Design And Application Of Modified PAN-based Ion Exchange Fiber

The intensification of water pollution has seriously affected human health.Various water treatment technologies such as adsorption method,advanced oxidation method,membrane separation method and biological treatment method have been applied to treat practical wastewater.The adsorption as one of the simplest and most efficient methods which has an unique advantage in removing refractory pollutants and heavy metals.PAN-based ion-exchange fiber has attracted much attention because of its high adsorption rate,high adsorption efficiency,good chemical stability,many times of recycling and wide application form.In this work,PAN-based fibers were prepared by a simple and low cost method.The modified PAN-based ion exchange fibers were firstly fabricated by amination with the aid of hydrazine hydrate,and then hydrolyzed by supplying potassium iodide in alkaline solution.The modified ion exchange fibers were applied to methylene blue（MB）and reactive brilliant red（X-3B）dye wastewater and heavy metal wastewater adsorption,respectively.The results demonstrate that the modified ion exchange fibers greatly improves their adsorption capacity toward cationic dye wastewater and heavy metal ions.The adsorption amount of MB which is cationic dye was about 94.12 mg/g while the adsorption capacity of X-3B was low.Moreover,the adsorption rate of Cu²⁺and Pb²⁺for heavy metal ions of 20mg/L was above 99%.Compared to the commercial ion exchange fibers,the ion exchange fibers prepared by in this study exhibit the enlargement of the adsorption capacity of cation dyes with 3⁵ times and the adsorption capacity of heavy metal ions with 5⁷ times.At the same time,the results demonstrate that the PAN-based ion-exchange fibers prepared by the modified method possess good temperature resistance and wide pH range.The stability and reusability of PAN-based ion exchange fibers were evaluated with a recycling test,the results illustrate that high adsorption activity was achieved even after 11 times,the adsorption rate is still more than 95%.It is proved that the modified PAN-based ion exchange fiber has good reproducibility,which can ensures the low cost of wastewater treatment and requirement of stability during industrial process.The adsorption mechanism of the modified fiber was also revealed.It was confirmed that the adsorption process was in accordance with Langmuir adsorption isotherm and pseudo second order kinetic model,and the adsorption process was endothermic.