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Natural Science Foundation for Distinguished Young Scholars of Anhui Province[2108085J41]
No full textImmobilized arginine/tryptophan-rich cyclic dodecapeptide on reduced graphene oxide anchored with manganese dioxide for microbial biofilm eradication
No full textTo avoid the accumulation of bacterial biofilms in water pipelines, it is critical to develop potent antimicrobial agents with good ability to reduce extracellular polymeric substances (EPS). In this study, cyclic dodecapeptides were synthesized, and different mutations for increasing the ratio of arginine (Arg) and tryptophan (Trp) were introduced. Separately, the synthesized dodecapeptides were immobilized on a reduced graphene oxide nanocomposite anchored with a hierarchical beta-MnO2 (RGO/beta-MnO2) hybrid. With a minimum inhibitory concentration of 0.97 g/mL, the immobilized Arg-Trp rich antimicrobial peptides (AMP) on RGO/MnO2 nanocomposite, Cdp-4/RGO/MnO2, showed superior efficacy against multidrug-resistant Pseudomonas aeruginosa ATCC 15692 (P. aeruginosa) planktonic cells. The immobilized Cdp-4/RGO/beta-MnO2 also eradicated the mature biofilm by 99% with a minimum inhibitory concentration value of 62.5 mu g/mL with significant reduction of EPS. These characteristics allow the use of the immobilized Arg-Trp rich AMP as a promising antimicrobial agent against microbial biofilms, present in water distribution systems
Effectively Converting Cane Molasses into 2,3-Butanediol Using Clostridium ljungdahlii by an Integrated Fermentation and Membrane Separation Process
No full textFirstly, 2,3-butanediol (2,3-BDO) is a chemical platform used in several applications. However, the pathogenic nature of its producers and the expensive feedstocks used limit its scale production. In this study, cane molasses was used for 2,3-BDO production by a nonpathogenic Clostridium ljungdahlii. It was found that cane molasses alone, without the addition of other ingredients, was favorable for use as the culture medium for 2,3-BDO production. Compared with the control (i.e., the modified DSMZ 879 medium), the differential genes are mainly involved in the pathways of carbohydrate metabolism, membrane transport, and amino acid metabolism in the case of the cane molasses alone. However, when cane molasses alone was used, cell growth was significantly inhibited by KCl in cane molasses. Similarly, a high concentration of sugars (i.e., above 35 g/L) can inhibit cell growth and 2,3-BDO production. More seriously, 2,3-BDO production was inhibited by itself. As a result, cane molasses alone with an initial 35 g/L total sugars was suitable for 2,3-BDO production in batch culture. Finally, an integrated fermentation and membrane separation process was developed to maintain high 2,3-BDO productivity of 0.46 g center dot L-1 center dot h(-1). Meanwhile, the varied fouling mechanism indicated that the fermentation properties changed significantly, especially for the cell properties. Therefore, the integrated fermentation and membrane separation process was favorable for 2,3-BDO production by C. ljungdahlii using cane molasses
Research on the Influence of Combustion Methods on NOx Emissions from Co-combustion of Various Tannery Wastes
No full textTo further increase combustion efficiency and reduce nitrogen oxide pollution caused by tannery wastes, three raw materials, including tannery sludge, chrome-tanned buffing dust, and chrome shavings, were burned together in a dual-bed model reactor under various conditions. In addition, a thermogravimetric analysis of co-combustion of three tannery wastes was studied in this study, which was conducive to understanding the combustion characteristics and positive effects. The comprehensive combustibility index S, the flammability index K-r, and the stable combustion characteristic index G(b) all increased when the tannery sludge was blended with chrome-tanned buffing dust and chrome shavings, indicating that the combustion behavior was improved by co-combustion. For normal combustion, decreasing the gas volume flow and temperature resulted in a decrease in the oxidation of nitrogen compounds, consequently lowering the NOx emission. During air staged combustion, at an appropriate secondary gas ratio of about 10-40%, the NOx reduction would be increased from 10.9 to 19.3%. By increasing the tertiary gas volume flow from 0.2 to 1.1 L/min in decoupling combustion, an average relative NOx reduction efficiency of 47% was attained compared with normal combustion. The results offered a viable technology that resulted in a lower NOx emission and realized the application of decoupling combustion
Lignocellulose particle size and rheological properties changes in periodic peristalsis enzymatic hydrolysis at high solids
No full textPeriodic peristalsis is an effective intensification method in high solids enzymatic hydrolysis. But the change law of slurry physical properties was not fully understood in periodic peristalsis enzymatic hydrolysis (PPEH) at high solids. This leads to the limitation of its application. Therefore, we studied particle size, viscosity and yield stress changes under periodic peristalsis. The D50 decreased by 42.59% and the viscosity decreased from 290.5 to 0.63 Pa s within 2 h under periodic peristalsis. The yield stress decreased from 245.9 Pa to 8.6 Pa and the fluidity of slurry can be pumped. Furthermore, the relationship between its physical properties and enzymatic hydrolysis efficiency and energy consumption was analyzed. And a method of calculating periodic peristalsis energy consumption was proposed. The energy consumption of periodic peristalsis is one-ninth of the stirring by calculation. These results provided guidance for its industrial application
Catalytic Transformation of PET and CO2 into High-Value Chemicals
No full textPolyethylene terephthalate (PET) and CO2, two chemical wastes that urgently need to be transformed in the environment, are converted simultaneously in a one-pot catalytic process through the synergistic coupling of three reactions: CO2 hydrogenation, PET methanolysis and dimethyl terephthalate (DMT) hydrogenation. More interestingly, the chemical equilibria of both reactions were shifted forward due to a revealed dual-promotion effect, leading to significantly enhanced PET depolymerization. The overall methanol yield from CO2 hydrogenation exceeded the original thermodynamic equilibrium limit since the methanol was in situ consumed in the PET methanolysis. The degradation of PET by a stoichiometric ratio of methanol was significantly enhanced because the primary product, DMT was hydrogenated to dimethyl cyclohexanedicarboxylate (DMCD) or p-xylene (PX). This synergistic catalytic process provides an effective way to simultaneously recycle two wastes, polyesters and CO2, for producing high-value chemicals