Effect of compression molding of CaCO3 powder on the kinetics of CO2 capture towards sustainable CO2 capture and sequestration cycle.

Reducing CO2 emissions from industrial sectors and motor vehicles is currently receiving much attention. There are different strategies for CO2 capture, one of which is using calcium oxide (CaO). In our proposed carbon dioxide cycle, limestone is first calcined to get CaO, which is then used to capture CO2 by converting it to CaCO3. Next, the released CO2 could be converted to different organic matter by different sequestration techniques. For this purpose, CaCO3 discs have been prepared by compression molding to investigate the effect of sintering temperature on the mechanical and chemical properties of CaO carbonation reaction. The aim of this work is to fill the knowledge gap for the effect of the contact profile between CO2 gas and CaO disc, particularly the effect of reducing the void fraction of CaO on the rate of carbonation reaction. It was found that the flexural strength of the CaO discs was influenced by several factors, such as the calcination temperature, duration of calcination, and pressing pressure. The carbonation step indicated that both CO2 and H2O are reacting with CaO simultaneously and progressively, with the progressive reaction of H2O and CO2 being a favorable route. The carbonation process happens as a surface reaction-controlled process followed by a slower internal diffusion-controlled process. Additionally, a kinetic study of the competing reactions indicated that two factors are controlling the process: diffusion of gases through the pores and then the reaction rate. Furthermore, our data showed that the CO2 uptake rate was 1352.34 mg/g CaO, indicating that 566.34 mg of CO2 was adsorbed inside the pores of the CaO disc. Based on these results, we propose a new mechanism of the sequence of the competing reactions. In summary, the CaO discs revealed a significant removal of CO2 from stack gases, which will be suitable for removing CO2 from exhaust gases generated by industrial processes and other sources of emissions such as vehicles and ships.

Swertia chirayita mediated modulation of interleukin-1beta, interleukin-6, interleukin-10, interferon-gamma, and tumor necrosis factor-alpha in arthritic mice.

The effect of aqueous extract of Swertia chirayita stem on the pro- and anti-inflammatory cytokines balance in primary joint synovium of adjuvant-induced arthritic mice has been studied. The level of pro-inflammatory cytokines was found elevated in the joint synovium of arthritic mice in comparison to normal joints. Administration of S. chirayita extract in varying doses through the oral route did not modulate the proinflammatory cytokines on day 2. In contrast, by day 12, a dose dependent (0, 11.86 and 23.72 mg/kg body weight) reduction of tumor necrosis factor-alpha (INF-alpha) interleukin-1beta, (IL-beta) and interferon-gamma, (IFN-gamma) and elevation of Interleukin-10 (IL-10) was observed in the joint homogenates of arthritic mice. Interleukin-6 (IL-6) was not down regulated in joint homogenate of arthritic mice at the dose 11.86 mg/kg but at higher doses (23.72 and 35.58 mg/kg) significant reduction was observed. The aqueous extract was found to possess two polar compounds, amerogentin and mangiferin but was devoid of swerchirin, chiratol, methyl swetianin, and swertanone. Mangiferin has been reported to possess potent anti-inflammatory property and we presume its presence in the aqueous extract of S. chirayita is responsible for reducing TNF-alpha, IL-1beta, IL-6, and IFN-gamma and/or elevating IL-10 in the joint homogenates of arthritic mice on day 12. This study will help in our understanding of the mechanism of anti-inflammatory action of S. chirayita in the light of proinflammatory and anti-inflammatory cytokine balance.