Chelating Resin Based On ATRP Technique And Its Adsorption Performance

Chelating resin, a kind of functional polymer materials, can form coordination complex with metal ions, separate and enrich heavy metal ions, widely used for the disposal of heavy metal ions. The specific surface area and the functional group density on the surface of the resin determine its adsorption capacity, while the variety of functional groups on the surface of the resin is an important factor that influences the adsorption selectivity. As far as this fact is concerned, the selection of resin with a proper specific surface area as the base materials, the introduction of selective functional groups on surface of the resin and the control of functional group density are the key in preparing chelating resin with high performance. This dissertation attached importances to three kinds of new methods in preparing chelating resins: chloromethylated polystyrene (CMPS) resin used as the base materials, the new technology of surface-initiated atom transfer radical polymerization (SI-ATRP) in macromolecular chemistry adopted, the functional monomer directly grafted on the surface; of CMPS resin or subquently chemical modification.In these methods, four kinds of chelating resins with high capacity were prepared.The adsorption performance on heavy metal ions of four kinds of chelating resins were studied.This dissertation includes four parts:1. Preparation of4-vinylpridine (4VP) resin and its adsorption performanceThis part focused on the preparation of the chelating resin with pyridine ring as the functional groups,4VP monomer directly grafted on the surface of CMPS resin via SI-ATRP, and the performance of adsorption of resin on Cr (â…¥), Pb (â…¡), Cr (â…¢), Zn (â…¡) and Cd (II).With the extension of ATRP time and increase of4VP consumption, the4VP grafting rate was linearly increased, indicating the increase of density of pyridine ring on the resin surface. Adsorption experiment indicated that the adsorption capacity of resin on metal ions considerably improved when compared with what was reported in literature, and the desorption rate and reusibility were equivalent to those of conventional resin. When pH value was greater than5.0, Pb (â…¡), Cr (â…¢), Zn (â…¡) and Cd (â…¡) ions could be adsorbed; however, when pH value was less than3.0, Cr (â…¥) could be selectively adsorbed. These results indicate that, the prepared resin is of application value in terms of the disposal of heavy metal waste water, and the adopting of one-step SI-ATRP is one of the effective methods in preparing chelating resin with high capacity through selecting of functional monomer.2. Preparation of salicylic chelating resin and its adsorption performanceIn this part, the chelating resin (ASA/PGMA/PS) with salicylic acid as the functional group was prepared via SI-ATRP of glycidyl methacrylate (GMA) on chloromethylated crosslinked styrene-divinylbenzene resin and introduction of5-aminosalicylic acid (5-ASA) to the molecular chain through the reaction between epoxy groups and amino groups. The adsorption performance of ASA/PGMA/PS resin on Fe(â…¢), Ag(â… ), Ni(â…¡) and Cu(â…¡) was studied. The findings were that, within a certain range of ATRP time and GMA consumption, adsorption capacity displayed a linear relation with ATRP time, GMA consumption and grafting rate. This article given an analysis on the adsorption mechanism of metal ions:it was concluded that, under the conditions of high density functional group, the adsorption mechanism of metal ions was different from that under low density. The synthetic resins had a relatively high adsorption capacity on metal ions and at the same time manifested the excellent adsorption performance and good reusibility, indicating that combination of ATRP and chemical modification is also a feasible method to regulate the density of resin surface functional group.3. Preparation of tetrazole-type chelating resin and its adsorption performanceThe novel high capacity polyvinyl tetrazole resin (PVT-g-PS) with tetrazole as the functional group was prepared by SI-ATRP, followed by a "click chemistry" reaction. When the structure of resin was analyzed, the chemical structure of tetrazole-modified resin was different from that of traditional chelating resin. Adsorption performance study indicated that, the common ions of Na (â… ) and K(â… ) in solution had little interference on the metal ion adsorption, indicating that Pb (â…¡), Cd (â…¡), Cu (â…¡) and Cr (â…¢) could be selectively adsorbed in industrial waste water. Compared with literature values, PVT-g-PS resin had a relatively higher adsorption capacity on Pb (â…¡), Cd (â…¡), Cu (â…¡) and Cr (â…¢). pH value and salt effect study revealed that, the adsorption of resin on metal ions mainly exerted the effect of chelation. In addition, this resin had a good desorption rate and reusability, and the resin exhibited excellent chemical stability under strong acidic and alkaline conditions. These findings suggest that the resin can be potentially applied to the efficient removal of heavy metal ions from waste water.4. Preparation of polyamine-type chelating resin and its adsorption performanceThis part explored the method of combining ATRP technology and hyperbranched polymer principle to prepare the high capacity chelating resin. First, SI-ATRP method was used to graft glycidyl methacrylate (GMA) on tchloromethylated crosslinked styrene-divinylbenzene resin, and then the novel polyamine chelating resin with a kind of hyperbranched structure was prepared through the amination reaction between epoxy group and amino group of (2-amino-ethyl) triamine and epoxy group in GMA. This resin had a selective effect on As(â…¤) and Cr (â…¥) at a relatively low pH and can be used for the disposal of waste water containing As (â…¤) and Cr (â…¥). It had a relatively strong adsorption effect on Cu (â…¡), Pb (â…¡), Cd (â…¡) and Cr (â…¢) and can be used for the disposal of heavy metal ion waste water. The finding was that, the adsorption capacity of resin on the studied heavy metal ions was higher than the chelating resin synthesized by traditional technology and also higher than the resin modified by ATRP technology and bifunctional chelator, indicating that the combination of ATRP and hyperbranched polymer concept is an effective method to prepare chelating resin with high capacity.