Influence of wet flue gas desulfurization on the pollutants monitoring in FCC flue gas.

Fluid catalytic cracking (FCC) unit emits a large amount of flue gas, which is a major concern of environmental protection supervision. Wet flue gas desulfurization (WFGD) technologies have been widely used to control the emissions of SO2 in refineries. In this study, stack tests for pollutants emission of a typical FCC unit were conducted. The emission characteristics of the FCC unit indicated that WFGD would cause a large amount of water vapor in the flue gas, which indirectly leads to large quantities of salt pollutants entrained in the flue gas including ammonium sulfite ((NH4)2SO3) and ammonium sulfate ((NH4)2SO4). A strong correlation among the concentrations of SO2, NH3, and H2O was observed, and factor analysis shows that these concentrations are dominated by a common factor. It was also found that a mass quantity of NH4+ and SO32- existed in the condensate water of the flue gas. The TG-MS analysis shows that (NH4)2SO3 could be decomposed at 94.1 °C, and NH3, SO2, and H2O are released as reaction products in the form of gas. Therefore, a part of the NH3 and SO2 obtained by Fourier transform infrared spectroscopy (FTIR) monitoring may be derived from the decomposition of (NH4)2SO3 in the flue gas due to the high temperature during the sampling process, which was also confirmed in a lab experiment. The hot and wet sampling process will lead to overestimation of NH3 and SO2 emissions rather than FTIR method itself when monitoring the high-humidity FCC flue gas. Thus, the concentration of H2O in the flue gas and the type of sampling process need to be taken into consideration during the monitoring process.

Endothelial glycocalyx degradation is associated with early organ impairment in polytrauma patients.

BACKGROUND: Endothelial glycocalyx (EG) abnormal degradation were widely found in critical illness. However, data of EG degradation in multiple traumas is limited. We performed a study to assess the EG degradation and the correlation between the degradation and organ functions in polytrauma patients. METHODS: A prospective observational study was conducted to enroll health participants (control group) and polytrauma patients (trauma group) at a University affiliated hospital between Feb 2020 and Oct 2020. Syndecan1 (SDC1) and heparin sulfate (HS) were detected in serum sample of both groups. In trauma group, injury severity scores (ISS) and sequential organ failure assessments (SOFA) were calculated. Occurrences of acute kidney injury (AKI), trauma-induced coagulopathy (TIC) within 48 h and 28-day all-cause mortality in trauma group were recorded. Serum SDC1 and HS levels were compared between two groups. Correlations between SDC1/HS and the indicators of organ systems in the trauma group were analyzed. ROC analyses were performed to assess the predictive value of SDC1 and HS for AKI, TIC within 48 h, and 28-day mortality in trauma group. RESULTS: There were 45 polytrauma patients and 15 healthy participants were collected, totally. SDC1 and HS were significantly higher in trauma group than in control group (69.39 [54.18-130.80] vs. 24.15 [13.89-32.36], 38.92 [30.47-67.96] vs. 15.55 [11.89-23.24], P <  0.001, respectively). Trauma group was divided into high degradation group and low degradation group according to SDC1 median. High degradation group had more severe ISS, SOFA scores, worse organ functions (respiratory, kidney, coagulation and metabolic system), and higher incidence of hypothermia, acidosis and shock. The area under the receiver operator characteristic curves (AUC) of SDC1 to predict AKI, TIC occurrence within 48 h and 28-day mortality were 0.838 (95%CI: 0.720-0.957), 0.700 (95%CI: 0.514-0.885) and 0.764 (95%CI: 0.543-0.984), respectively. CONCLUSIONS: EG degradation was elevated significantly in polytrauma patients, and the degradation was correlated with impaired respiratory, kidney, coagulation and metabolic systems in early stage. Serum SDC1 is a valuable predictive indicator of early onset of AKI, TIC, and 28-day mortality in polytrauma patients.

Molecular dynamics simulation of the interaction of water and humic acid in the adsorption of polycyclic aromatic hydrocarbons.

Humic acid (HA) and water play an important role in polycyclic aromatic hydrocarbons (PAHs) adsorption and biodegradation in soil. In this work, molecular dynamics (MD) and electrostatic potential surfaces (EPSs) simulations are conducted to research the contribution of quartz surface, leonardite humic acid (LHA), and water to PAH adsorption. The adsorption energies between PAHs and LHA are much higher than that between PAHs and quartz. Simulation shows that the hydroxyl and carboxyl groups' attraction by LHA is the main adsorption force between PAHs and LHA. The π-π interaction between PAHs and LHA also contributes to the adsorption process. In addition, the mobility of water on quartz surface is much higher than that of LHA. Water should be regarded as an adsorbate in the system as well as PAHs. However, the presence of water has a remarkable negative effect on the adsorption of PAHs on LHA and quartz. The bridging effect of water could only enhance the stability of the aggregation system. The adsorption contribution of quartz and LHA to PAHs in the soil model tends to 0 if the water layer reaches 2.0 nm. Graphical abstract.

Reactive adsorption desulfurization of NiO and Ni0 over NiO/ZnO-Al2O3-SiO2 adsorbents: role of hydrogen pretreatment.

Reactive adsorption desulfurization (RADS) of Fluidized Catalytically Cracked (FCC) gasoline on reduced and unreduced NiO/ZnO-Al2O3-SiO2 adsorbents was studied. Various characterizations such as powder X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), the H2/O2 pulse titration (HOPT), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) are used to evaluate the effects of hydrogen pretreatment of the adsorbents. XRD and HOPT results indicate that NiO is hard to be reduced to Ni0 under the conditions of RADS. H2-TPR shows that NiO might be reduced to Ni0 at the temperature of 598 °C, much higher than the temperature of RADS. The Ni 2p3/2 spectrum of Ni0 is not observed for the reduced adsorbent, but the main peak of Ni 2p3/2 of NiS is found for the spent adsorbent. The unreduced NiO/ZnO-Al2O3-SiO2 adsorbent performs a better desulfurization than the reduced adsorbent at the beginning of desulfurization process. NiO and Ni0 are assumed as the main active components and present a good desulfurization ability in RADS. Finally, a change in the RADS mechanism is presented and discussed.