Multifunctional Binding Sites on Nitrogen-Doped Carboxylated Porous Carbon for Highly Efficient Adsorption of Pb(II), Hg(II), and Cr(VI) Ions

Abstract

Heavy metal ions represent one of the most toxic and environmentally harmful pollutants of water sources. This work reports the development of a novel chelating nitrogen-doped carboxylated porous carbon (ND-CPC) adsorbent for the effective removal of the heavy metal ions Pb(II), Hg(II), and Cr(VI) from contaminated and polluted water sources. The ND-CPC adsorbent is designed to combine four different types of nitrogen functional groups (graphitic, pyrrolic, pyridinic, and pyridine oxide) with the carboxylic acid functional groups within a high surface area of 1135 ± 20 m 2 /g of the porous carbon structure. The ND-CPC adsorbent shows exceptionally high adsorption affinity for Pb(II) with a capacity of 721 ± 14 mg/g in addition to high uptake values of 257 ± 5 and 104 ± 2 mg/g for Hg(II) and Cr(VI), respectively. The high adsorption capacity is also coupled with fast kinetics where the equilibrium time required for the 100% removal of Pb(II) from 50 ppb and 10 ppm concentrations is 30 s and 60 min, respectively. Even with the very high concentration of 700 ppm, 74% uptake of Pb(II) is achieved within 90 min. Removal efficiencies of 100% of Pb(II), 96% of Hg(II), 91% of Cu(II), 82% of Zn(II), 25% of Cd(II), and 13% of Ni(II) are achieved from a solution containing 10 ppm concentrations of these ions, thus demonstrating excellent selectivity for Pb(II), Hg(II), and Cu(II) ions. Regeneration of the ND-CPC adsorbent shows excellent desorption efficiencies of 99 and 95% for Pb(II) and Cr(VI) ions, respectively. Because of the fast adsorption kinetics, high removal capacity and excellent regeneration, stability, and reusability, the ND-CPC is proposed as a highly efficient remediation adsorbent for the solidphase removal of Pb(II), Hg(II), and Cr(VI) from contaminated water.

The cross‐linked hyperbranched polyamide‐amines: The preparation and its adsorption for Pb(II)

“…Adsorption peaks at 2925.26 and 2853.99 cm À1 were related to the asymmetric and symmetric stretching vibrations of CH 2 groups, respectively. 33 It is easily found that the peaks at 1400.28 and 1629.41 cm À1 are consistent with the symmetric and antisymmetric telescopic peaks of COO À . 34 After adsorption for Pb(II), the telescopic vibration peak of amide group shift from 1663.71 to 1630.54 cm À1 .…”

Efficient removal of heavy metals from polluted water with high selectivity for Hg(ii) and Pb(ii) by a 2-imino-4-thiobiuret chemically modified MIL-125 metal–organic framework

“…The removal efficiencies diminished due to protonation of the binding sites on the adsorbent surface, which increased the repulsive forces between the positive ions and adsorbent surface. 49 Furthermore, at lower pH, there was more competition between positive ions and H + for binding sites due to the high contamination of protons. The adsorption capacities increased at higher pH due to the strong attractive forces between the binding sites on the ITB-MIL-125 surface that are negatively charged and the positive metal ions.…”

“…In the case of As( v ), the optimum pH was 2.0, which could be explained by the protonation of NH 2 groups on ITB-MIL-125 leading to q high electrostatic interaction between the anionic species [H 2 AsO 4 ] − and adsorbent surface. 49 A series of various concentrations was prepared to study the influence of the initial concentrations at the optimum pH for each metal ion. As illustrated in Fig.…”

“…After Hg adsorption, a new peak appeared at 404.8 eV assigned to N–O, which indicated both sulfur and nitrogen functional groups were coordinated to Hg( ii ) ions. 49,56 …”

Insights into lead removal in water using a novel carbonized material derived from the by‐product of oil refining: action mechanism and performance optimization

“…In recent years, environmental pollution caused by heavy metal has increasingly attracted global public attention 1 . Lead is one of the most toxic heavy metals, and it is difficult to degrade, easily enters the food chain, 2 and accumulates in the human body. After absorption of lead, it accumulates in various organs in the body, seriously affecting the central nervous and hematopoietic system of the human body and resulting in a range of neurological diseases, cardiovascular diseases, and even mental decline, especially in children 3 .…”