• Gill McCallum posted an update 1 week, 4 days ago

    Palladium plays a pivotal role in most of the industrial heterogeneous catalysts, because of its unique properties such as well-defined structure, great intrinsic carrier, outstanding electronic, mechanical and thermal stability. The combination of palladium and various porous carbons (PCs) can widen the use of heterogeneous catalysts. This review highlights the advantages and limitations of carbon supported palladium-based heterogeneous catalyst in reduction of toxic hexavalent chromium (Cr(VI)). In addition, we address recent progress on synthesis routes for mono and bimetallic palladium nanoparticles supported by various carbon composites including graphene-based materials, carbon nanotubes, mesoporous carbons, and activated carbons. The related reaction mechanisms for the Cr(VI) reduction are also suggested. Nafamostat datasheet Finally, the challenge and perspective are proposed. p-Coumaryl alcohol (p-CMA), as the simplest lignin precursor, was determined in the process of lignin polymer degradation and wood smoke. However, its transformation and migration in the atmosphere have not been well clarified. In this work, the gas-phase reaction mechanisms and kinetic parameters of ozone-initiated removal of p-CMA were performed by using quantum chemical calculations. Seven primary addition reaction pathways were summarized. A more comprehensive and detailed reaction routes of the favorable Criegee intermediate (IM9) were presented, including the reactions with small molecules, as well as its own isomerization and decomposition reactions. p-Hydroxybenzaldehyde (P1) is the most dominant product in the further reactions of IM9 and the subsequent ozonolysis mechanisms of P1 also were elucidated. All thermodynamic calculations were investigated on the density functional theory (DFT) method at the M06-2X/6-311 + G (3df, 2p)//M06-2X/6-311 + G (d,p) level. The overall and individual rate constants have estimated by using the KiSThelP under typical atmospheric temperature (198-338 K) and pressure. The total rate constant is 3.37 × 10-16 cm3 molecule-1 s-1 at 298 K and 1 atm. In addition, the atmospheric lifetime of p-CMA by ozone-determined is 1.18 h under the average ozone concentration of 7 × 1011 molecules cm-3. The short lifetime indicates that the degradation processes of p-CMA determined by O3 cannot be ignored, especially in areas where the tip concentration of O3 molecules is high. The present study provides a synthetical investigation on ozonolysis of p-CMA for the first time and enriches our understanding of atmospheric oxidation processes of other lignin compounds. The covalent organic framework (COF) is made light elements linked by covalent networks. This study synthesize and characterized, and for the first time applied the produced EB-COFBr as adsorbent for phosphate and arsenate removal from nearly neutral waters. The synthesized COF was first proven structurally stable in solutions of 75% H3PO4, 6 M HCl, or 6 M NaOH. Then the phosphate adsorption onto the EB-COFBr was shown to be an endothermic process with maximum adsorption capacity at 25, 35 and 45 °C as 25.3, 34.7 and 35.3 mg/g COF, respectively; and the corresponding arsenate adsorption process being an exothermic process with maximnum adsorption capacity as 53.1, 27.5 and 5.1 mg/g, respectively. The synthesized COF could also effectively adsorb phosphate and arsenate ions from river water (pH 7.45) but at reduced adsorption capacities. The electrostatic interactions between the negative charge on phosphate or arsenate ions and the positively charged (N+-) of COF, and the hydrogen bondings between H atom on phosphate or arsenate ions and the (-CO) group of COF were the dominating mechanisms for the present adsorption process. The strong electrostatic interactions for arsenate contributed to its higer adsorption capacity than noted for phosphate at 25 °C. However, the disturbed hydrogen bonding induced by mismatched sizes of arsenate ion and the adsorption sites surrounded by the (N+-) and the (-CO) groups reduced the stability of arsenate to against temperature and external anion challenges. The use of the EB-COF; Br as industrial adsorbent was also discussed. A bioscrubbing process named SONOVA has been developed, tested and assessed herein to valorize flue gases containing SOx. The process consists in a first scrubbing stage, to absorb and oxidize SO2 to sulfate, followed by a two-step biological stage. It consists of (1) an up-flow anaerobic sludge (UASB) reactor to reduce sulfate to sulfide with crude glycerol and (2) a continuous stirred tank reactor (CSTR) to partially oxidize sulfide to elemental sulfur (S0). SONOVA integrates the reutilization of resources, using the effluent of the biological stage as a sorbent agent and the residual heat of flue gases to dry the product. S0 is then obtained as a value-added product, which nowadays is produced from fossil fuels. In this research, SO2 concentrations up to 4000 ppmv were absorbed in 2 s of gas contact time in the spray-scrubber with removal efficiencies above 80%. The UASB reduced up to 9.3 kg S-Sulfate m-3 d-1 with sulfide productivities of 6 kg S m-3 d-1 at an hydraulic retention time (HRT) as low as 2 h. Finally, CSTR was fed with the UASB effluent and operated at HRT ranging from 12 h to 4 h without biomass wash-out. Sulfide was fully oxidized to S0 with a productivity of 2.3 kg S m-3 d-1 at the lowest HRT tested. Overall, this research has explored not only maximum capabilities of each SONOVA stage but has also assessed the interactions between the different units, which opens up the possibility of recovering S0 from harmful SOx emissions, optimizing resources utilization and costs. Bioaerosols have widely been a concern due to their potential harm to human health caused by the carrying and spreading of harmful microorganisms. Biofiltration has been generally used as a green and effective technology for processing VOCs. However, bioaerosols can be emitted into the atmosphere as secondary pollutants from the biofiltration process. This review presents an overview of bioaerosol emissions from gas bioreactors. The mechanism of bioaerosols production and the effect of biofiltration on bioaerosol emissions were analyzed. The results showed that the bioaerosol emission concentrations were generally exceeded 104 CFU m-3, which would damage to human health. Biomass, inlet gas velocity, moisture content, temperature, and some other factors have significant influences on bioaerosol emissions. Moreover, as a result of the analysis done herein, different inactivation technologies and microbial immobilization of bioaerosols were proposed and evaluated as a potential solution for reducing bioaerosols emissions.