Enrichment and removal of heavy metals contained in PCB boards by multiwalled carbon nanotubes for WEEE directive

2008 ◽  
Author(s):  
L. Hua ◽  
H. N. Hou
Keyword(s):  
Heavy Metals ◽  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Multiwalled Carbon ◽  
Removal Of Heavy Metals

scholarly journals Comparing the Adsorption Performance of Multiwalled Carbon Nanotubes Oxidized by Varying Degrees for Removal of Low Levels of Copper, Nickel and Chromium(VI) from Aqueous Solutions

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 723 ◽  
Author(s):  
Marko Šolić ◽  
Snežana Maletić ◽  
Marijana Kragulj Isakovski ◽  
Jasmina Nikić ◽  
Malcolm Watson ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Carbon Nanotubes ◽  
Aqueous Solutions ◽  
Multiwalled Carbon Nanotubes ◽  
Electrostatic Interactions ◽  
Positive Impact ◽  
Molar Ratio ◽  
Multiwalled Carbon ◽  
Removal Of Heavy Metals ◽  
Low Levels

Functionalized multiwalled carbon nanotubes (MWCNTs) have drawn wide attention in recent years as novel materials for the removal of heavy metals from the aquatic media. This paper investigates the effect that the functionalization (oxidation) process duration time (3 h or 6 h) has on the ability of MWCNTs to treat water contaminated with low levels of Cu(II), Ni(II) and Cr(VI) (initial concentrations 0.5–5 mg L−1) and elucidates the adsorption mechanisms involved. Adsorbent characterization showed that the molar ratio of C and O in these materials was slightly lower for the oxMWCNT6h, due to the higher degree of oxidation, but the specific surface areas and mesopore volumes of these materials were very similar, suggesting that prolonging the functionalization duration had an insignificant effect on the physical characteristics of oxidized multiwalled carbon nanotubes (oxMWCNTs). Increasing the Ph of the solutions from Ph 2 to Ph 8 had a large positive impact on the removal of Cu(II) and Ni(II) by oxMWCNT, but reduced the adsorption of Cr(VI). However, the ionic strength of the solutions had far less pronounced effects. Coupled with the results of fitting the kinetics data to the Elowich and Weber–Morris models, we conclude that adsorption of Cu(II) and Ni(II) is largely driven by electrostatic interactions and surface complexation at the interface of the adsorbate/adsorbent system, whereas the slower adsorption of Cr(VI) on the oxMWCNTs investigated is controlled by an additional chemisorption step where Cr(VI) is reduced to Cr(III). Both oxMWCNT3h and oxMWCNT6h have high adsorption affinities for the heavy metals investigated, with adsorption capacities (expressed by the Freundlich coefficient KF) ranging from 1.24 to 13.2 (mg g−1)/(mg l−1)n, highlighting the great potential such adsorbents have in the removal of heavy metals from aqueous solutions.

Preconcentration of heavy metals on multiwalled carbon nanotubes in water samples prior to analysis using FAAS

2017 ◽  
Vol 69 ◽  
pp. 261-267 ◽  
Author(s):  
Mohammad Saad Algamdi ◽  
Abdullah Saeed Alghamdi ◽  
Ibrahim Hotan Alsohaimi ◽  
Faiz Dakhil Allohybi ◽  
Ayoub Abdullah Alqadami
Keyword(s):  
Heavy Metals ◽  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Water Samples ◽  
Multiwalled Carbon

scholarly journals Enhanced Heavy Metal Removal from Acid Mine Drainage Wastewater Using Double-Oxidized Multiwalled Carbon Nanotubes

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 111 ◽  
Author(s):  
Carolina Rodríguez ◽  
Eduardo Leiva
Keyword(s):  
Heavy Metals ◽  
Carbon Nanotubes ◽  
Heavy Metal ◽  
Multiwalled Carbon Nanotubes ◽  
Sorption Capacity ◽  
Metal Removal ◽  
Heavy Metal Removal ◽  
Order Kinetic ◽  
Multiwalled Carbon ◽  
Oxidized Multiwalled Carbon Nanotubes

Due to the unique properties of carbon nanotubes (CNTs), they have attracted great research attention as an emergent technology in many applications including water and wastewater treatment. However, raw CNTs have few functional groups, which limits their use in heavy metal removal. Nevertheless, their removal properties can be improved by oxidation processes that modify its surface. In this study, we assessed the capacity of oxidized and double-oxidized multiwalled carbon nanotubes (MWCNTs) to remove heavy metals ions from acidic solutions. The MWCNTs were tested for copper (Cu), manganese (Mn), and zinc (Zn) removal, which showed an increment of 79%, 78%, and 48%, respectively, with double-oxidized MWCNTs compared to oxidized MWCNTs. Moreover, the increase in pH improved the sorption capacity for all the tested metals, which indicates that the sorption potential is strongly dependent on the pH. The kinetic adsorption process for three metals can be described well with a pseudo-second-order kinetic model. Additionally, in multimetallic waters, the sorption capacity decreases due to the competition between metals, and it was more evident in the removal of Zn, while Cu was less affected. Besides, XPS analysis showed an increase in oxygen-containing groups on the MWCNTs surface after oxidation. Finally, these analyses showed that the chemical interactions between heavy metals and oxygen-containing groups are the main removal mechanism. Overall, these results contribute to a better understanding of the potential use of CNTs for water treatment.

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