Electrospun ZnO was deposited on a glass substrate from zinc acetate dihydrate (Zn(CH3COO)2.2H2O) with polyvinyl acetate (PVAc) polymer dissolved in N, N, dimethyl formamide (DMF) and annealed in the presence of oxygen until organic molecules were decomposed. The resultant fibre was characterized using scanning electron microscope with energy dispersive spectrophotometry (SEMEDS), Fourier transform infrared (FTIR), and Rutherford backscattering spectroscopy (RBS). SEMEDS and FTIR exhibited a total decomposition of the organic precursor. The mean fibre width was found to be 260 nm, and fibre thickness was measured at 460 nm. XRD patterns indicate that ZnO was corundum with the hexagonal wurtzite structure. The crystallite size was determined by the Debye formula to be 54 nm. The optical analysis indicated that the percentage transmittance increased after calcination. The material band gap for this electrospun ZnO fibre was found to be 3.28 eV. The material optical parameters such as dispersion energy, average oscillator strength, and single oscillator strength were also calculated. The optical conductivity and dielectric plot demonstrated that the material conductivity and dielectric properties increase with increasing photon energy and increase sharply around the material energy bandgap. The Urbach tail analysis of the materials shows that they obey the Urbach rule. Therefore, the n-type electrospun ZnO fibre high refractive index is attributable to the presence of excess oxygen. Keywords: Electrospinning, Calcined, Semiconductor, Nanofibre, Zinc Oxid

This work presents low-cost sorbent powder obtained from agro-waste of poultry eggshells for the adsorption of contaminants and was elucidated with transmission electron microscopy, Fourier transform infrared, scanning electron microscope, X-ray diffraction and N₂ adsorption–desorption techniques. It was observed that a solution pH of 2.0 and 5.0 was enough for the maximum uptake of reactive yellow 145 dye (RY 145) and Cu(II) ions, respectively, which showed that the pollutants removal was affected by the pH of solution. Langmuir monolayer adsorption capacity was found to be 101.500 mg/g for Cu(II) and 88.450 mg/g for reactive yellow 145 dye, respectively. Redlich–Peterson and Sips models both fitted well with the adsorption data. The Pseudo-second-order equation demonstrated good relationship with the experimental data and thus explained the adsorption mechanism to be chemisorption. Values of different thermodynamic considerations gave the values of ΔH° and ΔS° to be 30452.020, 27194.180 and 100.930, 90.370 kJmol⁻¹ for Cu(II) and RY 145 dye, respectively. Findings from this current study revealed that the prepared sorbent from agro-waste of eggshell can be a useful material for the elimination of Cu(II) and RY 145 dye in aqueous solutions.

Pb²⁺ is considered to be a very toxic pollutant in the aquatic environmental media. Biopolymeric chitosan synthesized from snail shell has been studied for its potential to remove heavy metals from aqueous solution. The experiments were conducted in the range of 1–50 mg/L initial Pb²⁺ concentration at 298 K. The effects of pH, adsorbent dosage and contact time on the adsorptive property of the adsorbent were investigated and optimized. The derived chitosan was characterized using Fourier transform infrared spectrometer (FT-IR) and X-ray florescence (XRF). The experimental data obtained were analysed using the Langmuir and Freundlich adsorption isotherm models. The Langmuir model and pseudo second order kinetic model suitably described the adsorption and kinetics of the process with regression coefficient of 0.99 and 1.00, respectively. Sodium hydroxide was a better desorbing agent than hydrochloric acid and de-ionized water. From the results obtained, it is concluded that synthesized biopolymers from land snail shells has the potential for the removal of Pb²⁺ from aqueous solutions.