Fe loaded mesocellular silica foam: role of acid and 1,3,5-trimethylbenzene concentrations on the catalyst and its performance in the degradation of acid red B

摘要

Various mesocellular foam silica based materials were successfully synthesized by varying acid (HCl) concentration and 1,3,5-trimethylbenzene (TMB) dosage and the surface and textural characteristics of the resulting materials were elucidated. TEM images demonstrated that the combination of low TMB dosage (0.5 g) and high HCl concentration (2.5 M) assigned as MCFA led to the formation of multilamellar vesicle structures that showed large pore diameters (7-8 nm) with lengthy channels. Meanwhile, the combination of low HCl concentration (0.5 g) and medium range of TMB dosage (2.0 g) assigned as MCFB produced silica supports with worm-like structures that had small pore diameters (4-5 nm) and short mesochannels. However, when high TMB dosage (3.0 g) was combined with medium concentration of HCl (1.5 M) to produce MCFC, the material had large pore diameter (6 nm) and large pore volume and surface area (1.833 cm(3)/g, 740 m(2)/g). It was obtained with the formation of foam-like structures that resembled mesostructured cellular foam. All the synthesized silica supports were then loaded with 5.4 wt% of Fe and their catalytic performance was tested based on the degradation of ARB dye at different initial concentrations (25, 50 and 100 mg/L) via Fenton-like process. Fe-MCFA and Fe-MCFC showed high degradation of ARB for all the concentrations tested. Meanwhile, Fe-MCFB catalyst demonstrated high degradation efficiency at 25 mg/L and slowly decreased when the initial concentration of dye was increased to 50 and 100 mg/L. The best performance was shown by Fe-MCFC that demonstrated both high catalytic activities (100 % decolourisation and 92 % COD removal) under a wide range of ARB dye concentrations (25-100 mg/L). The performance was attributed to the unique structure and large pores that enabled the reaction process to occur effectively regardless of the initial concentration of ARB dye. Fe-MCFC showed the least leaching of Fe into the solution (< 0.5 mg/L) as well as high reusability and stability (could maintain 100 % decolourisation for up to three cycles). The least leaching of Fe was shown by Fe-MCFC and it could be attributed to the microenvironment of the catalyst.