Amidoximes: Promising Candidates for CO2 Capture

S. Zulfiqar, F. Karadas, J. Park, E. Deniz, G. D. Stucky, Y. Jung*, M. Atilhan*, C. T. Yavuz*
Energy Environ. Sci., 4, 4528-4531, (2011). [DOI] [pdf]

Monoethanolamine (MEA) dominates power plant carbon dioxide (CO2) scrubbing processes, though with major disadvantages such as a 8–35% energy penalty. Here we report that structurally comparable amidoximes are promising CO2 capture agents based on RIMP2 electronic structure calculations. This was experimentally verified by the synthesis and testing of representative amidoximes for capture efficiencies at pressures as high as 180 bar. Acetamidoxime, which has the highest percent amidoxime functionality showed the highest CO2 capacity (2.71 mmol/g) when compared to terephthalamidoxime (two amidoximes per molecule) and tetraquinoamidoxime (four amidoximes per molecule). Polyamidoxime surpassed activated charcoal Norit RB3 for CO2 capture per unit surface area. Adsorption isotherms exhibit Type IV behavior and acetamidoxime found to increase CO2 capture with temperature, a less observed anomaly. Porous amidoximes are proposed as valuable alternatives to MEA.

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A multiplexed separation of iron oxide nanocrystals using variable magnetic fields

J. T. Mayo, S. S. Lee, C. T. Yavuz, W. W. Yu, A. Prakash, J. C. Falkner, V. L. Colvin*
Nanoscale, 3, 4560-4563 (2011). [DOI] [pdf]

The size-dependent magnetic properties of nanocrystals are exploited in a separation process that distinguishes particles based on their diameter. By varying the magnetic field strength, four populations of magnetic materials were isolated from a mixture. This separation is most effective for nanocrystals with diameters between 4 and 16 nm.

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CO2 Adsorption Studies on Hydroxy Metal Carbonates M(CO3)x(OH)y (M = Zn, Zn Mg, Mg, Mg Cu, Cu, Ni, and Pb) at High Pressures up to 175 bar

F. Karadas, C. T. Yavuz, S. Zulfiqar, S. Aparicio-Martinez, G. D. Stucky, M. Atilhan*
Langmuir, 27 (17), 10642–10647 (2011). [DOI] [pdf]

Carbon dioxide (CO₂) adsorption capacities of several hydroxy metal carbonates have been studied using the state-of-the-art Rubotherm sorption apparatus to obtain adsorption and desorption isotherms of these compounds up to 175 bar. The carbonate compounds were prepared by simply reacting a carbonate (CO₃^2-) solution with solutions of Zn²⁺, Zn²⁺/Mg²⁺, Mg²⁺, Cu²⁺/Mg²⁺, Cu²⁺, Pb²⁺, and Ni²⁺ metal ions, resulting in hydroxyzincite, hydromagnesite, mcguinnessite, malachite, nullaginite, and hydrocerussite, respectively. Mineral compositions are calculated by using a combination of powder XRD, TGA, FTIR, and ICP-OES analysis. Adsorption capacities of hydroxy nickel carbonate compound observed from Rubotherm magnetic suspension sorption apparatus has shown highest performance among the other components that were investigated in this work (1.72 mmol CO₂/g adsorbent at 175 bar and 316 K).

 

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Investigation on novel thermoplastic poly(urethane-thiourea-imide)s with enhanced chemical and heat resistance

A. Kausar, S. Zulfiqar, C. T. Yavuz, M. I. Sarwar*
Polym. Degrad. Stabil., 96 (7), 1333-1341 (2011). [DOI] [pdf]

A new generation of segmented thermoplastic poly(urethane-thiourea-imide)s (PUTIs) was synthesized via reaction of polyethylene glycol and thiourea-based prepolymer with dianhydride as chain extenders. NCO-terminated prepolymer was synthesized from a new diisocyanate, 3-(3-((4-isocyanatophenyl)carbamoyl)thioureido)phenyl-4-isocyanatophenylcarbamate (IPCT), as a hard segment and PEG forming soft segment. The starting materials and polymers were characterized by conventional methods and physical properties such as solubility, solution viscosity, molecular weight, thermal stability and thermal behavior were studied. PUTIs showed partially crystalline structures. Weight average molecular weights of PUTIs (GPC measurements) were in the range of 1,68,694-1,97,035. Moreover, thermogravimetric analysis indicated that poly(urethane-thiourea-imide)s were fairly stable above 500 oC having T10 of 521-543 oC. Investigation of the results authenticated the approach of introducing thiourea (using IPCT) and imide structure in polyurethanes for the improvement of thermal stability. In comparison to typical polyurethanes, these polymers exhibited better heat resistance, chemical resistance as well as processability.

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