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Geopolymers: The influence of alkaline activator cations on efflorescence
Novotná, Martina ; Polonská, A. ; Šídlová, M. ; Perná, Ivana
This paper describes the effect of the type of cations in the alkaline activator on geopolymer properties and especially on the formation of efflorescence. The susceptibility to the formation of efflorescence is discussed according to the standard ČSN 72 1565-13. Cations in alkaline activators influence the mineralogical type of efflorescence: Li+ and Na+ cations form carbonates (Li2CO3 and Na2CO3, respectively), whereas K+ cations form sulphate (K2SO4). The mechanical properties, workability and pore structure of the geopolymer composites have been determined. Alkaline activators with sodium and potassium ions reach higher mechanical strength than those containing lithium cations. For lithium alkaline activators, there was a noticeable difference in the properties between the SiO2/Li2O ratios 1.8 and 2.6. Based on the properties of the mentioned geopolymer composites with various alkaline cations, it is possible to use lithium alkaline activators in geopolymer technology.
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Amine-functionalized Porous Polymers for Selective CO2 Adsorption.
Setničková, Kateřina ; Jeřábek, Karel ; Strašák, Tomáš ; Soukup, Karel
Porous materials have always attracted high scientific interest because of their outstanding performance and potential applications in various fields, including adsorption and gas separation. Hyper-crosslinked polymers (HCLPs) have several advantages over other porous materials, they show extremely high surface areas and porosity, low density, outstanding adsorption properties, high chemical, and thermal stability.\nHerein, we reported a synthesis, characterization, and the CO2 (and other gases) adsorption performance of series of novel styrene-divinylbenzene based HCPs. The material was prepared in two steps. The first step involved the radical copolymerization of divinylbenzene (DVB) and 4-vinylbenzyl chloride (VBC), under solvothermal condition to generate porous polymers with high surface area above 700 m2 g−1. In the second step, various polyamine species were applied to react with the alkyl chloride groups and functionalize the pore surface\nto improve the CO2/N2, CO2/CH4 and CO2/H2 selectivity.
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