TDS对制备纳米乳化油稳定性影响的实验研究

Experimental study on the effect of TDS on the stability of preparing nano⁃emulsified oil

为有效评估地下水中溶解组分对制备纳米乳化油的潜在影响,通过人工模拟配制天然地下水开展地下水TDS对制备纳米乳化油稳定性影响的批实验研究.分别采用动态光散和多重光散技术表征TDS影响下纳米乳化油粒径、背散射光通量、光子自由程以及峰厚度等指标的动态变化,以此来反映TDS对制备纳米乳化油稳定性的影响.结果显示:在TDS浓度为300、500和1000 mg·L^(-1)的情况下,TDS对纳米乳化油稳定性起到正向作用.反映纳米乳化油整体稳定性的TSI随TDS增大呈现先增大后减小的趋势,相较于空白样稳定性分别提高了68.1%、55.6%和14.3%,其中300 mg·L^(-1)的样品稳定性最好.依据局部TSI、背散射光强度、峰厚度和光子自由程的变化进行局部稳定性分析,识别出纳米乳化油的不稳定性主要受顶部不稳区和底部不稳区的影响.纳米乳化油顶部不稳区的不稳定性主要影响因素为液滴上浮、聚并,具体表现为体积分数增大,液滴粒径增大;而底部不稳区受上浮影响引起的纳米乳化油体积分数减小是其不稳的主要原因.进一步分析表明,TDS降低了纳米乳化油的布朗运动速率.相比于空白样,实验设计的TDS(300、500和1000 mg·L^(-1))对纳米乳化油的上浮现象和液滴的聚并现象起抑制作用,并随浓度增大逐渐减弱.300 mg·L^(-1)的样品对两种不稳定因素分别减轻了88%和87.7%.因此,适宜的地下水TDS可以减弱布朗运动,降低上浮现象和聚并现象,从而对纳米乳化油的稳定性起正向作用,有利于纳米乳化油在多孔介质中的迁移.

In order to effectively evaluate the potential influence of dissolved components in groundwater on the preparation of nano⁃emulsified oil,a batch experiment was conducted to investigate the influence of groundwater TDS on the stability of nano⁃emulsified oil preparation by artificial simulation of natural groundwater.Dynamic light dispersion and multiple light dispersion techniques were used to characterize the dynamic changes of the nano⁃emulsified oil particle size,backscattered light flux,photon free path,and peak thickness under the influence of TDS,so as to reflect the influence of TDS on the stability of preparing nano⁃emulsified oil.The results showed that TDS performed a positive effect on the stability of nano⁃emulsified oil at the concentration of TDS of 300,500 and 1000 mg·L^(-1).The TSI,which characterizes the overall stability of nano⁃emulsified oil,firstly increased and then decreased with the increase of TDS.Compared with the blank sample,the stability improved 68.1%,55.6%,and 14.3%,respectively,and the 300 mg·L^(-1) sample presented the best stability.According to the change of local TSI,backscattered light intensity,peak thickness,and photon free path,it was identified that the instability of nano⁃emulsified oil was mainly affected by the top and the bottom instability zone.The instability at the top is affected by droplet floating and coalescence,which are specifically manifested as the increase in the volume fraction and droplets size.The main reason of instability at the bottom is the decrease of nano⁃emulsion oil volume fraction caused by droplet floating.Further analysis results showed that TDS reduced the Brownian motion rate of nano⁃emulsified oil.Compared with blank sample,the experimental designed TDS(300,500 and 1000 mg·L^(-1))can inhibit the droplet flotation and agglomeration,and the inhibition gradually weakened with the increase of TDS.The 300 mg·L^(-1) sample reduced the two unstable factors by 88%and 87.7%,respectively.Therefore,suitable groundwater TDS can weaken Brownian motion and reduce the phenomenon of floating and coalescence,which has a positive effect on the stability of nano⁃emulsified oil and is conducive to the migration of nano⁃emulsified oil in porous media.