Preparation And Functionality Of Nano-structured Polyaniline/Lignin Composites

In this thesis, nanostructured polyaniline-lignin (PANI-EHL) composite was prepared via one-step chemical oxidative polymerization and was applied as an adsorbent of heavy metal ions. Next, polyaniline (derivatives)-lignosulfonate composite spheres were fabricated with lignosulfonate as a dispersant. Then, nitrogen-containing carbon micro/nanospheres with controllable morphology, structure and nitrogen content were obtained by pyrolysis of the polyaniline (derivatives)-lignosulfonate composite spheres at different temperatures under a nitrogen atmosphere, and they were used as anodes of lithium-ion batteries.Firstly, a hierarchical polyaniline-lignin (PANI-EHL) composite was facilely prepared from aniline and enzymatic hydrolysis lignin (EHL) and used as an adsorbent of silver and gold ions. It was found that redox adsorption is the main adsorption mechanism for the adsorption of silver and gold ions. As for the adsorption of silver ions, the maximum adsorption capacity and adsorptivity of PANI-EHL composite were 662.0 mg g-1 and 24.5%, respectively, when the initial concentration of silver ions was 50 mmol L-1. The products of PANI-EHL composite after silver ions adsorption contained serrated self-assembly silver threads with length up to 10 mm. As for the adsorption of gold ions, the maximum adsorption capacity and adsorptivity of PANI-EHL composite were 1452.2 mg g"1 and 98.3%, respectively, when the initial concentration of gold ions was 5 mmol L-1. The adsorption process of gold ions meets the equation of the pseudo-first model and the Freundlich isotherm model according to the kinetics and thermodynamics sorption models, respectively.Secondly, micro/nano-structured polyaniline-lignosulfonate (PANI-LS), poly(2-ethylaniline)-lignosulfonate (PEA-LS) and poly(N-ethylaniline)-lignosulfonate (PNA-LS) composites were obtained by the polymerization of aniline,2-ethylaniline and N-ethylaniline, respectively, with LS as a dispersing agent. The results showed that the content of LS played a very important part in the controllability of morphology, structure and properties of the three composites. PANI-LS and PEA-LS composites with an average diameter of 80 nm and 170 nm, respectively, could be prepared when the LS content was 20 wt.%; whereas PNA-LS composite microspheres with an average diameter of 1.3μm were obtained when the LS content was 2.5 wt.%.Thirdly, three nitrogen-containing carbon micro/nanospheres (i.e. CPAN,CPEA and CPNA) were prepared by direct pyrolysis of the PANI-LS, PEA-LS and PNA-LS composite spheres, respectively. When the carbonization temperature was 700℃, CPAN, CPEA and CPNA carbon spheres with a nitrogen content of 8.78%,7.77% and 7.60%, and an average diameter of 140 nm,136 nm and 780 nm, respectively, could be obtained. It could be easily found that elemental content, structures of pores and surface area changed largely in the carbonization process.Finally, nitrogen-containing carbon spheres obtained at different carbonization temperatures were used as anodes of lithium-ion batteries and charged/discharged at a current density of 100 mA g-1. The results revealed that carbon spheres obtained at 700 ℃, i.e. CPAN-700, CPEA-700 and CPNA-700, possessed better electrochemical performance than those carbon spheres obtained at other temperatures. In addition, the charge/discharge capacity of the CPAN-700 nanospheres at a current density of 60 and 200 mA g-1 was also measured. The results showed that the current density greatly affected the reversible capacity of the CPAN-700 nanospheres.