Preparation of amino functionalized titanium oxide nanotubes and their incorporation within Pebax/PEG blended matrix for CO2/CH4 separation

Abstract

Raw and tetraethylene pentamine (TEPA) functionalized titanium oxide nanotubes (TiNTs) were used as filler particles to prepare nanocomposite membranes. Polyethylene glycol (PEG) was blended with the Pebax-1657 as matrix and incorporated by TiNT-TEPA to prepare Pebax-1657/PEG/TiNT-TEPA nanocomposite membranes based on Response Surface and Central Composite Design methods of experimental design. The TiNT-TEPA and the Pebax/PEG/TiNT-TEPA were characterized using TEM, FESEM, SEM, FTIR or ATR-FTIR, XRD (EDS) and mechanical strength analysis. CO2 adsorption capacity of TiNTs and TiNT-TEPA-70% were found as 0.71 and 4.2mmol/g, respectively. CO2 permeability and ideal selectivity of optimum (in term of separation performance) membrane, as Pebax (7wt.%) /PEG (7.5wt.%)/TiNT-TEPA (3wt.%), were increased by 67.7 and 11.7%, respectively, compared with the neat Pebax membrane.The optimum membrane’s CO2 permeability and CO2/CH4 ideal selectivity were investigated at operating temperatures of 20–45°C and reveled 18.5 and −9% changes, respectively. Its transmembrane pressures increment form 4 to 10bar for single and CO2 (50)/CH4 (50) mixed gas resulted in CO2 permeability and CO2/CH4 ideal selectivity enhancements by 19 and 20%, respectively. The optimum membranes’ mixed gas separation performance were found lower than that of single pure gases at the same operating condition.