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  • Finally the effect of the BMIM BF concentration change

    2019-10-31

    Finally, the effect of the [BMIM][BF4] concentration change on the P-T diagram of methane hydrate was predicted using the proposed model. Three various concentrations (including 10%, 15% and 20%) were considered for calculations. The experimental data [49] and modeling results are demonstrated and compared in Fig. 10. The results indicate that the increasing of [BMIM][BF4] concentrations from 10 to 20 weight percent leads to slight upward shifts of P-T equilibrium diagram [49]. These slight shifts could be predicted satisfactorily using the model. Moreover, the calculated AADPs obtained were below 2% for various [BMIM][BF4] concentrations.
    Conclusions In this study, the P-T equilibrium diagrams of methane hydrate formations were predicted in the presence of six imidazolium-based ionic liquids within the temperature range of 274–288 K and pressure range of 20–140 bar. The thermodynamic modeling was performed using the two-step hydrate formation 5-Methoxy-UTP of Chen and Guo coupled with the CPA EoS for 10 weight percent of ionic liquids such as [EMIM][HSO4], [EMIM][EtSO4], [BMIM][BF4], [OH-EMIM][BF4], [BMIM][Cl], and [BMIM][Br] in the liquid phase. Also, to prove the validity of the model across various ionic liquid concentrations, the P-T equilibrium conditions of methane hydrate formations were predicted in the presence of 0.1, 0.15 and 0.20 weigh fractions of [BMIM][BF4]. To perform the modeling, The CPA pure component parameters for ionic liquids were adjusted using liquid density data. In addition, the water-ionic liquids and methane-ionic liquids binary interaction parameters were obtained from the binary VLE data except for the binary coefficients of CH4-[BMIM][Cl], CH4-[BMIM][Br], CH4-[EMIM][HSO4], and CH4-[OH-EMIM][BF4] systems which were obtained using the experimental data of gas hydrate phase equilibria. The results indicated that there were good agreements between the proposed model predictions and literature experiment data, such that the overall average absolute deviation of gas hydrate formation pressures obtained was lower than 4.2%. Among the studied ionic liquids, the minimum amounts of AADP% were obtained for [OH-EMIM][BF4] and [EMIM][EtSO4] (below 1.3%), while the maximum value belonged to [BMIM][Br] (4.2%). Moreover, the AADPs calculated for the gas hydrate equilibrium conditions in the presence of [EMIM][EtSO4] and [BMIM][BF4], whose binary coefficients were completely tuned using VLE data, were obtained as about 1.25% and 1.66%, respectively. It can prove the prediction validity of the proposed model. Finally, the effect of concentration changes of [BMIM][BF4] was predicted satisfactorily using the model, such that the trends were predicted and the calculated AADPs were obtained below 2% for various amounts of [BMIM][BF4].
    Introduction The ability to bank human tissues without compromising their viability is of paramount importance for transplantation and personalized medicine, translational research, biomarker discovery, and addressing the molecular basis of many diseases such as cancer. Tissue transplantation can be lifesaving (e.g., skin transplantation in severe burn cases) and/or life enhancing (e.g., replacing damaged ligaments) but suffers from a worldwide shortage of transplantable tissues according to the World Health Organization (WHO) [34]. Furthermore, the availability of diverse tissues cryobanked in a viable manner would enormously contribute to the emerging field of tissue engineering that also suffers from lack of a reliable cryopreservation method as identified by the Multi-Agency Tissue Engineering Science (MATES) [20]. Although some progress has been made in cryopreservation of certain tissues such as ovarian tissue and vein segments [33], [36] preservation of many multicellular tissues and organs still remains challenging [15], [21], [35]. Typically, cryoprotective agents (CPAs) such as dimethylsulfoxide (Me2SO), ethylene glycol (EG), and propylene glycol (PG) must be present both intra- and extracellularly to facilitate successful cryopreservation of tissues. However, addition and removal of such penetrating CPAs before and after cryopreservation, respectively, are challenging due to associated osmotic stresses and chemical toxicity of CPAs. In fact, mitigation of the CPA induced toxicity has been highlighted as one of the critical impediments of tissue and organ cryopreservation [28]. Consequently, innovative approaches are required to overcome such challenges. The objective of the present study was to develop an approach to optimize CPA addition toward minimizing osmotic stresses and chemical toxicity of CPAs.