Degradation of Rhodamine B by persulfate activation with iron-loaded biochar

Conventional wastewater treatment is inefficient in removing Rhodamine B (RhB) from dying wastewater. Wastewater treatment is a promising advanced oxidation process (AOP) based on biochar and iron-activated persulfate. Therefore, the current study explored the potential of iron-loaded biochar-activated persulfate to remove RhB. Based on morphology observation, iron-loaded biochar could be successfully prepared using slow pyrolysis inside an N-2 environment at 800 degrees C. Structure analysis revealed that the surface area of iron-loaded biochar was 1.5 times the size of unmodified biochar. Under the optimum reaction condition, the maximum removal rate of RhB was 99.96%, determined by single-factor experiments. The RhB removal rate was improved with increased activator dosage, PS dosage, and temperature but decreased with increased pH and initial dye concentration. The RhB adsorption rate was governed by pseudo-first-order reaction kinetics, and the Langmuir-Hinshelwood kinetic model (R-2 = 0.99853) helped explain the adsorption behavior. Recycling experiments of Fe-BC indicated a twice-cycle capacity which could be improved. Free radical quenching experiments showed that sulfate-free (SO4 center dot-) and hydroxyl ((OH)-O-center dot) radicals worked together in the RhB removal process, dominated by (OH)-O-center dot.