Wpływ chemii powierzchni węgli aktywnych na adsorpcję kwasu 2,4-dichlorofenoksyoctowego

• Autorzy: Kuśmierek K. , Świątkowski A.

Identyfikatory

DOI

10.17512/ios.2016.2.8

Warianty tytułu

EN

The influence of surface chemistry of the activated carbons on the adsorption of 2,4-dichlorophenoxyacetic acid

• Języki publikacji: PL

Abstrakty

PL

Celem pracy było zbadanie wpływu chemii powierzchni węgli aktywnych na adsorpcję kwasu 2,4-dichlorofenoksyoctowego (2,4-D) z wody. Adsorpcję prowadzono na węglu Norit R3-ex o niemodyfikowanej powierzchni (AC-NM), na węglu utlenionym stężonym kwasem azotowym(V) (AC-HNO<SUB>3</SUB>) oraz węglu wygrzewanym w amoniaku w temperaturze 900°C (AC-NH<SUB>3</SUB>). Do opisu adsorpcji zastosowano równania Freundlicha, Langmuira i Langmuira-Freundlicha. Pojemność adsorpcyjna badanych węgli wzrastała w kolejności AC-HNO<SUB>3</SUB><<AC-NM<AC-NH<SUB>3</SUB>. Najlepszym adsorbentem okazał się węgiel aktywny o zasadowym charakterze (AC-NH<SUB>3</SUB>), najgorsze właściwości adsorpcyjne zaobserwowano dla węgla aktywnego o kwaśnych właściwościach (AC-HNO<SUB>3</SUB>). Zbadano również wpływ pH na adsorpcję 2,4-D z wody. Adsorpcja zmniejszała się wraz ze wzrostem pH roztworu, spadek ten był skorelowany z właściwościami kwasowo-zasadowymi powierzchni adsorbentów. Wyniki pokazały, że chemia powierzchni węgli aktywnych jest ważnym czynnikiem wpływającym na adsorpcję 2,4-D z wody i powinna być brana pod uwagę przy wyborze adsorbentu do usuwania herbicydu z wody w celu zmaksymalizowania skuteczności procesu oczyszczania.

EN

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.

Słowa kluczowe

PL

2,4-D; adsorpcja; węgiel aktywny; chemia powierzchni

EN

2,4-D; adsorption; activated carbon; surface chemistry

• Wydawca: Wydawnictwo Politechniki Częstochowskiej
• Czasopismo: Inżynieria i Ochrona Środowiska
• Rocznik: 2016
• Tom: T. 19, nr 2
• Strony: 255--263
• Opis fizyczny: Bibliogr. 24 poz.

Twórcy

autor

Kuśmierek K.

• Wojskowa Akademia Techniczna, Instytut Chemii, ul. gen. S. Kaliskiego 2, 00-908 Warszawa

autor

Świątkowski A.

• Wojskowa Akademia Techniczna, Instytut Chemii, ul. gen. S. Kaliskiego 2, 00-908 Warszawa

Bibliografia

• [1] Bukowska B., Toxicity of 2,4-dichlorophenoxyacetic acid - molecular mechanisms, Polish Journal of Environmental Studies 2006, 15, 365-374.
• [2] Drożdżyński D., Folkman W., Kowalska J., Pozostałości pestycydów w próbkach wielkopolskich wód powierzchniowych pobieranych na terenach intensywnie użytkowanych rolniczo (2006-2007), Proceedings of ECOpole 2009, 3(2), 445-450.
• [3] Sadowski J., Kucharski M., Wujek B., Wysocki A., Multipozostałości herbicydów w wodach powierzchniowych i gruntowych na terenach rolniczych Dolnego Śląska, Progress in Plant Protection 2009, 49(4), 1920-1931.
• [4] Aksu Z., Kabasakal E., Batch adsorption of 2,4-dichlorophenoxy-acetic acid (2,4-D) from aqueous solution by granular activated carbon, Separation and Purification Technologies 2004, 35, 223-240.
• [5] Chingombe P., Saha B., Wakeman R.J., Effect of surface modification of an engineered activated carbon on the sorption of 2,4-dichlorophenoxyacetic acid and benazolin from water, Journal of Colloid and Interface Sciences 2006, 297, 434-442.
• [6] Kim T.Y., Park S.S., Kim S.J., Cho S.Y., Separation characteristics of some phenoxy herbicides from aqueous solution, Adsorption 2008, 14, 611-619.
• [7] Ignatowicz K., Selection of sorbent for removing pesticides during water treatment, Journal of Hazardous Materials 2009, 169, 953-957.
• [8] Hameed B.H., Salman J.M., Ahmad A.L., Adsorption isotherm and kinetic modeling of 2,4-D pesticide on activated carbon derived from date stones, Journal of Hazardous Materials 2009, 163, 121-126.
• [9] Salman J.M., Hameed B.H., Adsorption of 2,4-dichlorophenoxyacetic acid and carbofuran pesticides onto granular activated carbon, Desalination 2010, 256, 129-135.
• [10] Salman J.M., Njoku V.O., Hameed B.H., Batch and fixed-bed adsorption of 2,4-dichlorophenoxyacetic acid onto oil palm frond activated carbon, Chemical Engineering Journal 2011, 174, 33-40.
• [11] Njoku V.O., Hameed B.H., Preparation and characterization of activated carbon from corncob by chemical activation with H3PO4 for 2,4-dichlorophenoxyacetic acid adsorption, Chemical Engineering Journal 2011, 173, 391-399.
• [12] Salman J.M., Njoku V.O., Hameed B.H., Adsorption of pesticides from aqueous solution onto banana stalk activated carbon, Chemical Engineering Journal 2011, 174, 41-48.
• [13] Kuśmierek K., Świątkowski A., Wpływ liczby atomów chloru w cząsteczkach kwasów chlorofenoksyoctowych na ich adsorpcję z roztworów wodnych na węglu aktywnym, Ochrona Środowiska 2013, 35(1), 47-50.
• [14] Kuśmierek K., Sankowska M., Świątkowski A., Kinetic and equilibrium studies of simultaneous adsorption of monochlorophenols and chlorophenoxy herbicides on activated carbon, Desalination and Water Treatment 2014, 52, 178-183.
• [15] Kaminski W., Kusmierek K., Swiatkowski A., Sorption equilibrium prediction of competitive adsorption of herbicides 2,4-D and MCPA from aqueous solution on activated carbon using ANN, Adsorption 2014, 20, 899-904.
• [16] Moreno-Castilla C., Adsorption of organic molecules from aqueous solutions on carbon materials, Carbon 2004, 42, 83-94.
• [17] Biniak S., Świątkowski A., Pakuła M., Sankowska M., Kuśmierek K., Trykowski G., Cyclic voltammetric and FTIR studies of powdered carbon electrodes in the electrosorption of 4-chlorophenols from aqueous electrolytes, Carbon 2013, 51, 301-312.
• [18] Ferro-Garcia M.A., Rivera-Utrilla J., Bautista-Toledo I., Moreno-Castilla C., Adsorption of humic substances on activated carbon from aqueous solutions and their effect on the removal of Cr(III) ions, Langmuir 1998, 14, 1880-1886.
• [19] Hamdaoui O., Naffrechoux E., Modeling of adsorption isotherms of phenol and chlorophenols onto granular activated carbon Part I. Two-parameter models and equations allowing determination of thermodynamic parameters, Journal of Hazardous Materials 2007, 147, 381-394.
• [20] Bhatnagar A., Hogland W., Marques M., Sillanpaa M., An overview of the modification methods of activated carbon for its water treatment applications, Chemical Engineering Journal 2013, 219, 499-511.
• [21] Przepiórski J., Enhanced adsorption of phenol from water by ammonia-treated activated carbon, Journal of Hazardous Materials 2006, B135, 453-456.
• [22] Shaarani F.W., Hameed B.H., Ammonia-modified activated carbon for the adsorption of 2,4-dichlorophenol, Chemical Engineering Journal 2011, 169, 180-185.
• [23] Yin C.Y., Aroua M.K., Daud W.M.A.W., Review of modifications of activated carbon for enhancing contaminant uptakes from aqueous solutions, Separation and Purification Technology 2007, 52, 403-415.
• [24] Kuśmierek K., Świątkowski A., Adsorption of 2,4-dichlorophenoxyacetic acid from aqueous solution on fly ash, Water Environment Research 2016, 88(3), 231-238.

Uwagi

Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę.