Removal of Triphenylmethane Azo Dye by Immobilized Fungus: A Comparative Study with Physical Adsorption Processes
摘要
Malachite green, a triphenylmethane azo dye used for dyeing, is resistant to fading upon exposure to water and light. It must be eliminated from industrial effluent before environmental release. This study applied physical adsorption and bioremediation for malachite green decolorization. Physical adsorption used sugarcane bagasse as an adsorbent, while bioremediation used laccase-producing white-rot fungus, Trametes pubescens MB 89. Physical desorption using 0.5% sugarcane bagasse removed 91.65% malachite green in 40 min at 30 °C, but the dye was continuously desorbed. Free T. pubescens cells produced 556 IU mL−1 laccase and decolorized 51.65% malachite green. The fungus was then immobilized on coconut coir. Scanning electron microscopy revealed immobilized fungal mycelia on coconut coir surfaces. Factors affecting dye degradation by immobilized fungus were optimized using a Central Composite design. Under optimized conditions (30 °C, 59.5 h, 60 ppm dye concentration), 100% of malachite green was decolorized by immobilized T. pubescens MB 89. Recyclability assay showed the immobilized fungus remained effective for up to 12 cycles, with > 96% malachite green decolorization. Microbial toxicity assay showed fungal-treated malachite green solution did not affect Saccharomyces cerevisiae growth. This study demonstrates coconut coir’s potential as an immobilization matrix for azo dye degradation processes.