Removal of Heavy Metals from Industrial Acidic Effluents Using Electroless Plating

Acid mine drainage (AMD) is one of the biggest issues faced by the mining and mineral processing industries in terms of removing heavy metals from the effluents. The present study investigated the effects of glyoxylic acid, hydrazine and dimethylamine borane as reducing agents and the effect of using Ni, Fe, basic oxygen furnace slag (BOFS) and granulated blast furnace slag (GBFS) as seeding materials to remove metals from acidic effluents respectively. The experiments were conducted using acidic mine effluent in a 0.5 L batch reactor using different seeding materials and reducing agents respectively. The study is the first of its kind to examine and compare all four seeding materials using different reducing agents respectively. X-ray diffraction (XRD) patterns, scanning electron microscope (SEM), and a Fourier Transform Infrared (FTIR) spectrometer were used to analyse the seeding material before and after Electroless plating.. The study suggests that BOFS is a effective seed together with hydrazine reducing agent that yielded a 99.9% removal of Fe (III), whilst Ni and Fe powder failed to seed effectively. During reduction precipitation, nucleation and breakage were identified as the predominant particulate processes based on particle size distribution (PSD) evolution and its moments. There were significant mineral phases formed, such as bownmillerites Ca₂(Al, Fe)₂O₅, which formed by replacing Si with Al and Fe in all tetrahedral coordinations between Al, Fe and Si, suggesting chemisorption being a dominant mechanism.