Magnetic Nitrogen-Doped Porous Carbon Nanocomposite for Pb(II) Adsorption from Aqueous Solution

Rice husk valorization into sustainable Ni@TiO2/biochar nanocomposite for highly selective Pb (II) ions removal from an aqueous media

Herein, we successfully prepared sustainable nanocomposites from agriculture waste (rice husk)-derived biochar precursor, and followed by nickel-doped, base-treated titanium dioxide nanomaterials loading for efficient lead (Pb²⁺) removal from aqueous media. By varying the loading contents of active materials, the optimized sample (Ni_0.01@Na-TiO₂/BC) possessed an efficient Pb²⁺ adsorption capability of 122.3 mg g^-1 under the under optimum adsorption parameters, which is attributable to its specific surface area (138.09 m² g^-1) and excess functional sites. Kinetic and Isothermal examination illustrated that Pb²⁺ adsorption phenomena was well followed through pseudo 2nd order and Langmuir models. In addition, superior Pb²⁺ ions adsorption selectivity was recorded by optimized sample in a multi-metallic system over other existing ion (such as Cd²⁺, Mg²⁺, Ca²⁺, Cu²⁺, and Zn²⁺). Desorption experiments has been performed by using desorbing agent that demonstrates the good regeneration ability of sample. Hence, these findings provide new insight for the biowaste management by converting them into innovative adsorbents for commercial scale environmental remediation.

Evaluation of Pb (II) Removal by Tea Pulp Modified with Magnetite Nanoparticle

Tea waste was used to successfully synthesize magnetic nanoparticles (TWMNPs). In this investigation, Pb (II) was eliminated by tea waste modified with magnetite nanoparticles (TWMNPs) was investigated. To prepare the TWMNPs, FeCl3.6H2O was dissolved in double distilled water (DDW) and 20 g of pulp tea was added slowly and stirred, after 30 min TWMNPs adsorbent were separated through an external magnetic field and washed three times with double distilled water (DDW) and ethanol then dried at 60°C. The FESEM test of TWMNPs shows the particle size in the range of 15–20 nm and spherical/cuboid-shaped crystal structure of Fe3O4 (magnetite). X-ray analysis showed that the main XRD diffraction peaks of TWMNPs are related to Fe3O4, HighScore plus X’Pert software was used to identify the phase in this sample. The specific surface area of the prepared magnetite nanoparticles was 25.2 m2.g−1. The pore volume, maximum pore radius, and VSM of TWMNPs were 14.4 cm3.g−1, 2.3 nm, and 3.37–2.41, respectively. The effects of various parameters, such as contact time, pH, concentration, and adsorbent dosage, were studied. The experimental isotherm data were analyzed using the Langmuir and Freundlich models, and it was found that the removal process followed the Langmuir isotherm and the maximum adsorption capacity calculated by Langmuir fitting was 10.67 mg.g−1. In addition, the adsorption kinetics followed the first-order kinetic model and the value of rate constant was found to be 14.04 × 10−2 min−1. The results showed that increasing the pH level led to a rise in the response level and Pb (II) removal. Also, the trend in Pb (II) removal and response level had an increase with increasing the initial concentration of Pb (II). Increasing contact time from 5 to 20 minutes has a slight effect on Pb (II) removal. Considering the results, TWMNPs could lead to suitable results for the removal of Pb (II) from wastewater containing this metal. And the maximum adsorption capacity was found to be 10.67 mg.g−1.

The synthesis of nanocellulose-based nanocomposites for the effective removal of hexavalent chromium ions from aqueous solution

The present study reports the synthesis of a polydopamine (PDA)/nanocellulose (NC) nanocomposite for the effective removal of chromium ions from water. PDA was used to modify NC surface producing a nanocomposite namely PDA/NC, by in situ polymerization of dopamine on the surface of NC. Thereafter, the as-synthesized nanocomposite was characterized using familiar techniques such as Fourier transform infrared, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, and transmission electron microscopy. All results indicated the successful combination of PDA and NC in one nanocomposite. The PDA/NC nanocomposite was evaluated for the removal of hexavalent Cr(vi) ions from an aqueous solution. The adsorption conditions, such as pH, contact time, and initial Cr(vi) concentration, were optimized. Adsorption kinetic studies revealed that Cr(vi) removal on the surface of PDA/NC nanocomposite followed the pseudo-second-order kinetic model. Furthermore, isotherm studies revealed that Cr(vi) removal followed the Langmuir isotherm model with a maximum adsorption capacity (q m) of 210 mg/g. The adsorption mechanism study indicated that the Cr(vi) removal was reached via complexation, adsorption, and chemical reduction. The reusability of a PDA/NC nanocomposite for the removal of Cr(vi) ions was studied up to five cycles with acceptable results. The high adsorption capacity and multiple removal mechanisms validated the effective applicability of PDA/NC nanocomposite as a useful adsorbent for the removal of Cr(vi) ions from aqueous solution.

Synthesis, Characterization, and Application of Magnetized Lanthanum (III)-Based Metal-Organic Framework for the Organic Dye Removal from Water

A hybrid composite based on metal-organic framework (MOF) was chemically fabricated by embedding the magnetic Fe3O4 nanoparticles within amino-functionalized porous La-MOF (MOF/NH2) to produce a highly efficient and reusable composite of MOF/NH2/Fe3O4. Different proper techniques were used for the characterization of surface morphology and chemical arrangement of the prepared MOF/NH2/Fe3O4 composite. The characterization results using various techniques including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), Brunauer, Emmett, and Teller analysis (BET), and vibrating sample magnetometer (VSM) approved the successful fabrication of MOF with amino arms on its surface besides the well magnetization using magnetic nanoparticles. The MOF/NH2/Fe3O4 composite showed enhanced adsorption capacity (618 mg/g) toward methyl orange (MO) anionic dye which is higher than many commercial reported adsorbents due to the presence of many types of adsorption sites (NH2 groups and lanthanum sites), large surface area of MOF, and the synergetic effect of magnetic nanoparticles. Moreover, the MOF/NH2/Fe3O4 composite showed selective adsorption of MO dye from dye mixtures owing to the electrostatic attraction. Also, the MOF/NH2/Fe3O4 composite retained over 90% of its efficiency for the dye removal even after six successive cycles. So, the present study provided a practical strategy for the design of functional MOF hybrid composites. Furthermore, due to the adaptability of its architectural form, it is a potential adsorbent material for industrial wastewater treatment uses.

Magnetically Reusable Fe3O4@NC@Pt Catalyst for Selective Reduction of Nitroarenes

A novel reusable Fe3O4@NC@Pt heterogeneous catalyst was synthesized by immobilizing platinum on nitrogen-doped carbon magnetic nanostructures. It was characterized by infrared analysis (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The catalytic efficiency of Fe3O4@NC@Pt was investigated by reduction of nitro aromatic compounds. The catalyst showed good catalytic activity, wide range of substrates, and good chemical selectivity, especially for the substrates of compounds containing halide and carbonyl groups. The magnetically catalyst can readily be reused up to ten cycles without loss of catalytic activity. Moreover, the key pharmaceutical intermediate Lorlatini can be facilely achieved through this strategy.

The Biocatalytic Degradation of Organic Dyes Using Laccase Immobilized Magnetic Nanoparticles

Free laccase has limitations for its use in industrial applications that require laccase immobilization on proper support, to improve its catalytic activity. Herein, the nanoparticles of magnetic iron oxide (Fe3O4) and copper ferrite (CuFe2O4) were successfully used as support for the immobilization of free laccase, using glutaraldehyde as a cross-linker. The immobilization conditions of laccase on the surface of nanoparticles were optimized to reach the maximum activity of the immobilized enzyme. The synthesized free nanoparticles and the nanoparticle-immobilized laccase were characterized using different techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), vibrating sample magnetometer (VSM), and thermogravimetric analysis (TGA). CuFe2O4 nanoparticles, as support, enhanced laccase activity compared to free laccase and Fe3O4 nanoparticle-immobilized laccase that appeared during the study of pH, temperature, and storage stability on free and immobilized laccase. The CuFe2O4 and Fe3O4 nanoparticle-immobilized laccase showed superior activity in a wide pH range, temperature range, and storage period, up to 20 days at 4.0 °C, when compared to free laccase. Additionally, the synthesized nanobiocatalysts were examined and optimized for the biodegradation of the anionic dye Direct Red 23 (DR23). HPLC analysis was used to confirm the dye degradation. The reusability of immobilized laccases for the biodegradation of DR23 dye was investigated for up to six successive cycles, with a decolorization efficiency over 70.0%, which indicated good reusability and excellent stability.