This study focuses on the synthesis of a novel layered double hydroxide and its application in two environmental remediation processes. Graphene oxide, a two-dimensional material, has potential applications in this field. However, its tendency to agglomerate restricts its usability. Our objective was to increase the morphology and performance of layered double hydroxide (LDH) by combining GO with hydrotalcite. The LDH/GO nanohybrids were utilized as photocatalysts for the degradation of methylene blue (MB) dye and were investigated as sorbents for acid red (A.R) dye in water. In order to achieve this objective, ZnAl-NO₃ LDH was synthesized using the co-precipitation method, with a Zn:Al ratio of ~3. Subsequently, the LDH was intercalated with varying ratios of as-received graphene oxide. An array of analytical techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) measurements, N₂ physisorption, scanning electron microscopy–energy-dispersive X-ray analysis (SEM-EDX), and diffuse reflectance UV–vis spectra (DR UV-vis), were employed to examine the physicochemical properties of the synthesized LDH. These techniques confirmed that the obtained material is zinc-aluminum hydrotalcite intercalated with GO. The addition of graphene oxide (GO) to the layered double hydroxide (LDH) structure improved the performance of the hydrotalcite. As a result, the composite ZnAl-LDH-10 shows significant potential in the field of photocatalytic degradation of MB. Additionally, the incorporation of GO enhanced the absorption of light in the visible region of the spectra, leading to improved elimination of A.R compared to LDH without GO or other ratios of GO.

Silver (Ag) containing nanomaterials were successfully prepared by varying synthesis conditions to understand the influence of preparation conditions on the physicochemical and photocatalytic properties of these materials. Different analytical techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Diffuse reflectance UV-vis spectra (DR UV-vis), X-ray photoelectron spectroscopy (XPS) measurements, and N₂-physisorption were used to investigate the physicochemical properties of synthesized Ag containing nanomaterials. The samples (Ag-1 and Ag-2) prepared using AgNO₃, NaHCO₃, and polyvinylpyrrolidone (PVP) template exhibited pure Ag metal nanorods and nanoparticles; the morphology of Ag metal is influenced by the hydrothermal treatment. The Ag-3 sample prepared without PVP template and calcined at 250 °C showed the presence of a pure Ag₂O phase. However, the same sample dried at 50 °C (Ag-4) showed the presence of a pure Ag₂CO₃ phase. Interestingly, subjecting the sample to hydrothermal treatment (Ag-5) has not resulted in any change in crystal structure, but particle size was increased. All the synthesized Ag containing nanomaterials were used as photocatalysts for p-nitrophenol (p-NP) degradation under visible light irradiation. The Ag-4 sample (pure Ag₂CO₃ with small crystallite size) exhibited high photocatalytic activity (86% efficiency at pH 10, p-NP concentration of 16 mg L⁻¹, 120 min and catalyst mass of 100 mg) compared to the other synthesized Ag containing nanomaterials. The high photocatalytic activity of the Ag-4 sample is possibly due to the presence of a pure Ag₂CO₃ crystal structure with nanorod morphology with a low band gap energy of 1.96 eV and relative high surface area.

In this work, 6-aminocaproic acid-modified copper ferrite nanoparticles were synthesized and used as an adsorbent for removing Amaranth dye from water. The modified nanoparticles were easily prepared using a simple and cost-effective method, namely the coprecipitation method. The nanocomposite was characterized by techniques like FTIR, XRD, SEM with EDS, and TEM. To evaluate the adsorption capacity of Amaranth dye, concentrations of Amaranth, contact time, nanocomposite dose, and solution pH were optimized. Further, Langmuir and the Freundlich isotherm models have been investigated. Among these, the Freundlich model showed the most accurate correlation with the experimental result, indicating a multilayer and physico-chemical adsorption of Amaranth dye onto the heterogeneous surface of the prepared nanocomposite. The Langmuir maximum adsorption capacity of this study was ~17 mg g⁻¹. Thermodynamic parameters (∆G° and ∆H°) confirmed that the adsorption process was spontaneous and exothermic. Adsorption kinetic studies showed pseudo second-order fitting with the multi-step adsorption process. The current adsorption performance was best for the first two adsorption–desorption cycles.

In this study, manganese ferrite was grown on the surface of a low-cost powder substrate of a guava leaf using the co-precipitation method. The resulting material was characterized using various spectroscopic and microscopic techniques. The composite was formed through the electrostatic and non-electrostatic interactions between the manganese ferrite nanoparticles, and the functional groups present on the guava leaf substrate; consequently, a high content of functional groups was observed in the synthesized composite through the Fourier transform infrared spectroscopy. The average size of the nanoparticles grown on the guava leaf substrate was determined to be between 3 and 5 nanometers. The synthesized composite material was utilized for adsorption applications, employing Methylene blue dye as a model adsorbate. Methylene blue was removed from the aqueous solutions under various conditions—including variations in the pH, contact time, temperature, and concentration. Under optimal conditions, it was observed that an adsorbent dosage of 2 g L⁻¹ was capable of removing approximately 99% of the dye from a 10 mg L⁻¹ dye solution at pH 7. The dye removal efficiency (%) decreased with the increasing temperature, indicating an exothermic process; this was further confirmed by the thermodynamic parameter analysis (specifically, the change in enthalpy, or ΔH), which yielded a negative value. Gibbs Free Energy (ΔG) also yielded a negative value, signifying the feasibility and spontaneity of the adsorption process. In this study, the adsorption process followed the Freundlich isotherm model, with the value of ‘n’ falling between 1 and 10, which is indicative of heterogeneous adsorption. The adsorption kinetics were determined to follow a pseudo-second-order model, and the overall rate-limiting step of the process was identified as intraparticle diffusion. To assess the sustainability and stability of the adsorbent, regeneration and reusability experiments were conducted. The results revealed that the modified guava leaf performed effectively for up to five cycles, achieving an adsorption efficiency of approximately 24% after the final cycle. Thus, the developed adsorbent proved to be an effective material for the removal of Methylene blue dye.

This study reports the preparation of a nanocomposite using a black cumin surface as a carbon framework on which zinc oxide-doped manganese ferrite nanoparticles were deposited and grown. A simple precipitation method was used to prepare the nanocomposite. The resulting composite was characterized using various characterization analyses such as FTIR, XRD, EDX, SEM, TEM, and TGA. The composite surface was highly conformed with functional groups, and the nanocomposite was formed due to electrostatic and non-electrostatic interactions between the carbon framework and the nanoparticles. X-ray analysis revealed a crystalline structure with crystal sizes up to 45 nm. Microscopic images revealed the surface morphology, confirming the irregular distribution of particles within the composite. The resulting composite material was used for adsorption application. The composite material was tested for the removal of Congo red dye from water. It was found that under optimal conditions, a dose of 2 g per liter of absorbent removed nearly 100% of dye from a 10 mL volume of 10 mg per liter Congo red solution within 90 min and 7 pH. A monolayer adsorption was confirmed by the isotherm analysis. The monolayer adsorption capacity for the present study was ~13.0 mg per gram. The adsorption kinetics suggested the fitting of pseudo-second order. Based on the findings, it was concluded that the chemical mechanism was responsible for the present adsorption process. The regeneration study demonstrates the stability of current adsorbent up to two cycles only. This nanocomposite is the first of its kind which promotes the creation of nanocomposites in the future by using natural materials and reduces the dependency on activated carbon.