Cr (VI) adsorption from aqueous solution using a surfactant-modified Iranian zeolite: characterization, optimization, and kinetic approach

Abstract

A B S T R A C TThe impact of various operating parameters, including pH (2-12), concentrations of modified zeolite (0.1-1.25 g/L), initial concentration of Cr (VI) (0.1-1.5 mg/L), and contact time (5-120 min), was investigated on the removal of Cr (VI) from water through different experimental runs in the batch system. The results showed that modified zeolite had best performance for the removal of Cr (VI) at the pH 7. The time required for the removal of 90.95% of the Cr (VI) from a 1 mg/L solution was about 80 min using modified zeolite. The equilibrium assessment illustrated that the Langmuir model is the best fit for the experimental data, which attains a maximum adsorption capacity of 4.4 mg/g. Pseudo-second-order kinetic model was found to adequately describe the adsorption process. In the final part of the study, the efficacy of modified natural zeolite was examined to simultaneously removal of Cr (VI) and As (V) from aqueous solution. In summary, modified natural zeolite is an efficient in performance, simple to operate, and economical process and thereby affordable technology for the removal of Cr (VI) from the contaminated water source.

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

“…Adsorption data conformed well to the Langmuir isotherm according to a correlation coefficient of 0.99. Similar correlations were reported also by Zeng et al (2010) and Asgari et al (2013) for HDTMA-modified clinoptilolite samples and also by Cansever-Erdogan and Ulku (2012) for unmodified clinoptilolite of Turkish origin. LeyvaRamos et al (2008) described Langmuir as an eventual model for the adsorption of Cr(VI) on SMZs as the interaction occurred between one HCrO 4 anion and a single NH 4 group adsorbed on zeolite, thus confirming monolayer adsorption.…”

“…Therefore, 14.0 g l -1 OMC was selected as the optimal adsorbent dose and applied in further experiments. Though the optimal dose for zeolites, either raw or modified, often lies in the range of 10.0-30.0 g l -1 , in a very recent report by Asgari et al (2013), it was claimed that 0.7 g l -1 of HDTMA-modified zeolite was sufficient to attain C90.0 % Cr(VI) removal. This dramatic diversity is most probably caused by the difference in the studied concentration ranges.…”

“…The mean free energy of adsorption was calculated as 0.276 kJ mol -1 using the Dubinin-Radushkevich constant, which implied that physical adsorption was the prevailing mechanism for Cr(VI) adsorption on OMC rather than ion exchange (Asgari et al 2013;Aydin and Deveci Aksoy 2009;Chutia et al 2009). …”

“…Among these materials, natural zeolites, which can be briefly described as crystalline microporous aluminosilicates, constitute a major group with unique physicochemical properties (Mozgawa and Bajda 2005;Leyva-Ramos et al 2008). The tetrahedral framework of zeolites, composed of SiO 4 and AlO 4 , possesses a net negative structural charge that promotes the exchange of cations while hindering the adsorption of anions and organic pollutants (Zeng et al 2010;Asgari et al 2013;Xie et al 2013). However, the negative charge can be tuned by surface modification with either strong acids or with long-chain organic cations such as surfactants.…”

The Potential of Sargassum oligocystum Harvested From Persian Gulf for the Adsorption of Copper Ions From Aqueous Solutions

“…All the tests were performed in triplicate and the averages of values were stated herein. The SPSS software (version 19) was applied to analyze the data. Equations 1 were applied to determine the copper removal efficiency (CRE) and the adsorption capacity (mg/g) (19).…”