Kappa carrageenan was used to prepare hydrogels having novel compositions with poly(vinyl alcohol) (PVA) and a crosslinker (3-aminopropyl)triethoxysilane (APTES). FTIR was used to confirm the structure and composition of hydrogels. The swelling behavior of hydrogels was studied under different conditions of pH and electrolytic aqueous media. The most efficient swelling result (200%) was observed by the sample containing a low fraction of crosslinker. It also showed different swelling responses in different pH solutions that made it suitable for drug delivery. Thermogravimetric analysis (TGA) illustrated that with the increase in crosslinker amount, the stability of hydrogel was increased. The biodegradation analysis of the hydrogels exhibited the break down by various enzymes into small chain polysaccharides that further broke down in the metabolic pathways. It was revealed that all the hydrogel samples showed strong antibacterial activity against S. aureus and a little against E. coli. Cephradine was used as a model drug and its in vitro release was studied in simulated intestinal fluids (SIF). This release account of the cephradine demonstrated that the release of the drug increased as the time and pH increased, reaching its maximum amount of 85.5% after 7.5 h.

Nickel–zinc ferrites are soft magnetic materials that have different technological applications due to their low magnetic coercivity, high electrical resistivity and low eddy current loss. The soft ferrites are the best for manufacturing core of power transformers, recording heads, data storage devices, telecommunication equipment, media devices, microwaves and electronic devices. In current investigation, a series of zinc doped nickel ferrites (Zn_xNi_1−xFe₂O₄, x = 0.1, 0.2, 0.3, 0.4 and 0.5) were prepared by hydrothermal method (at 220 °C, 16 h). The structural, magnetic and dielectric properties were measured. X-ray diffractometer and fourier transform infrared spectroscopy (FTIR) were used to analyze the structural properties and structure of zinc doped nickel ferrites was spinel. As the concentration of Zn was increased, the structural properties (lattice constant, density, dislocation density, radii of tetra and octahedral sites and oxygen positional parameters) were also changed. FTIR results showed the strongest absorption band at 500–600 cm⁻¹, which indicate the intrinsic stretching vibration of Zn⁺² ↔ O bond (M_tetra ↔ O) at tetrahedral site. Vibrating sample magnetometer (VSM) was used to measure magnetic properties and it was observed that the value of saturation magnetization increased with Zn concentration. The investigation of frequency dependent dielectric property was measured by Impedance Analyzer. Dielectric constant and tangent loss decreased at higher frequency, whereas AC conductivity increased with frequency.

Cobalt ferrite was synthesized by hydrothermal route in order to investigate the effect of hydrothermal reaction time on structural, magnetic and dielectric properties. The synthesized cobalt ferrite was characterized by X-ray diffraction, Fourier transform infrared and Vibrating-Sample Magnetometer (VMS). XRD data analysis confirmed the formation of cubic inverse spinel ferrite for complete time series as the high intensity peak corresponds to cubic normal spinel structure. The ionic radii, cation distribution among tetrahedral and octahedral sites, lattice parameters, X-ray density, bond lengths were also investigated cobalt ferrite prepared at different hydrothermal reaction time. The crystallite size was found to be in the range of 11.79–32.78 nm. Tolerance factor was near unity that also confirms the formation of cubic ferrites. VSM studies revealed the magnetic nature of cobalt ferrite. The coercivity (1076.3Oe) was observed for a sample treated for 11 h. The squareness ratio was 0.56 that is close to 0.5 which shows uniaxial anisotropy in cobalt ferrite. Frequency dependent dielectric properties i.e. dielectric constant, AC conductivity, tangent loss and AC resistivity are calculated with the help of Impedance Analyzer. Intrinsic cation vibration of cubic spinel ferrites are confirmed from FTIR analysis in the range of 400–4000 cm⁻¹. In view of enhanced properties, this technique could possibly be used for the synthesis of cobalt ferrite for different applications.

Zinc oxide (ZnO) nanorods were fabricated through hydrothermal route and employed for the adsorption of Cr(VI) ions from aqueous medium. Zinc nitrate hexahydrate (Zn(NO₃)₂.6H₂O) was used as a zinc precursor and Triton-x 100 was used as a capping agent. As synthesized ZnO nanorods were characterized by UV-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-Ray spectroscopy (EDX) techniques. The adsorption affecting parameters were investigated for maximum adsorption of Cr(VI) onto ZnO nanorods. The adsorption kinetics, isotherms, and thermodynamics were applied for adsorption mechanism evaluation. Maximum adsorption of Cr(VI) ions (250 mg/g) was achieved using 0.055 g/L ZnO dose at pH 2.0 for the contact time of 30 min. Pseudo-second-order kinetic model and Langmuir isotherm explained well the Cr(VI) adsorption onto ZnO nanorods. The Cr(VI) adsorption onto ZnO was spontaneous and endothermic in nature. In view of promising adsorption efficiency, ZnO nanorods could possibly be used for Cr(VI) ions removal from wastewater and also extendable for the adsorption of other heavy metals ions.