Efficient and enhanced Hg 2+removal from water using a thio functionalized fibrous adsorbent prepared with microwave irradiation: Batch and fixed -bed column study

In this study, a thio functionalized polyacrylonitrile (PAN) fiber was promptly prepared with microwave irradiation which exhibited high removal efficiency for Hg2+. The modified fiber (PAN(MW)-Thio) was synthesized by initially cross-linked with diethylenetriamine and then further reacted with Na2S to introduce thio ligands onto the interface of PAN fiber. Following characterization of PAN(MW)-Thio fiber were performed by XRD, FTIR, SEM and elemental analysis. The Hg2+ uptake performance by modified fiber prepared with MW irradiation was compared with that of conventional heating in terms of adsorption kinetics, adsorption isotherm and adsorption thermodynamics. The results revealed that PAN(MW)-Thio exhibited much higher adsorption amount for Hg2+ with the maximum uptake amount of 357 mg/g. Moreover, multiple operation parameters in the dynamic adsorption test were also investigated, and the maximum adsorption amount of PAN(MW)-Thio fiber was obtained at initial Hg2+ concentration of 100 mg/L, bed height of 15 cm and 10 mL/min flow rate, respectively. Dynamic experiment results also proved that the capacities of PAN(MW)-Thio fiber improved when initial concentration and bed height increased and flow rate decreased. Furthermore, the Thomos, Yoon-Nelson and BDST models were utilized to analyze experiment data, while Thomas model exhibited best fitness with the breakthrough curves. Finally, the regeneration ability of PAN(MW)-Thio fiber in column was studied using 0.05 M HCl as the desorption eluent and the adsorption capacity remained well after five reuse cycles. This rapid preparation method and good adsorption performance of prepared adsorbent promise a new solution for Hg2+ pollution remediation in water.