Removal of Pb²⁺ Ions Using Rice Husk Ash and Metakaolin Based Geopolymer

Fatikhah Cahyani; Della  Arthamevia; Srie Muljani; Caecilia Pujiastuti; Ketut Sumada

Authors

Fatikhah Cahyani Universitas Pembangunan Nasional Veteran Jawa Timur Author
Della Arthamevia Universitas Pembangunan Nasional Veteran Jawa Timur Author
Srie Muljani Universitas Pembangunan Nasional Veteran Jawa Timur Author
Caecilia Pujiastuti Universitas Pembangunan Nasional Veteran Jawa Timur Author
Ketut Sumada Universitas Pembangunan Nasional Veteran Jawa Timur Author

Keywords:

geopolymer, rice husk ash, metakaolin, adsorption, Pb²⁺

Abstract

Heavy metal contamination in aquatic environments is a serious environmental issue due to its toxicity, persistence, and tendency to accumulate within living organisms. One promising approach to address this problem is adsorption using aluminosilicate-based geopolymers. This study aimed to evaluate the ability of rice husk ash and metakaolin-based geopolymers to remove Pb²⁺ ions and to investigate the effects of Si/Al molar ratio and NaOH concentration on geopolymer characteristics, removal efficiency, and adsorption capacity. Geopolymers were synthesized using rice husk ash as a silica source and metakaolin as an alumina source with varying Si/Al molar ratios and NaOH concentrations. The synthesized geopolymers were characterized using SEM-EDX and FTIR, while their adsorption performance was evaluated based on Pb²⁺ removal efficiency and adsorption capacity from Pb(NO₃)₂ solution. The results demonstrated that the geopolymer was successfully synthesized and showed potential as an effective adsorbent for Pb²⁺ removal. SEM-EDX and FTIR analyses confirmed the formation of an aluminosilicate structure and indicated that Pb²⁺ adsorption involved ion-exchange mechanisms and interactions with active functional groups on the geopolymer surface. Variations in the Si/Al molar ratio and NaOH concentration significantly affected the characteristics and adsorption performance of the geopolymer. The optimum adsorption condition was achieved at a Si/Al molar ratio of 4.2 and a NaOH concentration of 10 M, resulting in an adsorption capacity of 7.94 mg/g and a removal efficiency of 99.83%.

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