Synthesis and characterization of biopolymer modified with piperazine derivative for carbon dioxide adsorption

Abstract

A new adsorbent biopolymer which is an abundant renewable resource from the nature has been successfully modified with a piperazine derivative for CO2 adsorption. The biopolymer was purified by alkali treatment to obtain 96.43 % degree of deacetylation in the purified biopolymer and used as the reactive adsorbent for amine functionalization. For the modification, the purified biopolymer was functionalized with the piperazine-2-carboxylic acid in the mixture solution of glacial acetic acid, isopropyl alcohol, and water. The structure of the modified biopolymer was characterized by Fourier transform infrared spectroscopy (FTIR). It showed the evidence of the formation of amide linkages between the amine group of the biopolymer and the carboxyl group of the piperazine derivative. When the mole ratio of biopolymer to piperazine-2-carboxylic acid was varied (1:1, 1:2 and 1:5), the degree of substitution was determined by high performance liquid chromatography (HPLC). The ratio of 1:2 and 1:5 showed high degree of substitution that was 72.71% and 71.60%, respectively. However, both of these ratios are not significantly different, the optimal piperazine-2-carboxylic acid to biopolymer was the ratio of 1:2, where the modified biopolymer contained highly reactive amine groups (piperazine) in the structure for CO2 adsorption. Thermogravimetric analysis showed that the modified biopolymer was obtained thermally stable up to 190 °C, which could be used for CO2 adsorption and desorption.