ZnO is a semiconductor material that has important physical and chemical properties, which are frequently and significantly enhanced by the addition of impurities, such as doping. A study of the structural properties of pristine and functionalized (i.e., doped with Antimony and Tungsten) ZnO nanoparticles has been conducted for the photocatalyst-based degradation of methylene blue (MB) dye under both Ultraviolet (UV) and solar light. Authors have used a 1% concentration of dopant for doping purposes. The synthesized materials were characterized for structural analysis, functional group identification, spectroscopic measurements, and morphological examination using X-ray diffraction (XRD), Fourier transform-infrared (FTIR), UV-Vis spectroscopy (UV-Vis), and Field emission scanning electron microscope (FESEM) techniques. XRD analysis confirmed that the synthesized-doped materials retained the wurtzite hexagonal structure with a purity of 99%. Transmission electron microscope (TEM) analysis data reveals the average size of pure ZnO-NPs was found to be 7 nm; after doping the size was found to be increased to 18 nm and 9.55 nm, respectively, for ZnO-W and ZnO-Sb. As per FESEM analysis results, minor morphological changes were observed after doping. The Ultraviolet Differential reflectance spectroscopy UV-DRS study revealed the confirmation of ZnO doping with antimony and tungsten, which exhibited a blue shift. The decrease in the band-gap on doping makes the ZnO-NPs more efficient for photocatalytic applications. The photocatalytic efficiency of pristine and doped ZnO-NPs catalysts for methylene blue photocatalytic degradation (PCD) was analyzed under both UV and solar irradiation. This study analyzed the effect of pH, nano-photocatalyst dose, and initial dye concentration (ICD) on the PCD of MB. The obtained analytical results showed that the ideal conditions for the PCD of MB dye are as follows: pH = 9, the quantity of the nano-photocatalyst used was 300 mg/L, and an initial MB dye dose of 10 ppm. These conditions lead to a PCD of about 91% of the MB dye by using ZnO-Sb nano-photocatalyst on exposure to solar radiation. The reusability study also revealed the stability of nano-photocatalysts. The current research may pave the way for the removal of hazardous dyes from wastewater discharged by many industries.

Due to the increased demand for clothes by the growing population, the dye-based sectors have seen fast growth in the recent decade. Among all the dyes, methylene blue dye is the most commonly used in textiles, resulting in dye effluent contamination. It is carcinogenic, which raises the stakes for the environment. The numerous sources of methylene blue dye and their effective treatment procedures are addressed in the current review. Even among nanoparticles, photocatalytic materials, such as TiO₂, ZnO, and Fe₃O₄, have shown greater potential for photocatalytic methylene blue degradation. Such nano-sized metal oxides are the most ideal materials for the removal of water pollutants, as these materials are related to the qualities of flexibility, simplicity, efficiency, versatility, and high surface reactivity. The use of nanoparticles generated from waste materials to remediate methylene blue is highlighted in the present review.

The increased advancement in nanosciences in recent times has led to fascinating innovations. It has potential applications for altering the structural, surface, and physicochemical properties of nano-ranged metamaterials. The adaptable optical, structural, and surface characteristics of the nanoscopic regimes enhance the quality of integrated nanodevices and sensors. These are further used in optoelectronics, biomedicines, and catalysis. The use of nanomaterials for constructing nano-biosensors and various other organic and inorganic functional nanomaterials is quite promising. They have excellent electronic and surface-to-volume reactivity. Their various applications include metal and metal-oxides-based nanoparticles, clusters, wires, and 2D nanosheets as carbon nanotubes. More recently, hybrid nanomaterials are being developed to regulate sensing functionalities in the field of nanomedicine and the pharmaceutical industry. They are used as nano-markers, templates, and targeted agents. Moreover, the mechanical strength, chemical stability, durability, and flexibility of the hybrid nanomaterials make them appropriate for developing a healthy life for humans. This consists of a variety of applications, such as drug delivery, antimicrobial impacts, nutrition, orthopedics, dentistry, and fluorescence fabrics. This review article caters to the essential importance of nanoscience for biomedical applications and information for health science and research. The fundamental characteristics and functionalities of nanomaterials for particular biomedical uses are specifically addressed here.

Nanoparticles and nanomaterials have gained a huge amount of attention in the last decade due to their unique and remarkable properties. Metallic nanoparticles like zinc oxide nanoparticles (ZnONPs) have been used very widely as plant nutrients and in wastewater treatment. Here, ZnONPs were synthesized by using onion peel and characterized by various sophisticated instruments like Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and field emission scanning electron microscopes (FESEM). FTIR confirmed ZnONPs synthesis due to the formation of the band in the region of 400–800 cm⁻¹, while FESEM confirmed the spherical shape of the particles whose size varies in the range of 20–80 nm. FTIR revealed several bands from 1000–1800 cm⁻¹ which indicates the capping by the organic molecules on the ZnONPs, which came from onion peel. It also has carbonyl and hydroxyl groups, due to the organic molecules present in the Allium cepa peel waste. The average hydrodynamic size of ZnONPs was 500 nm as confirmed by DLS. The synthesized ZnONPs were then used as a plant nutrient where their effect was evaluated on the growth of Vigna radiate (mung bean) and Triticum aestivum (wheat seeds). The results revealed that the germination and seedling of mung and wheat seeds with ZnONPs were grown better than the control seed. However, seeds of mung and wheat with ZnONPs at median concentration exposure showed an enhancement in percent germination, root, and shoot length in comparison to control. Thus, the effect of ZnONPs has been proved as a nano-based nutrient source for agricultural purposes.

Environmental pollution is one of the major concerns throughout the world. The rise of industrialization has increased the generation of waste materials, causing environmental degradation and threat to the health of living beings. To overcome this problem and effectively handle waste materials, proper management skills are required. Waste as a whole is not only waste, but it also holds various valuable materials that can be used again. Such useful materials or elements need to be segregated and recovered using sustainable recovery methods. Agricultural waste, industrial waste, and household waste have the potential to generate different value-added products. More specifically, the industrial waste like fly ash, gypsum waste, and red mud can be used for the recovery of alumina, silica, and zeolites. While agricultural waste like rice husks, sugarcane bagasse, and coconut shells can be used for recovery of silica, calcium, and carbon materials. In addition, domestic waste like incense stick ash and eggshell waste that is rich in calcium can be used for the recovery of calcium-related products. In agricultural, industrial, and domestic sectors, several raw materials are used; therefore, it is of high economic interest to recover valuable minerals and to process them and convert them into merchandisable products. This will not only decrease environmental pollution, it will also provide an environmentally friendly and cost-effective approach for materials synthesis. These value-added materials can be used for medicine, cosmetics, electronics, catalysis, and environmental cleanup.

Nanotechnology and nanomaterials have gained much attention in recent years due to their remarkable features. Among nanoparticles, photocatalytic material, such as zinc oxide, have shown tremendous applications in each and every field of science. In the present research, investigators have synthesized zinc oxide nanoparticles (ZnONPs) using Scallion’s peel extract. ZnONPs were both spherical and rod-shaped, where the size for spherical particles was 40–100 nm and rod-shaped, particles size was more than 200 nm as confirmed by microscopic techniques. The typical trademark bands of ZnONPs at 400–800 cm⁻¹ were revealed by infrared spectroscopy, which also showed bands of carbonyl and hydroxyl groups. The hydrodynamic size by particle size analyzer (PSA) shows a size near about 200 nm in diameter. Furthermore, the synthesized ZnONPs were used to assess their potential as a micronutrient for the plant and nano adsorbent for the removal of antibiotics (ampicillin) and methylene blue dye from the simulated wastewater. The antibiotic and dye removal were observed under UV light and visible light against contact time. In comparison to control seeds, seeds grown with ZnONPs have shown better germination and seedling. It could be concluded that ZnONPs acted as an important nanosized source of nutrition for agricultural applications. Thus, the effect of ZnONPs has been proven as a nano-based nutrient source for agricultural purposes. The remediation study found that remediation of both ampicillin and methylene blue dye was efficient under UV light under similar experimental parameters from the simulated wastewater by the ZnONPs.