One-Pot Synthesis of High Surface Area Nano-Akaganeite Powder and Its Cation Sorption Behavior

A one-pot novel facile synthesis of a high surface area nanoakaganeite (β-FeOOH) involving formation of a chelate as the precursor has been described. Ferric chloride solution mixed with ethylenediaminetetraacetic acid (EDTA) solution was heated to 90 °C followed by neutralization with ammonia to obtain a pH of 9, and the precipitate was stirred for half an hour. The precipitate was filtered, washed, and dried at 90 °C. Chemical, X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman analyses confirmed the sample to be akaganeite. Transmission electron microscopy (TEM) studies showed the formation of monophase cigar-shaped akaganeite nanorods of (15 to 20) nm in width and (80 to 100) nm in length. The surface area obtained by the Brunauer−Emmett−Teller (BET) method was 176.16 m 2 ·g −1 . The nanopowder so obtained was used to generate sorption data for the removal of Pb(II), Cd(II), Cu(II), and Co(II) from aqueous solutions. The relative importance of experimental parameters such as solution pH, contact time, temperature, and concentration of adsorbate on the uptake of various cations was evaluated. The sorption kinetics followed a pseudosecond-order model. Both Langmuir and Freundlich models fitted the isothermic data of all of the cations well. High Langmuir monolayer capacities of (∼163.9, 70.4, 80, and 98) mg·g −1 were obtained for Pb(II), Cd(II), Co(II), and Cu(II), respectively. The XRD patterns of Pb(II)-, Co(II)-, and Cu(II)-loaded samples showed positive shifts in d -values for the three main planes, that is, (110), (200), and (311) of akaganeite, while Cd(II)-loaded sample showed a negative shift in d -values of the (110) and (400) planes, indicating a disturbance in the internal structure during sorption.