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Polyaniline-zinc oxide composite on Kapok paper were fabricated for methylene blue dye removal in aqueous solution. Kapok fibers were fabricated into papers. The fabricate paper served as substrate for the zinc oxide-polyaniline composite. Zinc oxide particles were deposited on the Kapok paper using an in-situ method while polyaniline molecules are deposited on paper using Successive Ionic Layer Adsorption and Reaction (SILAR) method. The polyaniline molecules were deprotonated using sodium hydroxide (NaOH) to be able adsorb cationic dyes in aqueous solution. The samples were characterized using scanning electron microscope (SEM), energy dispersive X-ray (EDX) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Results show that the deprotonated polyaniline nanocomposite was able to remove at about 75% more dye compared to the as-synthesized polyaniline nanocomposite.

Hematite (α-Fe2O3) is a low-cost n-type semiconductor with significant absorption of visible light owing to its low bandgap energy of 2.1 eV. The wide applications of hematite in renewable energy and environmental remediation continuously entice more studies. However, the low absorbance of solar energy in the UV-range significantly limits the efficiency of many photocatalytic materials. In this study, we tried to dope α-Fe2O3 with silver via chemical precipitation method to lower the bandgap energy and widen its absorbance. The effects of doping hematite with Ag on the structure, morphology, elemental composition, and optical absorbance were determined by characterizing the samples via X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, and UV-Vis spectroscopy, respectively. It was observed from the XRD patterns that the α-Fe2O3 crystallizes in hexagonal structure with lattice parameters a = 5.0380 Å and c = 13.7720 Å for the pure α-Fe2O3. Doping with 0.1M and 0.2M AgNO3 leads to a greater value of the lattice parameters indicating successful doping. SEM images show that the hematite formed was composed of particles with irregular shapes that have sizes in the range 0.865-0.883 μm. Excess silver particles were deposited on the surface of hematite. UV-Vis spectra show that there is a red-shift in the absorption band of the Ag-doped hematite. A notable decrease in the bandgap energy of the undoped α-Fe2O3 was observed from ~2.2eV to ~2.0eV with the increase in the amount of the dopant in the hematite as determined using Tauc’s plot.