Removal of chromate from wastewater using amine-based-surfactant-modified clinoptilolite

Abstract

This study presents the results of chromate adsorption upon organically modified clinoptilolite obtained by the treatment of Bigadic clinoptilolite with surfactants in primary amine structure, namely 1-dodecylamine, 1-hexadecylamine and oleylamine. Natural and organo-clinoptilolites were characterized by X-ray diffraction, thermal gravimetry and Fourier transform infrared spectrometry which proved the integration of amine groups followed by the order oleylamineOrgano-clinoptilolites were tested for their efficacy in chromate removal under base case conditions which implied 100 ppm initial concentration, pH 4.0, 10 g l -1 adsorbent dose and at 298 K. Results showed that amine loading induced chromate removal reaching up to 90 % for oleylamine-modified clinoptilolite. Experimentation was continued to determine the effects of pH, adsorbent dosage and initial concentration on chromate adsorption. Accordingly, maximum removal of 94.0 % was attained with 14 g l -1 of oleylamine-modified clinoptilolite, from Cr(VI) solution of 100 ppm initially at pH 3.0. Langmuir isotherm described the adsorption of chromate on oleylamine-modified clinoptilolite with 96.4 % consistency. Maximum theoretical uptake capacity was calculated as 6.72 mg g -1 . Kinetic data were consistent with pseudo-second-order model with the controlling steps being film and pore diffusions.

Synthesis and Modification of Clinoptilolite

“…Organically modified clinoptilolites are commonly produced by treating clinoptilolite with organic agents such as cationic surfactants [ 34 , 35 , 36 , 63 , 64 ], polymers [ 65 , 66 ], or amines [ 38 , 40 , 48 , 67 ]. The organic modification intensely changes the surface properties, allowing clinoptilolite to sorb anions or nonpolar molecules, for which the unmodified surface has a little affinity.…”

“…Wingenfelder et al [ 40 ] treated natural clinoptilolite with cysteamine and propyl amine with the aim to remove Cd and Pb and found that amine-modified clinoptilolite could not be effectively used for this purpose. In the research performed by Guzel et al [ 48 ], the interaction of natural clinoptilolite with primary amines including 1-dodecylamine, 1-hexadecylamine, and oleylamine was investigated. Results proved that the integration of amine groups was directly proportionate to the length of the hydrocarbon tail.…”

“…Clinoptilolite is used not only in its initial form but also in its modified form. In recent years, numerous studies [ 15 , 17 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ] have contributed to the issue of clinoptilolite modification. It was pointed out that the area of application could be intensively expanded by the functionalization of external as well as internal surfaces of clinoptilolite.…”

Crystal structure of bis[(oxalato-κ2O1,O2)(1,4,8,11-tetraazacyclotetradecane-κ4N)chromium(III)] dichromate octahydrate from synchrotron X-ray data

“…Cr can exist in all oxidation states from 0 to VI, the most common oxidation states in water being Cr III and Cr VI . In an aqueous environment, the toxicity of Cr VI has been shown to be greater than that of Cr III (Guzel et al, 2016). Transition metal complexes of the cyclam (1,4,8,11-tetraazacyclotetradecane, C 10 H 24 N 4 ) ligand have been the subject of numerous investigations because of their particular conformational stereochemistry (Poon & Pun, 1980;Choi, 2009;Subhan et al, 2011).…”

“…Therefore, knowledge of the conformation and hydrogen-bonding interactions in Cr III -Cr VI complex systems containing the cyclam ligand has become important in the development of new anti-HIV drugs (De Clercq, 2010). The use of such complexes for the more effective removal of toxic metals is also important (Guzel et al, 2016). As part of a study of the conformation and structure of (cyclam)chromium(III) complexes with auxiliary ligand(s) and various anions, we ISSN 2056-9890 report here the structural characterization of the new complex salt, [Cr(C 2 O 4 )(C 10 H 24 N 4 )] 2 [Cr 2 O 7 ]Á8H 2 O, (I).…”