In this work, agro-wastes coming from soursop (peel, seeds and pulp fiber) and sugarcane (bagasse) are used as low-cost biosorbents to remove methylene blue (MB) from aqueous media. Batch experiments ...are performed under different experimental conditions investigating the effects of biosorbent amount, dye concentration and stirring rate. The best results were found using soursop wastes for a MB concentration of 100 mg L−1, using 0.75 g of residue and a stirring rate of 110 rpm, removing a percentage above 90%. Theoretically, adsorption kinetic can be successfully described by the pseudo-second order model. Redlich-Peterson and Sips models are adopted to interpret the equilibrium adsorption of MB on sugarcane bagasse and soursop residue, respectively. Interestingly, the monolayer model with single energy derived by statistical physics theory is also applied for a deeper explanation of the adsorption mechanism of MB on both the adsorbents. The application of this model allows defining the adsorption geometry of the investigated adsorbate and provides important information about the interactions between the adsorbate and sorbents. In particular, the modelling analysis by statistical physics allows defining that the dye molecules are adsorbed in vertical position and the adsorption process is multi-molecular (i.e. n > 1). Finally, the estimation of adsorption energy suggested that MB adsorption on biosorbent is a physisorption process.
•Single and binary adsorption of antibiotics on activated carbon was investigated.•Statistical physics modeling of antibiotics adsorption was performed.•Monolayer and competitive monolayer models ...explained the adsorption mechanism.•Antibiotic antagonistic adsorption was associated to statistical physics parameters.
The adsorption mechanism of two antibiotics, namely amoxicillin (AMX) and tetracycline (TCN), on durian shell activated carbon (AC) was investigated in single and binary systems. Adsorption isotherms were determined under the same experimental conditions and they showed that the adsorption capacities of AMX were higher than those of TCN at all tested temperatures suggesting that this adsorbent preferred to remove AMX from the aqueous solution. It was also observed that all adsorption capacities decreased from single to binary systems, which was reasonably explained by an antagonistic adsorption between AMX and TCN on the active sites of AC creating an inhibition effect between these adsorbates. Monolayer and competitive monolayer models were developed via statistical physics theory and they were applied to explain and understand the adsorption mechanism of AMX and TCN via steric and energetic parameters. Results suggested that the parallel and non-parallel orientations of both antibiotics on the adsorbent surface of AC could be possible at tested experimental conditions. Modeling results demonstrated that the numbers of accepted antibiotic molecules per active site of AC varied with linear and inverse trends in single and binary systems, respectively, at all tested temperatures thus corroborating the adsorption inhibition effect caused by both adsorbates. An estimation of adsorption energies was also performed to describe and characterize the interactions between both antibiotics and AC surface. The assessment of the parameters of statistical physics models contributed to the explanation of the single and binary adsorption mechanisms of these water pollutants.
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•Insertion of chitosan between activated anthracite produced a new An/Ch adsorbent.•Cr(VI) and MO adsorption by An/Ch was investigated in single and binary systems.•Adsorption ...mechanism was evaluated via advanced statistical physics models.•An/Ch Active sites were more selective for MO than Cr(VI) in the adsorption systems.
A novel composite was prepared from chitosan and hydrogen peroxide–treated anthracite sheets and it was applied for the single and simultaneous adsorption of Cr(VI) and methyl orange (MO) at different temperature (25–45 °C) and pH (2–10). Experimental results showed that Cr(VI) as HCrO4− species was mainly removed by electrostatic interactions, while the reduced form Cr(III) was adsorbed via ion exchange and complexation reactions, thus concluding that Cr(VI) uptake was governed by adsorption–reduction coupled mechanism. Adsorption of MO on this composite was controlled by hydrogen bonding, n–π and also electrostatic attractions. Experimental data were fitted satisfactorily with Langmuir and Freundlich equations indicating that the composite was more selective for MO adsorption. Langmuir-based monolayer adsorption capacities (qmax) ranged from 188.01 to 201.77 mg/g for Cr (VI) and from 297.28 to 295.75 mg/g for MO in the single and binary systems, respectively, at 25 °C. Physicochemical parameters of statistical physics models were estimated and utilized to understand the adsorption mechanism of both adsorbates. A multi-docking and multi-molecular mechanisms could be present in the adsorption of Cr(VI) and MO, respectively. Density of receptor sites (NM) proved to be an essential factor that was associated to the adsorption capacities of the studied adsorbates and its values confirming the high selectivity of anthracite/chitosan active sites for MO uptake. The values of the adsorbed capacity ratio (Qb/Qs) revealed that MO enhanced uptake of Cr(VI) due to the newly formed active sites (i.e., synergism interaction), while MO adsorption was slightly decreased in the binary system at all temperatures reflecting a weak antagonism interaction. The adsorption energies corresponded to an exothermic process governed by physical forces for both pollutants.
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•Lignin-based activated carbons were prepared by chemical activation with FeCl3.•The best-activated carbon described a high 1500 m2⋅g−1 specific surface area.•Maximum acetaminophen ...adsorption capacity at 655 mg·g−1.•Maximum acetamiprid adsorption capacity at 765 mg·g−1.•Both target compounds adsorbed in two layers on the activated carbon surface.
Lignin has been employed as a precursor to synthesize activated carbons with the aim of lignin-biomass revalorization. The properties of these activated carbons were compared, and the best adsorbent was employed to remove two emerging pollutants from water, acetaminophen and acetamiprid. The adsorption mechanisms of pharmaceutical and pesticide compounds were analyzed, modeled and interpreted via statistical physics models. In particular, adsorption kinetics and isotherms of acetaminophen and acetamiprid at temperatures between 20 and 60 °C were quantified experimentally. Equilibrium data were fitted to different statistical physics-based isotherm models to establish the corresponding adsorption mechanism. A double layer adsorption model with one type of functional group was the best to correlate and explain the removal of these organic molecules. Steric parameters for the adsorption of these organic compounds were also calculated thus determining that their adsorption was multi-molecular. At tested operating conditions, acetaminophen adsorption was endothermic, while acetamiprid removal was exothermic. Physical adsorption forces were expected to be responsible for the removal of both compounds. This study reports new insights on the adsorption mechanisms of relevant emerging pollutants commonly found in water worldwide.
The biosorption isotherms of Ni(II) on four agro-wastes (sugarcane bagasse, passion fruit wastes, orange peels, pineapple wastes) were studied experimentally and theoretically at different ...temperatures (298, 308, 318 and 328K) using the statistical physics formulism. The double layer model with two biosorption energies was the more adequate to explain the biosorption process. The parameters like, number ions/molecules per site (n), density of receptor sites (NM), biosorbed quantity at saturation (Qbioso) and biosorption energies (−E1 and –E2) were estimated by numerical simulation. Thermodynamically, the entropy was also calculated to characterize the biosorption process. The results showed that the biosorption was exothermic and occurred by physisorption. The Ni(II) biosorption occurred by the formation of two layers on the biosorbents surface. The first layer was formed by electrostatic interactions, with energies varying from −21 to −14kJmol−1. The second layer was formed by Ni(II)–Ni(II) interactions with energies varying from −11 to −5kJmol−1.
•Ni(II) biosorption was studied on the basis in statistical physics theory.•New physicochemical and thermodynamic findings were revealed.•The double layer model with two energies was adequate to explain the biosorption.•Ni(II) aggregate during the biosorption.•The Ni(II) biosorption occurred by the formation of two layers.
•Recovery of grape bagasse biomass to prepare adsorbents was proposed.•New adsorbents for mercury removal were synthetized from grape bagasse.•Pyrolysis of grape bagasse was analyzed to improve ...mercury adsorption.•Mercury – grape bagasse char interactions were analyzed via DFT.•Oxygenated and silicon-based functional groups were involved in mercury adsorption.
This study has focused on the recovery of grape bagasse biomass to prepare new adsorbents for the removal of mercury from aqueous solutions.
•Adsorption of three dyes brilliant blue, sunset yellow and tartrazine on chitosan was studied.•Adsorption mechanism was analyzed with a multilayer statistical physics model.•Adsorption was performed ...with a horizontal position of molecules on the chitosan surface.
This study reports the statistical physics modeling of the adsorption of three dyes brilliant blue (BB), sunset yellow (SY) and tartrazine (TT) on chitosan from aqueous solution. A multilayer statistical physics model was applied to understand the dye adsorption at different temperatures (i.e., 298–328 K) and pH 3. Modeling results showed that the adsorption was performed with a horizontal position of BB, SY, and TT molecules on the chitosan surface. Dye adsorption capacities ranged from 406.19 to 814.27 mg/g for BB, from 924.88 to 1432.98 mg/g for SY and from 611.27 to 1065.55 mg/g for TT, respectively. Overall, the chitosan showed the highest adsorption capacities for dye SY (Q0 (SY-chitosan) > Q0 (TT- chitosan) > Q0 (BB- chitosan)). The analysis of adsorption energies indicated that the removal of these dyes was an exothermic physisorption process, which could be governed by steric parameters according to the results obtained with the multilayer statistical physics model. This study contributes with new theoretical and experimental findings of the dye adsorption using natural polymers.
•Two new adsorbents were prepared for dye adsorption from aqueous solution.•Statistical physics modeling was performed to characterize dye adsorption mechanism.•Physical interactions were involved in ...the endothermic dye adsorption.•Dye adsorption capacities ranged from 281 to 632 mg/g.
Activated carbons were prepared from ashitaba waste and a walnut shell to study the adsorption mechanism of congo red and methylene blue dyes in aqueous solution. These adsorbents were characterized via XRD, FTIR and SEM techniques and the dye adsorption isotherms at three temperatures were quantified. A statistical physics model was applied to interpret the adsorption mechanism of tested dyes and adsorbents. Modeling results showed that these dyes were practically separated in the solution leading to an absence of the aggregation process. Adsorption orientations of dye molecules on the adsorbents changed depending on the temperature and nature of systems. The adsorption capacity of ashitaba waste activated carbon for the removal of congo red was significant thus indicating strong interactions between this dye and tested adsorbent. Calculated adsorption energy varied from 7.25 to 20.43 kJ/mol and they showed that the adsorption of both adsorbates occurred via physical interactions at different temperatures where the removal process was endothermic.
Distribution of the molecules adsorbed on a solid material according to a multilayer model with saturation.
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•New statistical model was developed in this work (multilayer model with ...saturation).•The adsorption isotherms of ibuprofen were modeled using statistical model.•Energetic interpretation of the different adsorption isotherms.
The adsorption isotherms network at three temperatures of ibuprofen on a raw activated carbon and two chemically modified samples of the same carbon were simulated using models established through statistical physics formalism. Among the different tested models, a multilayer model with saturation was found to be the best to reproduce the experimental data. In this model, five parameters affecting the adsorption process were adjusted, namely the number of molecules per site, the density of receptor sites, the two energetic parameters and the number of layers. These parameters deduced from the fitting of the experimental adsorption isotherms by numerical simulation were discussed and interpreted for their temperature dependence.
In this work, a modeling analysis based on experimental tests of cadmium/zinc adsorption, in both single-compound and binary systems, was carried out. All the experimental tests were conducted at ...constant pH (around neutrality) and temperature (20 °C). The experimental results showed that the zinc adsorption capacity was higher than that of cadmium and it does not depend on cadmium presence in binary system. Conversely, cadmium adsorption is affected by zinc presence. In order to provide good understanding of the adsorption process, two statistical physics models were proposed. A monolayer and exclusive extended monolayer models were applied to interpret the single-compound and binary adsorption isotherms of zinc and cadmium on activated carbon. Based on these models, the modeling analysis demonstrated that zinc is dominant in solution and more favorably adsorbed on activated carbon surface. For instance, in single-compound systems, the number of ions bound per each receptor site was
n
(Zn
2+
) = 2.12 >
n
(Cd
2+
) = 0.98. Thus, the receptor sites of activated carbon are more selective for Zn
2+
than for Cd
2+
. Moreover, the determination of adsorption energy through the adopted models confirmed that zinc is more favored for adsorption in single-compound system (adsorption energies equal to 12.12 and 7.12 kJ/mol for Zn and Cd, respectively) and its adsorption energy does not depend on the cadmium presence in binary system. Finally, the adsorption energy values suggested that single-compound and binary adsorption of zinc and cadmium is a physisorption.
