Preparation Of Flexible Porous Polymers By Pickering Emulsion And Its Adsorption And Separation Of Tetrodotoxin

Tetrodotoxin（TTX）is a natural neurotoxin and is extremely toxic.It can be fatal in small amounts and has no specific drugs.However,TTX has pharmacological effects of sedation,analgesia,and local anesthesia,and it has a major role in the treatment of epilepsy,arrhythmia and renal failure.Although TTX artificial synthesis technology has been reported,it still relies on biological extraction due to the difficulty of synthesis,low product yield,and high production price.Therefore,the development of TTX separation and purification methods is of great significance.The TTX extraction technology mostly stays in the rough extraction stage,and the refining and purification process is complicated and cumbersome.The adsorption method is widely applied in the field of separation and extraction because of its simplicity,high efficiency,and economy.Preparation of adsorbent with strong adsorption performance for TTX is the key to extracting TTX by adsorption method.Porous flexible polymers have the advantages of large specific surface,sturdiness and ease of recycling.Pickering emulsion polymerization is a simple and environmentally friendly method for preparing porous polymers.In this paper,flexible porous polymer adsorbent for TTX in different environments were prepared using Pickering emulsion polymerization and Si O₂ nanoparticles/graphene oxide（GO）as stable particles,combined with ammonia modification.A variety of characterization methods were used to analyze the physical and chemical properties of the adsorbent and test its adsorption and separation performance.The main contents are as follows:（1）Using Si O₂ nanoparticles as stable particles and imidazole-modified brominated butadiene rubber（IBR）as shape memory monomers,Si O₂@IBR-AA flexible macroporous polymer was prepared by Pickering O/W HIPEs method and used to adsorb TTX in aqueous solution.The characterization results revealed that it had a good macroporous structure and flexibility.The results of adsorption experiments showed that Si O₂@IBR-AA had a good adsorption effect on TTX.At 35℃,the maximum adsorption capacity calculated by the Langmuir model was208.14 mg/g.The fitting results of the quasi-first-order and quasi-second-order kinetic models showed that the adsorption process involved chemical adsorption and physical adsorption.After 10 cycles of regeneration experiments,the adsorption capacity dropped by less than 0.03%,proving that Si O₂@IBR-AA had good adsorption regeneration performance.But this polymer was difficult to separate TTX under acidic conditions.（2）In order to increase the adsorption capacity of the adsorbent under acidic conditions,Si O₂@IBR-AA prepared by Pickering O/W HIPEs method was modified with ammonia to obtain NH₃-Si O₂@IBR-AA flexible macroporous polymer,which was used to adsorb TTX in acetic acid aqueous solution.The characterization results show that the surface of NH₃-Si O₂@IBR-AA has good large porous structure and flexibility.The adsorption experiment showed that the adsorption process of the polymer for TTX was mainly chemical adsorption,the kinetic equation fitting result accorded with the quasi-second order,and the calculated equilibrium adsorption capacity was 4.82 mg/g.The Freundlich equation could better fit the experimental data of isotherm adsorption,indicating that the adsorption process was multi-layer adsorption.NH₃-Si O₂@IBR-AA had a good adsorption effect on TTX in acid solution,but the adsorption capacity still needed to be further improved.（3）Using GO as stable particles,GO@IBR-AA polymer was prepared by Pickering emulsion polymerization,and then modified with ammonia to obtain ammonia-modified NH₃-GO@IBR-AA flexible porous polymer,which was used to adsorb TTX in acetic acid aqueous solution.The characterization results showed that the NH₃-GO@IBR-AA polymer had a uniform porous structure and good flexibility.The results of adsorption experiments proved that the quasi-second-order kinetic equation and Langmuir adsorption model could better fit the experimental data.The adsorption process was single-layer chemical adsorption,and the maximum adsorption capacity at 35°C was 44.33 mg/g.NH₃-GO@IBR-AA had a good adsorption effect on TTX in acid solution.