the typical locations for bubble-particle detachment, and significant advancements have been achieved in the detachment theory of the slurry phase and foam phase. However, the microscopic detachment mechanism of particles at the slurry-foam phase interface is still unclear. Specifically, there is still debate concerning the collision detachment mechanism of bubble-particle aggregates. Thus, this work investigated the effects of particle size and hydrophobicity on bubble-particle collision detachment. First, a tensiometer detected the detachment force between particles and bubbles. Next, using a high-speed dynamic camera, the collision detachment probability and detachment behavior of bubble-particle aggregates at the interface (solid surface) were statistically recorded and captured. Last, MATLAB software was used to analyze the trajectory and velocity of the particles and the velocity and projected area of the bubbles in the process of bubble-particle collision detachment. This allows for a deeper investigation of the mechanism underlying the detachment of particles of various sizes and hydrophobicity. It is discovered that as particle hydrophobicity increases, the probability of bubble-particle collision detachment reduces. This is because when particle hydrophobicity increases, so does the interaction force between particles and bubbles, improving the stability of the bubble-particle aggregates. Simultaneously, it is discovered that there are notable differences in the collision detachment mechanisms of various particle sizes. Due to their low gravity, the fine particles in the bubble-particle aggregate will slide down the bubble's surface when it collides with the solid surface. This differential velocity motion between the particle and the bubble plays a significant role in the fine particles' detachment. However, the gravity of the coarse particles is strong enough to squeeze the bubbles vertically, and bubble oscillation is an important reason for the detachment of the bubble-particle aggregates. The study's findings advance our understanding of the bubble-particle collision detachment mechanism and offer a theoretical direction for investigating collision detachment behavior at the real slurry-foam phase interface.

Biochemical fulvic acid derived amorphous carbon modified microcrystalline graphite as low-cost anode for potassium-ion storage.

Graphite anode has great potential toward potassium ion storage for abundant reserves, yet it suffers from the large volume expansion and slow diffusion rate. Herein, the low-cost biochemical fulvic acid-derived amorphous carbon (BFAC) is employed to modify the natural microcrystalline graphite (BFAC@MG) by a simple mixed carbonization strategy. The BFAC smooths the split layer and folds on the surface of microcrystalline graphite and builds the heteroatom-doped composite structure, which effectively alleviates the volume expansion caused by K+ electrochemical de-intercalation processes, together with improving electrochemical reaction kinetics. As expected, the optimized BFAC@MG-0.5 exhibits superior potassium-ion storage performance, which delivers a high reversible capacity (623.8 mAh g-1), excellent rate performance (147.8 mAh g-1 at 2 A g-1), and remarkable cycling stability (100.8 mAh g-1 after 1200 cycles). As a practical device application, the potassium-ion capacitors are assembled using the BFAC@MG-0.5 anode and commercial activated carbon cathode, which exhibits a maximum energy density of 126.48 Wh kg-1 and superior cycle stability. Significantly, this work demonstrates the potential of microcrystalline graphite as the host anode material for potassium-ion storage.