Enhanced adsorption of anionic surfactants on negatively charged quartz sand grains treated with cationic polyelectrolyte complex nanoparticles

摘要

The objective of this study is to examine the potential of using polyelectrolyte complex (PEC) nanoparticles to enhance the adsorption of anionic surfactants on negatively charged surface of quartz sand grains. The hypothesis is that a cationic PEC layer formed on the negatively charged quartz surface can enhance the adsorption of anionic surfactants on quartz sand grains. Both static adsorption tests and a quartz crystal microbalance with dissipation monitoring (QCM-D) were used to test the hypothesis. We measured the rate and extent of adsorption of an anionic sulfate surfactant onto bare quartz sand grains versus sand grains pre-treated with PECs. Total organic carbon (TOC) and total nitrogen (TN) analyses were used to quantitatively measure the adsorption of surfactant and PECs. Real-time adsorption monitoring was performed on silica model surfaces by QCM-D. Consistent with our hypothesis, the results showed that the level of adsorption of the anionic sulfate surfactant on PEC treated quartz sand grains (21.5?mg/g of sand) was indeed significantly higher than that on bare untreated sand grains (negligible adsorption). Our results also confirmed a proposed four-stage adsorption mechanism for the enhanced adsorption of anionic surfactants on negatively charged quartz sand grains treated with PEC nanoparticles.