Microwave-Assisted Synthesis of Bismuth Silicate (Bi2SiO5) from Natural Tunisian Sand for Efficient Solar Photocatalytic Degradation of Rhodamine B

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The contamination of aquatic environments by synthetic dyes such as Rhodamine B (RhB) represents a growing environmental and public health concern. In this work, a bismuth silicate composite (Bi2SiO5) was successfully synthesized via a rapid microwave-assisted co-precipitation route using silica extracted from natural Tunisian sand as a sustainable and low-cost precursor. The material was systematically characterized by XRD, FTIR, UV-Vis DRS, SEM, TEM, and EDX analyses, revealing a highly crystalline orthorhombic structure with an average crystallite size of 57.1 nm (Debye–Scherrer), primary particle dimensions of approximately 43.1 nm, and an optical bandgap of 2.74 eV. Under simulated solar irradiation, Bi2SiO5 achieved near-complete decolorization (≈ 99 %) of RhB within 15 min and a significant Chemical Oxygen Demand (COD) removal efficiency of 75 % after 50 min, demonstrating substantial organic scaffold breakdown. Non-linear Kinetic analysis revealed that RhB degradation followed pseudo-first order (PFO) kinetics (k1 = 0.142 min-1, R2 = 0.962). Radical Scavenger experiments identified •OH and •O2- as the dominant reactive species, with h+ playing a secondary role, indicating a radical-mediated oxidative degradation mechanism. Bi2SiO5 demonstrated good reusability over five consecutive cycles, retaining 95% RhB removal efficiency after the fifth run. These findings establish Bi2SiO5 as a promising, eco-friendly photocatalyst derived from abundant natural resources for solar-driven wastewater remediation. Copyright © 2026 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

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