Preparation And Adsorption Properties Of Fiber-based Ion-imprinted Adsorbents

Heavy metals are widely available,highly toxic,non-biodegradable and easily enriched in organisms,which seriously endanger human health.It is of great significance to remove heavy metals from aqueous solutions.In this paper,the adsorbents were synthesized using a high electron beam irradiation pre-grafting and post-surface ion imprinting method using Cr（VI）、Pb（II）and Cd（II）as the template respectively.The prepared sample was characterized by various techniques,and the adsorption performances were studied through batch experiments.We synthesize PP fiber-based Cr（VI）-IIPs through specific steps including grafting of DMAEMA onto the inexpensive PP fibers by high electron beam irradiation graft polymerization,functionalization of quaternary ammonium with epichlorohydrin（ECH）,and Cr（VI）imprinting.The maximum adsorption capacity is 156.5 mg g^-1 at298 K;the removal rate>91.5%at p H 2–7,indicating that Cr（VI）-IIPs have a wide working p H range;the relative selectivity coefficients of Cr（VI）-IIPs for Cr₂O₇^2-/HPO₄^2-,Cr₂O₇^2-/NO₃^-and Cr₂O₇^2-/SO₄^2-were 36.7,39.9,1.49;simultaneously,it showed favorable stability and regeneration ability,which had a negligible change in adsorption capacity after at least five adsorption cycles.Polypropylene（PP）and polytetrafluoroethylene（PTFE）fibers with large specific surface area are used as substrates to synthesize surface imprinting materials with functional ligands through specific steps including grafting of acrylic acid（AA）onto the inexpensive fibers,then mesoporous silica gel is introduced,acid treatment,aminosilane treatment,chloroacetic acid substitution reaction,Pb（II）、Cd（II）imprinting and other steps.The imprinting materials were used for fast adsorption of heavy metal ions in wastewater.When p H value is 4,the Pb（II）-IIPs achieves the maximum adsorption capacity of Pb（II）;the equilibrium adsorption is achieved within 60 min;the process of adsorption fits with Langmuir isotherm model,and the equilibrium adsorption capacity of Pb（II）-IIPs toward Pb（II）is 49.9 mg g^-1 at 298 K;the Pb（II）-IIPs exhibits good selectivity toward Pb（II）,and the selectivity coefficients（k）of Pb（II）/Cd（II）,Pb（II）/Co（II）,Pb（II）/Ni（II）and Pb（II）/Zn（II）are much larger than1.When p H value is 6,Cd（II）-IIPs achieves the maximum adsorption capacity of Cd（II）;the equilibrium adsorption is achieved within 30 min;the Cd（II）-IIPs shows good selectivity toward Cd（II）,and the selectivity coefficient（k）of Cd（II）/Zn（II）,Cd（II）/Ni（II）and Cd（II）/Co（II）is 5.12-11.8.The material properties show that the preparation method has certain universality and has a good prospect in the preparation of heavy metal ion imprinted materials;the related results show that the preparation method will supply convincing support for the simple and universal multi-functional monomer imprinting strategy.The prepared three imprinted materials have good selectivity and are easy to separate from aqueous solution,which have good application prospects in selective removal of heavy metal.