Sono-assisted Adsorption of As(V) from Water by Rice-Husk-Ash-Derived Iron-Modified Mesoporous Zeolite Y: A Cradle-to-Cradle Solution to a Problematic Solid Waste Material

Sono-assisted adsorption process is a clean, resourceful and rapid method for elimination of toxic species from water. Mesoporous zeolite Y (NaY) was synthesized from rice husk ash (RHA), using a three-step technique and then modified with iron using an ion-exchange method. As-synthesized NaY, iron-modified zeolite Y (IMZY), and commercial zeolite Y (CZY) were characterized by X-ray fluorescence (XRF) spectroscopy, X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) equipped with an energy-dispersive X-ray spectroscopy (EDX), and Brunauer-Emmett-Teller (BET) analysis. The EDX analysis implies the presence of iron in the structure of NaY. The swift sono-assisted adsorption of As(V) from aqueous solution was compared with conventional adsorption in the presence of all three adsorbents: NaY, IMZY, and CZY. The batch sono-adsorption technique was investigated using influenced parameters of solution pH (2-12), adsorbent dose (0.01-1.0 g/L), sonication time (0-90 min), and initial As(V) concentration (10-50 mg/L), based on the percentage of As(V) removal. The highest removal of As(V) was obtained as 40.31% by NaY, 99.90% by IMZY and 41.24% by CZY. The adsorption isotherms was best fitted with the Freundlich isotherm model, which indicates the multimolecular surface adsorption and pseudo-second-order kinetic model for all three adsorbents. The maximum adsorption capacities of NaY, IMZT, and CZY for As(V) were 3.38, 94.51, and 3.34 mg/g, respectively, for 0.5 g/L adsorbents. The batch experimentation results demonstrated that IMZY could be used for swift and effective removal of As(V), which are frequently existing in groundwater. The work also provides a cradle-to-cradle solution to address problematic solid-waste RHA.