Squaramide-Immobilized Carbon Nanoparticles for Rapid and High-Efficiency Elimination of Anthropogenic Mercury Ions...

Water pollution due to environmental remediation and poor waste administration in certain areas of the globe signifies a serious problem in acquiring safe and clean drinking water. This problem is especially critical in rural areas, where advanced water purification techniques are deficient, and it remains a daunting task for ecosystem and public health protection. This critical task can be addressed herein by developing scalable poly squaramide-phenyl methacrylamide (PSQ)-functionalized carbon nanoparticles (CNPs) (PSQ-CNPs) with densely populated chelating sites with strong Hg²⁺-binding capacity. The PSQ-CNPs have shown high efficiency in removing Hg²⁺ from aqueous solution, providing a Hg²⁺ capacity of 2840 mg g^-1, surpassing all the amine and thiol-based adsorbents reported hitherto. More significantly, the adsorbent reveals the largest distribution coefficient value (K_d) of 9.09 × 10¹⁰ mL g^-1, which allows it to reduce Hg²⁺ content from 10 ppm to less than 0.011 ppb, well below the United States Environmental Protection Agency (EPA) limits for drinking water standards (2 ppb). The adsorption measurements of the adsorbent followed the Langmuir isotherm model and pseudo-second order. The practical applicability of PSQ-CNPs was verified with the real samples (the lake, river, and industrial wastewater) and has been proven to be excellent. The adsorbent could still retain its Hg²⁺ removal efficacy even after 12 sorption cycles. It is attributed that the remarkable performance of PSQ-CNPs arises from the high-density chelating sites and pores on the surface of CNPs. The present work shows a new benchmark for Hg²⁺-removal adsorbents and presents a novel practical approach for decontaminating Hg²⁺ and other heavy metal ions from wastewater.