Heavy metal toxicity in water is a serious problem that may have harmful effects on human health and the ecosystem. Lead [Pb(II)] and cadmium [Cd(II)] are two such heavy metal ions, present in water, whose severity is well-known and well-studied. In the current research, magnetic biochar composite (MBC) is studied as an adsorbent material for the effective removal of lead and cadmium ions from water solutions. Magnetite (Fe₃O₄) nanoparticles and pine-needle-derived ultrasonicated magnetic biochar were used in different weight ratios to prepare APTES (3-aminopropyl triethoxysilane)-functionalized MBC (FMBC). An average crystalline size of ~10 nm for magnetite NPs was obtained via XRD analysis. The adsorption characteristics of both Pb(II) and Cd(II) ions were investigated in a batch experiment. The FTIR spectra of raw biochar, MBC, FMBC, and metal-loaded FMBC were obtained at different stages. The decrease in the intensity of the –NH₂ functional group in the FTIR spectra of the residue confirmed the successful adsorption of heavy metal ions. The SEM-EDX spectra of the residue showed the uniform adsorption of Pb(II) and Cd(II) heavy metal ions onto the surface of the adsorbent. Magnetic biochar composite (MBC) was found to be a very effective adsorbent at basic pH, as a maximum of 97% instantaneous heavy metal removal was observed for both ions in synthetic water solutions. The Langmuir isotherm model predicted the monolayer adsorption and good affinity between the metal ions and adsorbent. The prepared MBC is low-cost, environmentally friendly, and it has shown good adsorption performance. Therefore, our study suggests that the magnetic biochar composite under study is an effective adsorbent for lead and cadmium metal ion removal from aqueous solutions at normal room temperature. Only a few hundred milligrams of the adsorbent dose is sufficient to remove higher concentrations (~100 ppm) of lead and cadmium at basic pH conditions of aqueous solutions.

The surge of interest in ferrimagnetic materials over the years has been driven by their fascinating multifunctional properties. The elastic properties of these materials are a subject of much interest and vital importance due to their wide range of technological and industrial applications. In the present work, the structural and elastic properties of tetragonal copper ferrite (CuFe₂O₄) nanoparticles synthesized by a citrate assisted sol-gel auto combustion technique have been investigated. The nanocrystalline powder of copper ferrite was characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and UV–Visible spectroscopic techniques. The X-ray diffraction pattern revealed pure spinel structure of copper ferrite nanoparticles with Jahn–Teller tetragonal distortion. The band gap of copper ferrite nanoparticles was found to be 3.14 ± 0.03 eV using the diffuse reflectance spectra. The values of elastic moduli (Young’s modulus (E) = 186.3 ± 0.5 GPa, bulk modulus (B) = 124.1 ± 0.3 GPa, and rigidity modulus (G) = 74.4 ± 0.2 GPa) and Debye temperature (θ _D = 500.5 ± 0.5 K) suggest that the synthesized nano-structured copper ferrite is a promising candidate for high temperature and high pressure applications.

In present work, NiFe₂O₄ nanoparticles doped with 4% Ce ions were synthesized by chemical route using nitrates of iron, nickel and cerium with citric acid. Irradiation with swift heavy ions can modify the properties of ferrites significantly. Modification depends upon type of ion, energy and fluence used for irradiation. Presently NiCe_0.04Fe_1.96O₄ sample was irradiated with 100 MeV O⁷⁺ beam at fluencies of 1×10¹² ions/cm², 5×10¹² ions/cm², 1×10¹³ ions/cm² and 2×10¹³ ions/cm². All samples (pristine and irradiated) were characterized by XRD, FTIR, Raman and UV-Vis spectroscopy. XRD patterns and FTIR spectra confirmed the spinel structure of sample. XRD parameters like crystallite size, lattice parameter, strain etc. were calculated, which show significant change only at the fluence of 5×10¹² ions/cm². UV-Vis spectra show two direct band gaps corresponding to low and high spin in all samples. Band gap was found to be higher for sample irradiated at 2×10¹³ ions/cm² fluence in comparison to pristine sample. It is found that irradiation with 100 MeV oxygen affect the structural parameters in random way while optical band gap shows increasing trend with fluence.