Nanobioparticle-prepared biochar enhanced Fenton oxidation for treatment of saline organic wastewater†

Abstract

Fenton oxidation technology is an effective pretreatment method for saline organic wastewater, yet it suffers from issues such as low hydrogen peroxide utilization efficiency, large dosages of reagents and sludge production, high-cost operation, and potential secondary pollution. This study aims to enhance the Fenton oxidation treatment of saline organic wastewater using nanobioparticle-prepared biochar in a traditional Fenton system to address these shortcomings. Initially, nano-bioparticles of FeS were synthesized using Bacillus cereus and carbonized at 700 °C under the protection of argon to produce biochar, which was characterized by SEM, EDS, and XRD. Subsequently, the efficiency and optimal operational conditions of the enhanced Fenton system for treating saline organic wastewater were investigated. Results indicated that the optimal dosage of biochar was 0.1 g L⁻¹, with a reagent ratio (mass ratio) of COD : Fe²⁺ : H₂O₂ = 1 : 1 : 0.8, pH = 3, and a reaction time of 40 minutes. Under these conditions, the COD removal efficiency of the enhanced Fenton system reached 50.5%, showing a significant improvement compared to the traditional Fenton system (38.8%). Finally, the mechanism of strengthening the Fenton reaction by FeS nano-biochar was explored from four aspects: ·OH generation, H₂O₂ consumption, Fe(II) to Fe(III) conversion, and redox capability. The study demonstrated that FeS nanoparticles could activate molecular oxygen to produce ·O₂⁻, promote Fe(II)/Fe(III) cycling, indirectly enhance ·OH generation from H₂O₂, reduce its ineffective decomposition, and utilize the electronic conductivity of biochar to enhance the system's redox capability, thereby improving the COD removal efficiency of the enhanced Fenton system for saline organic wastewater. This research advanced the operational cost and treatment efficiency of traditional Fenton technology, providing parameters and scientific foundations for accelerating the practical application of novel enhanced Fenton technology in treating refractory industrial wastewater.