Adsorption potential of orange rind-based nanosorbents for the removal of cadmium(II) and chromium(VI) from contaminated water.

Heavy metals (HMs) in water are highly poisonous and carcinogenic agents for human health. To alleviate the toxic impacts of HMs, green remediation technologies are the need of the hour. In this regard, different nanosorbents (CMCG@ORP, ORAC, NiO/NPs, and NiO@ORAC/NCs) were synthesized in the present study, and the percentage removal of heavy metals [chromium(VI) and cadmium(II) ions] was evaluated. The nanosorbents were characterized by using FTIR, SEM, UV-Vis spectroscopy, and XRD. UV-Vis spectroscopy confirmed the synthesis of nanosorbents such as NiO/NPs and NiO@ORAC/NCs at 330.5 nm and 352.55 nm, respectively. The characterization studies show that the surface of synthesized nano-sorbents was highly coarse, uneven, and abrasive. XRD pattern deduced that the sample was of single phase, and no other impurity was detected except the face-centered cubic-phase peak of NiO. The maximum adsorption of Cd (91%) and Cr (92%) was found at initial concentrations of 100 and 60 ppm respectively at contact time = 180 min, temperature 25 °C, and with an adsorbent dose of 0.5 g. Isothermal, kinetic, and thermodynamic studies were also performed to evaluate the adsorption mechanisms and feasibility of the process. Adsorption mostly followed Freundlich isotherm which indicates the multilayer adsorption phenomenon and the negative value of Gibb's free energy showed the spontaneous nature and feasibility of the adsorption reaction. Surface complexation, ion exchange, surface precipitation, and the phenomenon of physical adsorption occurred on the sorbent surface which led to the attachment of Cd and Cr to the tested nanosorbents. In conclusion, NiO@ORAC/NCs were the most effective in the alleviation of Cd(II) and Cr(VI) ions in contaminated water.

Grapefruit Extract-Mediated Fabrication of Photosensitive Aluminum Oxide Nanoparticle and Their Antioxidant and Anti-Inflammatory Potential.

Aluminum oxide nanoparticles (Al2O3 NPs) were synthesized using a simple, eco-friendly green synthesis approach in an alkaline medium from the extract of grapefruit peel waste. The pre-synthesized, nano-crystalline Al2O3 NPs were characterized by using spectroscopic (UV-vis, FTIR, XRD, and EDX) and microscopic (SEM and TEM) techniques. The formed Al2O3 NPs exhibited a pronounced absorption peak at 278 nm in the UV-vis spectrum. The average particle size of the as-prepared Al2O3 NPs was evaluated to be 57.34 nm, and the atomic percentages of O and Al were found to be 54.58 and 45.54, respectively. The fabricated Al2O3 NPs were evaluated for antioxidant, anti-inflammatory, and immunomodulatory properties. The Al2O3 NPs showed strong antioxidant potential towards all the four tested assays. The anti-inflammatory and immunomodulatory potential of Al2O3 NPs was investigated by measuring the production of nitric oxide and superoxide anion (O2•-), as well as proinflammatory cytokines tumour necrosis factor (TNF-α, IL-6) and inhibition of nuclear factor kappa B (NF- κB). The results revealed that Al2O3 NPs inhibited the production of O2•- (99.4%) at 100 µg mL-1 concentrations and intracellular NO•- (55%), proinflammatory cytokines IL-6 (83.3%), and TNF-α (87.9%) at 50 µg mL-1 concentrations, respectively. Additionally, the Al2O3 NPs inhibited 41.8% of nuclear factor kappa B at 20 µg mL-1 concentrations. Overall, the outcomes of current research studies indicated that Al2O3 NPs possess anti-inflammatory and immunomodulatory properties and could be used to treat chronic and acute anti-inflammatory conditions.