Study On Preparation And Application Of Amino Methylene Phosphonic Acid Resins

With industrial developing and the worsening environmental pollution, the heavy metals in foods and the drinking water which people feed on have injured the health more obviously. The article gives the preparation of chelating resin which is from acetylated polystyrene micro-beads.The chelating resin can reduce the quantities of heavy metals.The method is of simple equipment, small occupy area and also make water be used repeatly by metal enrichment with no second pollution.In this paper, the new amino resin was prepared from acetylated polystyrene micro-beads, formaldehyde and tetraethylene pentamine by Mannich reaction, which can substitute anion-exchange resin prepared from chloromethyl polystyrene resin which used chloromethyl methylether as reactant, that is strong carcinogen due to methylene bridge exists in the chloromethyl polystyrene. Then the amino methylene phosphonic acid resin was prepared from the new amino resin. The static adsorption and the regeneration character of the resin for Pb2+ were preliminary studied.Influencing factors were discussed such as time and temperature of the reaction, molar ratio of materials and so on. Their mechanism was also discussed in the paper. In the process of preparing acetylated polystyrene micro-beads, the optimum experimental conditions were as follows: AlCl3 : polystyrene(molar ratio)=2.5:1, acetic anhydride : polystyrene(mass ratio) =2:1, reaction time=3 hours. The maximum loading of the acetyl polystyrene could be about 65%. Substituted PS was quantified by infrared spectrum analysis from which we got absorbance of several characteristic peaks.After the new amino resin was prepared, the mass-gain rate of products may reach at 80% in the following reaction conditions. Amine: formaldehyde: hydrochloride: Acetyl=10:10:2.5:1, reaction temperature=60℃and reaction time=9 hours. The certain equation was provided by the regression analyzed data. So we can get the resin which has the given rate of amination by the equation in the future.In the process of preparing amino methylene phosphonic acid resin, the amino-transferring of products may reach at 90% in the following conditions, such as phosphorous acid: formaldehyde: hydrochloride: amino=8:8:2:1, reaction temperature =70℃and reaction time=10 hours. The data of each reaction condition have been analysed and we found more important influence conditions and the linear relationship between conditions and amino-transferring of products.The static adsorption and the regeneration character of the resin for Pb2+ was studied. It shows that when the low concentration of Pb2+ varies from 0 to 1mg/L, the adsorption is difficult. When amino phosphonic acid chelating resin loading 1.64mmo1/g of phosphorous acid groups adsorbs Pb2+ in a saturated adsorption state, the ratio between functional groups and Pb2+ is 1:0.009 near 100:1.But the desorption is more effective, especially using hydrochloric acid (the concentration is 0.3mol/l) as the stripping agent. Its stripping ratio is about 99%.