Every day, globally, synthetic dyes are released into wastewater and as a result pollute the environment, calling for sophisticated methods of water purification. Researchers from Korea, Russia, and India have worked collaboratively to create a nano-filter method that can effectively remove synthetic dyes from wastewater.
The nano-filter was fabricated using a graphene oxide-manganese dioxide (GO-MnO2) nanocomposite which, according to the researchers, can remove up to 100% of harmful compounds from wastewater.
The study, led by Dr. Dipti Vaya of Amity University Noida, India, and Professor Hyunook Kim of the University of Seoul, states, “All these results give a direct visual impression of the fast kinetics efficiency and high adsorption capacity for real wastewater treatment application.”
Synthetic dyes are used across a wide range of industries, including textiles, fashion, cosmetics, and paper, as well as in industrial chemistry and pharmaceuticals. They then tend to find their way into the surrounding environment causing serious health risks to both fish and wildlife.
Furthermore, these dyes are non-degradable and can have a number of severe effects on human health, causing symptoms such as nausea, vomiting, breathing difficulties, and visual impairments. Additionally, some of the compounds found in these dyes can be carcinogenic, which expedites the need to find solutions for their removal.
Water purification, or wastewater treatment is considered a vital part of the ecosystem because it is interconnected with all other uses of water. Therefore, ensuring fisheries, wildlife habitats, and the human environment are all sufficiently protected against excessive pollution demands novel, advanced solutions.
Research has been geared towards finding cost-effective and environmentally-friendly water purification methods, and various applications supporting the removal of dyes have been reported, but until now, adsorption methods have often demonstrated poor selectivity and reusability.
Thus, this collaborative study makes novel use of a graphene-based nanocomposite, which can be used up to seven times without losing efficiency, to tackle this problem. Graphene was chosen for its high-surface area, honeycomb structure, conductivity, and mechanical strength, all attributes which make it suitable for various applications, including wastewater treatment.
“Graphene oxides have attracted great attention because of their broad spectrum of applications in the various fields including removal of different types of pollutants from water,” said Vinod Kumar, RUDN University professor and contributing of the study.
In order to create the nano-filter the team utilized a single-step hydrothermal process to fabricate the nanocomposite, which would then form the basic structure of the adsorbent. They then studied and tested the characteristics of the nanocomposite using scanning electron microscopy (SEM) and spectroscopy.
The team measured water contamination levels in a water-based solution contaminated with methyl orange and methylene blue dyes to put the nano-filter to the test. After just five minutes it was observed that the adsorbent had removed 50.48% of methyl orange and 85.35% of methylene blue from the solution.
After an hour had passed, the water-based solution was almost free of pollutants, with around 94% and 100% of the dyes removed, respectively. What’s more, the team was able to reuse the nanocomposite adsorbent and reapply other solutions containing contaminants. The graphene-based nano-filter demonstrated consistent results – 90% removal efficiency – for seven consecutive cycles.
From these results, it can be assumed that the synthesized adsorbent can be used to purify the water by filtration. By considering the low cost and higher adsorption potential, GO-MnO2 nanocomposite will be becoming a promising candidate for simultaneous removal of cationic and anionic dyes from polluted water for water purification.
Dr. Dipti Vaya, Amity University Noida
This study offers promise for the cleaning and decontamination of wastewater which would theoretically have a positive environmental impact while protecting marine life and mitigating any potential health risks in humans.
References and Further Reading
1. Monu Verma, Inderjeet Tyagi, Vinod Kumar, Simpy Goel, Dipti Vaya, Hyunook Kim, Fabrication of GO–MnO2 nanocomposite using hydrothermal process for cationic and anionic dyes adsorption: Kinetics, isotherm, and reusability, Journal of Environmental Chemical Engineering, Volume 9, Issue 5, 2021, https://www.sciencedirect.com/science/article/abs/pii/S2213343721010228.