Adsorption of Sudan-IV contained in oily wastewater on lipophilic activated carbons: kinetic and isotherm modelling

Abstract

Up to nine kinetic and fourteen isotherm adsorption models are employed to model the adsorption of Sudan IV, a lipophilic model pollutant present in a biphasic mixture of cyclohexane-water system to simulate oily wastewater. Six different modified activated carbons were used as adsorbents. The highest amount adsorbed of Sudan IV was found in the material prepared by successive treatments of the parent commercial activated carbon Norit ROX 0.8 with nitric acid and urea, followed by thermal treatment at 800°C under continuous flow of nitrogen. Kinetic and isotherm adsorption models can be employed to simulate the process, since the effect of the presence of water in the adsorption of Sudan IV from the cyclohexane phase was found to be negligible, owing to the high lipophilic character of both adsorbent and adsorbate. All kinetic and isotherm coefficients, coupling with statistical parameters (r 2 , adjusted r 2 and sum of squared errors), are determined by non-linear regression fitting and compared to literature data. The model of Avrami is found to be the most appropriate model to represent the adsorption of the pollutant in any of the six modified carbons tested, the highest value of the kinetic constant being 0.055 min −1. The isotherm adsorption is wellmodelled by using the general isotherm equation of Tóth and the multilayer Jovanović expression for the adsorption of Sudan-IV on that material, resulting in a high monolayer uptake capacity (q m = 193.6 mg g −1).

Performance and modeling of Ni(II) adsorption from low concentrated wastewater on carbon microspheres prepared from tangerine peels by FeCl3-assisted hydrothermal carbonization

“…The modelling of the adsorption process is invaluable, not only for the prediction of the solute adsorption onto the adsorbent at different operating conditions, but also for a better understanding of the adsorption mechanism occurring on a system [20,28]. Adsorption isotherms data (quantification of adsorbed solute per unit mass of adsorbent at a constant temperature for different solute concentrations in solution at the equilibrium) can be processed for a deep understanding of the interaction between the solute (Ni(II) in this work) and the adsorbent.…”

“…To improve the fitting of Langmuir and Freundlich equations, Redlich and Peterson developed their model [68], which is mathematically equal to the Radke and Prausnitz isotherm model developed in the adsorption of solutes from dilute aqueous solutions on activated carbon [20,67]. Redlich and Peterson isotherm model is typically expressed as Eq.…”

“…where q t and q e refer the solute adsorbed (Ni(II)) per mass of adsorbent (mg g − 1 ) at a time of contact t (min) and at the equilibria stage, respectively, and k represents the rate constant of the adsorption process (min − 1 ). The pseudo-second-order model [58], also found as an hyperbolic model [20], is typically used to describe adsorption processes controlled by chemisorption, involving valence forces through sharing or exchange of electrons between the adsorbent and the adsorbate. Eq.…”

“…The Elovich equation is a model based on chemical adsorption [70], typically used in the simplified form obtained by Chien and Clayton [20]. In this work, the integrated form of Elovich equation was used, as shown in Eq.…”

Kinetic insights on wet peroxide oxidation of caffeine using EDTA-functionalized low-cost catalysts prepared from compost generated in municipal solid waste treatment facilities

“…1). The differences observed in the samples PC and PC-SA are due to the acid attack undergone by sample PC-SA that results in the leaching of metals and in the generation of surface oxygen and sulfur groups (Diaz de Tuesta et al, 2020c). The incorporation of TEOS on the sample PC-SA-TE is evident if the corresponding FT-IR spectra is compared to that of TEOS, since significant bands are observed at 1071, 946 and 793 cm −1 , in line with other reports (Gui-Long et al, 2011;Wencel et al, 2013).…”