In recent years, minuscule gas bubbles called bulk nanobubbles (BNBs) have drawn increasing attention due to their unique properties and broad applicability in various technological fields, such as biomedical engineering, water treatment, and nanomaterials. However, questions remain regarding the stability and behavior of BNBs. In the present work, BNBs were generated in water using a gas–liquid mixing method. NB analysis was performed using a nanoparticle tracking analysis (NTA) method to investigate the coarsening behavior of BNBs in water over time. The diameters of the BNBs increased, and their cubic radii increased linearly (r³ ~ t) over time. While the concentration of BNBs decreased, the total volume of BNBs remained the same. The size distribution of the BNBs broadened, and the concentration of larger BNBs increased over time. These results indicate that relatively small BNBs disappeared due to dissolution and larger BNBs grew through mass transfer between BNBs instead of coalescence. In other words, BNBs underwent Ostwald ripening: gas molecules from smaller BNBs diffused through the continuous phase to be absorbed into larger BNBs.

近年来，被称为块状纳米气泡 (BNB) 的微小气泡由于其独特的性质和在生物医学工程、水处理和纳米材料等各个技术领域的广泛适用性而受到越来越多的关注。然而，关于 BNB 的稳定性和行为的问题仍然存在。在目前的工作中，使用气液混合方法在水中生成 BNB。NB 分析是使用纳米粒子跟踪分析 (NTA) 方法进行的，以研究 BNB 在水中随时间的粗化行为。BNB 的直径增加，其立方半径线性增加（r ³ ～t) 随着时间的推移。虽然 BNB 的浓度下降，但 BNB 的总量保持不变。BNB 的大小分布变宽，并且随着时间的推移，较大的 BNB 的集中度增加。这些结果表明，相对较小的 BNB 由于溶解而消失，而较大的 BNB 通过 BNB 之间的传质而不是聚结而生长。换句话说，BNB 经历了奥斯特瓦尔德熟化：来自较小 BNB 的气体分子通过连续相扩散，被吸收到较大的 BNB 中。