Influence of filtration and addition of nanoparticles on the Non-Photochemical Laser Induced Nucleation of EthyleneDiamine Sulfate
Résumé
Non-Photochemical Laser Induced Nucleation (NPLIN) is a phenomenon discovered in 1996 by Garetz et al[1]. This process allows nucleation control of supersaturated solution. A higher probability of nucleation and shorter induction time are found for samples exposed to the laser compared to samples not exposed. The NPLIN process depends on several parameters to optimize the nucleation control. The most significant parameters are the supersaturation of the solution and the laser parameters such as the energy and the number of pulses.
However, another parameter seems to have a large influence on NPLIN nucleation. Indeed, Javid et al[2] and Ward et al[3] have studied the impact of filtering the homogeneous solution before cooling down to the temperature of investigation at which the compound is supersaturated. They have shown that the filtration suppressed or strongly reduced the NPLIN effect (i.e., a decrease of the probability of nucleation and increase of induction time). In their study about ammonium chloride NPLIN, Ward et al[3] identified that the impurities trapped on the filter are iron and phosphorus. They also found that doping these filtered solutions with iron oxide nanoparticles allows to reverse the effect of filtration in terms of NPLIN kinetics.
In this study, we focus on the NPLIN of ethylenediamine sulfate (EDS) from aqueous solutions. To evaluate the influence of filtration, homogeneous supersaturated solutions of EDS were filtered with a syringe filter (PTFE 0.2 and 0.45µm) and the kinetics of NPLIN was compared to that observed without filtration. To identify the remaining impurities, a Nylon membrane filter (0.45µm) commonly used for solvent purification prior to HPLC was used and the membrane was analyzed by means of scanning electron microscopy (SEM), ATR-FTIR, Raman and ICP spectroscopies and X-ray diffraction. Then, filtered solutions were intentionally doped with three different types of nanoparticles (silver, gold and iron) and their NPLIN behavior was investigated.