Simultaneous removal of manganese and cadmium ions by graphene oxide nanocollector: Optimization and mechanism study of ion flotation

Abstract

Heavy metal contamination by manganese and cadmium ions from industrial sources poses a significant environmental threat. This study introduces a highly efficient method for their simultaneous removal from wastewater employing graphene oxide (GO) as a novel nanocollector in the ion flotation process. The research optimized key operational parameters, identifying optimal conditions as pH=10, GO = 25 ppm, and Hexadecyltrimethylammonium Bromide (HTAB) = 25 ppm. Under these conditions, the process achieved superior removal efficiencies: 91.83% for Mn and 90.64% for Cd, with an acceptable water recovery of 28%. The mechanism investigation revealed that the high removal efficiency at pH=10 is driven by the deprotonation of GO’s surface functional groups, resulting in a strong electrostatic attraction and surface complexation with the dominant positive metal species ([Mn₂(OH)₃]⁺, Cd²⁺, and [Cd (OH)]⁺). Characterization via FTIR confirmed the formation of metal-oxygen (Mn-O, Cd-O) bonds, and SEM-WDX verified the successful co-adsorption of both metals’ ions onto the GO sheets. This GO-assisted ion flotation technique provides an eco-friendly and cost-effective strategy for effectively mitigating manganese and cadmium pollution, demonstrating significant potential for industrial wastewater treatment applications.

Keywords

graphene oxide / ion flotation / heavy metal removal / manganese / cadmium

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