Synthesis and characterization of magnetite carbon nanocomposite from agro waste as chromium adsorbent for effluent treatment

Hagenia abyssinica-Biomediated Synthesis of a Magnetic Fe3O4/NiO Nanoadsorbent for Adsorption of Lead from Wastewater

Magnetic nanocomposite adsorbents are cost-effective, environmentally friendly, easy to use, and highly efficient at removing metals from large volumes of wastewater in a short time by using an external magnetic field. In this study, an Fe3O4/NiO composite nanoadsorbent was prepared by varying the mass percent ratios of NiO (50, 40, 30, 20%), which are denoted Fe3O4/50%NiO, Fe3O4/40%NiO, Fe3O4/30%NiO, and Fe3O4/20%NiO, respectively, using Hagenia abyssinica plant extract as the template/capping agent and a simple mechanical grinding technique. The nanocomposites were characterized using an X-ray diffractometer (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, nitrogen adsorption, and ζ-potential measurements. The adsorption performance of the nanoadsorbent was assessed for the removal of lead (Pb2+) ions from aqueous solutions. Among the composite adsorbents, Fe3O4/50%NiO demonstrated the best Pb(II) removal efficiency (96.65%) from aqueous solutions within 80 min at pH 8, at a 100 mg/L lead concentration and 0.09 g of adsorbent dose. However, with the same parameter, only 62.8% of Pb(II) was removed using Fe3O4 nanoparticles (NPs). The adsorptive performance indicated that the optimum amount of porous material (NiO) in the preparation of the Fe3O4/NiO composite nanoadsorbent, with the aid of H. abyssinica plant extract, enhances the removal of toxic heavy metals from aqueous solutions. Multiple isotherm and kinetic models were used to analyze the equilibrium data. Adsorption isotherm and kinetic studies were found to follow the Freundlich isotherm and pseudo-second-order kinetics, respectively.

Sequestration of Ni (II), Pb (II), and Zn (II) utilizing biogenic synthesized Fe3O4/CLPC NCs and modified Fe3O4/CLPC@CS NCs: Process optimization, simulation modeling, and feasibility study

The present study reports low-cost novel biogenic magnetite Citrus limetta peels carbon (Fe3O4/CLPC) nanocomposites and modified Fe3O4/CLPC@CS nanocomposites cross-linked with glutaraldehyde and subsequently employed in batch mode sequestration of heavy metals ions. Diverse techniques fully characterized them, and the influence of operating variables on adsorption reactions from aqueous solutions was investigated. The Brunauer, Emmett, and Teller (BET) surface areas of synthesized Fe3O4/CLPC and Fe3O4/CLPC@CS NCs were 53.91 and 32.16 m2/g, while the mesoporous diameters were 7.69 and 7.57 nm, respectively. The Langmuir isotherm and Pseudo second order kinetic were well-fitting and capable of explaining the adsorption reaction. The Langmuir-based monolayer adsorption (qmax) for Fe3O4/CLPC@CS NCs was 82.65, 95.24, and 64.10 mg/g, higher than Fe3O4/CLPC NCs, which were 70.92, 84.75, and 59.17 mg/g for Ni (II), Pb (II), and Zn (II), respectively. Each metal's pseudo second order correlation coefficient (R2 ≥ 0.99) reveals that nanocomposites surface binding functional groups controlled the adsorption rate via chemisorption. Further, thermodynamic results confirm that each studied metal ions' adsorption was spontaneous, endothermic, and characterized by an increase in randomness. In addition to magnetic separability, three ad-desorption cycles yielded exceptional adsorption efficacy and > 93% regenerability. The present study also reveals the effective utilization of Fe3O4/CLPC and Fe3O4/CLPC@CS NCs as cost-effective magnetic separable green adsorbents for heavy metals sequestration from electroplating wastewater.

2,4-Dichlorophenoxyacetic acid (2,4-D) adsorptive removal by algal magnetic activated carbon nanocomposite

In the present study, ferric oxide nanoparticles impregnated with activated carbon from Ulva prolifera biomass (UPAC-Fe₂O₃) were prepared and employed to remove 2,4-Dichlorophenoxyacetic acid (2,4-D) by adsorption. The UPAC-Fe₂O₃ nanocomposite was characterized for its structural and functional properties by a variety of techniques. The nanocomposite had a jagged, irregular surface with pores due to uneven scattering of Fe₂O₃ nanoparticles, whereas elemental analysis portrayed the incidence of carbon, oxygen, and iron. XRD analysis established the crystalline and amorphous planes corresponding to the iron oxide and carbon phase respectively. FT-IR analyzed the functional groups that confirmed the integration of Fe₂O₃ nanoparticles onto nanocomposite surfaces. VSM and XPS studies uncovered the superparamagnetic nature and presence of carbon and Fe₂O_3, respectively, in the UPAC-Fe₂O₃ nanocomposite. While the surface area was 292.51 m²/g, the size and volume of the pores were at 2.61 nm and 0.1906 cm³/g, respectively, indicating the mesoporous nature and suitability of the nanocomposites that could be used as adsorbents. Adsorptive removal of 2,4-D by nanocomposite for variations in process parameters like pH, dosage, agitation speed, adsorption time, and 2,4-D concentration was studied. The adsorption of 2,4-D by UPAC-Fe₂O₃ nanocomposite was monolayer chemisorption owing to Langmuir isotherm behavior along with a pseudo-second-order kinetic model. The maximum adsorption capacity and second order rate constant values were 60.61 mg/g and 0.0405 g/mg min respectively. Thermodynamic analysis revealed the spontaneous and feasible endothermic adsorption process. These findings confirm the suitability of the synthesized UPAC-Fe₂O₃ nanocomposite to be used as an adsorbent for toxic herbicide waste streams.

Potential of sugarcane bagasse in remediation of heavy metals: A review

Presence of heavy metal (HM) ions in wastewater have emerged as among the most prominent issues for improving water quality and reducing it's consequences for the environment, animal and public health. This paper mainly focuses on the remediation of HM ions from wastewater utilizing the relatively inexpensive and widely accessible agricultural waste-Sugarcane Bagasse (SCB). For this, a brief understanding of HMs was discussed (by understanding the sources and toxicity of HM, advantages and shortcomings of conventional processes). Apart from that, to understand the potential of SCB, this review would provide vital information on employing SCB biosorbent in natural and modified forms for HM removal. Therefore, various ways of SCB modifications (including physical, chemical, and composite formation), essential optimal operational conditions (solution pH, dosage of biosorbent, initial metal concentration, contact time, agitation speed, temperature, suitable isotherm and kinetic model) and involving adsorption mechanism were also studied. Finally, significant study gaps were identified to facilitate future research since SCB has been confirmed as a potential bio-adsorbent for removing HM ions.

Bandgap and visible-light-induced photocatalytic performance and dye degradation of silver doped HAp/TiO2 nanocomposite by sol-gel method and its antimicrobial activity

Silver doped hydroxyapatite and titanium oxide nanocomposites have been obtained by sol-gel techniques with novel antimicrobial activities for biomedical applications. The synthesis of Ca_10-X Ag_X (PO₄)₆(OH)₂ along with titanium oxide nanoparticles with X_Ag = 0 (HAp/TiO₂), 0.1, 0.25 and 0.5 (Ag:HAp/TiO₂-NCS) was performed. The developed crystalline phase was characterized via X-ray diffraction (XRD), and the morphological features were executed via scanning and transmission electron microscopy (SEM/TEM). The HAp/TiO₂ and silver doped HAp/TiO₂ nanocomposites were spherical grains, with needle and flower-like structures. XRD examination revealed the crystalline phases of HAp/TiO₂ and Ag-doped HAp/TiO₂ nanocomposites. The crystallite size of HAp/TiO₂ and Ag-doped HAp/TiO₂ nanocomposites determined from the XRD pattern was ranged between 16 nm and 20 nm. The FTIR analysis confirms the presence of stretching and vibrational peaks for the presence of silver doped HAp/TiO₂. The EDAX analysis showed the existence of major elements of HAp/TiO₂ and Ag-HAp/TiO₂ nanostructured composites. HAp/TiO₂ and silver doped HAp/TiO₂ were active against both Gram-positive and Gram-negative bacteria such as, E. coli (MTCC 443), S. typhi (MTCC 733), and S. aureus (MTCC 3160). The photocatalytic absorption spectrum implied an increased absorption rate of methylene blue by HAp/TiO₂ and silver doped HAp/TiO₂ nanocomposites. The photocatalytic activity revealed that 50% Ag doped HAp/TiO₂ optimally improved photocatalytic activity.