Adsorption of Quaternary Ammonium Compounds onto Activated Sludge

Rong Ren, Dongfang Liu, Kexun Li, Jie Sun, Chong Zhang

.

DOI: 10.4236/jwarp.2011.32012                

Abstract

The performance of activated sludge in the removal of tetradecyl benzyl dimethyl ammonium chloride (C14BDMA) by adsorption from aqueous solution was investigated with different PH, contact time, ionic strength and temperature. Equilibrium was achieved within 2 h of contact time. The adsorption capacity increased largely with increasing solution pH and remained constant above pH 9. The ionic strength had a negative effect on C14BDMA removal. The adsorption isotherms were analyzed by Langmuir and Freundlich isotherm models, and equilibrium partitioning data was described well by both models. Kinetics data was best described by the pseudo second-order model. Experimental results indicated that the adsorption was favorable at lower temperatures. Thermodynamic parameters, including the Gibbs free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0), were also calculated. These parameters indicated that adsorption of C14BDMA onto activated sludge was feasible, spontaneous and exothermic in the temperature range of 15-35℃. The activated sludge was shown to be an effective adsorbent for C14BDMA.

Keywords

Activated Sludge, Adsorption, Kinetics, Quaternary Ammonium Compounds, Thermodynamics Analysis

1. Introduction

Quaternary ammonium compounds (QACs) are molecules with at least one hydrophobic hydrocarbon chain linked to a positively charged nitrogen atom with other alkyl or aryl groups being mostly short-chain substituent [1]. QACs belong to the group of cationic surfactants. Because of their unique physical/chemical properties, QACs are primarily used as disinfectants, biocides or detergents, but QACs are also used as anti-electrostatics and phase transfer catalysts in a wide range of applications [2].

The widespread use of QACs causes them to be released and to accumulate in aquatic environments and wastewater treatment plants (WWTPs) [3-4]. Due to their biocidal properties they may have potential impacts on organisms in activated sludge. It was revealed in literature that QACs had an adverse effect on nitrification [5] and denitrification [6]. Moreover, it was reported that QACs, at a concentration of 50 mg L^-1, adversely affected the anaerobic degradation, which resulted in significantly reduced methane production and accumulation of volatile fatty acids [7]. Due to the hydrophobic and electrostatic interactions, QACs can rapidly adsorb onto solids and extensively accumulate in aquatic sediments [4, 8-10] . The adsorption of QACs has been studied previously using various adsorbents, such as coal [11], clinoptilolite [12], and activated carbon [13-15] .

Activated sludge is a well-known biomass used for the purification of both industrial effluent and domestic wastes. Although a large number of studies have reported on biosorption of heavy metals as well as organic pollutants onto activated sludge [16-18] , there have been few studies on the use of sludge to remove QACs [19-22] . Garcia et al. [20] investigated the adsorption isotherms on activated sludge from wastewater treatment plants and surface properties in aqueous solutions of alkyl benzyl dimethyl ammonium compounds (BAC). They reported that the Langmuir and Freundlich isotherms agreed very well with experimental data, and adsorption capacity increased with increasing the alkyl chain length.

The objective of this study was to investigate the adsorption potential of activated sludge for removal of Tetradecyl benzyl dimethyl ammonium chloride (C₁₄BDMA), which is one of the most commonly used QACs. Effects of different parameters, such as pH, contact time, temperature and ionic strength on the adsorption were investigated. The adsorption thermodynamics and kinetics of C₁₄BDMA onto activated sludge were evaluated.

2. Materials and Methods

2.1. Preparation of the Adsorbent

The activated sludge used in this study was obtained from the wastewater treatment plant of the Technical and Economic Development Area (TEDA) in Tianjin, China. The activated sludge was centrifuged at 1750 g for 5 min and washed twice with DI water to remove easily suspended materials. The remaining solids were placed into flasks, immediately inactivated by autoclaving (120℃, 30 min), and then stored at 4℃ to ensure that only the adsorption effect, rather than a combined adsorption and degradation effect, was assessed.

2.2. Chemicals

Tetradecyl benzyl dimethyl ammonium chloride (C₁₄BDMA, C₂₃H₄₂NCl, 368.0 g mol^-1) used in this study was purchased from Shanghai Jinchun company in China and was used without further purification. Stock solution (10 g L^-1) of C₁₄BDMA was prepared based on the active ingredient purity and concentration and was used in all experiments after dilution with DI water.

2.3. Adsorption Experiments

Kinetic removal of C₁₄BDMA was performed as follows: batch experiments were conducted using 250 mL screw-topped flasks, and the mixed liquor suspended solids (MLSS) was 250 mg L^-1. A sample of C₁₄BDMA solution was then added to attain the desired initial C₁₄BDMA concentrations (5, 20, 50 mg L^-1). The flasks were sealed with stoppers and shaken at a rate of 150 rpm with a shaker at room temperature, and samples were obtained at given time intervals (0, 0.25, 0.5, 1, 2, 4 and 8 h). After centrifugation (11,410 g for 15 min), the liquid phase concentration was measured, and the mass of C₁₄BDMA adsorbed to the sludge was calculated based on the difference between the total and aqueous C₁₄BDMA mass. Blank experiments were carried out with C₁₄BDMA solution and without adsorbent to ensure that no C₁₄BDMA was adsorbed onto the walls of the flasks.

Adsorption isotherm assays were determined at initial C₁₄BDMA concentrations of 10, 20, 40, 60, 80, 100, 120, 140 mg L^-1 and 250 mg L^-1 sludge concentration (MLSS). The flasks were shaken at a rate of 150 rpm with a shaker for 4 h. The experiments were repeated at 15, 25, and 35℃. When the sorption procedure was completed, the samples and data were treated in the same way as in the kinetic experiments.

In order to evaluate the effect of pH and ionic strength on the adsorption of C₁₄BDMA onto activated sludge, the adsorption experiments were carried out over a pH range of 1-13 and the concentrations of NaCl ranging from 0 to 0.40 mol L^-1, respectively.

2.4. Analytical Methods

The concentrations of QACs in whole and centrifuged sludge samples were determined by using the previously reported modified disulfine blue (DSB) method [23]. The Mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS) and pH were measured according to the Standard [24].

3. Results and Discussion

3.1. Effect of Contact Time

In order to establish the equilibration time for maximum uptake, the adsorption of C₁₄BDMA onto activated sludge was studied as a function of contact time.

The adsorption rate was high at the beginning, and equilibrium adsorption of C₁₄BDMA onto activated sludge was achieved within 2 h (Figure 1). Therefore the equilibration period of 4 h was selected for all further experiments. The rapid attainment of equilibrium was consistent with previously published reports on the adsorption of cationic surfactants onto sludge. Ismail et al. [21] investigated the batch adsorption of four tested QACs to sludge and reported the optimum equilibrium time as 4 h. All the systems studied by Garcia et al. [25] to determine the rate of BAC adsorption onto activated sludge achieved equilibrium within three hours.

Figure 1 also shows that the uptake of the C₁₄BDMA increased with increasing initial C₁₄BDMA concentration. Raising the initial C₁₄BDMA concentration from 5 to 50 mg L^-1 allows the sludge to increase the adsorption capacity from 17.61 to 148.5 mg g^-1. The results are in agreement with literature on the adsorption of organic substances onto activated sludge [26,27]. This is due to an increase in the driving force of the concentration gradient as an increase in the initial adsorbate concentration. The initial concentration is an important driving force to overcome all mass transfer resistances of the C₁₄BDMA

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	E. Martinez-Carballo, A. Sitka, C. Gonzalez-Barreiro, N. Kreuzinger, M. Furhacker, S. Scharf and O. Gans, “Determination of Selected Quaternary Ammonium Compounds by Liquid Chromatography with Mass Spectrometry. Part I. Application to Surface, Waste and Indirect Discharge Water Samples in Austria,” Environmental Pollution, Vol. 145, No. 2, 2007, pp. 489-496. doi:10.1016/j.envpol.2006.04.033
[2]	N. Kreuzinger, M. Fuerhacker, S. Scharf, M. Uhl, O. Gans and B. Grillitsch, “Methodological Approach towards the Environmental Significance of Uncharacterized Substances--Quaternary Ammonium Compounds as an Example,” Desalination, Vol. 215, No. 1-3, 2007, pp. 209-222. doi:10.1016/j.desal.2006.10.036
[3]	L. Games, J. King and R. Larson, “Fate and Distribution of a Quaternary Ammonium Surfactant, Octadecyl Trimethyl Ammonium Chloride (OTAC), in Wastewater Treatment,” Environmental Science & Technology, Vol. 16, No. 8, 1982, pp. 483-488. doi:10.1021/es00102a011
[4]	H. Sun, A. Takata, N. Hata, I. Kasahara and S. Taguchi, “Transportation and Fate of Cationic Surfactant in River Water,” Journal of Environmental Monitoring, Vol. 5, No. 6, 2003, pp. 891-895. doi:10.1039/b308988f
[5]	R. Boethling, “Environmental Fate and Toxicity in Wastewater Treatment of Quaternary Ammonium Surfactants,” Water Research, Vol. 18, No. 9, 1984, pp. 1061- 1076. doi:10.1016/0043-1354(84)90220-3
[6]	U. Tezel, J. Pierson and S. Pavlostathis, “Effect of Didecyl Dimethyl Ammonium Chloride on Nitrate Reduction in a Mixed Methanogenic Culture,” Water Science and Technology: A Journal of the International Association on Water Pollution Research, Vol. 57, No. 4, 2008, pp. 541-546.
[7]	U. Tezel, J. Pierson, S. Pavlostathis, “Effect of Polyelectrolytes and Quaternary Ammonium Compounds on the Anaerobic Biological Treatment of Poultry Processing Wastewater,” Water Research, Vol. 41, No. 6, 2007, pp. 1334-1342. doi:10.1016/j.watres.2006.12.005
[8]	P. Fernandez, A. Alder, J. Marc and W. Giger, “Determination of the Quaternary Ammonium Surfactant Ditallowdimethylammonium in Digested Sludges and Marine Sediments by Supercritical Fluid Extraction and Liquid Chromatography with Postcolumn Ion-Pair Formation,” Analytical Chemistry, Vol. 68, No. 5, 1996, pp. 921-929. doi:10.1021/ac9505482
[9]	F. Merino, S. Rubio and D. Perez-Bendito, “Mixed Aggregate-Based Acid-Induced Cloud-Point Extraction and Ion-Trap Liquid Chromatography-Mass Spectrometry for the Determination of Cationic Surfactants in Sewage Sludge,” Journal of Chromatography A, Vol. 998, No. 1-2, 2003, pp. 143-154. doi:10.1016/S0021-9673(03)00565-X
[10]	H. Sutterlin, R. Alexy, A. Coker and K. Kummerer, “Mixtures of Quaternary Ammonium Compounds and Anionic Organic Compounds in the Aquatic Environment: Elimination and Biodegradability in the Closed Bottle Test Monitored by LC-MS/MS,” Chemosphere, Vol. 72, No. 3, 2008, pp. 479-484. doi:10.1016/j.chemosphere.2008.03.008
[11]	S. Mishra and D. Panda, “Studies on the Adsorption of Brij- 35 and CTAB at the Coal-Water Interface,” Journal of colloid and interface science, Vol. 283, No. 2, 2005, pp. 294-299. doi:10.1016/j.jcis.2004.09.017
[12]	M. Ghiaci, R. Kia and R. Kalbasi, “Investigation of Thermodynamic Parameters of Cetyl Pyridinium Bromide Sorption onto ZSM-5 and Natural Clinoptilolite,” The Journal of Chemical Thermodynamics, Vol. 36, No. 2, 2004, pp. 95-100. doi:10.1016/j.jct.2003.09.002
[13]	C. Basar, A. Karagunduz, A. Cakici and B. Keskinler, “Removal of Surfactants by Powdered Activated Carbon and Microfiltration,” Water Research, Vol. 38, No. 8, 2004, pp. 2117-2124. doi:10.1016/j.watres.2004.02.001
[14]	O. Duman and E. Ayranci, “Adsorptive Removal of Cationic Surfactants from Aqueous Solutions onto High-Area Activated Carbon Cloth Monitored by in Situ UV Spectroscopy,” Journal of Hazardous Materials, Vol. 174, No. 1-3, 2010, pp. 359-367. doi:10.1016/j.jhazmat.2009.09.058
[15]	H. Tamai, M. Kunihiro and H. Yasuda, “Adsorption of Tetraalkylammonium Ions on Microporous and Mesoporous Activated Carbons Prepared from Vinylidene Chloride Copolymer,” Journal of Colloid and Interface Science, Vol. 275, No. 1, 2004, pp. 44-47. .doi:10.1016/j.jcis.2003.12.039
[16]	J. Laurent, M. Pierra, M. Casellas and C. Dagot, “Fate of Cadmium in Activated Sludge after Changing Its Physico-Chemical Properties by Thermal Treatment,” Che- mosphere, Vol. 77, No. 6, 2009, pp. 771-777. doi:10.1016/j.chemosphere.2009.08.024
[17]	V. Ochoa-Herrera and R. Sierra-Alvarez, “Removal of Perfluorinated Surfactants by Sorption onto Granular Activated Carbon, Zeolite and Sludge,” Chemosphere, Vol. 72, No. 10, 2008, pp. 1588-1593. doi:10.1016/j.chemosphere.2008.04.029
[18]	A. Kipopoulou, A. Zouboulis, C. Samara and T. Kouimtzis, “The Fate of Lindane in the Conventional Activated Sludge Treatment Process,” Chemosphere, Vol. 55, No. 1, 2004, pp. 81-91. doi:10.1016/j.chemosphere.2003.11.020
[19]	M. Clara, S. Scharf, C. Scheffknecht and O. Gans, “Occurrence of Selected Surfactants in Untreated and Treated Sewage,” Water Research, Vol. 41, No. 19, 2007, pp. 4339-4348. doi:10.1016/j.watres.2007.06.027
[20]	M. Garcia, E. Campos, J. Sanchez-Leal and F. Comelles, “Sorption of Alkyl Benzyl Dimethyl Ammonium Compounds by Activated Sludge,” Journal of Dispersion Science and Technology, Vol. 27, 2006, pp. 739-744. doi:10.1080/01932690600662554
[21]	Z. Ismail, U. Tezel and S. Pavlostathis, “Sorption of Quaternary Ammonium Compounds to Municipal sludge,” Water Research, Vol. 44, No. 7, 2010, pp. 2303-2313. doi:10.1016/j.watres.2009.12.029
[22]	C. Zhang, U. Tezel, K. Li, D. Liu, R. Ren, J. Du and S. Pavlostathis, “Evaluation and Modeling of Benzalkonium Chloride Inhibition and Biodegradation in Activated Sludge,” Water Research, Vol. 45, No. 3, 2011, pp. 1238-1246. doi:10.1016/j.watres.2010.09.037
[23]	M. Idouhar and A. Tazerouti, “Spectrophotometric Determination of Cationic Surfactants Using Patent Blue V: Application to the Wastewater Industry in Algiers,” Journal of Surfactants and Detergents, Vol. 11, No. 4, 2008, pp. 263-267. doi:10.1007/s11743-008-1079-1
[24]	X. Wang, G. Yin, Q. Liu, et al., “The Monitoring Analysis Method of Water and Waste Water,” 4th Edition, China Environmental Protection Agency, China Environmental Science Press, 2002.
[25]	M. Garcia, E. Campos, J. Sanchez-Leal and F. Comelles, “Structure-Activity Relationships for Sorption of Alkyl Trimethyl Ammonium Compounds on Activated Sludge,” Tenside, Surfactants, Detergents, Vol. 41, No. 5, 2004, pp. 235-239.
[26]	M. Chiou and H. Li, “Adsorption Behavior of Reactive Dye in Aqueous Solution on Chemical Cross-Linked Chitosan Beads,” Chemosphere, Vol. 50, No. 8, 2003, pp. 1095-1105. doi:10.1016/S0045-6535(02)00636-7
[27]	D. Ju, I. Byun, J. Park, C. Lee, G. Ahn and T. Park, “Biosorption of a Reactive Dye (Rhodamine-B) from an Aqueous Solution Using Dried Biomass of Activated Sludge,” Bioresource Technology, Vol. 99, No. 17, 2008, pp. 7971-7975. doi:10.1016/j.biortech.2008.03.061
[28]	S. Lagergren, “Zur Theorie der Sogenannten Adsorption gel Ster Stoffe, Kungliga Svenska Vetenskapsakademiens,” Handlingar, Vol. 24, No. 4, 1898, pp. 1-39.
[29]	Y. Ho and G. McKay, “The Kinetics of Sorption of Divalent Metal Ions onto Sphagnum Moss Peat,” Water Research, Vol. 34, No. 3, 2000, pp. 735-742. doi:10.1016/S0043-1354(99)00232-8
[30]	Y. Ho, G. McKay, D. Wase and C. Forster, “Study of the Sorption of Divalent Metal Ions on to Peat,” Adsorption Science & Technology, Vol. 18, No. 7, 2000, pp. 639-650. doi:10.1260/0263617001493693
[31]	R. Juang, F. Wu and R. Tseng, “Mechanism of Adsorption of Dyes and Phenols from Water Using Activated Carbons Prepared from Plum Kernels,” Journal of Colloid and Interface Science, Vol. 227, No. 2, 2000, pp. 437-444. doi:10.1006/jcis.2000.6912
[32]	Y. Shu, L. Li, Q. Zhang and H. Wu, “Equilibrium, Kinetics and Thermodynamic Studies for Sorption of Chlorobenzenes on CTMAB Modified Bentonite and Kaolinite,” Journal of Hazardous Materials, Vol. 173, No. 1-3, 2010, pp. 47-53. doi:10.1016/j.jhazmat.2009.08.043
[33]	G. Walker, L. Hansen, J. Hanna and S. Allen, “Kinetics of a Reactive Dye Adsorption onto Dolomitic Sorbents,” Water Research, Vol. 37, No. 9, 2003, pp. 2081-2089. doi:10.1016/S0043-1354(02)00540-7
[34]	N. Caner, I. Kiran, S. Ilhan and C. Iscen, “Isotherm and Kinetic Studies of Burazol Blue ED Dye Biosorption by Dried Anaerobic Sludge,” Journal of Hazardous Materials, Vol. 165, No. 1-3, 2009, pp. 279-284. doi:10.1016/j.jhazmat.2008.09.108
[35]	I. Mall, V. Srivastava, N. Agarwal and I. Mishra, “Adsorptive Removal of Malachite Green Dye from Aqueous Solution by Bagasse Fly Ash and Activated Carbon-Kin- etic Study and Equilibrium Isotherm Analyses,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 264, No. 1-3, 2005, pp. 17-28. doi:10.1016/j.colsurfa.2005.03.027
[36]	I. Langmuir, “The Adsorption of Gases on Plane Surfaces of Glass, Mica and Platinum,” Journal of the American Chemical Society, Vol. 40, No. 9, 1918, pp. 1361-1403. doi:10.1021/ja02242a004
[37]	H. Freundlich, “Over the Adsorption in Solution,” The Journal of Chemical Physics, Vol. 57, 1906, pp. 385-470.
[38]	U. Tezel, J. Pierson and S. Pavlostathis, “Fate and Effect of Quaternary Ammonium Compounds on a Mixed Methanogenic Culture,” Water Research, Vol. 40, No. 19, 2006, pp. 3660-3668. doi:10.1016/j.watres.2006.06.019
[39]	H. Park and C. Na, “Adsorption Characteristics of Anionic Nutrients onto the PP-g-AA-Am Non-Woven Fabric Prepared by Photoinduced Graft and Subsequent Chemical Modification,” Journal of Hazardous Materials, Vol. 166, No. 2-3, 2009, pp. 1201-1209.
[40]	H. Senturk, D. Ozdes, A. Gundogdu, C. Duran and M. Soylak, “Removal of Phenol from Aqueous Solutions by Adsorption onto Organomodified Tirebolu Bentonite: Equilibrium, Kinetic and Thermodynamic Study,” Journal of Hazardous Materials, Vol. 172, No. 1, 2009, pp. 353-362. doi:10.1016/j.jhazmat.2009.07.019
[41]	W. Cheng, S. Wang, L. Lu, W. Gong, X. Liu, B. Gao and H. Zhang, “Removal of Malachite Green (MG) from Aqueous Solutions by Native and Heat-Treated Anaerobic Granular Sludge,” Biochemical Engineering Journal, Vol. 39, No. 3, 2008, pp. 538-546. doi:10.1016/j.bej.2007.10.016
[42]	W. Weber Jr and W. Huang, “A Distributed Reactivity Model for Sorption by Soils and Sediments. Intraparticle Heterogeneity and Phase-Distribution Relationships under Nonequilibrium Conditions,” Environmental Science & Technology, Vol. 30, No. 3, 1996, pp. 881-888.
[43]	J. Yang, “Fate and Effect of Alkyl Benzyl Dimethyl Ammonium Chloride in Mixed Aerobic and Nitrifying Cultures,” MS Thesis, Georgia Institute of Technology, Atlanta, GA, 2007.
[44]	K. Xu, W. Harper Jr and D. Zhao, “17α-Ethinylestradiol Sorption to Activated Sludge Biomass: Thermodynamic Properties and Reaction Mechanisms,” Water Research, Vol. 42, No. 12, 2008, pp. 3146-3152. doi:10.1016/j.watres.2008.03.005
[45]	V. Garg, R. Gupta, A. Bala Yadav and R. Kumar, “Dye Removal From Aqueous Solution by Adsorption on Treated Sawdust,” Bioresource Technology, Vol. 89, No. 2, 2003, pp. 121-124. doi:10.1016/S0960-8524(03)00058-0
[46]	Y. Feng, Z. Zhang, P. Gao, H. Su, Y. Yu and N. Ren, “Adsorption Behavior of EE2 (17α-Ethinylestradiol) onto the Inactivated Sewage Sludge: Kinetics, Thermodynamics and Influence Factors,” Journal of Hazardous Materials, Vol. 175, No. 1-3, 2009, pp. 970-976. doi:10.1016/j.jhazmat.2009.10.105
[47]	S. Netpradit, P. Thiravetyan, S. Towprayoon, “Adsorption of Three Azo Reactive Dyes by Metal Hydroxide Sludge: Effect of Temperature, pH, and Electrolytes,” Journal of Colloid and Interface Science, Vol. 270, No. 2, 2004, pp. 255-261. doi:10.1016/j.jcis.2003.08.073
[48]	M. Gorgenyi, J. Dewulf, H. Van Langenhove and K. Heberger, “Aqueous Salting-Out Effect of Inorganic Cat- ions and Anions on Non-Electrolytes,” Chemosphere, Vol. 65, No. 5, 2006, pp. 802-810. doi:10.1016/j.chemosphere.2006.03.029