Adsorption and desorption of dissolved organic matter by carbon nanotubes: Effects of solution chemistry

Engel, Maya; Chefetz, Benny

doi:10.1016/j.envpol.2016.02.009

Cited by 58 publications

(16 citation statements)

References 54 publications

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“…In contrast to our results, a severe reduction in adsorption was observed for triazine-based pollutants by CNTs in the presence of NOM [266][267][268]. Surprisingly, the presence of HA has only slightly affected the adsorption of ATZ on the LIG, emphasizing the affinity of LIG to ATZ and the importance of hydrophobic interactions between them in the presence of HA.…”

Section: Adsorption Of Atz By Lig In the Presence Of Hacontrasting

confidence: 99%

Interaction at the solid-water interface of 0d and 2d carbon nanoparticles : environmental impacts and applications for contaminant removal

Bayati¹

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Carbon dots (CDs) and graphene oxide (GO) are rapidly emerging carbon-based nanomaterials that, due to their growing applications, will inevitably find their way to natural waters; however, their environmental fate is mostly unknown. Carbon dots with different surface functionality and graphene oxide were fabricated and characterized. Their surface charge, given by the zeta potential, and their hydrodynamic diameter in suspension were investigated under a variety of environmentally relevant conditions. The effect of ionic strength was studied in the presence of monovalent (NaCl) and divalent (CaCl2) cations, for pH levels from 3 to 11; humic acid was used as a model for dissolved natural organic matter. Total potential energies of interactions were modeled by classical DLVO theory. The experimental results for CDs showed that water chemistry altered the surface charge of the nanomaterials, but their hydrodynamic size could not be correlated to those changes. Nanoparticles remained largely stable in suspension, with some exception at the highest ionic strength considered. DLVO theory did not adequately capture the aggregation behavior of the system. Moreover, cation and/or humic acid adsorption negatively affected the emission intensity of the particles, suggesting limitations to their use in natural water sensing applications. The results for GO showed that the GO is negatively charged over a wide range of pH and the pH did significantly affect GO stability at a level of 4 or higher, but the particles became unstable below pH 3 due to protonation of âˆ’COOH at the edge. Ionic strength (IS) and salt type had observable effects on stability as a result of electrical double layer compression and specific interactions. CaCl2 affects GO more noticeably than NaCl because of the binding ability of Ca2+ ions with carboxyl and hydroxyl functional groups. The applicability of DLVO theory as a predictive tool was investigated by modeling GO sheets in two different geometries; three-dimensional sphere like particles and two-dimensional particles at different values of pH and IS. Overall, the specific interactions and chemical structure of adsorbed organics had a dominant role in GO stability. Laser induced graphene (LIG) can be fabricated in one-step, scalable, reagent-free process, by irradiation of a commercial polyimide (PI film) by a CO2 infrared laser under ambient conditions. This approach is environmentally and economically promising fabrication method. Laser induced graphene (LIG) was successfully fabricated on microporous ceramic membranes. The surface area, morphology, and chemical characterizations were performed on the LIG layer. Water contact angle measurements showed the hydrophobicity of LIG. Pure water and solvents with different polarities were used to understand the solvent flux behavior of LIG membrane. The LIG membrane showed very high non-polar solvent fluxes and remarkably low water permeability, and thus, the transport through the LIG membrane is related to dipole moment and dielectric constant, represented by solvent polarity. The LIG membrane achieved 90 [percent] rejection for 255 nm diameter silica particles, suggesting the presence of submicron size connecting pore channels that dominate the transport mechanism. Furthermore, LIG was used as adsorbent for the removal of atrazine (ATZ) from water. The effect of water chemistry, presence of humic acid (HA), adsorption time, and initial ATZ concentration on the adsorption process was explored. The prepared LIG exhibited significant removal of ATZ from aqueous solutions; hydrophobicity and [pi]-[pi] interactions played important roles in the process. Adsorption of ATZ on LIG followed a pseudo-second order kinetic model and Langmuir model for the isotherm with maximum adsorption capacity of 15.0 mg ATZ/g LIG. Adsorption was more favorable at higher pH and not affected by ionic strength. LIG exhibited enhanced performance over many previously reported adsorbents. The introduction stage of HA with respect to ATZ influenced the results: pre-introduction of HA reduced ATZ adsorption by 32 [percent], whereas post-introduction of HA resulted in a slight release of ATZ from the LIG.

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Section: Adsorption Of Atz By Lig In the Presence Of Hacontrasting

confidence: 99%

Interaction at the solid-water interface of 0d and 2d carbon nanoparticles : environmental impacts and applications for contaminant removal

Bayati¹

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“…Adsorption capacities and mechanisms responsible for the interaction between organic contaminants and functionalized CNTs at different experimental conditions are described in Table 9. The increase in oxygen-containing functional groups on the surface of nanotubes results in a decrease in natural organic maters (NOM), because the π-π interaction decreases due to more electrostatic repulsion [270]. The same type of results were shown in the case of higher pH [270].…”

Section: Removal Of Organicsmentioning

confidence: 77%

“…The increase in oxygen-containing functional groups on the surface of nanotubes results in a decrease in natural organic maters (NOM), because the π-π interaction decreases due to more electrostatic repulsion [270]. The same type of results were shown in the case of higher pH [270]. Therefore, π-π interactions are responsible between the large specific surface area of functionalized CNTs and NOM for the adsorption area of CNT [271,272].…”

Section: Removal Of Organicsmentioning

confidence: 87%

Functionalized Carbon Nanotubes (CNTs) for Water and Wastewater Treatment: Preparation to Application

et al. 2021

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As the world human population and industrialization keep growing, the water availability issue has forced scientists, engineers, and legislators of water supply industries to better manage water resources. Pollutant removals from wastewaters are crucial to ensure qualities of available water resources (including natural water bodies or reclaimed waters). Diverse techniques have been developed to deal with water quality concerns. Carbon based nanomaterials, especially carbon nanotubes (CNTs) with their high specific surface area and associated adsorption sites, have drawn a special focus in environmental applications, especially water and wastewater treatment. This critical review summarizes recent developments and adsorption behaviors of CNTs used to remove organics or heavy metal ions from contaminated waters via adsorption and inactivation of biological species associated with CNTs. Foci include CNTs synthesis, purification, and surface modifications or functionalization, followed by their characterization methods and the effect of water chemistry on adsorption capacities and removal mechanisms. Functionalized CNTs have been proven to be promising nanomaterials for the decontamination of waters due to their high adsorption capacity. However, most of the functional CNT applications are limited to lab-scale experiments only. Feasibility of their large-scale/industrial applications with cost-effective ways of synthesis and assessments of their toxicity with better simulating adsorption mechanisms still need to be studied.

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Section: Introductionmentioning

confidence: 99%

“…These ionizable negatively charged functional groups on the surface of the CNTs enable the nanotubes to repel each other, keeping them uniformly dispersed; thereby improving the water-solubility. The presence of functional groups on the sidewall of CNTs to establish π−π electrostatic interactions could facilitate adsorption of chemical pollutants such as aniline, 10 phenol, 11 dissolved organic matters, 12 aromatic compounds, 13 and several divalent metal ions 14,15 , E 0 = 2.01 V) is a strong oxidant with redox potential of 2.01 V and commonly used for in situ chemical oxidation remediation of subsurface contamination. 16 Because sodium persulfate (SPS) has a higher water solubility than that of KPS, SPS proves to be advantageous for a broader range of applications.…”

Section: Introductionmentioning

confidence: 99%

Persulfate Chemical Functionalization of Carbon Nanotubes and Associated Adsorption Behavior in Aqueous Phase

Huang

Liang

Chen

2016

Ind. Eng. Chem. Res.

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The chemical functionalization of carbon nanotubes (CNTs) using sodium persulfate (SPS) oxidation was designed to improve their dispersion stability in water. The test results indicated that base activated SPS oxidation of CNTs (BSPS/CNTs) adds a significant amount of oxygen functional groups to the surface of CNTs. The BSPS/CNTs dispersion is dependent on a solution within the pH range of 5−12. Experimental results obtained by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated that CNTs were successfully modified and the carboxylic functional groups (e.g., −COO − Na + or −COO − H + ) were created. The BSPS/CNTs, which carry negative charges, enhance the dispersion characteristics of CNTs. The BSPS/CNTs adsorption capacities of inorganic ions (e.g., copper ion) and organic compounds (e.g., benzene) were higher than those obtained by raw CNTs mainly due to enhanced CNTs dispersion. Furthermore, Langmuir and Freundlich adsorption models were applied to examine both raw CNTs and BSPS/CNTs adsorption behaviors. Copper and benzene sorption onto BSPS/CNTs fit the Freundlich isotherm model well, while raw CNTs adsorption did not fit any model. The findings of this study are of great significance for the base activated persulfate oxidation process, indicating that the functionalization of CNTs enhances CNTs dispersivity in water.

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Adsorption and desorption of dissolved organic matter by carbon nanotubes: Effects of solution chemistry

Cited by 58 publications

References 54 publications

Interaction at the solid-water interface of 0d and 2d carbon nanoparticles : environmental impacts and applications for contaminant removal

Interaction at the solid-water interface of 0d and 2d carbon nanoparticles : environmental impacts and applications for contaminant removal

Functionalized Carbon Nanotubes (CNTs) for Water and Wastewater Treatment: Preparation to Application

Persulfate Chemical Functionalization of Carbon Nanotubes and Associated Adsorption Behavior in Aqueous Phase

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