Efficient removal of refractory dyestuffs from textile wastewater by composite hydrated alumina derived from waste aluminum polishing solution

Abstract

The present investigation is aimed at fabricating a cheap and efficient adsorbent for the removal of refractory dyestuffs from wastewater. By using waste aluminium polishing solution as the raw material, a composite hydrated alumina (CHA) was successfully prepared and its properties were characterized by the methods of FTIR, SEM, EDS, BET, TGA, and XPS. It was shown that the resulting two-layer adsorbent exhibits a flower-like shape, in which, alumina acts as the core and the surface is modified by phosphate groups and hydrogen bonds in the outer layer. Various functional groups on the surface provide multiple interactions with anionic dyestuffs such as Congo red (CR) and Reactive blue (RB). However, due to the contained N- double bond in the molecular structure in CR, the adsorbent exhibits an especially excellent selectivity and adsorption capacity for the removal of CR, which is caused by the formation of the hydrogen bonds between the hydroxyl groups of CHA and the azo and aromatic rings in CR molecule. The obtained results provide a novel approach to remove refractory organic pollutants from wastewater by using a cheap adsorbent derived from industrial waste.