Investigation of Removing Basic Yellow 28 and Basic Blue 3 Dyes from Water Using Mulberry Leaves (Morus nigra L.) and Assessment of Ultrasonic Effects

Many industries release untreated synthetic dye effluents into water bodies, harming ecosystems and human health. Therefore, an economical and sustainable solution for treating dye-contaminated water must be developed. In this study, mulberry leaves (<i>Morus nigra</i> L.), as a cost-effective and sustainable adsorbent, were prepared to remove Basic Yellow 28 (BY28) and Basic Blue 3 (BB3) cationic dyes from industrial dye wastewater using adsorption. Batch experiments with key variables such as initial dye concentration, adsorbent dosage, contact time, temperature, stirring speed, and pH were conducted to find optimal conditions. The effectiveness of mulberry leaves as an adsorbent after multiple regeneration cycles was examined. The adsorbent was characterized through various instrumental methods, including FTIR, SEM, XRD, and BET analysis. Adsorption performance was analyzed using the Langmuir and Freundlich isotherm models. The results showed that the mulberry leaf adsorbent best fits the Langmuir model, with R² values of 0.999 for BY28 and 0.973 for BB3. The maximum adsorption capacities were 0.15 mg/g for BY28 and 7.19 mg/g for BB3, indicating their upper limits for dye uptake. The optimal conditions achieving removal efficiencies of over 99% were 1.5 g, 50 mL, 15 min, 180 rpm, and 10 mg/L at 30 °C for BY28 in neutral pH (7) and 1.5 g, 50 mL, 45 min, 100 rpm, and 30 mg/L at 40 °C for BB3 in basic pH (10). The regeneration of mulberry leaves as an adsorbent through acid treatment with 0.1 M HCl and 0.1 M CH₃COOH solutions maintained a high performance, achieving up to 98% dye removal efficiency after two regeneration cycles. It has been observed that successful results can be achieved in terms of reusability. Additionally, the removals of BB3 and BY28 performed in an ultrasonic-bath-assisted environment successfully achieved removal efficiencies of 84.87% and 75.41%, respectively. According to the results, mulberry leaves can effectively be used in wastewater treatment to remove dyes, can be reused multiple times, and thus serve as an environmentally friendly and sustainable adsorbent.