Malachite green dye removal with aluminosilicate nanopowder from aluminum dross and silicomanganese slag

Abstract

Malachite green is a persistent, bioaccumulative, mutagenic, carcinogenic, and teratogenic dye that poses significant risks in water sources, making its removal from water a critical necessity. This study aims to fabricate a sorbent comprising amorphous aluminosilicate nanopowder utilizing silicomanganese slag (SMS) and secondary aluminum dross (SAD) waste materials to remediate dye-contaminated water. The silica and alumina components of the SMS and SAD were extracted as sodium silicate and sodium aluminate leachates, respectively, through an effective hydrometallurgical conversion process. An empirical formula of Al₂O₃·2.3SiO₂ was deduced from the X-ray fluorescence analysis of the synthesized material. The X-ray diffraction (XRD) pattern indicated the amorphous nature of the synthesized aluminosilicate, with no evidence of nanocrystals or ordered clusters observed via high-resolution transmission electron microscopy (TEM). Based on TEM micrographs, the aluminosilicate particles ranged in size from 20 to 80 nm. The synthesized aluminosilicate nanopowder was utilized to treat wastewater containing malachite green dye, demonstrating a remarkable dye removal efficiency of 97% after a 15-min contact time using 30 mg of adsorbent in a 30 mL dye solution at 200 rpm. The methodology proposed in this study could facilitate the production of amorphous aluminosilicate powder as a high-value product from industrial waste. Studies on its reusability demonstrated that it could remove over 90% of the dye after three cycles of use.