Adsorption Of Phthalates In Wastewater By The Modified Chitosan

A kind of environmental hormone, phthalates (PAEs), has gained more attention by researchers. The common methods to remove PAEs from waste-water are adsorption, biological and chemical metods. But these methods have their advantages and disadvantages on treatment efficiency and cost. Chitosan, as a natural polymer, is harmless non-toxic and biodegradable. However, its unstablity in acid medium and acid hydrolysis limit its applications.This paper mainly embarks on the modification of chitosan to remove the PAEs from wastewater. (1)With chitosan and citral as raw materials, a citral cross-linking chitosan resin is prepared by reversed-phase suspension method; (2) Compared the adsorption capacity of the chitosan to treat simulated wasterwater containing DMP, DBP and DEHP before and after modified, the influence of yield of Schieff's, amount of added sodium chloride and adsorption capacity of the resin are studied, and then study their dynamic theory; (3) Under the static adsorption conditions, with the actual simulate wastewater, the influence of pH, time, the amount of the resin on the removal rate of DBP and DEHP was studied; (4) The dynamic adsorption conditions are:the initial concertration of the wastewater, pillar altitude and the velocity of effluent are studied for the removal rate of PAEs. Then the desorption characteristics of PAEs and continuous running control experiment were carried on. Study on feasility and the adsorption effect of the novel water treatment adsorbent resin. The experimental results are summarized as follows:1. The optimum conditions were confirmed by orthogonal experiments:reaction time 8 hour, temperature 60℃, ratio of chitosan to monomer mass was 1:6, the yield of the chitosan was 84.13%.2. The experimental results indicated that the resin has better absorption capacity to DMP, DBP and DEHP, especially to DBP. The whole process for the resin to adsorb the PAEs can be described by The first level dynamic equation. The Longmuir adsorption fits the isotherm equations very well.3. The static adsorption experiment test result showed the modified chiston has higher absorption capacity. The optimum adsorption experimental condition was that pH value is 7. After 2 hours the removal rate is stability, when the quantity is 0.1g, the removal rate is 83%.4. The dynamic adsorption result showed the optimum dynamic adsorption condition was 25℃, pH 6.8, pillar alttitude 200mm, effluent velocity 2BV/h, removal rate of PAEs is 87.4%, removal rate of COD is 62.1%. The resin was effectively regenerated by pure methanol, when effluent velocity is 3.2 BV/h, and desorption rate is 97.1%. 5. The continuous dynamic adsoption showed that when the effluent velocity is 2 BV/h, the removal rate is 31.3% after 180 min, the concentration is 10.3 mg L-1, the cumulative processing water is 0.087 L.A natural aldehyde was chose as graft to chitosan with rich sources and low prices. The material meet the demands of green chemistry, and highlightened by its simple operation. Application of these adsorbent materials will be more broad prospects for development.