Study on treatment of acid red G with bio-carbon compound immobilized white rot fungi

Corn straw biochar was used as a carrier to immobilize white rot fungi and the removal performance of immobilized pellets for acid red G (ARG) dye was studied. The results showed that the removal rate of ARG could reach 96.17% under the best preparation conditions of immobilized pellets (3% sodium alginate concentration, 0.7% corn straw biochar, 5% white rot fungus mycelium suspension, 4% CaCl₂, and 36 h immobilization time). The orthogonal test results showed that the best combination was the immobilized pellets dosage of 200/100 mL, pH of 4.5, rotation speed of 150 r/min, and initial concentration of 20 mg/L dye at 30 °C. The degradation pathway of ARG by immobilized microspheres was studied by ultraviolet-visible spectrometer, Fourier transform infrared spectroscopy, and liquid chromatography-mass spectrometry. The results showed that ARG was degraded into aniline and 5-(acetamino)-4-hydroxy-3-amino-2,7-naphthalene disulfonic acid. Aniline was further deaminated to form benzene, and benzene was ring opened to form other organic compounds; 5-(acetylamino)-4-hydroxy-3-amino-2,7-naphthalene disulfonic acid was dehydroxylated to form 5-(acetylamino)-3-amino-2,7-naphthalene disulfonic acid. This study shows that the prepared biochar immobilized pellets can be used as an efficient water treatment material to remove ARG dye from wastewater.