Methylene blue removal on nano-Fe₃O₄/poly(vinyl alcohol)/polyacrylamide hydrogel

This paper reports the preparation of nanosized iron (II,III) oxide (Fe₃O₄) and iron (II,III) oxide-impregnated poly(vinyl alcohol)/polyacrylamide (iron (II,III) oxide-im-PVA/PAM) hydrogel by insitu polymerisation technique. Thus, prepared hydrogels have been characterised by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction techniques. The effects of iron (II,III) oxide impregnation and PVA grafting on the physical properties (such as swelling, absorption, bulk density and porosity) of the PAM hydrogel were studied. Further, obtained hydrogel was explored for removal of methylene blue from laboratory prepared water sample. The methylene blue removal efficiency of iron (II,III) oxide-im-PVA/PAM hydrogel was studied as a function of pH, time and adsorbent dose. The result reveals the improvement in dye removal capacity of hydrogel due to impregnation Fe₃O₄ in hydroegel matrix. The adsorption isotherms of the nanocomposite hydrogel could be described well by the Langmuir isotherm equation. On the basis of obtained results a possible removal mechanism is proposed along with regeration possibilities of hydrogel.