Adsorption behaviors and capacities of Cr(VI) onto environmentally activated carbon modified by cationic (HDTMA and DDAB) surfactants

This research studied on the preparation of low cost-activated carbon from the carbonized carbon of Leucaena leucocephala (Lam.) de Wit. It was found that the activated carbon prepared at 500 degrees C for 3 h (503) showed the best adsorption capacity and/or performance of non-polar iodine molecule. Both of adsorbents (503 and commercial activated carbon-UCS) modified by cationic surfactants (HDTMA and DDAB) were also applied for removal chromium (VI) ion (Cr2O72-), which as expected, adsorption capacity of Cr2O72- was clearly enhanced, comparing with adsorbent without modification. The physicochemical properties of as-modified adsorbents were investigated. Adsorption behaviour of Cr(2)O(7)(2-)onto modified adsorbent was well fitted on Langmuir and Dubinin-Radushkevich isotherms as well as pseudo-secondorder kinetic model, suggesting to fast monolayer-physisorption process. The activated carbon (UCS-DDAB) exhibited a maximum q(max) of 3.46 mg g(-1). Thermodynamic study indicated that the adsorption of Cr2O72- onto absorbent surface was endothermic process with spontaneous nature. This research was expected to improve the efficiency of activated carbon modified by cationic surfactants, and could be definitely applied for removal of Cr(VI) ion from wastewater. (C) 2019 Elsevier B.V. All rights reserved.