Boosted sono-oxidative catalytic degradation of Brilliant green dye by magnetic MgFe2O4 catalyst: Degradation mechanism, assessment of bio-toxicity and cost analysis

• Published in: Ultrasonics sonochemistry 2021-07, Vol.75, p.105592, Article 105592
• Main Authors: Bose, Saptarshi, Kumar Tripathy, Binay, Debnath, Animesh, Kumar, Mathava
• Format: Article
• Language: English
• Subjects: Brilliant green dye; Cost analysis; MgFe2O4 nanoparticles; Optimization; Original; Persulfate oxidation; Sono-catalysis; Toxicity assessment
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2021.105592

[Display omitted] •Magnetic MgFe2O4 nanoparticles were used in sono-oxidative degradation of Brilliant Green dye.•BG dye degradation of 91.63% and COD removal of 90.31% were achieved at optimum experimental conditions.•Treatment cost was found to be 140 $/kg of BG dye removed at optimum conditions.•BG molecule (M/Z ratio 385) degraded into simpler fractions with M/Z ratio of 193, 161, 73, and 61.•Inhibition toxicity level of BG dye reduced from 93.9% to 5.13% after treatment. The magnetic MgFe2O4 nanoparticles (NPs) were fabricated via a facile co-precipitation technique and was comprehensively characterized by XRD, FTIR, SEM, EDX and VSM. The prepared NPs were used as catalyst in presence of ultrasound (US) irradiation to activate persulfate (PS) for generation of sulfate radicals (SO4·-) for boosted degradation of toxic Brilliant Green (BG) dye. Preliminary experiments revealed that highest BG dye degradation efficiency of 91.63% was achieved at MgFe2O4 catalyst dose of 1.0 g/L, PS dose of 300 mg/L, and initial dye concentration of 70 ppm within 15 min of US irradiation. However, only US, US in presence of PS oxidation and US in presence of MgFe2O4 catalyst have shown 20.2%, 83.6% and 45.0% of BG dye removal, respectively. Furthermore, response surface methodology (RSM) based central composite design (CCD) was executed to investigate the effect of interaction between independent variables such as MgFe2O4 catalyst dose (0.5–1.5 g/L), PS dose (150–350 mg/L), initial BG dye concentration (50–150 ppm) and US irradiation time (4–12 min). The RSM based quadratic model was used to predict the experimental data, and the prediction accuracy was confirmed by analysis of variance (R2 = 0.98). The established RSM model has predicted the optimum experimental conditions as MgFe2O4 catalyst dose of 0.75 g/L, PS dose of 300 mg/L, initial dye concentration of 75 ppm and sonication time of 10 min. Subsequently, the treatment cost analysis was performed for all thirty experimental runs of CCD, and the RSM predicted response was found to be evidently optimum as this has delivered best economic condition (140 $/kg of BG removed) with respect to relative dye removal (%). COD removal and residual sulfate analysis have demonstrated satisfactory reduction of COD (90.31%) as well as sulfate ions (42.87 ppm) in the dye solution after treatment. Results of degradation pathway analysis portrayed the transformation of BG molecule (M/Z ratio 385) into simpler fractions with M/Z ratio