Weirui Chen,Yixiang Bao,Xukai Li,Jun Huang,Yiming Tang,Laisheng Li
Mesoporous Fe-Cu@SiO 2 core-shell catalyst was synthesized and assessed for its catalytic activity in the ozonation of salicylic acid (SA). The synthesized catalyst was characterized by XRD, TEM, SEM, XPS, H 2 -TPR, etc. Fe-Cu@SiO 2 exhibited a regular spherical shape and had the surface area at 1216 m 2 g −1 . The wrapping of metal components and their strong interaction prevented metal leaching. Fe-Cu@SiO 2 showed the highest activity for SA mineralization when compared with Fe@SiO 2 and Cu@SiO 2 . In Fe-Cu@SiO 2 /O 3 , 88% TOC was removed, which was 2.5 times as much as that in sole ozonation. SA degradation efficiency in Fe-Cu@SiO 2 /O 3 increased with initial pH. O 3 , ·OH and H 2 O 2 were the main reactive oxygen species accounting for SA mineralization. Due to their scavenging effect of ·OH, NH 4 + , NO 3 − and humic acids would inhibit the degradation efficiency of Fe-Cu@SiO 2 /O 3 . Acidic sites, oxygen vacancies and the Fe-Cu(I/II) electron transfer were responsible for ozone decomposition and ·OH generation. SA mineralization proceeded through the ·OH mechanism. Moreover, SA mineralization in O 3 and Fe-Cu@SiO 2 /O 3 both exhibited a two-stage pseudo first-order kinetics (stage I: 0–45 min; stage II: 45–120 min). The degradation intermediates were detected to investigate the reaction pathway. ORP and EEM were used to monitor the degradation process. Great difference was found for carboxylic acids accumulation in O 3 and Fe-Cu@SiO 2 /O 3 . The accelerated removal of oxalic acid and humic acid-like intermediates were responsible for the two-stage pseudo first-order kinetics.
To harmlessly treat and effectively utilize manganese residue (MR), a novel MR-based catalyst, mechanical activation (MA)-pretreated MR-derived Fe-Cu@SiO 2 /starch-derived carbon (MAMR-Fe-Cu@SiO 2 /SC) composite, was prepared through a facial method by reduction roasting of MA-pretreated precursors. The prepared catalysts were systematically characterized to explore the formation and catalytic activities. The results showed that the formation of CuFeO 2 anchored on the MR could be ascribed to the close contact and mutual diffusion between solid components caused by MA, and the higher specific surface area, strong interaction of Fe-Cu and more accessible reactive sites of MAMR-Fe-Cu@SiO 2 /SC contributed to the greater catalytic activity in photo-Fenton system for tetracycline (TC) degradation. The MAMR-Fe-Cu@SiO 2 /SC catalyst showed excellent degradation efficiency at pH range of 2.5–9.5, and about 100% TC removal in 40 min and 85.6% TOC removal in 120 min could be obtained. The MAMR-Fe-Cu@SiO 2 /SC exhibited the highest apparent reaction rate constant of 0.066 min –1 , being about 4.0, 2.8, and 2.2 times that for the catalyst of Cu/SC, MAMR-Fe 3 O 4 @SiO 2 /SC and MR-Fe-Cu@SiO 2 /SC, respectively. This enhancement could be attributed to that anchored Cu could accelerate the charge transfer, and short the reaction pathway between photo and Fenton reaction. XPS results showed that the presence of Fe 2+ -Fe 3+ , Mn 2+ -Mn 3+ and Cu + -Cu 2+ cycles were responsible for the radical generation on the surface of the catalyst. This environmentally-friendly method for the preparation of composite catalysts may provide new insights for harmless fixed treatment and valorization of MR and large-scale production of catalyst.
危险品化学品经营许可证（带存储）