In this study, the Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 composite catalyst was synthesized by co-precipitation method. The morphology and the structure of Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 composites were characterized by XRD, FTIR, SEM, TEM, EDS, XPS, VSM. The results showed that the removal rate of RhB (10 mg/L) reached 99.5% in 40 min in the 0.4-Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 (200 mg/L) + PMS (50 mg/L) system with a pseudo first-order degradation rate constant (k) of 0.121 min −1 , which is nearly 2.16 times of that (0.0561 min −1 ) in the Co 3 [Co(CN) 6 ] 2 + PMS system and 18.9 times of that (0.0064 min −1 ) in the Fe 3 O 4 + PMS system. The observed synergistic catalysis between Fe 3 O 4 and Co 3 [Co(CN) 6 ] 2 in Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 enhanced the degradation of RhB. The electron paramagnetic resonance (EPR) analysis and quenching experiment indicated that SO 4 − and OH played important roles in the degradation process of RhB. A synergistic catalytic mechanism of PMS activation by Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 , which mainly involves the enhanced Co 2+ /Co 3+ cycle by Fe 2+ donated electrons, was proposed. In summary, owing to its easy preparation, excellent catalytic activity, and reusability, the Fe 3 O 4 /Co 3 [Co(CN) 6 ] 2 composite catalyst is a good candidate for remediation of contaminated water.
Peishan Li,Hui Ma,Sijia Qian,Yi Chen,Bo Lai,Shengyan Pu
Ferric sulfide is an appealing activator in persulfate (PS) activation process for degrading pollutants from aqueous environment, but the drawback of easy-agglomeration lead to a low utilization efficiency. In this study, we modified nFeS with sodium carboxymethyl cellulose (CMC) to improve its stability, and the performance for PS activation and p -nitrophenol (PNP) degradation is tested. After modification, the size further decreased from 23.8 to 18.4 nm, but with higher stability and catalytic reactivity. The CMC and nFeS is bonded by bidentate bridging of Fe-O bond. The degradation performance increased ∼7 times. The PS activation with CMC-nFeS activator shows higher reaction rate constant (0.093 min -1 ) with ∼90% of PNP removed compared to the pure nFeS with ∼80% of PNP removal at a low rate (0.014 min -1 ) with the same condition of 0.6 g/L activator, 8 mM PS, room temperature and initial pH in 90 min. Acidic condition and high temperature were more favorable for releasing Fe(II) to activate PS and produce active radicals. SO 4 - ·and HO·radicals played critical roles to attack on PNP. Detailed XPS analysis of the activator before and after reaction described the removal pathway as heterogeneous and homogeneous systems. Density Functional Theory (DFT) simulation results confirmed that CMC addition effectively decreased the interaction energy and improved adsorption ability of PS onto the activator surface.
Lu Gan,Qiang Zhong,Aobo Geng,Linjie Wang,Chi Song,Shuguang Han,Juqing Cui,Lijie Xu
We prepared carbon nanofiber (CCNF) using cellulose as the carbon source in this study and utilized for the first time as the support to enhance the catalytic performance of the cobalt ferrite (CoFe 2 O 4 ) for peroxymonosulfate (PMS) activation. The catalytic capability of the CoFe 2 O 4 /CCNF nanocomposites activated PMS was investigated through degrading dimethyl phthalate (DMP), a classical organic pesticide pollutant, in water media. The influence factors like CCNF content, nanocomposite and PMS dosage, DMP content, and pH value on the degradation speed were systematically investigated and analyzed. Since CoFe 2 O 4 is a spinel structured molecule which is magnetically separable, the reusability of the prepared CoFe 2 O 4 /CCNF nanocomposites under multiple cycles was also tested. Besides, the degradation intermediates during the catalytic process were also analyzed and identified by liquid chromatography-mass spectrometry (LC-MS) with a possible degradation mechanism. The results indicated that the prepared nanocomposite had promising catalytic capability in degrading DMP, in which the SO 4 − radicals played the main role as the active oxidation agent. Furthermore, the CoFe 2 O 4 /CCNF nanocomposites exhibited very good stability and reusability. The present study provides a clean biochar supported catalyst which could readily enhance the PMS activation efficiency for recycled decontamination of refractory organic pollutants in water media.
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