Environmental Benefit Assessment for the Carbonation Process of Petroleum Coke Fly Ash in a Rotating Packed Bed.

A high-gravity carbonation process was deployed at a petrochemical plant using petroleum coke fly ash and blowdown wastewater to simultaneously mineralized CO2 and remove nitrogen oxides and particulate matters from the flue gas. With a high-gravity carbonation process, the CO2 removal efficiency was found to be 95.6%, corresponding to a capture capacity of 600 kg CO2 per day, at a gas flow rate of 1.47 m3/min under ambient temperature and pressure. Moreover, the removal efficiency of nitrogen oxides and particulate matters was 99.1% and 83.2%, respectively. After carbonation, the reacted fly ash was further utilized as supplementary cementitious materials in the blended cement mortar. The results indicated that cement with carbonated fly ash exhibited superior compressive strength (38.1 ± 2.5 MPa at 28 days in 5% substitution ratio) compared to the cement with fresh fly ash. Furthermore, the environmental benefits for the high-gravity carbonation process using fly ash were critically assessed. The energy consumption of the entire high-gravity carbonation ranged from 80 to 169 kWh/t-CO2 (0.29-0.61 GJ/t-CO2). Compared with the scenarios of business-as-usual and conventional carbon capture and storage plant, the economic benefit from the high-gravity carbonation process was approximately 90 and 74 USD per ton of CO2 fixation, respectively.

[The effect of intermittent hypoxia with different degrees and frequencies on levels of superoxide dismutases and malondialdehyde in vascular endothelial cells].

OBJECTIVE: To investigate the effect of degree and frequency of intermittent hypoxia on level of superoxide dismutase (SOD) and malondialdehyde (MDA) in vascular endothelial cell. METHODS: We used umbilical vein endothelial cell ECV304 to set up cell model. The experiment cell strains contained one control group and eight experimental groups. We exposed cells by 3 different degree and 5 different frequency intermittent hypoxia gas separately as experimental groups, and the cells exposed to normal air as a control group. We determined levels of SOD and MDA by the way of ELISA in cytoblastema. RESULTS: The level of MDA of three different degree intermittent hypoxia groups were higher than the level in the control group (P < 0.01). The level of SOD in three different degree hypoxia groups is lower than the level in the group (P < 0.01). The level of SOD was decreased and the level of MDA was increased gradually with the decreasing of hypoxia degree (P < 0.01). There is a trend as the level of MDA and SOD increased and decreased with frequency decreased. The level of MDA was no different between the group of frequency in 40 per hour and 20 per hour (P > 0.05). When hypoxia frequency decreased, the level of MDA increased, and the level of 9.2 per hour exposure group was the lowest, but the level of MDA decreased again when the frequency was reaching 6.3 per hour (P < 0.01). When hypoxia frequency decreased, the level of SOD decreased, and the level of 9.2 per hour group was the highest, but the level of SOD decreased again if the hypoxia frequency was reaching 6.3 per hour (P < 0.01). The level of SOD was negative correlated to that of MDA under different hypoxia degree exposure (r = 0.932, P = 0.000), and the level of SOD was negative correlated to that of MDA under different frequency exposure (r = 0.832, P = 0.000). CONCLUSION: The intermittent hypoxia activates oxidative stress reaction in endothelial cells, and that induces the increasing of reactive oxygen species, and the antioxygen capacity become weaker. The decreasing and increasing of oxidative stress reaction depends on the degree of hypoxia and, is correlated to the frequency of hypoxia. Exposed to intermittent hypoxia, the balance of oxidative stress reaction and antioxygenative system of endothelial cell was disturbed.

[Effect of different intermittent hypoxia patterns on interleukin-6 and interleukin-8 levels of human umbilical vein endothelial cells].

OBJECTIVE: To investigate the effect of different patterns of intermittent hypoxia on the levels of interleukin-6 (IL-6) and interleukin-8 (IL-8) of vascular endothelial cell. METHODS: The human umbilical vein endothelial cells of the line ECV304 were used to set up the cells model. The experiment cell strains contained one control group and eight experimental groups, 1 constance normoxia group (control group), 3 different intermittent hypoxia (IH) degree groups (10% O2 group, 1.5% O2 group, 0.5% O2 group with 12 times/h), 4 different IH frequency groups (40 times/h, 20 times/h, 12 times/h, 9 times/h and 6 times/h with 0.5%O2). The specimen were put into a program-controlled gas delivery system with different level and frequency of IH respectively. Then enzyme linked immunosorbent assay (ELISA) was used to examine the levels of IL-6 and IL-8. RESULTS: Higher level of IL-6 and IL-8 were found in 3 different IH degree groups than in control group (F were 1961.100 and 103.855 respectively, P all < 0.001). The level of IL-6 and IL-8 was gradually increased with the decreasing of IH degree. The difference of IL-6 and IL-8 levels between each two different groups in IH degree was significant (P all < 0.05). The level of IL-6 and IL-8 groups was significantly different in severe IH exposure (F were 544.396 and 149.328 respectively, P all < 0.001 in both groups). There was a trend as the IH frequency decreased, the level of IL-6 and IL-8 was tenderly increased in 20/hour group (P < 0.05), highest in 12/hour group (P < 0.05), decreased in 9/hour group (P < 0.05), and decreased further in 6/hour group (P < 0.05) in severe IH expose. There was statistical significance between each two different frequency IH groups (P < 0.05). CONCLUSIONS: Intermittent hypoxia caused significant inflammatory reaction in vascular endothelial cells. The secreted level of IL-6 and IL-8 depended on the degree of hypoxia. There was a trend as the level of IH frequency decreased, the level of IL-6 and IL-8 gradually increased at first, and then decreased in the same way.