Treatment Of 3’-nitro-4’-methoxyacetanilide Wastewater By Resin Adsorption Method

3’-amino-4’-methoxyacetanilide is an important dye intermediates.However,the poisonous organic wastewater with high concentration and poor biodegradability is a serious problem to solve during its production.In recent years,the treatments of industrial wastewater contains high concentration of organic pollutants using polymer adsorbents have made great progress in China.The synthesis and the use of novel adsorbents have become a hot topic in environmental protection.The hypercrosslinked polymeric resins such as NDA-150,NDA-99 and SYS were prepared by post-crosslinking of chloromethylatead PS-DVB and chemical modification reaction in this work.The physical and chemical properties of NDA-150,NDA-99,SYS and commercially available adsorbent resin XAD-4 were characterized using fourier transform infrared spectroscopy(FTIR),specific surface area analyzer(BET and BJH)and thermal gravimetric analysis methods.The adsorption and desorption mechanism of 3’-nitro-4’-methoxyacetanilide on the above resins were also studied according to the static and dynamic adsorption experiments.The main conclusions are as follows:(1)The characteristics of the NDA-150,XAD-4,NDA-99 and SYS resins which have a polystyrene-diethylene benzene skeleton were analyzed in this work.With the comparison of the specific surface area of the four resins indicated that NDA-150>XAD-4>NDA-99>SYS.From the results,we also found that the NDA-150,NDA-99 and SYS resins contained a large number of micropores while the XAD-4resin had a large number of mesopores.And all resins had showed high thermal stability from thermal gravimetric analysis.(2)The static adsorption experiments of 3’-nitro-4’-methoxyacetanilide on NDA-150,XAD-4,NDA-99 and SYS resins were studied.Adsorption isotherm of3’-nitro-4’-methoxyacetanilide was monolayer adsorption which fitted the Langmuir model.The adsorption process of 3’-nitro-4’-methoxyacetanilide on NDA-150 and NDA-99 resins were endothermic reaction while the adsorption process on XAD-4and SYS resins were thermopositive reaction.With high specific surface area,theNDA-150 resin showed a higher adsorption capacity for3’-nitro-4’-methoxyacetanilide than the other three resins.(3)Two-components adsorption experiments of 3’-nitro-4’-methoxyacetanilide and 4’-methoxyacetanilide on NDA-150 and XAD-4 indicated that the main adsorption function was π—π effect of the aromatic ring and resin skeleton benzene ring in adsorbate molecules.Based on the competition of adsorbate molecules on resin adsorption π—π sites,the direct competition for adsorption sites was the main dominant mechanism.Modified Langmuir model fitted two-component competitive adsorption behavior well,and 3’-nitro-4’-methoxyacetanilide competition ability was slightly better than 4’-methoxyacetanilide in coexisting system.(4)Based on the dynamic adsorption experiments,the resin column height,flow velocity and the initial concentration of solution had a great influence on penetrating time and adsorption quantity of these resins.With the increase of flow velocity,penetrating time was shorted which reduced the adsorption quantity.With the increase of initial concentration of solution,penetrating time was shorted which enhanced the adsorption quantity.With the rasied of the resin column height,penetrating time was extended which increased the adsorption quantity.(5)According to adsorption behavior of 3’-nitro-4’-methoxyacetanilide on the four resins,Thomas model and LDF model fitted adsorption data well,and the adsorption equilibrium adsorption quantity was closed to the actual adsorption quantity.With the increase of flow velocity,the Thomas rate constant increased,and the equilibrium adsorption quantity decreased.With the increase of initial concentration,the rate constant decreased,and equilibrium adsorption quantity increased.When the resin column height increased,the removal rate was also increased.The slower the flow velocity,the higher initial concentration and the larger column height can improve the maximum adsorption capacity of3’-nitro-4’-methoxyacetanilide.(6)The NDA-150 resin showed a better regeneration effect when using 80%ethanol solution as desorption solution.The desorption rate of NDA-150 could reach up to 84% when desorption velocity was 1.0 mL/min.After reuse by several times,resin desorption rate reached up to 80% without broken,which verified that resins have a good mechanical strength and resistance to pollution.