Nanostructured Carbon Florets as Scavenger of As³⁺, Cr⁶⁺, Cd²⁺, and Hg²⁺ for Water Remediation

Abstract

Anthropogenically triggered escalating contamination of water by heavy-metal ions (As 3+ , Cr 6+ , Cd 2+ , and Hg 2+ ) demands newer and efficient types of adsorbents for their comprehensive scavenging. The wide pH range (pH 2−13) at which such contamination persists makes it challenging to realize a single-step remediation approach. Addressing these escalating demands, a singular adsorbent capable of capturing multiple heavy metal ions with high adsorption capacity across a wide range of pH is herewith reported for sustainable water remediation. Threedimensional dendritic mesoporous nanostructured carbon florets (NCFs) with high specific surface area (936 m 2 /g) and easily accessible open-ended pore structure (1.23 cm 3 /g) achieve highly efficient removal of multiple heavy metal ions (As 3+ , Cr 6+ , Cd 2+ , and Hg 2+ ). The hydrophilic surface of NCF ensures extensive and efficient interfacing with the water feedstock, while its chemical stability ensures its effectiveness as an adsorbent over a wide pH range (pH 2 to pH 13). The synergistic combination of these factors enables excellent adsorption efficiency (AE; ranging from 80% to 90%) and uniformly high adsorption capacity (q e ) toward a variety of heavy-metal ions such as Hg 2+ (395 ± 4 mg/g), Cd 2+ (402 ± 5 mg/ g), Cr 6+ (436 ± 3 mg/g), and As 3+ (412 ± 4 mg/g). Moreover, the gravity-driven purification of water does not demand any external source of electrical power and is scalable for on-site implementation. Facile regeneration of the NCF and its reusability over multiple cycles is also demonstrated for practical and sustainable application in water remediation.

Metal–Dielectric Interfacial Engineering with Mesoporous Nano-Carbon Florets for 1000-Fold Fluorescence Enhancements: Smartphone-Enabled Visual Detection of Perindopril Erbumine at a Single-molecular Level

“…Furthermore, this strategy effectively utilizes the high diffusion coefficient (0.9 cm 2 /s at 740 °C) of the gas-phase carbon precursors to provide controllable and three-dimensional conformal coating of carbon on the surface of DFNS. Subsequent removal of the template ensures that the resulting NCF is an exact complementary replica of DFNS and thus exhibits large accessible surface areas, tunable porosities, and fiber densities. − The HAADF–TEM images establish complete removal of the DFNS template, providing an all-carbon NCF (Figure S2).…”

“…Here, we overcome such traditional and persistent drawbacks of metallic nanostructures by demonstrating 300-fold SPCE enhancements with non-metallic, porous, all-carbon-based nanostructured carbon florets (NCF). − Morphologically, the NCF exhibits a spherically isotropic, three-dimensional arrangement of conically graded microcavities, mimicking the floral assembly of marigold. This results in a large pore volume (0.44 cm 3 /g) and a highly accessible surface area (920 m 2 /g) .…”

Joule Heating-Driven Transformation of Hard-Carbons to Onion-like Carbon Monoliths for Efficient Capture of Volatile Organic Compounds

“…The free-standing porous nature of the OLCMs points to several interesting applications in the domains of energy storage , and environmental remediation. − In this direction, the extensive graphitic surface of the OLCMs was exploited to adsorb and trap VOCs such as toluene. The experiments were conducted with toluene as the model VOC in flow-through geometry to mimic the smoke filter of a cigarette.…”

Nitrogen and sulfur co-doped fluorescent carbon dots for the trapping of Hg(ii) ions from water

“…Table 4 displays the adsorption capacity (Q) of the CDs for Hg 2+ ions and it was found out that the capacity of the as-synthesized CDs is higher than those from several reports in the literature, which employed various adsorbents such as carbon nanotubes, graphene oxide derivatives, and nanocomposites. [56][57][58][59][60][61][62][63][64][65][66][67] It was also discovered that in spite of the higher surface area in case of carbon nanotubes, silica-loaded CDs exhibit significantly higher adsorption capacity owing to the presence of specific surface functionalities that are unique to the metal ions. The CDs outperformed several other adsorbent materials and provided positively superior support for real-time water remediation.…”

“…Various adsorbent materials such as carbon-based materials, metal oxides, metal-organic-frameworks, and polymers, having a large surface area, appropriate pore/cavity size, and suitable binding sites have been employed. 30 In this work, we have employed CDs adsorbed on the surface of silica for trapping toxic Hg 2+ ions in the aqueous medium. The CDs were characterized using SEM technique and known concentrations of Hg 2+ ions were passed through the column under pressure and a controlled flow rate.…”