Selective Capacitive Removal of Heavy Metal Ions from Wastewater over Lewis Base Sites of S-Doped Fe–N–C Cathodes via an Electro-Adsorption Process

Abstract

The pollution of toxic heavy metals is becoming an increasingly important issue in environmental remediation because these metals are harmful to the ecological environment and human health. Highly efficient selective removal of heavy metal ions is a huge challenge for wastewater purification. Here, highly efficient selective capacitive removal (SCR) of heavy metal ions from complex wastewater over Lewis base sites of S-doped Fe−N−C cathodes was originally performed via an electro-adsorption process. The SCR efficiency of heavy metal ions can reach 99% in a binary mixed solution [NaCl (100 ppm) and metal nitrate (10 ppm)]. Even the SCR efficiency of heavy metal ions in a mixed solution containing NaCl (100 ppm) and multicomponent metal nitrates (10 ppm for each) can approach 99%. Meanwhile, the electrode also demonstrated excellent cycle performance. It has been demonstrated that the doping of S can not only enhance the activity of Fe−N sites and improve the removal ability of heavy metal ions but also combine with heavy metal ions by forming covalent bonds of S − clusters on Lewis bases. This work demonstrates a prospective way for the selective removal of heavy metal ions in wastewater.

Water Treatment Method for Removal of Select Heavy Metals and Nutrient Ions Through Adsorption by Magnetite

“…Researchers are currently exploring various methods to address contaminant removal, including ion exchange, biochar, reverse osmosis, adsorption, and a selective capacitive removal technology employing electro-adsorption or capacitive deionization. 7,10,12,19,23,24 This work examined the adsorption method, using magnetite (Fe 3 O 4 ) particles as the adsorbent. Adsorption is efficient, simple, and produces less byproducts than methods such as membrane filtration, ion exchange, and chemical precipitation.…”

“…The release and improper care of contaminated wastewaters pose serious threats to the environment, aquatic life, and human health, and the need for an efficient and economical method for contaminant removal is apparent. Researchers are currently exploring various methods to address contaminant removal, including ion exchange, biochar, reverse osmosis, adsorption, and a selective capacitive removal technology employing electro-adsorption or capacitive deionization. ,,,,, This work examined the adsorption method, using magnetite (Fe 3 O 4 ) particles as the adsorbent. Adsorption is efficient, simple, and produces less byproducts than methods such as membrane filtration, ion exchange, and chemical precipitation. ,,, Fe 3 O 4 is inexpensive, already exists in the environment, and has several favorable characteristics including biocompatibility, magnetic susceptibility, and an easily modified surface. ,,,,− Magnetic properties allow for easy and efficient collection, reducing chemicals needed for removal and decreasing the production of secondary pollutants. ,, Additionally, Fe 3 O 4 can effectively capture anions and cations across a range of pH values. ,,,, Further, Fe 3 O 4 has demonstrated potential in applications such as magnetic inks, MRI contrast agents, and water treatment. − …”

Coordination/cation exchangeable dual sites intercalated multilayered T3C2Tx MXene for selective and ultrafast removal of thallium(i) from water

“…17 On the other hand, surface functional groups such as -OH and -COOH always serve as anchoring sites for metal ions via electrostatic attraction or coordination, playing a critical role in heavy metal removal. [18][19][20][21] Zhang et al reported a titanium peroxide-based adsorbent for the removal of Tl + via the formation of an inner-surface complex with hydroxyl groups. 22 To date, cation exchange and surface functional group-assisted coordination are the most mainstream adsorption mechanisms for Tl + removal from water.…”

Adsorption Performance of Amino Functionalized Magnetic Molecular Sieve Adsorbent for Effective Removal of Lead Ion from Aqueous Solution

“…These dissolved heavy metal ions in water can cause adverse effects on aquatic ecosystems. Long−term exposure to water which has been contaminated by heavy metals can cause serious harm to human health [3][4][5][6]. Lead ion (Pb 2+ ) is a common pollutant in industrial wastewater, which can cause human dysfunction or serious lesions if ingested in large quantities or for a long time [7,8].…”