Study of the bubble collapse mechanism and its influencing factors on stability under ultra-low surface tension

Dual-functional natural rubber latex foam composites for solar-driven clean water production and heavy metal decontamination

Solar steam generation (SSG) offers a sustainable approach to fresh water production. Herein, a novel dual-functional natural rubber/carbon black composite foam evaporator is presented for a cost-efficient SSG system that both produces fresh water and eliminates heavy metals present in the water. The composite foam is produced using the Dunlop process, and in its optimized form, it absorbed >96 % of sunlight. The foam evaporator exhibited a thermal conductivity of 0.052 W/m⋅K, a water evaporation rate of 1.40 kg/m2/h, converted 83.38 % of light to heat under 1 sun irradiation, and showed outstanding stability. The technology required to produce this composite foam is already available to make large-scale production feasible, while the natural raw materials are abundant. On the basis of its performance qualities, the rubber foam composite appears to be an excellent candidate for application as a viable solar absorber for SSG to produce fresh, clean water for commercial purposes.

Probing the Coalescence Mechanism of Oil Droplets in Fluids Produced by Oil Wells and the Microscopic Interaction between Molecules in Oil Films

The microscopic interactions between oil droplets during the coalescence process have an important impact on the stability of the emulsion. In this paper, a model that can present the phenomenon of coalescence of oil droplets was established. Experiments were carried out to evaluate the stability of the emulsion. Combined with molecular dynamics simulation technology, the coalescence behaviors of emulsified oil droplets in fluids produced by oil wells were studied. Factors affecting the coalescence of emulsified oil droplets were analyzed. The results show that the fluid velocity was relatively high at the position where two oil droplets were close to each other. After the coalescence of oil droplets was completed, the emulsion system became stable. There was no obvious correlation between oil droplet size and coalescence time. When two adjacent oil droplets with different radii coalesced, the larger oil droplet moved a shorter distance overall. At the initial moment, there was a clear boundary between the oil film and the water phase. The longer the carbon chain, the more stable the emulsion. Among the following four crude oil molecules with the same number of carbon atoms, chain-like saturated hydrocarbons were the most stable, followed by chain-like carbon–carbon double bonds in component crude oil. Crude oils containing chain-like carbon–carbon triple bonds were the third most stable. Cyclane were the least stable. An increase in the asphaltene content was an important reason for the enhancement of the emulsifying ability and stability in the emulsion system. This work can help improve oil–water separation efficiency, thus reducing storage and transportation burden of crude oil.