Fluoride contamination of groundwater is a persistent problem in the Indian Peninsula and also in many parts of the world. Zirconium oxide-impregnated polymers have demonstrated promising fluoride removal capacity; however, their restricted operating range of pH and interference from co-existing anions invariably limit the feasibility of field application. To obviate the problem, a strong-base polymeric anion exchanger (INDION 830S) was modified with the impregnation of dual metal (Zr and Mn) hydroxide nanoparticles. The synthesized resin (HAIX/Mn-Zr) demonstrated preferential fluoride capture in the presence of competing anions in the pH range of 4.5–5, with the point of zero charge measured at pH around 5.1 and a good removal efficiency of 80.7 % up to pH 6.0. Adsorption of fluoride by HAIX/Mn-Zr followed the Freundlich isotherm model and the pseudo-second-order kinetics. The maximum fluoride adsorption capacity was 28.1, 29.7, and 31.5 mg/g at 20, 30, and 40 °C temperatures, respectively. The adsorption process was endothermic, exhibiting an activation energy of 12.61 kJ/mol, a negative Gibbs free energy, and a positive enthalpy change. Fourier-transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis indicated chemisorption of fluoride onto HAIX/Mn-Zr, while X-ray diffraction (XRD) confirmed its amorphous structure. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS) revealed a visible morphology change after the loading of Mn (2.2 wt%) and Zr (21.8 wt%). The column study demonstrated that around 2000 bed volumes of contaminated water were treated before the breakthrough of 1.5 mg/L of fluoride. Overall, the HAIX/Mn-Zr is a low-cost sorbent with a facile synthesis and regeneration procedure, reusability up to five cycles, and high fluoride removal efficiency, indicating its high potential for the defluoridation of contaminated groundwater.
扫码关注我们
求助内容:
应助结果提醒方式:
