Ammonia-modified activated carbon for the adsorption of 2,4-dichlorophenol

Shaarani, F.W.; Hameed, B.H.

doi:10.1016/j.cej.2011.03.002

Cited by 153 publications

(42 citation statements)

References 31 publications

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“…Modification of the surface properties of N-CNMs forms a basis for their application as the adsorbents for wastewater purification from organic substances. The adsorption efficiency of various activated carbons doped with nitrogen was shown to result from the improved interaction of organic molecules with the carbon surface due to the presence of nitrogen sites [81,82].…”

Section: Surface Properties Of N-cnmsmentioning

confidence: 98%

Nitrogen-doped carbon nanomaterials: To the mechanism of growth, electrical conductivity and application in catalysis

2015

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Section: Surface Properties Of N-cnmsmentioning

confidence: 98%

Nitrogen-doped carbon nanomaterials: To the mechanism of growth, electrical conductivity and application in catalysis

2015

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“…Functional groups on the activated carbon surface contain predominantly oxygen, but they may also contain hydrogen, nitrogen, and sulfur. The activated carbon surface can be acid, basic, or neutral depending on the type and quantity of its functional groups (Green and Martin, 1968;Shaarani and Hameed, 2011). The basic character of activated carbon is associated with pyrone and chromene functional groups, as well as oxygen-free Lewis base sites on the basal planes; whereas carboxylic, carbonyl, phenols, enols, lactones, and quinones are related to acid functional groups.…”

Section: Introductionmentioning

confidence: 99%

Phenol and methylene blue adsorption on heat-treated activated carbon: Characterization, kinetics, and equilibrium studies

Sáenz-Alanís

García-Reyes

Soto-Regalado

et al. 2017

Adsorption Science & Technology

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A comprehensive study was performed for a thermally treated activated carbon to evaluate the influence of this treatment on the physical and chemical properties of the mineral activated carbon, as well as the adsorption toward phenol and methylene blue. After the heat treatment, surface area decreased and total pore volume diminished about 8.5%, and the total basic groups decreased 18% while the total acid groups increased 8% in comparison with the raw activated carbon. Equilibrium adsorption of phenol and methylene blue was described well with the Freundlich and Langmuir isotherm models, respectively. Adsorption kinetics of phenol and methylene blue was predicted adequately with the empirical pseudo-second-order model, the intraparticle diffusion model, and the homogeneous solid diffusion model, but mass transfer coefficients of the diffusion models help to better understand the adsorption phenomenon. Intraparticle diffusion seems to be the ratecontrolling step in the adsorption process, and heat-treated activated carbon in an inert atmosphere was a better adsorbent for both phenol and methylene blue than raw activated carbon.

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“…Dodatkowo, zasadowy charakter powierzchni węgla aktywnego sprzyja reakcjom grup funkcyjnych adsorbentu z grupami -COOH w cząsteczkach herbicydu. Podobne zjawisko zwiększenia zdolności adsorpcyjnych węgli aktywnych modyfikowanych amoniakiem zaobserwowano w przypadku fenolu [21], 4-chlorofenolu [17] czy też 2,4-dichlorofenolu [22].…”

Section: Wyniki I Dyskusjaunclassified

The Influence of Surface Chemistry of the Activated Carbons on the Adsorption of 2,4-dichlorophenoxyacetic Acid

Kuśmierek

Świątkowski

2016

Eng. Prot. Environ.

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The aim of this study was to investigate the effect of surface chemistry of the activated carbons on the adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D). The 2,4-D was adsorbed on non-modified Norit R3-ex activated carbon (AC-NM) as well as on activated carbons modified by oxidation with concentrated nitric acid (AC-HNO3) and by heat treatment in ammonia at 900°C (AC-NH3). Adsorption isotherms of the 2,4-D on the activated carbons were analyzed using the Freundlich, Langmuir and Langmuir-Freundlich models. The Langmuir equation was slightly better fitted to the experimental data with the correlation coefficients better than 0.99. The values of the Langmuir maximum adsorption capacity (qm) were 2.945, 2.740 and 3.297 mmol/g for the AC-NM, AC-HNO3 and AC-NH3 activated carbons, respectively. The adsorption capacity of the activated carbons increased in the order: AC-HNO3 < AC-NM < AC-NH3. The best adsorbent was activated carbon with basic properties, while the worst adsorption properties were observed for the activated carbon with acidic properties. The acid treatment of activated carbon produced a large number of oxygen-containing functional groups on the carbon surface as it increases its acidic property and, in consequence, reduces the adsorption of the 2,4-D. The treatment of activated carbon with ammonia at high temperature leads to the formation of nitrogen-containing groups. The basic properties of the carbon surface enhance the interaction between activated carbon and acid molecules (dipole-dipole, H-bonding, covalent bonding) causing the increased adsorption of the 2,4-D from water. The effect of pH on the adsorption of 2,4-D onto activated carbons was also studied. The adsorption of the 2,4-D was almost constant at the pH range of 2.0-2.6 and decreased with the further increasing in the pH. The solution pH determines the adsorbent charge and the protonation or dissociation of the adsorbate. The pKa of 2,4-D is 2.8, and at a pH greater than the pKa value, the herbicide existed predominantly in anionic forms. As the pH increased, the degree of dissociation of 2,4-D increased, thereby making it more negatively charged. The values of the point of zero charge (pHPZC) were 6.10, 3.35 and 7.85 for the AC-NM, AC-HNO3 and AC-NH3 activated carbons, respectively. At pH of less than the pHPZC, the surface of the carbon had a net positive charge; at a pH greater than pHPZC, the surface had a net negative charge. The large reduction in the 2,4-dichlorophenoxyacetic acid adsorption at highly basic conditions can be attributed to the electrostatic repulsion between the negatively charged activated carbons and the dissociated 2,4-D molecules. The experimental results demonstrate that the surface chemistry of the activated carbons affects significantly the adsorption of the 2,4-D and should be taken into account when choosing an adsorbent for the removal of the herbicide from water.

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Ammonia-modified activated carbon for the adsorption of 2,4-dichlorophenol

Cited by 153 publications

References 31 publications

Nitrogen-doped carbon nanomaterials: To the mechanism of growth, electrical conductivity and application in catalysis

Nitrogen-doped carbon nanomaterials: To the mechanism of growth, electrical conductivity and application in catalysis

Phenol and methylene blue adsorption on heat-treated activated carbon: Characterization, kinetics, and equilibrium studies

The Influence of Surface Chemistry of the Activated Carbons on the Adsorption of 2,4-dichlorophenoxyacetic Acid

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