Conductive polymer and synthetic polymer based nanoparticle for removal of Hexavalent Chromium and Arsenide form agueous solution

Abstract

In order to address the issue of water contamination by toxic and carcinogenic hexavalent chromium and arsenite species, a new polymer nanocomposite (PNC) was fabricated with blend of polypyrrole (PPy)/polyvinyl alcohol (PvOH) and reinforcement of magnetite nanoparticles (Fe3O4). PNC was designed to selectively remove Cr (VI) and As (III) ions from aqueous solutions using adsorption and magnetic separation technology. The conductive electroactive PPy was synthesized by in situ polymerization of pyrrole monomers using FeCl3 as an oxidant. the PvOH was prepared by hydrolysing polyvinyl acetate dissolved in ethanol with potassium hydroxide and Fe3O4 nanoparticle was synthesized by co-precipitation in the presence of Fe (II) and Fe (III) ions as precursors in solution with ration 1:2. Thereafter, the polymer nanocomposite was prepared solution blending method. The PNC was characterized using fourier transform infrared (FT-IR) to identify the functional groups present in the compound, x-ray diffraction (XRD) to confirm the degree of crystallinity and the crystal orientation, scanning electrode microscope (SEM) to determine the surface morphology, transmission electron microscopy (TEM) for analysis of the internal morphology and braunner emmet tellet (BET) for analysis of the pore size and surface area. The adsorption studies will be carried out after optimization of effect of pH on adsorption kinetics experiment will be conducted by varying adsorbent grade, adsorbent mass and initial Cr (VI) concentration. Adsorption kinetics studies were performed under batch operation mode and the influence of PvOH polymer and magnetic content in the nanocomposite, individual constituent components, adsorbent dose and initial Cr (VI) concentration were all explored at room temperature and constant pH 12. It was revealed that the ratios of constituent components in the polymer blend significantly increased the adsorption process whereby 56:42 PPy-PvOH nanocomposite performed better [96%, 30 ppm] than 74:26, 64:36, and 52:48 polymer blend. The 56:44 polymer blend performance was exemplary compared to its constituent components. Fe3O4 was introduced to the blend in order to increase the polymer blend efficiency. However, a slight decrease in the removal percentage was observed after adding 2% of Fe3O4 nanoparticle. This may be due to particle agglomeration of the nanoparticle. Adsorption capacity of the nanocomposite increased with increase in adsorbent dosage and increase in initial Cr (VI) concentration and reached maximum at 91% removal efficiency. When adsorption kinetic data was fitted to both linear and nonlinear kinetic models, it was established that adsorption of Cr (VI) on PPy-PvOH- Fe3O4 is through a chemisorption process and that intra-particles played a key role in controlling the adsorption process in both cases that includes Cr(VI) and As(III). Furthermore, results revealed that by using 10 ml of 30ppm Cr (VI) aqueous solution with 0.12g at 45 minutes and pH 12 optimum conditions, the Cr (VI) removal of was sufficient and achieved 91.3%.And also using 10 ml of 150 ppm of As(III) aqueous solution with 0.10g at 30 minutes and pH 12 optimum conditions. The removal of As(III) from aqueous solution was also sufficient and 100% removal under the optimal conditions.