Study On Synthesis Of Polyvinylpyridine Resin And Its Application In Wastewater Treatment

To remove and purify water containing toxic oxyanions(e.g.arsenate,chromate,etc.)and refractory oxyanions(e.g.aromatic sulfonate,fumarate,etc.)has been a research hotspot in the environmental protection.Ion exchange and adsorption have been mostly used for removal of these substances,which enjoys a wide scope of application,high removal efficiency,simple operation,and low energy consumption,etc.However,adsorbing the said oxyainons with high solubility by polymeric adsorbents may be quite hard,since the contaminants are normally adsorbed by polymeric adsorbents via hydrophobic interaction.Anion exchange resin may have high affinity towards the oxyanions,but the exchange capacity and selectivity are usually affected by other coexisting anions.Additionally,the thermal stability of the commercial anion exchange resins is poor that shortens the resins'lifetime.In order to remove the said oxyanions from water,new separating polymers with high performance are needed to be developed.Polyvinylpyridine resin can be synthesized through suspension copolymerization by using vinylpyridine as the monomer and divinylbenzene as the crosslinking agent.And N in the pyridine ring,which contains bare lone pair of electrons,is the hydrogen bond receptor,thus the available hydrogen donor compounds can be adsorbed by forming a donor-acceptor complex.Moreover,N atoms in pyridine ring have a sp2 hybrid orbital that is not involved in bonding,thus can coordinate with transition metal ion containing the empty orbit.In addition,thermal stability of N in pyridine rings as the anion exchange functional groups is higher than the groups of aliphatic amines in the traditional anion exchange resins.However,vinylpyridine has the high solubility and reactivity,which may lower the polymer yield and mechanic stability.Based on the above-mentioned background,the study on the polyvinylpyridine synthesis has been carried out in this thesis.Meanwhile,the research work also contains adsorption performance valuation of the said oxyanions by the new resin and mechanism discussion of the adsorption processes.Furthermore,the new resin can catalyze maleic acid to be fumaric acid by isomerization was unexpectedly found in the study,and the adsorption performance towards fumaric acid by the resin has been valuated as well.The main results and conclusions are given as follows:1.Synthesis and characterization of polyvinylpyridine resin.Polyvinylpyridine resin was synthesized through suspension copolymerization by using vinylpyridine as the monomer and divinylbenzene as the crosslinking agent in the presence of initiator.By thermal gravimetric analysis of the thermal stability of the resin,the synthesis of polyvinylpyridine resin heat resistance performance is higher than 400?.By varying the degree of crosslinking,the kind and amount of the porogen,the different specific surface area of polyvinylpyridine resins was formed.When crosslinking degrees are increased from 8%to 50%,the specific surface area of resin varies from 4.8 m2 g-1 to 401.7 m2 g-1,while N content decreases from 11.12%to 3.32%.In the case of the same degree of crosslinking,when the amount of good solvent toluent in the mixed porogen(200#gasoline,toluene)is increased,microgel nucleus of macromolecular chain winding will decrease,and make the internal structure of microspheres become looser,resulting in the increase of specific surface area.2.Study on adsorption behavior of 5-sodiosulfoisophthalic acids by poly(2-vinylpyridine)resin.The effluent in manufacturing SIPM often has high concentration of 5-sodiosulfoisophthalic acids(SIPA,15,000-25,000 mg L-1).The thesis has systematically studied the performance of polyvinylpyridine resin adsorbing SIPA,the influence of acid concentration and salt concentration on the adsorption.The four commercial resins,i.e.,strong base anion exchange resin D201,weak base anion exchange resin D301,hypercrosslinked resin NDA-100 and macroporous resin Amberlite XAD-4 are used as reference.At the same acid concentrations,the performance of D201 resin and D301 is better than that of polyvinylpyridine resin.While it is difficult to avoid the presence of some inorganic salts in wastewater,in the adsorption process,the capacities of the polyvinylpyridine resin for the adsorption of SIPA are 1.40 mmol g-1,which is found to be negligibly decreased even if in the presence of SO42-.On the contrary,the capacities of D201 and D301 for the adsorption of SIPA are conspicuously reduced in the presence of SO42-.The capacities of D201 and D301 for the adsorption of SIPA are respectively 2.05 mmol g-1 and 2.02 mmol g-1 in the absence of SO42-.However,when sulfate is added in the solution,the capacities of D201 and D301 towards SIPA are markedly decreased at the concentration of SO42-ranged from 50 to 350 mg L-1.Column assay shows SIPA can be easily desorbed from polyvinylpyridine resin with 2 wt%sodium hydroxide and 100%desorption efficiency is achieved as expected,which further indicates polyvinylpyridine is a quite effective sorbent for removal and recovery of aromatic acids from aqueous solution,such as SIPA.3.Copper(?)-bound polyvinylpyridine resin for selective removal of arsenate from water.Arsenic(As)has been recognized as a poison that negatively impacts on environment.Polyvinylpyridine resin N containing bare lone pair of electrons and the elpty orbital transition metal ions Cu2+ can form the coordination complex(named,WH-4-Cu).The thesis has studied the coordination complex to remove As(?)from the aqueous solution in one component and in the presence of coexisting ions(Cl-?SO42-?SiO32-?PO43-)and the humic acid,a commercial strong base anion exchanger(D201)is tested as reference.It has revealed that the solution pH has an important effect on As(?)sorption onto WH-4-Cu,and the optimal As(?)uptake occurs in the pH range of 6.0-8.0.WH-425-Cu exhibits unusually high selectivity for As(?)even in the presence of high concentrations of chloride and sulfate except for silicate(at concentration value>200 mg L-1)and phosphate(at concentration value>25 mg L'1),and humic acid(18.7mg L-1).When sulfate is added in the solution,the removal efficiency of As(?)by D201 is markedly decreased.When the concentration of SO42-is increased to 250 mg L-1,the removal efficiency of As(?)by D201 ranges from 92%to 0.55%,and even approached to zero in the presence of SO42-at concentration of 250 mg L-1.The removal efficiency of As(?)by WH-4-Cu is maintenance 85%.Such different sorption performance between D201 and WH-425-Cu is attributed to their different sorption mechanisms for As(?).For As(?)sorption by D201,only electrostatic interaction(ion-pair formation)is formed between the positively charged quaternary ammonium group(R4N+)and the anion(HAsO42-),because R4N+ does not have any electron-acceptor characteristic,while mechanism between As(?)and WH-4-Cu is electrostatic interaction and Lewis acid-base interactions.The As(?)loaded on WH-425-Cu can be completely rinsed with 6%NaCl at 9.0 of pH value.4.Study on poly(4-vinylpyridine)resin catalytic conversion of maleic acid and adsorption behavior of towards fumaric acid.Wastewater of fumaric production containing a large amount of maleic acid and fumaric acid(maleic acid,6680 mg L-1,fumaric acid,8530 mg L-1,COD,6,000-12,000 mg L-1)is hard to be efficiently treated owing to the high concentrations of organic wastewater.It is found that the isomerization of maleic acid to fumaric acid can be efficiently catalyzed by poly(4-vinylpyridine)resin,and meanwhile the resin has high adsorption capacity towards fumaric acid.In the presence of poly4-vinylpyridine resin,the catalytic conversion rate of maleic acid is more than 90%at 100?.The maximum value of the catalytic conversion rate appeared at 1.5 of pH value.The catalyst is reusable and maintains the activity after seven cycles.The mechanism of the catalyzed isomerization of maleic acid to fumaric acid is acid addition and elimination of the transformation.In the adsorption process,the adsorption capacity of fumaric acid is 69.9 mg g-1,which is barely decreased even if in the presence of the inorganic salts.On the contrary,the adsorption capacities by using D201 and D3 01 for the adsorption of fumaric acid are conspicuously reduced in the presence of the inorganic salts.The capacities of strong base D201 and weak base D301 anion exchange resins for the adsorption of fumaric acid are respectively 112.4 mg g-1 and 129.9 mg g-1 in the absence of SO42-.However,when sulfate is added in the solution,the capacities of D201 and D301 anion exchange resins towards fumaric acid are markedly decreased and even approached to zero at the concentration of SO42-ranged from 50 to 350 mg L-1.A new idea of resource reuse of phthalic anhydric production wastewater has been put forward by this research work,which is catalytic conversion of maleic acid to fumaric acid and adsorption of fumaric by using poly(4-vinylpyridine).