Carbon aerogel and polyaniline/carbon aerogel adsorbents for Acid Green 25 dye: synthesis, characterization and an adsorption study

Abstract

Carbon aerogel powder and polyaniline/carbon aerogel nanocomposites have been used for the remediation of Acid Green 25 (AG25), an anionic dye. Polyaniline/carbon aerogel nanocomposites have been synthesized via in situ polymerization. The AG25 adsorption study was done by involving different parameters. i.e., pH, initial dye concentration, time, adsorbent loading, and temperature. The characterization of carbon aerogel (CA) and polyaniline/carbon aerogel (PANI/CA) was done by Fourier-transform infrared spectroscopy, field emission scanning electron microscopy , BET, and X-ray diffraction techniques. All the experiments were performed at neutral pH =7. For all concentrations studied (50 − 300 mg/L) of AG25, removal by using CA was more than 99% at all temperatures in a short time. At the initial adsorption stage, the AG25 removal rate by CA was very fast, i.e., more than 98% in 1 min. The removal with PANI/CA was 95.98% to 99.28% (50 mg/L) in 60 min period. CA showed better adsorption of AG25 than PANI/CA. The best description of the adsorption equilibrium for AG25 on CA was with two models Langmuir and Freundlich. For PANI/CA, the data fit was best described by the Langmuir model and suggesting monolayer adsorption. The highest adsorption capacity of 518 mg/g was obtained for AG25 onto CA. The pseudo-second-order model has well defined the kinetics of AG25 onto carbon aerogel and polyaniline/carbon aerogel. The present study demonstrated the high efficiency of the carbon aerogel adsorbent for textile wastewater treatment.