Preparation And Application Of Poly(N-alkyl Aniline)-lignin Composite Microspheres

Polyaniline has a good comprehensive performance and has widely potential applications including adsorption materials, antistatic materials, electromagnetic shielding materials, and secondary battery electrodes. However, polyaniline is very difficult to process because its chain is rigid, and has strong hydrogen bonding in its chains. To overcome this limitation, more and more researchers turn their attentions to the development of the polyaniline derivatives and their composites.In this thesis, poly(N-methylaniline)-lignosulfonate (PNMA/LS) and poly(N-butylaniline)-lignosulfonate (PNBA/LS) composite nanospheres were prepared facilely by using in-situ unstirred polymerization of N-methylaniline (NMA) and N-butylaniline (NBA) with lignosulfonate (LS) as a dispersant and dopant, respectively. The results showed that the kinds of monomers and the LS content had great effects on the size, structure and properties of the PNMA/LS and PNBA/LS composite spheres. Uniform PNMA/LS 10 composite spheres with a mean diameter of 1.03～1.27 μm were achieved at the reaction temperature of 25℃ for 24 h with the molar ratio of N-methylaniline to oxidant of 1:1 when the LS content was 10wt.%; and the PNMA/LS 10 composite spheres were assembled by their final nanofibers with an average diameter of 19～34 nm. However, PNBA/LS 10 composite solid spheres with a mean diameter of 375 nm were obtained under the same polymerization conditions.Furthermore, the adsorption of silver ions from aqueous solution onto PNMA/LS and PNBA/LS composite spheres were studied. Batch experiments were conducted over a range of the LS content, adsorption temperature (20～50℃), adsorption time (0.25～96 h) and silver ions initial metal concentration (0.03～0.16 mol L-1). Moreover, kinetics and thermodynamics of the adsorption were also studied. The study showed that when the adsorption time was 48 h, the temperature was 35℃, the initial concentration of the silver ions was 0.16 mol L-1, the maximum adsorption capacity of PNMA/LS10 composite spheres was up to 2160.0 mg g-1, whereas the maximum sorption capacity of PNBA/LS10 composite spheres was 1118.1 mg g-1 when the adsorption time was 96 h. TEM image and wide angle X-ray results of the PNMA/LS10 composite spheres after silver ions adsorption showed that the silver ions were reduced to silver nanoparticles with a mean diameter about 11.2 nm through a redox reaction between the PNMA/LS10 composite spheres and the silver ions, while Ag nanoparticles with a diameter size range from 6.8 nm to 55 nm was achieved on the PNBA/LS10 composite spheres after adsorption. These results indicate that these two adsorbents possess a strongly reactive adsorbability of silver ions. In addition, the absorption processes of PNMA/LS10 and PNBA/LS10 composite spheres were spontaneous endothermic reactions.