The adsorption of crystal violet (CV) onto date palm fibers (DPFs) was examined in aqueous solution at 25°C. The experimental maximum adsorption capacity value was 0.66 × 10⁻⁶. Langmuir, Freundlich, Elovich and Temkin models were applied to describe the equilibrium isotherms. The influence of pH and temperature on dye removal was evaluated. The percentage removal of CV dye by adsorption onto DPF at different pH and temperatures showed that these factors play a role in the adsorption process. Thermodynamic analysis was performed, and the Gibbs free energy ΔG^ο, enthalpy change ΔH^ο, and entropy ΔS^ο were calculated. The negative values of ΔG^ο indicate spontaneous adsorption. The negative value of ΔH^ο indicates that the interaction between CV and DPF is exothermic, and the positive value of ΔS^ο indicates good affinity between DPF and CV. The kinetic data were fitted to a pseudo‐second‐order model.

CoO/Co₃O₄ nanoparticles (NPs) were synthesized by using a fresh egg white-assisted combustion method which acts as a new approach for green synthesis of this composite. This method was carried out by the direct heat of cobalt precursor with egg white at low temperature for very short period. In fact, this route is a novel, cheap and appropriate technique yielding nanoparticle-based materials. CoO/Co₃O₄ nanoparticles were characterized by examining the structure and identifying the elements and determining the morphology via XRD, FTIR, SEM, EDS and TEM techniques. The sample magnetic observations were measured through the use of a vibrating sample magnetometer (VSM). The results of XRD, EDS, SEM and TEM confirmed the positive synthesis of the cubic CoO/Co₃O₄ NPs with sponge crystals which proceed. For the as synthesized composite, 57.75 m²/g, 0.0148 cc/g and 10.31 nm were identified to be the S_BET, V_p and ȓ, respectively. The cobalt oxide particles in their nature were polycrystalline, and the crystallite sizes varied from 10 to 20 nm. The magnetic measurement showed that the prepared nanocomposite displays room temperature ferromagnetism with an optimum value, 3.45 emu/g, of saturation magnetization.

In this study, a polyvinyl alcohol–sodium alginate blend, PVA:SA 3:1 (w:w), was doped with different contents of TiO₂ nanoparticles (NPs) prepared by aloe vera leaf extract to form the investigated nanocomposites. The nonlinear parameters of third-order susceptibility (χ⁽³⁾) and refractive index (n₂) were detected by using UV-Vis spectroscopy and Z-scan techniques. Some different optical parameters were also determined, including the refractive index (n), optical dielectric parameters, volume and surface energy loss functions, and some others. The best solar skin protection factor (SSPF) was investigated by 5 wt.% of TiO₂ NPs doped in PVA:SA 3:1, which was about 84.6% compared to the corresponding value of the host blend (41%). The studied nanocomposites were examined for their utility in the optical limiting of CUT-OFF laser filters utilizing a continuous He-Ne laser working at 632.2 nm. As a result, our finding demonstrated that TiO₂ NPs doped in the host blend of PVA:SA positively influences a laser light blocking for the investigated laser source. Using the estimated gap energies values, different models were used to deduce theoretical values of the linear refractive index (n). The presence of Ti peaks in the EDX spectrum confirmed the doping of TiO₂ NPs in the nanocomposites. SEM showed that the TiO₂ NPs are homogeneously dispersed through the host blend with some agglomerates. XRD spectra showed that the values of the lattice strain ε_str. detected at 2ϴ = 19.78° are 0.058, 0.055, and 0.060, corresponding to 1, 3, and 5 wt.% of TiO₂ NPs doped in the PVA:SA blend.