Magnetite-based pumice silica nanocomposite for lead adsorption from aqueous solution: The green synthesis approach

doi:10.1016/j.cjche.2025.01.013

Abstract

Abstract: Lead (Pb) is a toxic metal found in wastewater, posing significant health risks to both humans and the environment. This study aimed to develop a novel adsorbent for lead removal from aqueous solutions. This adsorbent, a coffee husk extract-capped magnetite with pumice silica nanocomposite (CHE-capped M/PU/Si-NC), was synthesized using a completely green approach. The novelty of this study lies in the green synthesis of silica nanoparticles (SiO₂-NPs) throughout the process. Coffee husk extract (CHE) served as both a stabilizing and capping agent for the SiO₂-NPs, which were synthesized from sodium silicate (Na₂SiO₃) extracted from bagasse ash (BA). Subsequently, the CHE-capped silica was co-precipitated with phyto-fabricated magnetite and integrated into a pumice matrix to produce the final CHE-capped M/PU/Si-NC adsorbent. The CHE-capped M/PU/Si-NC was characterized using SEM, XRF, FTIR, BET, XRD, TGA, and zeta potential analysis. The surface area of the CHE-capped M/PU/Si-NC was determined to be 313 m²·g^-1, and TGA results indicated good thermal stability up to 690 °C. The zeta potential was measured at -37.7 mV. XRD analysis of CHE-capped M/PU/Si-NC confirmed the formation of magnetite and revealed its crystal structure. The maximum adsorption performance of this material was observed to be 95% at an adsorbent dosage of 2 g·L^-1 and an initial Pb²⁺ concentration of 100 g·L^-1. The adsorption kinetics were best described by the pseudo-second-order kinetic model. The Langmuir isotherm provided a good fit with a maximum adsorption capacity of 150 mg·g^-1 (R² = 0.99). Regeneration studies demonstrated that the adsorbent maintained its high Pb²⁺ uptake capacity for up to five cycles. Overall, these findings suggest that this adsorbent is a promising candidate for the removal of Pb²⁺ from water and wastewater.

Key words: Adsorbent, Toxic metal, Nanomaterial, Bio-based, Phyto-fabrication, Water treatment

摘要： Lead (Pb) is a toxic metal found in wastewater, posing significant health risks to both humans and the environment. This study aimed to develop a novel adsorbent for lead removal from aqueous solutions. This adsorbent, a coffee husk extract-capped magnetite with pumice silica nanocomposite (CHE-capped M/PU/Si-NC), was synthesized using a completely green approach. The novelty of this study lies in the green synthesis of silica nanoparticles (SiO₂-NPs) throughout the process. Coffee husk extract (CHE) served as both a stabilizing and capping agent for the SiO₂-NPs, which were synthesized from sodium silicate (Na₂SiO₃) extracted from bagasse ash (BA). Subsequently, the CHE-capped silica was co-precipitated with phyto-fabricated magnetite and integrated into a pumice matrix to produce the final CHE-capped M/PU/Si-NC adsorbent. The CHE-capped M/PU/Si-NC was characterized using SEM, XRF, FTIR, BET, XRD, TGA, and zeta potential analysis. The surface area of the CHE-capped M/PU/Si-NC was determined to be 313 m²·g^-1, and TGA results indicated good thermal stability up to 690 °C. The zeta potential was measured at -37.7 mV. XRD analysis of CHE-capped M/PU/Si-NC confirmed the formation of magnetite and revealed its crystal structure. The maximum adsorption performance of this material was observed to be 95% at an adsorbent dosage of 2 g·L^-1 and an initial Pb²⁺ concentration of 100 g·L^-1. The adsorption kinetics were best described by the pseudo-second-order kinetic model. The Langmuir isotherm provided a good fit with a maximum adsorption capacity of 150 mg·g^-1 (R² = 0.99). Regeneration studies demonstrated that the adsorbent maintained its high Pb²⁺ uptake capacity for up to five cycles. Overall, these findings suggest that this adsorbent is a promising candidate for the removal of Pb²⁺ from water and wastewater.

关键词: Adsorbent, Toxic metal, Nanomaterial, Bio-based, Phyto-fabrication, Water treatment

Genet Tsegaye, Zebene Kiflie, Jemal Fito Nure, Abera D. Ambaye. Magnetite-based pumice silica nanocomposite for lead adsorption from aqueous solution: The green synthesis approach[J]. Chinese Journal of Chemical Engineering, 2025, 82(6): 281-293.

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