Application of Carbon Nanotubes (CNTs) for Remediation of Emerging Pollutants - A Review

Abstract

Nanotechnology is currently an upward trend in diverse fields, and therefore, its application will be reviewed in this paper. One of the nanotechnologies which can be used in environmental remediation is carbon nanotube (CNT). Its excellent mechanical and chemical properties allow it to have better achievement in remediating a wide range of organic and inorganic pollutants. CNT can be categorized into two types: single-walled carbon nanotube and multi-walled carbon nanotube. Due to urbanization, various types of pollutants have been released into the environment in great amounts. For instance, estrogen is the hormone generated and released from animals and humans. However, the overconcentration of estrogen affects the physiology of biological life. Besides, pesticides are frequently used by farmers to increase the fertility of the land for agricultural purposes, while heavy metals are commonly found during anthropogenic activities. Long-term absorption of heavy metals into the body tissues will accumulate toxic effects, leading to body system dysfunction. Hence, CNT technologies, including adsorption, membrane filtration, disinfection, hybrid catalysis, and sensing and monitoring, can be applied to remediate these pollutants. However, the application of nanotechnology and CNT faces several challenges, such as production costs, toxicity, ecological risks, and public acceptance. Application of CNT also has pros and cons, such that the lightweight of the CNT allows them to replace metallic wires, but dealing with nano-sized components makes it challenging.

Carbon-Based Nanoadsorbents for the Removal of Emerging Pollutants

“…Because of their open structure, CNTs have a larger surface area, faster access to reactive sites, faster kinetics, and improved adsorption capacity [6]. Cost and development of sustainable production procedures, on the other hand, are hindering the widespread use of carbon nanotubes.…”

“…Personal care products, home cleansers, perfluorinated compounds (PFCs), endocrinedisrupting compounds (EDCs), prescription drugs, and other commodities emit a wide range of chemicals into the environment [2,3]. Emerging contaminants (ECs) are chemicals (synthetic or natural) and microorganisms of any sort that are not routinely monitored, have not previously been examined, and may pose harm to ecosystems, human health, and safety [6][7][8]. Hormone activity; damage to the skin, brain, and neurological system; cancer; and ecological toxicity are some of the most important health and environmental problems linked with ECs.…”

“…These innovative adsorbents can remove pollutants down to the atomic level, in addition to having a remarkable adsorption capacity. Recent studies have concentrated on the development of nanoscale adsorbents for EC removal [6,25,26]. The adsorbent's capacity to remove a wide spectrum of pollutants is enhanced by the surface functional groups [27][28][29][30][31].…”

“…Even regenerated AC’s efficiency is inferior to that of fresh AC [1]. As a result, the quest for new adsorbents has risen in recent years [1, 6, 7]. Nanotechnology is being applied in a range of scientific sectors, including water purification, as it advances.…”

Occurrence of cadmium in groundwater in China: a review

“…The process of filtration is constantly ongoing as the flow of groundwater enables the reaction to happen without the need of pumping the groundwater Efficiency will reduce when clogging occurs on the reactive walls (Blowes et al 1997;Phillips 2009;Martin and Kempton 2000) Lime and calcium carbonate Addition of chemicals to coagulate the heavy metals in the groundwater source Cheap reagents and easy to handle during operation of remediation on contaminated site Insoluble products formed might be mobilized and cause secondary pollution to the groundwater (Lee et al 2007;Hashim et al 2011) Nanoremediation Involves the use of nanosized particles to undergo the adsorption process in groundwater The process of filtration using nanosized particles will be faster and more efficient as a larger surface area increases the rate of reaction The cost of manufacturing large-scale nanosized parts is high (Rajan 2011;Savage and Mamadou 2005;Chung et al 2021;Kristanti et al 2021) heavy metal ions are no longer mobile. Hence, this can reduce the contamination of groundwater (Blowes et al 1997).…”