Oxidative Treatment of Rhodamine B Solution on CoOx/sepiolite Catalysts

Abstract

Sepiolite loaded with different cobalt oxide contents has been prepared by the precipitation method followed by calcination at 410ºC. The synthesized Co-loaded samples were characterized by physical methods using XRD, SEM, BET, and H2-TPR. The obtained solids have a large specific area and good distribution of cobalt oxide nanoparticles on sepiolite carrier. The catalysts were tested for the oxidative removal of rhodamine B solution and found that 1.0 – 3.0 wt.% cobalt ion/sepiolite samples exhibited the highest decoloration efficiency of rhodamine B (88-90%) in the presence of hydrogen peroxide at room temperature after the treatment of 30 mg/L of RhB solution in 210 minutes.

Preparation of CoOx/magenium silicate for the liquid oxidation of benzyl alcohol

“…This indicates an important role of CoOx component in the oxidation of benzyl alcohol with TBHB. As compared with previeous results [4,[8][9][10], sepiolite-loaded CoOx system is more active than MnOx, CuO, NiO-supported catalysts under the same oxidation conditions. Furthermore, CoOx/sepiolite is selective production for benzaldehyde product with a high selectivity degree (Fig.…”

“…CoOx/seopiolite catalysts were prepared by the precipitation of cobalt nitrate in basic environment [8]. In experiment, cobalt(II)nitrare (Sigmal-Aldrich, 99%) and sepiolite (Sigmal-Aldrich, 98%) were mixed in a 250 mL flask containing 100 mL of distilled water and then precipitated by the addition of NaOH 0.05 M solution under constant stirring for 2 hrs at room temperature.…”

“…In detail, colbat was loaded on sepiolite from 3-5 wt.%, the benzyl alcohol conversion gradually increases, but then the decreases over 7.0 wt.% CoOx/magnesium silicate. This observation was interpreted by the agglomerate of cobalt oxide particles [6,8,10]. The formation of larger particles of CoOx would remarkably reduce the contacting probability between active cobalt ion sites and reactants, and therefore prevent benzyl alcohol from conversion into the corresponding aldehyde [3,5,10].…”

“…Therefore, the catalytic oxidation of benzyl alcohol is a good choice to surpass these obstacles [4][5][6]. Typical catalysts are widely used for the oxidation of benzyl alcohol consisting of transition metal oxides loaded on the carriers as Au-Au-Pd/ceria-zirconia [5], Pd/SBA-15 [6], CoOx/MnOx [7]… Magnesium silicate, a soft white clay mineral known as sepiolite, has the theoretical unit cell formula of (Si12Mg8O30)(OH2)4.8H2O [8]. Sepiolite is usually consisted of nanofibers and has large surface area and good sorptive property.…”

“…Sepiolite is usually consisted of nanofibers and has large surface area and good sorptive property. Hence, sepiolite is subjected to be a good carrier for loading of metal oxides in the heterogeneous catalysis [4,7,8]. In the present work, CoOx particles were distributed on sepiolite to be a promising catalyst candidate for the oxidation of benzyl alcohol.…”