Degradation of Rhodamine B Using Metal-Based Catalyst through Sulfite Activation with Oxalic Acid as a Chelating Agent
Keywords:
Rhodamine B, FeSO₄, Sodium Sulfite, Oxalic Acid, Wastewater Treatment, Advanced Oxidation ProcessesAbstract
Purpose: Synthetic dyes such as Rhodamine B (RhB) in textile effluents pose serious environmental and health hazards due to their toxicity, carcinogenicity, and resistance to biodegradation. Since conventional treatment methods often fail to achieve complete removal, this study aims to develop and evaluate an efficient, sustainable catalytic system for RhB degradation in wastewater.
Design/methodology/approach: RhB degradation was investigated using a metal-based catalytic system composed of ferrous sulfate (FeSO₄), sodium sulfite (Na₂SO₃), and oxalic acid as a chelating agent. The process relies on sulfite activation to generate reactive radicals (SO₄•⁻, SO₃•⁻, and •OH) that attack the chromophoric structure of RhB. Key operational parameters—catalyst dose, Na₂SO₃ concentration, oxalic acid addition, RhB loading, and pH—were systematically varied to determine optimal degradation conditions.
Findings: Under optimal conditions (FeSO₄ = 5 mM, Na₂SO₃ = 7 mM, oxalic acid = 3 mM, RhB = 5 mg/L, pH ≈ 5.9), the system achieved a maximum degradation efficiency of 90.3%. Oxalic acid stabilized the Fe²⁺/Fe³⁺ redox cycle through chelation, sustaining radical generation. The observed RhB degradation and decolorization demonstrated the effectiveness of the developed system for pol-lutant removal, without directly confirming complete mineralization or detoxification.
Originality: This study presents a novel, cost-effective FeSO₄/Na₂SO₃/oxalic acid advanced oxida-tion process (AOP) for dye wastewater treatment, offering a practical alternative to conventional methods, especially for textile-producing regions such as Pakistan.
Practical implications: The system offers a low-cost, scalable option for treating dye-laden industri-al effluents, supporting cleaner production practices in the textile sector.
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Copyright (c) 2026 Asghar Abbas, Ahmad Faraz Ali, Maria Sophy, Dr. Meesam Ali, Dr. Usman Saeed (Author)
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