Preparation and properties of nitrogen-containing hollow carbon nanospheres by pyrolysis of polyaniline–lignosulfonate composites

Polyaniline–lignosulfonate composite hollow spheres were synthesized by using one-step unstirred polymerization of aniline in the presence of lignosulfonate. Novel nitrogen-containing hollow carbon nanospheres were prepared by direct pyrolysis of the polyaniline–lignosulfonate composite spheres at different temperatures under a nitrogen atmosphere. Thermal behavior of the polyaniline–lignosulfonate composite spheres was studied by TG–DTG, FTIR and element analyze instruments. The resultant carbon spheres were characterized by SEM, XRD and nitrogen adsorption–desorption measurement. It was found that the pyrolysis products of the polyaniline–lignosulfonate composite spheres were made up of uniform hollow carbon nanospheres with an average diameter of 135 nm. Furthermore, the hollow carbon nanospheres exhibit high BET surface area range from 381.6 m2 g−1 to 700.2 m2 g−1. The hollow carbon nanospheres could be used as adsorbents of papain. The papain adsorption capacity for the carbon spheres prepared at 1200 °C was up to 1161 mg g−1 at an initial papain concentration of 10 mg mL−1 at 25 °C.