Microwave absorption properties were systematically studied for synthesised barium hexaferrite (BaFe12O19) nanoparticles and spiraled multiwalled carbon nanotubes (MWCNTs) hybrid. BaFe12O19 nanoparticles were synthesised by a high energy ball milling (HEBM) followed by sintering at 1400 °C and structural, electromagnetic and microwave characteristics have been scrutinized thoroughly. The sintered powders were then used as a catalyst to synthesise spiraled MWCNTs/BaFe12O19 hybrid via the chemical vapour deposition (CVD) process. The materials were then incorporated into epoxy resin to fabricate single-layer composite structures with a thickness of 2 mm. The composite of BaFe12O19 nanoparticles showed a minimum reflection loss is − 3.58 dB and no has an absorption bandwidth while the spiraled MWCNTs/BaFe12O19 hybrid showed the highest microwave absorption of more than 99.9%, with a minimum reflection loss of − 43.99 dB and an absorption bandwidth of 2.56 GHz. This indicates that spiraled MWCNTs/BaFe12O19 hybrid is a potential microwave absorber for microwave applications in X and Ku bands.

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Chitosan membrane has the potential to separate lead(II) ions from aqueous solution. However, the kind of membrane has a drawback due to the low structural properties. Thus, this study investigates the role of silica in improving chitosan-based flat sheet membrane for removal of lead(II) ions from aqueous solution. The functional groups and structural morphologies were characterized using Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR) spectrometer and Scanning Electron Microscope (SEM), respectively. The membrane performance in terms of adsorption study was conducted at different pHs and initial concentration of lead(II) solution. The FTIR-ATR spectrum showed the existence of new absorption peak of chitosan/silica membrane. SEM images revealted the presence of microvoids on the cross-section of the chitosan/silica membrane whereas pure chitosan membrane possessed dense structure. The adsorption study showed that the composite membrane exhibited higher efficiency of lead(II) removal at optimum pH of 7.0 which was 89.27% as compared to 11.50% of pure chitosan membrane. The amount of lead(II) adsorbed onto the membrane was 57.60 mg/g. Therefore, it indicates the potential use of silica to improve the properties of chitosan membrane for removal of heavy metal from water solution.

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The present study was conducted to establish adsorbent potential of magnetite nanoparticle ferrous ferric oxide (Fe3O4) for removal of Cu(ll) ions in wastewater. In the study, Fe3O4 was prepared by synthesizing low-cost recycled mill scale waste in an aqueous solution. Samples of scale wastes were milled and ground using high-energy ball milling (HEBM) at three milling times of 5, 7 and 9 hours. Extraction of Fe3O4 was accomplished by magnetic separation technique (MST) and Curie temperature separation technique (CTST). The morphologies and structural properties of Fe3O4 were characterized by using X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier-transform infrared spectroscopy (FTIR). HRTEM yielded images in the range of 10-22 nm. Maximum adsorption capacity, qe,and percentage removal of Cu(II) ions were achieved at 4.45 mg/g and 62.61% respectively after 7 hours of milling time. The present study recorded the smallest particle size of Fe3O4 imparting high qe, and percentage removal of Cu (II) ion in an aqueous solution, suggesting its high adsorbent potential.