Abstract

The effect of the hydrodynamic situation (mainly conditions of mixing of the solutions of the reagents) on the composition and sizes of the nanoparticles being formed in an impinging-jet microreactor (IJMR) upon the impinging of the jets of the reagents—aqueous solutions of lanthanum nitrate and ammonium dihydrogen phosphate—is studied. Unique conditions are generated in the IJMR providing a short-term contact of the jets of the solutions that move at a high velocity (of about 10–20 m/s). The characteristics of turbulence in the IJMR are calculated. It is shown that the rate of dissipation of turbulent kinetic energy in the zone of impinging of the jets may reach 10⁷–10⁹ W/kg, which is comparable to the level of dissipation of energy in ultrasonic baths and is several orders of magnitude higher when compared to almost any other type of reactor. The effect of the region that has a size of the minimum Kolmogorov turbulence scale, i.e., a self-organizing “nanoreactor,” on the size of the particles being formed upon the deposition of particles with a complex composition is determined. Comparing the results of the calculation with the experimental data shows that, in some cases, the volume of the nanoreactor, taking into account the concentration of the solutions, determines the weight and size of the particles being formed. An explanation for the effect of a different influence of the velocity of impingement of the jets on the size of the nanoparticles being formed during the microreactor mixing of the reagents, depending on the characteristic features of the mechanisms of chemical reactions under the conditions of “soft” chemistry, is provided.

中文翻译：

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射流微反应器中的流体动力学条件对基于复合氧化物的纳米颗粒形成的影响

摘要

流体动力学情况（主要是试剂溶液的混合条件）对在撞击射流微反应器（IJMR）中形成的纳米颗粒的组成和大小的影响。研究了硝酸镧和磷酸二氢铵。IJMR中产生了独特的条件，提供了高速运动（约10–20 m / s）的溶液射流的短期接触。计算了IJMR中的湍流特性。结果表明，在射流撞击区域内湍动能的耗散率可能达到10 ⁷ –10 ⁹W / kg，与超声波浴中的能量耗散水平相当，与几乎任何其他类型的反应器相比，高出几个数量级。确定具有最小Kolmogorov湍流尺度的区域（即自组织的“纳米反应器”）对沉积具有复杂成分的颗粒时形成的颗粒大小的影响。将计算结果与实验数据进行比较表明，在某些情况下，考虑溶液的浓度，纳米反应器的体积决定了所形成颗粒的重量和尺寸。解释了在试剂的微反应器混合期间，射流的撞击速度对所形成的纳米颗粒尺寸的不同影响的影响，