Effect of Calcium-Modified Alginate/Amorphous Co₃O₄ Nanoparticles for Photocatalytic and Fenton-Like Degradation of Methylene Blue

Yap, Zhi Qing (2026) Effect of Calcium-Modified Alginate/Amorphous Co₃O₄ Nanoparticles for Photocatalytic and Fenton-Like Degradation of Methylene Blue. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Methylene blue (MB), a widely used cationic dye in industrial applications, poses significant environmental concerns due to its toxicity and resistance to biodegradation. In this study, alginate-stabilised amorphous cobalt oxide nanocomposites were synthesised via a room-temperature NaBH₄ reduction method and further modified through calcium incorporation to enhance structural and catalytic properties. Various catalyst formulations, including 0.5%-SA/Co₃O₄, 3%-SA/Co₃O₄, 3%-SA/CaCl2/Co₃O₄, and 3%-SA/Ca(OH)₂/Co₃O₄, were prepared and systematically evaluated. The catalysts were evaluated under both UV-C photocatalytic and H₂O₂-assisted Fenton-like conditions. Under UV-C irradiation, the catalysts demonstrated effective MB degradation, where the 3%-SA/Ca(OH)₂/Co₃O₄ catalyst achieved ~55.23% removal with only a 10 mg dosage, while ~67.90% removal was achieved using 30 mg of the 3%-SA/CaCl2/Co₃O₄ catalyst, confirming the photocatalytic activity of Co₃O₄. In Fenton-like conditions, the 3%-SA/Ca(OH)₂/Co₃O₄ system exhibited the highest degradation efficiency, achieving approximately 90.2% removal within 30 minutes under Fenton-like conditions, while the Ca²⁺-crosslinked system achieved moderate performance (~76.3%). In contrast, the uncrosslinked system showed poor stability, with an apparent increase in MB concentration due to dye release from structural degradation of the alginate matrix. Characterisation studies indicated that calcium incorporation improves catalytic activity by enhancing surface properties and facilitating redox reactions, although it compromises structural integrity under reaction conditions, leading to reduced magnetic recoverability. The results highlight that catalyst performance is strongly influenced by composition, structural stability, and the balance between catalytic activity and material integrity. Overall, this study demonstrates the potential of calcium-modified alginate–cobalt oxide nanocomposites as effective catalysts for dye degradation, while emphasising the importance of structural design in achieving both high efficiency and practical recoverability.