As new emerging pollutants, phthalic acid monoesters (PAMs) pose potential ecological and human health risks. In the present study, adsorption performance of monobutyl phthalate (MBP) onto two macroporous base anion-exchange resins (D-201 and D-301) was discussed. It was found that the adsorption isotherms were best fitted by the Langmuir equation while the adsorption kinetics were well described by pseudo-first-order model. Analyses of sorption isotherms and thermodynamics proved that the adsorption mechanisms for DBP onto D-201 were ion exchange. However, the obtained enthalpy values indicate that the sorption process of MBP onto D-301 is physical adsorption. The equilibrium adsorption capacities and adsorption rates of DBP on two different resins increased with the increasing temperature of the solution. D-301 exhibited a higher adsorption capacity of MBP than D-201. These results proved that D-301, as an effective sorbent, can be used to remove phthalic acid monoesters from aqueous solution. 1. Introduction Water pollution by phthalic acid esters (PAEs) has attracted increasing attention in recent decades. They are widely used as plasticizers in the manufacture of polyvinyl chloride [1]. Phthalic acid monoesters (PAMs) as degradation products of PAEs or synthetic intermediates for the preparation of PAEs have attained more attention. They are mutagenic endocrine disrupting compounds, posing the adverse reproductive effects on humans and wildlife equal to PAEs. Some studies have shown that the hydrolytic breakdown products of some PAEs have higher toxicity than PAEs [2]. Recently, many PAMs have been detected in surface water, sea water, and landfill leachate [3]. Previous research proved that some PAMs have greater solubility than corresponding PAEs, especially for monomethyl phthalate (MMP, 3721？mg/L), monobutyl phthalate (MBP, 409？mg/L), and mono-ethyl-hexyl-phthalate (MEHP, 1.85？mg/L). Thus, some polluted aquatic environment may contain high concentration of PAMs [4, 5]. For instance, Jonsson found that, in landfill leachate, MBP appeared at a concentration of 2500？μg/L that was much higher than that of dibutyl phthalate (DBP) (50？μg/L) [6]. Therefore, as a new type of organic pollutants, how to effectively remove PAMs from aqueous solution is an important issue. Many previous studies have reported that PAMs can be removed from aqueous environment through different methods, such as activated sludge process [7] and adsorption [8, 9]. In the active sludge process, PAMs can be further broken down to phthalic acid, benzoic acid, and finally carbon
References
[1]
X. W. Peng, L. J. Feng, and X. G. Li, “Pathway of diethyl phthalate photolysis in sea-water determined by gas chromatography-mass spectrometry and compound-specific isotope analysis,” Chemosphere, vol. 90, no. 2, pp. 220–226, 2013.
[2]
C. K. Lim, S. Kim, D. S. Ko et al., “Differential cytotoxic effects of mono-(2-ethylhexyl) phthalate on blastomere-derived embryonic stem cells and differentiating neurons,” Toxicology, vol. 264, no. 3, pp. 145–154, 2009.
[3]
J. D. Blair, M. G. Ikonomou, B. C. Kelly, B. Surridge, and F. A. P. C. Gobas, “Ultra-trace determination of phthalate ester metabolites in seawater, sediments, and biota from an urbanized marine inlet by LC/ESI-MS/MS,” Environmental Science and Technology, vol. 43, no. 16, pp. 6262–6268, 2009.
[4]
A. M. Calafat, A. R. Slakman, M. J. Silva, A. R. Herbert, and L. L. Needham, “Automated solid phase extraction and quantitative analysis of human milk for 13 phthalate metabolites,” Journal of Chromatography B, vol. 805, no. 1, pp. 49–56, 2004.
[5]
S. Jonsson, J. Ejlertsson, A. Ledin, I. Mersiowsky, and B. H. Svensson, “Mono- and diesters from o-phthalic acid in leachates from different European landfills,” Water Research, vol. 37, no. 3, pp. 609–617, 2003.
[6]
S. Jonsson, J. Ejlertsson, and B. H. Svensson, “Behaviour of mono- and diesters of o-phthalic acid in leachates released during digestion of municipal solid waste under landfill conditions,” Advances in Environmental Research, vol. 7, no. 2, pp. 429–440, 2003.
[7]
S. V. Otton, S. Sura, J. Blair, M. G. Ikonomou, and F. A. P. C. Gobas, “Biodegradation of mono-alkyl phthalate esters in natural sediments,” Chemosphere, vol. 71, no. 11, pp. 2011–2016, 2008.
[8]
B. V. Chang, Y. S. Lu, S. Y. Yuan, T. M. Tsao, and M. K. Wang, “Biodegradation of phthalate esters in compost-amended soil,” Chemosphere, vol. 74, no. 6, pp. 873–877, 2009.
[9]
H. Liu, D. Zhang, M. J. Li, L. Tong, and L. Feng, “Competitive adsorption and transport of phthalate esters in the clay layer of JiangHan plain, China,” Chemosphere, vol. 92, no. 11, pp. 1542–1549, 2013.
[10]
J. Catherine, S. H. Liu, and J. F. Kennedy, “Comparative study of the adsorption on chitosan beads of phthalate esters and their degradation products,” Carbohydrate Polymers, vol. 81, no. 3, pp. 640–644, 2010.
[11]
T. T. H. Pham, R. D. Tyagi, S. K. Brar, and R. Y. Surampalli, “Effect of ultrasonication and Fenton oxidation on biodegradation of bis(2-ethylhexyl) phthalate (DEHP) in wastewater sludge,” Chemosphere, vol. 82, no. 6, pp. 923–928, 2011.
[12]
S. Chatterjee and T. K. Dutta, “Metabolism of butyl benzyl phthalate by Gordonia sp. strain MTCC 4818,” Biochemical and Biophysical Research Communications, vol. 309, no. 1, pp. 36–43, 2003.
[13]
T. Saito, P. Hong, R. Tanabe, K. Nagai, and K. Kato, “Enzymatic hydrolysis of structurally diverse phthalic acid esters by porcine and bovine pancreatic cholesterol esterases,” Chemosphere, vol. 81, no. 11, pp. 1544–1548, 2010.
[14]
B. C. Pan, Q. X. Zhang, F. W. Meng et al., “Sorption enhancement of aromatic sulfonates onto an animated hyper-cross-linked polymer,” Environmental Science and Technology, vol. 39, no. 9, pp. 3308–3313, 2005.
[15]
Z. W. Xu, W. Z. Zhang, L. Lv, B. C. Pan, P. Lan, and Q. Zhang, “A new approach to catalytic degradation of dimethyl phthlate by a macroporous OH-type strongly basic anion exchange resin,” Environmental Science and Technology, vol. 44, no. 8, pp. 3130–3135, 2010.
[16]
K. Kato, M. J. Silva, L. L. Needham, and A. M. Calafat, “Determination of total phthalates in urine by isotope-dilution liquid chromatography-tandem mass spectrometry,” Journal of Chromatography B, vol. 814, no. 2, pp. 355–360, 2005.
[17]
B. Von Oepen, W. Kordel, and W. Klein, “Sorption of nonpolar and polar compounds to soils: processes, measurements and experience with the applicability of the modified OECD-Guideline 106,” Chemosphere, vol. 22, no. 3-4, pp. 285–304, 1991.
[18]
J. L. Wang, L. J. Chen, C. Shi, and Q. Yi, “Microbial degradation of phthalic acid esters under anaerobic digestion of sludge,” Chemosphere, vol. 41, no. 8, pp. 1245–1248, 2000.
[19]
Q. J. Zhang, Z. W. Xu, K. Zheng et al., “Adsorption behavior of p-nitroaniline on macroporous polymer and its application,” Ion Exchange and Adsorption, vol. 22, no. 6, pp. 503–511, 2006.
[20]
Y. Liu, “Is the free energy change of adsorption correctly calculated?” Journal of Chemical and Engineering Data, vol. 54, no. 7, pp. 1981–1985, 2009.
[21]
C. H. Wu, “Studies of the equilibrium and thermodynamics of the adsorption of Cu2+ onto as-produced and modified carbon nanotubes,” Journal of Colloid and Interface Science, vol. 311, no. 2, pp. 338–346, 2007.
[22]
S. Shrestha, G. Son, S. H. Lee, and T. G. Lee, “Isotherm and thermodynamic studies of Zn (II) adsorption on lignite and coconut shell-based activated carbon fiber,” Chemosphere, vol. 92, no. 8, pp. 1053–1106, 2013.
[23]
D. M. Nevskaia, A. Santianes, V. Mu？oz, and A. Guerrero-Ruíz, “Interaction of aqueous solutions of phenol with commercial activated carbons: an adsorption and kinetic study,” Carbon, vol. 37, no. 7, pp. 1065–1074, 1999.
