Modification And Boron Adsorption Performance Of Poly (Vinylbenzyl Chloride-co-divinylbenzene) Nanofibers

As an important basic raw material,boron has been used in many industrial fields.With the gradual increase of boron consumption,boron minerals with commercial value cannot meet the needs of the market.There are abundant salt lake resources in china,which have not been efficiently explored and utilized for a long time,so it attracted more and more researchers'attention to develop liquid boron resources to make up for the shortage of boron.Meanwhile,the extraction from industrial wastewater,irrigation water or drinking water is also of great significance to the growth and development of animals and plants.Compared with other adsorption methods,ion exchange was paid more attention for the advantages of simple operation,large adsorption capacity and high selectivity,it is highly desired to research and develop new adsorption materials with potential applications.In this work,polymer nanofibers were prepared by a cationic polymerization method,which has some advantages of simple synthesis process,controllable crosslinked degree and batch production.As a matrix for boron sorbents,polymer nanofibers were grafted with N-methyl-D-glucamin?NMDG?,aminopropylene glycol?APD?and tris?hydroxymethyl?aminomethane?TRIS?,leading to the formation of three boron sorbents.In addition,the sorbents grafted with N-methyl-D-glucamine were modified further by doping Fe₃O₄ nanoparticles,and a magnetic sorbent was synthesized which realized magnetic separation under the magnetic field.The main contents are as follows:1.Chloromethyl styrene and divinylbezene as raw materials,polymer nano-fibers with different mass ratios were synthesized in batch by the cationic polymerization method.Then a polymeric sorbent?Poly?n/m?-NMDG?was obtained by grafting N-methyl-D-glucamine onto the polymers.According to the FT-IR spectra?FT-IR?,elemental analysis?EA?,scanning electron microscopy?SEM?,adsorption and cyclic stability tests,the best mass ratio of the polymer nano-fibers was selected as a matrix in the further work.The effect of pH,concentration,contact time and interfering ions on the adsorption capacity of sorbents were systematically explored.The results indicated that the optimum adsorption capacity was obtained at pH=9 and the maximum adsorption amount was 18.15 mg/g.The adsorption process fits well with Langmuir model and pseudo-second-order kinetics,respectively.The existence of Na⁺?Ca²⁺?Mg²⁺cations in the aqueous interfere with the selectivity of the sorbent.Besides,Poly?2/1?was modified with Fe₃O₄ nanoparticles,and the magnetic sorbent Poly?2/1?@Fe₃O₄-NMDG was synthesized whose optimum adsorption capacity was5.4 mg/g.It realizes magnetic separation of the sorbent under magnetic field,which supplies an efficient method for separation and reclaim of the sorbent.2.The polymeric boron adsorbent denoted Poly?5/1?-APD was synthesized with Poly?5/1?as a matrix and APD as a functional group.It was characterized by FT-IR,EA and SEM,the results confirmed that the functional group APD was grafted onto Poly?5/1?successfully.The effect of pH,concentration,contact time and interfering ions on the adsorption capacity of Poly?5/1?-APD was systematically explored.The results indicated that the optimum boron adsorption capacity of Poly?5/1?-APD was 8.9mg/g at pH=8.The isothermal adsorption process was more suitable for Langmuir model,and the theoretical maximum adsorption capacity was 7.68 mg/g.The kinetic adsorption process fitted pseudo-second-order kinetics.After four cycles of adsorption,the adsorption capacity can still keep 85%.The presence of Na⁺?Ca²⁺?Mg²⁺cations in the aqueous has obvious effect on the selectivity of the sorbent.3.The polymeric boron adsorbent denoted Poly?5/1?-TRIS was synthesized with Poly?5/1?as matrix and TRIS as functional group.It was characterized by FT-IR,EA and SEM,the results confirmed that the functional group TRIS was grafted onto Poly?5/1?successfully.The influence of pH,concentration,contact time and interfering ions on the adsorption capacity of Poly?5/1?-TRIS was systematically explored.The results indicated that the optimum boron adsorption capacity of Poly?5/1?-TRIS was9.7 mg/g at neutral solution.The adsorption process was more suitable for Langmuir model and pseudo-second-order kinetics.After four cycles of adsorption,the adsorption capacity can still keep 87%.The presence of Na⁺?Ca²⁺?Mg²⁺cations in solution has little effect on the selectivity of the sorbent under the lower concentration.Compared with Poly?5/1?-APD,the boron adsorption performance of Poly?5/1?-TRIS has been improved in adsorption capacity and cycling stability.