Abstract
Adsorption of orange and yellow dyes, containing mono- and di-azoic groups, respectively, were studied by the use of a natural and organo-bentonites, which were obtained by treatment with hexadecyl-trimethyl-ammonium bromide (Br-HDTMA). Two different bentonites from Argentina were used. X-ray diffraction, UV–visible spectrometry, infrared spectrometry and thermal analysis were used for the characterizations. The results were interpreted by using isotherms that fit properly to the mathematical model of Langmuir. The structural and physicochemical properties of the clay, and the arrangement of hexadecyl-trimethyl-ammonium cation (HDTMA+) into the interlayer of the smectites, the main clay mineral composition of the bentonites, were responsible for the retention of dyes. The retention of the azo dyes not only increased with the HDTMA+ modification of the bentonites but also depended on the clay mineral (smectite types) composition of the pristine bentonite.
Highlights
Textile industry is constantly growing and high consumption of dyes is required
The retention of dyes in clay minerals will depend both on the physicochemical properties of the dyes, as well as on the adsorbent material
Z bentonite contains smectite as clay mineral and feldspar and gypsum as impurities, whereas S bentonite is rich in smectite with a little amount of quartz (Fig. 1)
Summary
Textile industry is constantly growing and high consumption of dyes is required. During the staining stage of the fibers, large volumes of various substances are used, among which are the dyes of organic origin [1,2,3]. A solution, economically viable, for this problem is the adsorption using as adsorbent material clays, abundant in nature and with adsorptive properties widely studied, which come mainly from its capacity of cation exchange and large surface area [10]. The retention of dyes in clay minerals will depend both on the physicochemical properties of the dyes, as well as on the adsorbent material. Clay minerals having negative charges between their sheets, and being naturally organophobic, require pretreatment retention tests of anionic organic dyes
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