Tailoring innovative adsorbents from discarded weathered basalt waste by calcination and activated carbon impregnation for efficient Fe (III) and Zn (II) remediation

Abstract

This study explores the potential of utilizing weathered basalt waste, discarded from basalt stone quarrying, as a resource for producing efficient adsorbents to remove Fe (III) and Zn (II) from aqueous and real wastewater. Raw weathered basalt (RWB), and its calcined derivatives at 750 °C for 3 h (CWB-750) and at 950 °C for 1 h with activated carbon impregnation (CWB/AC-950), were prepared and characterized. Characterization using XRD, FTIR, SEM, and surface area analyzer revealed that calcination improved porosity and surface area with some privilege for CWB/AC-950. CWB/AC-950 revealed remarkable removal efficiency for Fe (III) at a pH value of 5, achieving 98.30%, closely matching that of RWB (98.00%), and outperforming CWB-750 (96.20%). In contrast, RWB exhibited the highest removal capacity for Zn (II) at a pH value of 6, with an efficiency of 55%, surpassing both CWB-750 and CWB/AC-950, which achieved approximately 36%. For both contaminants, Pseudo-2nd-order equation (R² > 0.98) provided a superior fit, showcasing favorable sorption process by all the addressed materials. The Fe(III) sorption data for all the investigated materials were better described by the Freundlich (FL) model compared to the Langmuir (LM) model. Similarly, the Zn(II) sorption data for the calcined derivatives (CWB-750 and CWB/AC-950) were well-explained by the FL model. These findings are supported by the very high determination coefficients (R² > 0.96) and significantly lower average relative error (ARE) values (8.66 and 13.69) compared to those obtained from the LM model (55.99 and 189.25, orderly). In contrast, for RWB, despite the very high R² values (> 0.98) for both models, neither adequately captured the Zn(II) sorption behavior, as evidenced by the exceptionally high ARE values (52.67 and 161.19 for LM and FL, respectively). These findings are supported by the very high determination coefficients (R² > 0.96) and significantly lower average relative error (ARE) values compared to those obtained from the LM model. In contrast, for RWB, despite the very high R² values (> 0.98) for both models, neither adequately captured the Zn(II) sorption behavior, as evidenced by the exceptionally high ARE values (52.67 and 161.19 for LM and FL, respectively). The remediation mechanism of both Fe (III) and Zn (II) by all adsorbents was not exclusively governed by inter-particle diffusion. Eventually, these findings highlight the sustainable potential of repurposing RWB waste and its calcined derivatives for water remediation applications.