Jian-Gang Lu

CO2 Capture Using Activated Amino Acid Salt Solutions in a Membrane Contactor

An activated solution based on amino acid salt was proposed as a CO2 absorbent. Piperazine (PZ) was selected as an activating agent and added into the aqueous glycine salt to form the activated solution. A coupling process, which associated the activated solution with a PP hollow fiber membrane contactor, was set up. An experimental and theoretical analysis for CO2 capture was performed. The performances of CO2 capture by the coupling process were evaluated using the PZ activated solution and the non-activated glycine salt solution. A numerical model for the simulation of the hollow fiber membrane gas–liquid mass transfer was developed. Typical parameters such as outlet gas phase CO2 concentration, capture efficiency, and mass transfer coefficient for the activated solution were determined experimentally. The effects of operation temperature and liquid CO2-loading on mass transfer coefficient and capture efficiency were discussed in this work. Axial and radial concentration profiles of CO2 in the fiber lumen and mass transfer flux were simulated by the model. Results show that the performances of the PZ activated glycine salt solution are evidently better than that of the non-activated glycine salt solution in the membrane contactor for CO2 capture. Elevation of the operation temperatures can enhance the overall mass transfer coefficient. The activated solution can maintain higher capture efficiency especially in the case of high CO2-loadings. The gas phase CO2 concentration with the activated solution is lower than that with the non-activated solution whether along axial or radial distances in the fiber lumen. The model simulation is validated with experimental data.

Adsorption of Monobutyl Phthalate from Aqueous Phase onto Two Macroporous Anion-Exchange Resins

As new emerging pollutants, phthalic acid monoesters (PAMs) pose potential ecological and human health risks. In the present study, adsorption performance of monobutyl phthalate (MBP) onto two macroporous base anion-exchange resins (D-201 and D-301) was discussed. It was found that the adsorption isotherms were best fitted by the Langmuir equation while the adsorption kinetics were well described by pseudo-first-order model. Analyses of sorption isotherms and thermodynamics proved that the adsorption mechanisms for DBP onto D-201 were ion exchange. However, the obtained enthalpy values indicate that the sorption process of MBP onto D-301 is physical adsorption. The equilibrium adsorption capacities and adsorption rates of DBP on two different resins increased with the increasing temperature of the solution. D-301 exhibited a higher adsorption capacity of MBP than D-201. These results proved that D-301, as an effective sorbent, can be used to remove phthalic acid monoesters from aqueous solution.

Membrane Contactor as Reactor for CO2 Capture

A novel composite solution consisting of N-methylmonoethanolamine (MM-EA) and 2-amino-2-methyl-1-propanol (AMP) as a CO2 absorbent was proposed. Coupling process of membrane contactor and the composite solution was investigated. The performance of the coupling was experimentally compared between the single and composite solution. Overall mass transfer coefficients were determined. Effects of various factors, such as flow rates and operation temperatures on mass transfer of membrane contactor, were studied. Comparison of prediction for overall mass transfer coefficients using a resistance in series model with experimental values was performed. Results show that performance of the composite solution is evidently better than that of the single MMEA solution. The overall mass transfer coefficient with the composite solution is much higher than that with the single MMEA solution. Higher operation temperature can enhance mass transfer of membrane contactor. Operation parameters such as flow rates can promote mass transfer, but the promotion is limited. Enhance of mass transfer relies essentially on chemical reaction. Model values are in good agreement with experimental ones.