Incorporation of Iron (III) Oxide in Mesoporous Aluminosilicates from Lapindo Mud: Structural, Textural, and Surface Properties

Mesoporous aluminosilicate (MAS) is widely recognized as a versatile inorganic material due to its high surface area, tunable porosity, and the presence of Brønsted and Lewis acid sites originating from Si–O–Al bonds. Its structural and surface characteristics are strongly influenced by the homogeneity of Si–Al mixing, which can be effectively achieved through the sol–gel synthesis route. The pore architecture of MAS synthesized via the sol–gel method is affected by synthesis parameters such as pH during hydrolysis, gel aging, heat treatment temperature, and the Si/Al ratio.

The incorporation of metal oxides into the mesoporous aluminosilicate framework has been extensively explored to tailor its structural, textural, and surface properties. Metal oxides exhibit favorable characteristics, including outstanding chemical and thermal stability. Moreover, they can be modified to enhance the strength of MAS while reducing its inherent limitations. The combination of metal oxides with MAS produces synergistic effects, offering promising prospects in various applications, such as enhanced adsorption and catalysis. Among available metal oxides, iron(III) oxide (Fe₂O₃) is an attractive modifier due to its multiple oxidation states, surface reactivity, and ability to introduce additional Lewis acid sites. However, bulk Fe₂O₃ inherently exhibits a low surface area and a tendency to agglomerate, which limits its performance and accessibility when used alone. Incorporating Fe₂O₃ into MAS can significantly improve its dispersion and prevent agglomeration, while the porous MAS structure facilitates the distribution of iron species and promotes stronger interactions between the metal oxide and the aluminosilicate matrix.

Recent studies indicate that MAS can be synthesized from natural precursors rich in silica and alumina, including clays and various types of sludge. The use of natural resources provides an environmentally friendly and cost-effective pathway for producing aluminosilicate materials while enhancing the value of abundant local resources. Lapindo mud, originating from the mud and gas eruption at a hydrocarbon exploration drilling site in Sidoarjo, East Java, Indonesia, in 2006, contains significant amounts of silica and alumina and has been identified as a promising precursor for aluminosilicate synthesis.

The Department of Chemistry, Faculty of Science and Technology, Universitas Airlangga (UNAIR), through the Beginner Lecturer Research program, has synthesized mesoporous aluminosilicate from Lapindo mud using the sol–gel method and subsequently modified it with varying amounts of Fe₂O₃ via a simple wet impregnation method. This incorporation resulted in unprecedented improvements in structural, textural, morphological, acidity, and surface properties. These findings provide comprehensive insight into how Fe₂O₃ addition influences the physicochemical properties of MAS derived from natural precursors. The novelty of this research lies not only in the synthesis technique but also in the detailed analysis of the resulting nanocomposite properties. By exploring these innovative aspects, the researchers aim to contribute substantial advancements to the field of aluminosilicates and their composites, opening new possibilities for high-performance materials as catalysts in acylation or selective oxidation reactions, as well as adsorbents in various environmental applications.

Author: Qurrota A’yuni, S.Si., M.Si.

Source: https://www.sciencedirect.com/science/article/pii/S0167732225022846