The xylonate was bioproduced directly from lignocellulosic residues, and the application properties of crude xylonate powder were investigated with a promising potential as a bio-based concrete water reducer. The overall integrated process was evaluated on the view of mass balance and techno-economic analysis using Aspen Plus modeling. 56 g/L of calcium xylonate (XA-Ca) can be obtained within 8 h from acidic corncob hydrolysate (ACH) at a 100 % yield with the whole-cell catalysis of Gluconobacter oxydans . At the addition of 0.2 wt% in the dry concrete content, XA-Ca powder and sodium xylonate powder prepared from pure xylose and ACH could reduce water used in concrete by 15 %, 14 %, 13 %, and 13 %, respectively. XA-Ca from ACH led to a 33% increase in concrete compressive strength and a 24% increase in concrete flexural strength at day 7 compared to the blank group. The techno-economic analysis showed the minimum XA-Ca powder price to be $ 0.806/kg which can be economically feasible. This study provides a practical and economical process prototype for the industrial concrete water reducer application of novel bio-based xylonate produced from lignocellulosic residues.
In this work, the effect of activated carbon particles on the production of xylonic acid from xylose by Gluconobacter oxydans in a stirred tank bioreactor was investigated. The enhancement of the oxygen transfer coefficient by activated carbon particles was experimentally evaluated under different solids volume fractions, agitation and aeration rates conditions. The experimental conditions optimized by response surface methodology (agitation speed 800 rpm, aeration rate 7 L min −1 , and activated carbon 0.002%) showed a maximum oxygen transfer coefficient of 520.7 h −1 , 40.4% higher than the control runs without activated carbon particles. Under the maximum oxygen transfer coefficient condition, the xylonic acid titer reached 108.2 g/L with a volumetric productivity of 13.53 g L −1 h −1 and a specific productivity of 6.52 g/g x /h. In conclusion, the addition of activated carbon particles effectively enhanced the oxygen mass transfer rate. These results demonstrate that activated carbon particles enhanced cultivation for xylonic acid production an inexpensive and attractive alternative.
Synthesis of D-xylonic acid, a high value chemical feedstock, from biomass chemicals through a photocatalytic process is of great significance in respect of economical and sustainable concerns, and therefore has aroused considerable attention. Herein, a TiO2/Ti3C2(TT) photocatalyst was designed for the oxidation of xylose to D-xylonic acid under ambient conditions. The photocatalyst is fabricated by in situ growth of TiO2 nano-particles on Ti3C2 nanosheets and exhibits 64.2% of D-xylonic acid yield with excellent stability. The mechanistic study indicates that the electron transfer from TiO2 to Ti3C2 significantly increases the life time of light-induced charge carriers, and hence improved photocatalytic performance.
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