Chemical and Biological Regeneration of HDTMA-Modified Montmorillonite after Sorption with Phenol

Abstract

Hexadecyltrimethylammonium (HDTMA)-modified montmorillonite (HMM) has recently been recognized as a potential sorbentto remove organic contaminants from environmental systems. Potential applications of this material highly depend on the efficiency of regenerating contaminant-sorbing HMM. In this study, we investigated a chemical (NaOH solution) and a biological (yeast Pityrosporum sp.) method to regenerate phenol-sorbing HMM. Our results showed that the sorption coefficient of phenol to HMM is not a linear function of the ratio of the substitution of HDTMA in HMM. Chemical regeneration of HMMs (0-0.7 times of its cation exchange capacity (CEC)) proved the existence of a phenol residual amount of about 3 mg x g(-1) in the HMMs tested when aqueous pH is maintained above 11. In addition, the obvious deductions in the sorption capacity of the chemically regenerated HMMs were observed after four cycles of sorption-regeneration. However, the sorption capacities of intermediate substituted HMMs (0.3-0.7 CEC) can be completely restored by bioregeneration with yeast for extended cycles of reuse. The results imply that the bioregeneration method with yeast could be a promising technique for in-situ bioremediation of phenol-contaminated groundwater in the subsurface or for treatment of phenol containing wastewater.

Effect of lead on the sorption of phenol onto montmorillonites and organo-montmorillonites

“…1, the sorption capacities of phenol showed no systematic variations between pH 3.0 and 10.0, while it declined dramatically between 10.0 and 12.0. This observation is consistent with Juang et al [2], Li et al [32], and Yang et al [11]. However, phenol sorption to montmorillonite, kaolinite, and organobentonite decreased when pH was higher than 8 [1,3,33], and to organo-montmorillonite increased when pH was higher than its pK a 9.89 [4,34].…”

“…Banat et al [1] examined the feasibility of using natural bentonite (mainly montmorillonite) for the sorption of phenol from aqueous solution. Treatment of clays with quaternary amine cationic surfactants could increase sorption capacity of phenol greatly [8][9][10][11][12]. Quaternary ammonium cations may be retained by both the outer and interlayer surfaces of an expandable clay particle via an ion-exchange, which are not easily displaced by smaller cations, such as H + , Na + , or Ca 2+ .…”

Preparation and characterization of zwitterionic surfactant-modified montmorillonites

“…The three driving forces of surfactant interaction with montmorillonites are, namely, (1) the electrostatic interaction between the positively charged trimethylammonium group and the negatively charged montmorillonite inner surface; (2) the hydrophobic interaction between the surfactant alkyl chains; and (3) the electrostatic interaction between the positively charged trimethylammonium and the negatively charged sulfonate groups [21]. The locations and packing of the adsorbed surfactants are mainly determined by these factors.…”

“…In the past decades, cationic [11], anionic [12,13], nonionic [14], and amphoteric surfactants [15,16] with various length, and number of the alkyl chains have been used to modify montmorillonite, and the resulting organo-montmorillonites are shown to have quite different structural characteristics [17][18][19]. The material behavior and physical and chemical properties of the corresponding organo-montmorillonites are studied in different research areas [20][21][22][23][24][25], for example, the organoclays with high thermal stability are critical for synthesis and processing of polymer layered silicate nanocomposites. In addition, the sorptive characteristics of the resulting organomontmorillonites have also been extensively studied, and it 0021-9797/$ -see front matter Ó 2011 Elsevier Inc. All rights reserved.…”

Sorption of methyl-parathion and carbaryl by an organo-bentonite

“…The treated soils can intercept and immobilize leached pollutants, preventing further groundwater and aquifer contamination. Cetyltrimethylammonium bromide (CTMAB) has been widely studied for HOC immobilization because it is strongly adsorbed by clays and has little degradability (Yang et al 2003).…”