Enhancing CO−Water Mass Transfer by Functionalized MCM41 Nanoparticles

Abstract

Organic groups are grafted to ∼250-nm-diameter MCM41 nanoparticles with a spherical morphology to enhance the CO-water volumetric mass-transfer coefficient (kLa) for synthesis gas fermentation. The results indicate that (i) ∼250-nm MCM41 nanoparticles show a higher kLa value than large silica particles (1.4 and 7 μm), (ii) surface hydroxyl groups on MCM41 nanoparticles play an important role in mass-transfer enhancement, (iii) organic groups grafted to MCM41 modify the mass-transfer enhancement, and (iv) mercaptan groups grafted to MCM41 show the most mass-transfer enhancement of ∼1.9 times that of no nanoparticle addition. The CO-water mass-transfer enhancement depends on the interaction between the nanoparticles and the CO molecules, which is influenced by the hydrophobicity of the nanoparticles and the functional group on the nanoparticles. Organic groups are grafted to ∼250-nm-diameter MCM41 nanoparticles with a spherical morphology to enhance the CO-water volumetric mass-transfer coefficient (k L a) for synthesis gas fermentation. The results indicate that (i) ∼250-nm MCM41 nanoparticles show a higher k L a value than large silica particles (1.4 and 7 µm), (ii) surface hydroxyl groups on MCM41 nanoparticles play an important role in mass-transfer enhancement, (iii) organic groups grafted to MCM41 modify the mass-transfer enhancement, and (iv) mercaptan groups grafted to MCM41 show the most mass-transfer enhancement of ∼1.9 times that of no nanoparticle addition. The CO-water mass-transfer enhancement depends on the interaction between the nanoparticles and the CO molecules, which is influenced by the hydrophobicity of the nanoparticles and the functional group on the nanoparticles.

Characterizations of Nanofluid Heat Transfer Enhancements

“…Findings of no effect or decreased mass transfer rates for nanofluids in our study is contrary to other studies that report enhanced diffusion or mass transfer in nanofluids [11][12][13][14]. The reasons for this discrepancy are unclear.…”

“…The reasons for this discrepancy are unclear. Measurement uncertainty can be dismissed as the cause; the lowest reported mass transfer enhancement 190% [14] and, based upon a first-order second-moment uncertainty analysis [15] our propagated experimental uncertainty is only 6% for the NaCl transfer measurements and only 5% for the oxygen transfer measurements. Particle type may play a role.…”

Enhanced mass transfer rate of methane via hollow fiber membrane modules for Methylosinus trichosporium OB3b fermentation

“…Various factors including diffusivity of gases, 40 viscosity and density of liquid medium, and gas-liquid affinity 41 have been known to affect k L values [10]. For instance, addition of 42 (nano)particles in the media have been demonstrated to enhance 43 k L values by facilitating the transport of gas molecules into the bulk 44 liquid [12,13]. However, additives with potential toxicity in the 45 fermentation media could lead to cell damage, possibly interrupt-46 ing the cultivation of microorganism [14].…”

Effect of Electrolytes on CO−Water Mass Transfer

“…Extending the recent results of Zhu et al 17 for CO-water mass-transfer enhancement with nanoparticle addition, masstransfer measurements (k L ) were determined in selected MCM41 solutions, which are also included in Table 1. For the CO-water mass-transfer enhancement upon MCM41 nanoparticle addition with and without a functionalized mercaptopropyl group at a low nanoparticle concentration of 0.4 wt %, both the CO-water mass-transfer coefficient and the CO-water interfacial area increased; this trend is different from the enhancement due to electrolyte addition.…”