چكيده به لاتين
The purpose of this research is to modify the surface of vermiculite to optimize its surface wettability for enhancing its performance in adsorbing organic compounds such as n-hexane, as well as utilizing it in separating water-oil mixtures. In this way, after identifying the parameters affecting soil properties and examining its adsorption capacity and wettability, the optimal adsorbent was determined in two stages using the one-factor-at-a-time experimental design method: (1) The impact of acid washing with sulfuric acid, base washing with potassium hydroxide, and ultimately surface modification with the surfactant CTAB on the oil to water adsorption ratio; (2) The effect of different levels of surfactant concentrations on wettability. Thus, in the first stage, among the 9 adsorbents examined, acidic (0.5 M)-basic (0.5 M) vermiculite modified with surfactant (0.5 mM) was selected as the adsorbent with a higher oil-to-water adsorption ratio (19.11). It is worth mentioning that this ratio has increased 40 times compared to the raw sample with the selectivity rate of 0.44. In the second stage, the results showed that the sample modified with a surfactant concentration of 0.9 mM CTAB had better hydrophobic properties with a contact angle of 147.5 ˚ compared to other samples. To evaluate the effect of the surface modification on structural properties, morphology, specific surface area, phase structure, surface chemical composition, as well as the wettability behavior of the produced samples, analyses such as X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), specific surface area measurement (BET), zeta potential analysis, and static contact angle analysis were utilized. In evaluating the performance test results of the optimal adsorbent for the separation of immiscible water-oil mixtures, it was found that the adsorbent was sufficiently efficient. Based on the conducted experiments, it was determined that the separation flux increases with the increase in the volume of the immiscible water-oil mixture, reduction in soil thickness, increase in the hydrostatic pressure of the repelled phase, and decrease in the viscosity of the passing oil. Furthermore, the results of the study on the effect of adsorbent dosage on adsorption capacity in an oil-in-water emulsion with a concentration of 250 ppm showed that with an increase in the adsorbent dosage, the adsorption capacity decreases and in the optimal adsorbent dosage (0.4 g), the adsorption capacity equal to 36.15 was obtained. On the other hand, with an increase in contact time up to the equilibrium contact time of 60 minutes, the adsorption capacity increases. The separation efficiency for a water-in-oil emulsion mixture with a 20 % weight concentration was more than 90 %. The investigation of the adsorbent's regenerative ability in adsorbing edible oil also showed that after five cycles, the adsorbent maintains its hydrophobicity and has decreased by approximately 22 % when compared to the first cycle, and has a 36 % higher adsorption capacity compared to the raw sample.
