Synthesis Approaches of Zinc Oxide Nanoparticles: The Dilemma of Ecotoxicity

Abstract

Human’s quest for innovation, finding solutions of problems, and upgrading the industrial yield with energy efficient and cost-effective materials has opened the avenues of nanotechnology. Among a variety of nanoparticles, zinc oxide nanoparticles (ZnO) have advantages because of the extraordinary physical and chemical properties. It is one of the cheap materials in cosmetic industry, nanofertilizers, and electrical devices and also a suitable agent for bioimaging and targeted drug and gene delivery and an excellent sensor for detecting ecological pollutants and environmental remediation. Despite inherent toxicity of nanoparticles, synthetic routes are making use of large amount of chemical and stringent reactions conditions that are contributing as environmental contaminants in the form of high energy consumption, heat generation, water consumption, and chemical waste. Further, it is also adding to the innate toxicity of nanoparticles (NPs) that is either entirely ignored or poorly investigated. The current review illustrates a comparison between pollutants and hazards spawned from chemical, physical, and biological methods used for the synthesis of ZnO. Further, the emphasis is on devising eco-friendly techniques for the synthesis of ZnO especially biological methods which are comparatively less hazardous and need to be optimized by controlling the reaction conditions in order to get desired yield and characteristics.

Zinc Oxide Nanoparticles Obtained by Supercritical Antisolvent Precipitation for the Photocatalytic Degradation of Crystal Violet Dye

“…In this perspective, the method employed to produce ZnO nanoparticles plays an important role in the control of morphology and size. Traditional synthesis methods, such as precipitation, coprecipitation, colloidal methods, sol-gel processing, water-oil microemulsions method, hydrothermal synthesis, solvothermal, sonochemical, as well as polyol method [24], make it difficult to obtain well-separated nanoparticles with a narrow particle size distribution (PSD). Moreover, a massive use of organic and inorganic solvents, like nitrates, ammonia, diethylene glycol [25], ethylene glycol [26], 2-methoxyethanol with monoethanolamine [27], and hydroxides, are often required to obtain ZnO nanopowders [28][29][30][31].…”

Synthesis and Characterization of Zinc Oxide Nanoparticles with Small Particle Size Distribution

“…Heiligtag et al 10 has also stated that the potential applications of ZnO NPs make them one of a primary focus in NPs research. Naveed Ul Haq et al 13 also described that ZnO NPs is one of the cheap materials that this causes the extensive productions in industries. Morphologically, ZnO NPs is an attractive compound that possess thermal and chemical stability.…”

The cytotoxic properties of zinc oxide nanoparticles on the rat liver and spleen, and its anticancer impacts on human liver cancer cell lines

“…Moreover, the applications of NPs in the health, food, chemistry, and cosmetics industries are developing rapidly. It should be noted that the synthesis of NPs is feasible by different methods, which are known as green, chemical, or physical synthesis . Expensive equipment and the difficult conditions of synthesis in the physical methods, as well as dangerous and toxic chemicals for patients and researchers in the chemical methods, have increased the applications of green synthesis approaches .…”