Adsorption of benzene, toluene, and xylene (BTX) from binary aqueous solutions using commercial organoclay

Abstract

Organoclays are promising alternative adsorbents for the removal of organic pollutants. The aromatic hydrocarbons benzene, toluene, and xylene (BTX) are typical petroleum contaminants found simultaneously in natural leaking. Therefore, investigations on multi‐component adsorption become essential to study this issue. Based on that, in the present study, a commercial organoclay from Brazil has been tested for its adsorption potential for binary aqueous mixtures of BTX. Kinetic and equilibrium batch adsorption experiments were performed to elucidate the differences in the affinities between the BTX contaminants and the organoclay. The kinetic study indicated that for benzene‐toluene, benzene‐xylene, and toluene‐xylene systems the contaminants preferentially adsorbed were toluene, p‐xylene, and p‐xylene (in the beginning of the assays), respectively. The affinity for the organoclay might be related to physicochemical properties of BTX. In the adsorption equilibrium studies, the obtained BTX isotherms were all linear, characterized by constant adsorption affinities. The observed differences between BTX adsorption capacities at equilibrium for mono and bi‐component systems confirmed the competition for adsorption sites of the organoclay.

Fixed Bed Adsorption of Benzene, Toluene, and Xylene (BTX) Contaminants from Monocomponent and Multicomponent Solutions Using a Commercial Organoclay

“…Luz et al 44 employed activated carbon for BTX multicomponent adsorption in fixed bed and also reported xylene as being the most competitive compound for the available active sites of the adsorbent and that it displaces the other BTX contaminants. Stofela et al 33 performed batch studies on binary BTX adsorption onto the same organoclay of the present work and verified that toluene was preferentially adsorbed in the B + T system and p-xylene in the B + X and T + X systems.…”

“…Given that p-xylene is more commercially sought than m-or o-xylenes, 31 this isomer was employed in the present work, as well as in previous studies regarding kinetic and equilibrium BTX adsorption onto the organoclay. 32,33 As presented in Table 1, the initial concentrations evaluated in monocomponent tests were 0.6, 1.2, and 1.6 mmol/L, similarly to Stofela et al 26 and Stofela et al 32 The maximum concentration investigated was chosen based on the water solubility of p-xylene (175 mg/L, ∼1.6 mmol/L), which is the least soluble BTX compound. 34 For multicomponent experiments, equimolar solutions were prepared with fixed initial concentration of 0.9 mmol/L.…”

“…Benzene, toluene, and p -xylene were purchased from Sigma-Aldrich, Brazil (purity of 99.9%), and the solutions were prepared using Milli-Q water (Millipore, Brazil). Given that p -xylene is more commercially sought than m - or o -xylenes, this isomer was employed in the present work, as well as in previous studies regarding kinetic and equilibrium BTX adsorption onto the organoclay. , …”

“…Indeed, linear isotherms have been reported in previous studies employing Spectrogel organoclay as BTX adsorbent. 26,32,33 Therefore, in this work, partition can be regarded as the prevailing mechanism in BTX uptake and the main adsorption sites can be associated with the nanosized organic phases formed by the surfactant dialkyl dimethylammonium used in the functionalization of the organoclay.…”

Remediation of Emerging Contaminants

“…red mud, sludge), coal derived from non-conventional resources, biosorbents (e.g. peat, chitosan, alginate, cyclodextrin polymers), aquatic macrophytes, and biomass (Adriano et al 2005;Crini 2005Crini , 2006Bekçi et al 2006Bekçi et al , 2007Kang et al 2010;Braga et al 2011;Liu et al 2012a, b;Lian et al 2014;Xie et al 2014;Freitas et al 2017;Stofela et al 2017;Portinho et al 2017;Maia et al 2017Maia et al , 2019de Andrade et al 2018;de Souza et al 2018de Souza et al , 2019Osei et al 2019;Fenyvesi et al 2020;Macedo et al 2020).…”