Organic Modification Of Natural Clay Minerals And The Adsorption Study Of Anionic PPCPs

Pharmaceuticals and personal care products(PPCPs) residues in the environment on a global scale are prevalent and based the most frequently detection on antibiotics and analgesics. How efficient, advanced treatment PPCPs in water pollution has become a hot topic and the difficulties in the field of global environmental scientists. Surface of natural clay minerals are generally negatively charge, which contributed to the characteristics of cationic PPCPs adsorption, but low adsorption of anionic DS、CAP. Therefore, surface modification and electrical change of clay to efficiently control and remove anionic DS、CAP is very urgent and necessary. This study investigated the adsorption behavior of anionic(DS、CAP) on organic modified natural clay minerals. Results showed that organic modified natural clay minerals precent a significant removal of anionic DS、CAP. Four main parts included as follow:(1) This study invenstigated adsorption of anionic diclofenac sodium(DS) on natural clay minerals. Results showed low adsorption of DS on natural clay minerals. Organic modified zeolite, kaolinite, montmorillonite and illite were successfully synthesized by using cetyl trimethyl ammonium bromide(CTAB). Structure, morphology and property of CTAB modified clay minerals were characterized by: XRD, SEM, contact angle measurements, and IR. The study found that the adsorption DS on four kinds of modified clay mineral surfaces based mainly electrostatic adsorption, zeolite, kaolinite and illite surface area resulting in poor absorption difference DS on three kinds of mineral surfaces. DS can enter the layer gap forming monolayer, which contributed to the best adsorption.(2) This study investigated adsorption of anionic chloramphenicol(CAP) on natural clay minerals. Results showed low adsorption of CAP on natural clay minerals. By using modification of green solvents-ionic liquids on natural clay minerals, we get the environmental friendly organic clay minerals, which also have good adsorption on CAP. Adsorption of CAP on zeolite only corresponed to surface adsorption, which could attributed to the pore size of zeolite is much smaller than molecule size of CAP. In addition, interlayer adsorption of CAP on montmorillonite was also testified.(3)Computer simulation studied the behavior of surface and interface modification or adsorption on clay minerals. Results explored that mechanism of modification and adsorption could both attribute to electrostatic interaction. Different load made different adsorption of anionic DS and CAP, which was consistented with experiments.(4) Based on the study of dynamic adsorption, we select two optimal clays to characterize the adsorption property of organic modified clay: zeolite and montmorillonite. Results showed that with increase of montmorillonite percentage, the adsorption property would enhanc, while the system permeability would reduce.This research has been first studied the mechanism of adsorption of anionic DS、CAP on organic modified clay. Static and dynamic experiments showed a significant adsorption of anionic DS、CAP on modified clay. Computer simulation displayed the distribution of DS、CAP on clay surface. This research has significant guidance for learning the transfer and fate of DS、CAP in the soil. Mechanism of reaction is helpful to develop an efficient, low-cost adsorbent material, which providing important theoretical guide and basis on high efficient treatment of DS、CAP pollution and protection of drinking water.