Preparation of HDTMA‐bentonite: Characterization studies and its adsorption behavior toward dibenzofuran

Abstract

Bentonite is one of the most commonly used raw materials in the water treatment processes because of its low cost, easily availability and high mechanical and chemical stability. In this study, natural bentonite was modified with a large organic surfactant, which is hexadecyltrimethyl ammonium (HDTMA) bromide. The modified bentonite was called organobentonite. The surface characterization of natural bentonite and HDTMA-bentonite was examined by Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) and thermogravimetric (TG) analysis. FTIR spectroscopy showed the existence of HDTMA functional groups on bentonite surface. XRD results revealed randomly lateral-monolayer arrangements of the intercalated alkylammonium cation. The BET surface area significantly decreased after the modification due to the coverage of the pores of natural bentonite. Differences in the differential thermogravimetric (DTG) peaks for naturaland HDTMA-bentonite were observed and interpreted. HDTMA-bentonite was then tested as an adsorbent for the removal of organic compounds such as dibenzofuran (DBF) from aqueous solutions. The amount of adsorption for HDTMA-bentonite was found to be around 20 times higher than that of natural bentonite in 10 mg dm −3 DBF solution at 20• C. The adsorption kinetics of DBF onto HDTMA-bentonite was also studied at 20, 30 and 40• C and thermodynamic parameters were calculated. The overall adsorption process was exothermic and physical in nature. The results indicate that HDTMA-bentonite is an effective and a low-cost adsorbent for the removal of heterocyclic aromatic compounds such as DBF.

Sorption and Desorption of Atrazine on Natural Bentonite and Organically Modified Bentonite

“…Intercalation of humic acid and HDTMA in the interlayers of bentonite displayed a different effect on d 001 -spacing value. The dvalue for natural bentonite corresponded to 14.05Å expanded to 21.70Å for HDTMA-bent which is in agreement with other studies (Erdem et al, 2010 andDutta andSingh 2015). The basal spacing expansion is owing to the interpenetration of HDTMA ion into the layers of bentonite.…”

“…This value is close to the theoretical estimation of C/N ratio which was computed as 16.29. This ratio demonstrates that the modification of natural bentonite by HDTMA was effectively realized (Erdem et al, 2010). The BET surface areas and total pore volume of natural bentonite were 44.77 m 2 g -1 and 0.062 cm 3 g -1 , respectively, which is consistent with Mockovčiaková et al, (2009) andJiang et al,(2002).…”

“…Ksiezopolska and Pazur (2011) reported that the specific surface area of bentonite and illite reduced after complexion with humic acids at all pH values as a result of lodged humic acid in the active sites on clays and making the surface of the complex hydrophobic. Whereas, in surfactant modified bentonite the interparticle pores are covered and clogging of the interlayer space by HDTMA molecules prevented the N 2 access to the inner surface of material Erdem et al, 2010;Emam 2013). …”

“…The third step attributed to desurfactant is split into two stages; the first stage is occurred around 198-306 °C with 8.16% weight loss is corresponding to the decomposition of some HDTMA cations on the surface of bentonite. The second stage at 306-449 °C with 4.86% weight loss is assigned to the decomposition of some HDTMA cations between the layers of bentonite (Tiwari et al, 2008;Erdem et al, 2010). The fourth step is referring to the loss of dehydroxylation of the structural OH units of the bentonite at 449-745 °C (13% weight loss).…”

A thermal, sorptive and spectral study of HDTMA-bentonite loaded with uranyl phosphate

“…In the present study, we investigated thermal degradation of sorption products to elucidate the mechanism of interaction between the surfactant and the bentonite matrix. There is relatively little research concerning thermal analysis of HDTMA-bentonite [10][11][12][13][14][15][16][17]; however, this problem has received sufficient scrutiny in the works concerning the analog of bentonite, montmorillonite [18][19][20][21][22]. The introduction of phosphate ions to a sorption system is a new problem, and there is a dearth of research concerning thermal analysis of HDTMA-P(V)-bentonite and its modifications with U(VI).…”