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Recently, the potential dangers of viral infection transmission through water and air have become the focus of worldwide attention, via the spread of COVID-19 pandemic. The occurrence of large-scale outbreaks of dangerous infections caused by unknown pathogens and the isolation of new pandemic strains require the development of improved methods of viruses' inactivation. Viruses are not stable self-sustaining living organisms and are rapidly inactivated on isolated surfaces. However, water resources and air can participate in the pathogens' diffusion, stabilization, and transmission. Viruses inactivation and elimination by adsorption are relevant since they can represent an effective and low-cost method to treat fluids, and hence limit the spread of pathogen agents. This review analyzed the interaction between viruses and carbon-based, oxide-based, porous materials and biological materials (e.g., sulfated polysaccharides and cyclodextrins). It will be shown that these adsorbents can play a relevant role in the viruses removal where water and air purification mostly occurring via electrostatic interactions. However, a clear systematic vision of the correlation between the surface potential and the adsorption capacity of the different filters is still lacking and should be provided to achieve a better comprehension of the global phenomenon. The rationalization of the adsorption capacity may be achieved through a proper physico-chemical characterization of new adsorbents, including molecular modeling and simulations, also considering the adsorption of virus-like particles on their surface. As a most timely perspective, the results on this review present potential solutions to investigate coronaviruses and specifically SARS-CoV-2, responsible of the COVID-19 pandemic, whose spread can be limited by the efficient disinfection and purification of closed-spaces air and urban waters.
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The fast growth in the anthropogenic activities, that involve a wide use of pharmaceuticals, has led to the appearance of new toxic and hazardous chemical compounds, called "emerging pollutants", which could cause unpredictable consequences to the ecosystems. The current review is focused on emerging pollutants occurring in food or air and include caffeine and nicotine, as well as on pharmaceuticals, in particular amoxicillin, and the concerns caused by its wide usage for medical purposes. This review, for the first time, analyzes and discusses the potential risks and implications of caffeine, nicotine and amoxicillin as emerging environmental pollutants, a field that remains underrepresented to date. Both caffeine and nicotine belong to life style compounds, while pharmaceutical amoxicillin is one of the very popular ß-lactam antibiotics used to take care of human and animal infections. The review covers the toxic effect caused by caffeine, nicotine and amoxicillin on humans and animals and describes some of the main adsorbents utilized for their removal (e.g., grape stalk, tea waste, wheat grains, bentonite, activated carbon, acid and base modified grape slurry wastes, graphene oxides, modified graphene oxides, zeolites, etc.). The isotherm and kinetic models for the analysis of caffeine, nicotine and amoxicillin adsorption by different adsorbents are presented. The impact of pH, temperature, adsorbent dosage and thermodynamic studies were deeply analyzed. The review also discusses the mechanism of adsorption for the above-mentioned emerging pollutants, which includes π-π interaction, cation-π bonding, electron-donor and electron-acceptor forces, van der Waals forces, electrostatic interactions, etc. The present review has a potential value for chemists, ecologists, toxicologists, environmental engineers, and other professionals that are involved in environmental protection.
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Aguas Residuales , Contaminantes Químicos del Agua , Adsorción , Amoxicilina , Cafeína , Ecosistema , Cinética , NicotinaRESUMEN
Herein, adsorption isotherms of Pb(ii) and Cu(ii) ions on treated sea mango fruit in both single-compound and binary systems were experimentally realized at different temperatures in the range of 30-50 °C. Experimental results show that adsorption of Pb(ii) was more as compared to that of Cu(ii) ions; however, for both ions, a significant reduction in the adsorption capacity was observed in the binary system as compared to that in the single-compound systems. Moreover, under all the investigated conditions, adsorption seems to be promoted by an increase in temperature. To understand and interpret the experimental evidences, the Hill and competitive Hill models developed on the basis of the grand canonical ensemble were applied for the analysis of adsorption equilibrium data. These models contain some physicochemical parameters that allow an exhaustive analysis of the dynamics of single-compound and binary adsorptions. Based on the fitting results, in particular, through the evaluation of the number of ions bonded per site (n and ni), it was found that lead and copper ions interacted by inclined and horizontal positions on treated sea mango in single-compound and binary systems, respectively. In addition, based on the same parameters, a significant interaction between ions was retrieved. A study focused on the saturation adsorption capacity in single-compound and binary systems affirmed that the adsorbent was more selective for lead than for copper. The reduction of the adsorbed capacity ratio between the binary and single-compound systems (i.e. Qb/Qs) explained and confirmed that an inhibition effect between copper and lead ions at the same receptor site occurred. Finally, based on the energetic investigations, it was deduced that the adsorption energy represented the dominant factor promoting the greater adsorption of lead than that of copper in both systems.
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The removal of caffeine (CFN) and acetaminophen (ACT) from water using low-cost activated carbons prepared from artichoke leaves (AAC) and pomegranate peels (PAC) was reported in this paper. These activated carbons were characterized using various analytical techniques. The results showed that AAC and PAC had surface areas of 1203 and 1095 m2 g-1, respectively. The prepared adsorbents were tested for the adsorption of these pharmaceuticals in single and binary solutions. These experiments were performed under different operating conditions to evaluate the adsorption properties of these adsorbents to remove CFN and ACT. AAC and PAC showed maximum adsorption capacities of 290.86 and 258.98 mg g-1 for CFN removal, 281.18 and 154.99 mg g-1 for the ACT removal over a wide pH range. The experimental equilibrium adsorption data fitted to the Langmuir model and the kinetic data were correlated with the pseudo-second order model. AAC showed the best adsorption capacities for the removal of these pharmaceuticals in single systems and, consequently, it was tested for the simultaneous removal of these pollutants in binary solutions. The simultaneous adsorption of these compounds on AAC was improved using the central composite design and response surface methodology. The results indicated an antagonistic effect of CFN on the ACT adsorption. AAC regeneration was also analyzed and discussed. A statistical physics model was applied to describe the adsorption orientation of the tested pollutants on both activated carbon samples. It was concluded that AAC is a promising adsorbent for the removal of emerging pollutants due to its low cost and reusability properties.
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Contaminantes Ambientales , Contaminantes Químicos del Agua , Carbón Orgánico/química , Cafeína , Acetaminofén , Agua , Biomasa , Contaminantes Químicos del Agua/análisis , Adsorción , Cinética , Preparaciones Farmacéuticas , Concentración de Iones de HidrógenoRESUMEN
The work deals with the removal of two dyes, namely methylene blue (MB) and methyl orange (MO), from polluted water by adsorption onto CuO nanoparticles synthesized with a green synthesis procedure, starting from plant resources. Adsorption isotherms are determined at different temperatures aiming at investigating the adsorption mechanisms of the two dyes. The experimental results indicate that, for both MB and MO, the adsorption capacity increases with increasing temperature, with slight differences in the case of MO. Comparatively, the CuO nanoparticles show a higher MB adsorption capacity with respect to MO. A modelling analysis is carried out with a multilayer model derived from statistical physics, selected among a group of models, each hypothesizing a different number of adsorbed molecules layers. The analysis of model parameters allows determining that the adsorbate molecules exhibit a non-parallel orientation on the surface of biosynthesized CuO nanoparticles and each functional group of the adsorbent binds multiple molecules, simultaneously.The model also allows determining the number of dye molecule layers formed on adsorbent surface, in all the cases resulting higher than three, also confirming the effect of temperature on the maximum adsorption capacity.Specifically, the total number of dye layers formed on biosynthesized CuO nanoparticles surface exhibited a range of 4.17-4.55 for MB dye and of 3.01-3.51 for MO dye.Finally, the adsorption energies reveal that adsorption likely involves physical forces (all resulting all below 22 kJ/mol), i.e. hydrogen bonding and van der Waals forces. The adsorption energies for the interactions between dye molecules are lower than those calculated for the interactions between the dye molecules and the adsorbent surface.
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This study presents a theoretical analysis of the adsorption process of pharmaceutical pollutants, specifically acetaminophen (ATP) and diclofenac (DFC), onto activated carbon (AC) derived from avocado biomass waste. The adsorption isotherms of ATP and DFC were analyzed using a multilayer model, which revealed the formation of two to four adsorption layers depending on the temperature of the aqueous solution. The saturation adsorption capacities for ATP and DFC were 52.71 and 116.53 mg/g, respectively. A steric analysis suggested that the adsorption mechanisms of ATP and DFC involved a multi-molecular process. The calculated adsorption energies (ΔE1 and ΔE2) varied between 12.86 and 22.58 kJ/mol, with the highest values observed for DFC removal. Therefore, the adsorption of these organic molecules was associated with physisorption interactions: van der Waals forces and hydrogen bonds. These findings enhance the understanding of the depollution processes of pharmaceutical compounds using carbon-based adsorbents and highlight the potential of utilizing waste biomass for environmental remediation.
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Carbón Orgánico , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico/química , Contaminantes Químicos del Agua/química , Diclofenaco/química , Preparaciones Farmacéuticas/química , Carbono/química , Acetaminofén/químicaRESUMEN
The adsorption of ammonium from water was studied on an activated carbon obtained using raw oil palm shell and activated with acetic acid. The performance of this adsorbent was tested at different operating conditions including the solution pH, adsorbent dosage, and initial ammonium concentration. Kinetic and equilibrium studies were carried out, and their results were analyzed with different models. For the adsorption kinetics, the pseudo-first order equation was the best model to correlate this system. Calculated adsorption rate constants ranged from 0.071 to 0.074 g/mg min. The ammonium removal was 70-80% at pH 6-8, and it was significantly affected by electrostatic interaction forces. Ammonium removal (%) increased with the adsorbent dosage, and neutral pH condition favored the adsorption of this pollutant. The best ammonium adsorption conditions were identified with a response surface methodology model where the maximum removal was 91.49% with 2.27 g/L of adsorbent at pH 8.11 for an initial ammonium concentration of 36.90 mg/L. The application of a physical monolayer model developed by statistical physics theory indicated that the removal mechanism of ammonium was multi-ionic and involved physical interactions with adsorption energy of 29 kJ/mol. This activated carbon treated with acetic acid is promising to depollute aqueous solutions containing ammonium.
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Ácido Acético , Compuestos de Amonio , Contaminantes Químicos del Agua , Adsorción , Ácido Acético/química , Compuestos de Amonio/química , Contaminantes Químicos del Agua/química , Cinética , Concentración de Iones de Hidrógeno , Arecaceae/química , Carbón Orgánico/química , Purificación del Agua/métodosRESUMEN
In this paper, the adsorption of the herbicide 2,4-D and the drug ketoprofen on wheat husks Fagopyrum esculentum treated with H2SO4 is experimentally and analytically analyzed. The adsorbent is fully characterized through some techniques such as FT-IR, SEM, and XRD. Adsorption tests are carried out to optimize the performances in terms of adsorbent dosage and solution pH. Subsequently, the impact of temperature is determined through the realization of adsorption isotherms. A multilayer model is employed to microscopically interpret the adsorption mechanism of both the investigated compounds. The modelling analysis shows that the number of molecules bound per adsorption site varied from 0.68 to 2.77 and from 2.23 to 3.59 for ketoprofen and herbicide 2,4-D, respectively. These estimated values testify that an aggregation process occurs during adsorption. The global number of formed layers of each adsorbate is also determined, showing a significant reduction from 5.73 to 2.61 for ketoprofen and from 1.79 to 1.5 for herbicide 2,4-D with the temperature. For a complete understanding of the adsorption mechanism, the saturation adsorption capacity and adsorption energy were calculated and interpreted. Overall, it may be inferred that physical interactions govern how these contaminants adsorb on the tested adsorbent.
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Fagopyrum , Herbicidas , Cetoprofeno , Contaminantes Químicos del Agua , Triticum , Adsorción , Contaminantes Químicos del Agua/análisis , Espectroscopía Infrarroja por Transformada de Fourier , Ácido 2,4-Diclorofenoxiacético , Cinética , Concentración de Iones de Hidrógeno , TermodinámicaRESUMEN
An activated carbon (AC) deriving from sludge is used in this research for the adsorption of two water pollutants, namely Reactive Black 5 (RB5) and Green Alizarin (GA) dyes, at different temperatures. The adsorption capacities varied from 277.2 to 312.69 mg/g for GA and from 225.82 to 256.02 mg/g for RB5. Comparatively, this adsorbent presents good performances in removing these dyes from wastewater. The application of physical models to adsorption experiments is advantageous to provide new insights into the dyes' adsorption mechanism. A dedicated physical adsorption model suggests that RB5 and GA dyes are adsorbed in a monolayer. Moreover, the orientation of RB5 and GA dyes on AC resulted in an angled position, determining a multi-molecular process. In addition, both dyes are adsorbed by the occurrence of an aggregation process, forming a dimer. The impact of temperature can be also interpreted, allowing concluding that it plays a relevant role in removing these dyes. The calculation and interpretation of adsorption energies show that the dyes are removed via an endothermic process, and physical forces are involved.
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Colorantes , Contaminantes Químicos del Agua , Aguas del Alcantarillado , Carbón Orgánico , Adsorción , Contaminantes Químicos del Agua/análisis , Cinética , Concentración de Iones de HidrógenoRESUMEN
This paper evaluates the adsorption mechanism of perfluorooctanoic carboxylic acid (PFCA) and heptadecafluorooctane sulfonic acid (HFOSA) on magnetic chitosan for the first time via a statistical physics modeling. Magnetic chitosan (MC-CoFe2O4) was produced from shrimp wastes and used in standard batch adsorption systems to remove PFCA and HFOSA. The experimental isotherms indicated that the maximum adsorption capacities ranged from 14 to 27.12 mg/g and from 19.16 to 45.12 mg/g for PFCA and HFOSA, respectively, where an exothermic behavior was observed for both compounds. The adsorption data were studied via an advanced model hypothesizing that a multilayer process occurred for these adsorption systems. This theoretical approach indicated that the total number of formed layers of PFCA and HFOSA adsorbates is about 3 (Nt = 2.83) at high temperatures (328 K) where a molecular aggregation process was noted during the adsorption. The maximum saturation-multilayer adsorption of PFCA and HFOSA on magnetic chitosan was 30.77 and 50.26 mg/g, respectively, and the corresponding adsorption mechanisms were successfully investigated. Two energies were responsible for the formed adsorbate layer directly on the surface and the vertical layers were computed and interpreted, reflecting that physical interactions were involved to bind these molecules on the adsorbent surface at different temperatures where the calculated adsorption energies ranged from 14 to 31 kJ/mol. Overall, this work provides theoretical insights to understand the adsorption mechanism of PFCA and HFOSA using the statistical physics modeling and its results can be used to improve the adsorbent performance for engineering applications.
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Quitosano , Contaminantes Químicos del Agua , Adsorción , Fenómenos Magnéticos , Ácidos Sulfónicos , Cinética , Concentración de Iones de HidrógenoRESUMEN
This work describes the modeling and analysis of methylene blue molecule on different adsorbents, namely, nickel alginate/graphene oxide (NA/GO) aerogel, nickel alginate/activated carbon (NA/AC) aerogel, and Trichosanthes kirilowii maxim shell activated carbon (TKAC). A multilayer statistical physics model was used to calculate the energetic and steric parameters of the adsorption of methylene blue on these adsorbents. Based on the modeling investigation, it was concluded that the formation of multiple dye adsorbed layers on these adsorbents could be feasible where physical adsorption interactions could be involved. Adsorption capacities at saturation of these adsorbents ranged from 542.97 to 470.03 mg/g, 790.66 to 684.47 mg/g, and 401.11 to 1236.24 mg/g for NA-GO aerogel, NA-AC aerogel, and TKAC, respectively. This research contributes with new findings for the understanding of dye adsorption on novel materials, which can be used in water pollution control.
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Contaminantes Ambientales , Contaminantes Químicos del Agua , Adsorción , Alginatos , Carbón Orgánico , Grafito , Azul de Metileno , Níquel , TextilesRESUMEN
The work reports a modeling analysis of single-compound and binary adsorption of Pb2+ and Cd2+ ions from polluted water onto the activated carbon at room temperature. The homogeneous model for single adsorption (HM) and the exclusive extended monolayer model for binary adsorption (EEMM) are applied for the interpretation of the experimental data set. The adopted models correlate the entire set of adsorption data, allowing a thorough description of the occurring phenomena. The overall objective of the study is to determine the adsorption mechanisms, also through a comparative analysis between the single-compound and binary modeling data. The parameters of both models are used for to retrieve useful indications about the adsorption of these two ions. In particular, the number of ions adsorbed per single functional groups changed from single-compound to binary adsorption, allowing to explain the competitive behavior of the investigated system. The adsorption energy values vary between 21.39 (Pb2+) and 24.06 kJ/mol (Cd2+), and 27.17 (Pb2+) and 32.59 kJ/mol (Cd2+) in single-compound and binary systems, respectively, indicating that adsorption is a physisorption process.
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Lanthanum-based adsorbents have been used extensively to capture phosphate from wastewater. However, the attenuation effect that arises from the coexistence of sediment and humic acid is the major drawback in practical applications. The Lanthanum-layered rare earth hydroxides (LRHs)-Cl (La-LRH-Cl) was synthesized and achieved high elemental phosphorus (P) adsorption capacity (138.9 mg-P g-1) along with a fast adsorption rate (k2 = 0.0031 g mg-1·min-1) over a wide pH range while avoiding the attenuation effect that arises from the coexistence of sediment and humic acid in lake water. The La-LRH-Cl effectively captured phosphate through multiple interactions, such as the ion exchange of Cl- and phosphate, the memory effect of LRH and the inner-sphere complexation of La-P. Moreover, physical models demonstrated that the adsorption of phosphate onto La-LRH-Cl was a monolayer endothermic process, during which PO43- interacted by multi-docking via parallel orientation at 293 K and multi-ionic interactions through pure non-parallel orientation at 303 K. Hence, 1000 L of 11.08 mg-P L-1 of the acquired lake water was decontaminated by 30 g of La-LRH-Cl to 0.09 mg-P L-1 within 7 days. In addition, over ~12,125 BV of an industrial effluent containing 3.26 mg-P L-1 was treated to below USEPA's discharge limit in fixed-bed tests. It was found that the memory effect of LRH was responsible for the stable performance and reusability. Therefore, more focus should be placed on the collective role of La and LRH layered structure as a means of preventing the attenuation effect in the real water matrix.
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Lantano , Contaminantes Químicos del Agua , Adsorción , Sustancias Húmicas , Hidróxidos , Cinética , Lagos/química , Lantano/química , Fosfatos/química , Agua/química , Contaminantes Químicos del Agua/químicaRESUMEN
The paper describes a theoretical analysis of the adsorption of nicotinamide and propranolol onto a magnetic-activated carbon (MAC). For a better evaluation of the adsorption mechanism, adsorption isotherms expressing the variation of the adsorption capacity as function of adsorbate concentration were determined at different temperatures ranging from 20 to 45 °C. For both the analytes, experimental tests reveal that adsorption capacity increases with temperature. An advanced multi-layer model derived from the statistical physics is set for the interpretation of the entire adsorption data set. The modelling results show that the propranolol molecules change their adsorption orientation from a mixed (parallel and non-parallel) orientation to a multimolecular process. For nicotinamide, the aggregation of molecules is practically absent, except for the data at lower temperatures. The model allows stating that the adsorption of both the pharmaceutical compounds occurs via the formation of one or two layers on MAC adsorbent, the propranolol showing a higher tendency to form multiple layers. Finally, adsorption energy is estimated suggesting that the adsorption is endothermic and physical interactions are the responsible of the adsorption of both the compounds onto MAC adsorbent.
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Carbón Orgánico , Contaminantes Químicos del Agua , Adsorción , Cinética , Fenómenos Magnéticos , Niacinamida , Propranolol , Termodinámica , Contaminantes Químicos del Agua/análisisRESUMEN
Adsorption modeling via statistical physics theory allows to understand the adsorption mechanism of heavy metal ions. Therefore, this paper reports the analysis of the mechanism of copper ion (Cu2+) adsorption on four activated carbons using statistical physics models. These models contain parameters that were utilized to provide new insights into the possible adsorption mechanism at the molecular scale. In particular, a monolayer adsorption model was the best alternative to correlate the Cu2+ adsorption data at 25-55 °C and pH 5.5. Furthermore, the application of this model for copper adsorption data analysis showed that the removal of this heavy metal ion was a multi-cationic process. This theoretical finding indicated that Cu2+ ions interacted via one functional group of activated carbon surface during adsorption. In this direction, the adsorption energy was calculated thus showing that Cu2+ removal was endothermic and associated with physical interaction forces. Furthermore, these activated carbons showed saturation adsorption capacities from 54.6 to 87.0 mg/g for Cu2+ removal, and their performances outperformed other adsorbents available in the literature. Overall, these results provide new insights of the adsorption mechanism of this water pollutant using activated carbons.
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Metales Pesados , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , Cobre/química , Concentración de Iones de Hidrógeno , Iones , Cinética , Física , Contaminantes Químicos del Agua/análisisRESUMEN
In the present study, lanthanum hydroxide (La OH)-engineered sewage sludge biochar (La-SSBC) was utilized for efficient phosphate elimination from an aqueous medium. A high adsorption capacity of 312.55 mg P/g was achieved using La-SSBC at 20 °C, which was an excellent adsorbent performance in comparison to other biochar-based adsorbents. Additionally, the performance of La-SSBC was stable even at wider range of pH level, the existence of abundant active anions, and recycling experiments. Statistical physics modeling with the fitting method based on the Levenberg-Marquardt iterating algorithm, as well as various chemical characterizations, suggested the unique double-layered mechanism of phosphate capturing: one functional group of La-SSBC adsorbent describing a prone direction of the PO4 ions on the stabilize surface in a multi-ionic process, forming the first layer adsorption. Additionally, SSBC played an important role by releasing positively charged cations in solution, overcoming the electronic repulsion to form a second layer, and achieving excellent adsorption capacity. The calculation of multiple physicochemical parameters including adsorption energy further evidenced the process. This two-layered mechanism sheds light on the complex interaction between phosphate and biochar. Moreover, the management of sewage sludge associated with the requirement of cost-effectively and environmentally acceptable mode. Therefore, the present investigation demonstrated an efficient approach of the simultaneous sewage sludge utilization and phosphate removal.
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Aguas del Alcantarillado , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , Cinética , Lantano , Fosfatos , Contaminantes Químicos del Agua/análisisRESUMEN
Wide-ranging researches have been executed to treat groundwater from different mining areas, although complex behaviors of diverse metal ion species in the groundwater have not been illustrated clearly. This research study explored the mechanisms through which Pb(II) and V(V) are eliminated in single and binary-metal removal processes by oxygen, nitrogen, and sulfur-doped biochars also considering the kinetic and characterization techniques. The adsorption efficiency of V (V) was enhanced by oxygen-doped biochar at pH 4 with an adsorption capacity of ~70 mg/g. However, Pb (II) was rapidly removed at pH 6 with a higher adsorption capacity of ~180 mg/g by the nitrogen and sulfur-doped biochar forming PbCO3 and V(CO)6 crystals along the single-metal removal process. These results could be explained by the Hard Soft Acid Base theory. The hard Lewis acid vanadium was attracted by the hard Lewis base oxygen, and the intermediate Lewis acid lead was attracted by the intermediate and soft Lewis base nitrogen and sulfur. Besides, the removal ability of Pb(II) and V(V) in the binary-metal removal process showed a similar phenomenon for all types of biochars at pH 4 with the adsorption capacity of ~400 mg/g for Pb(II) and 175 mg/g for V(V), but the composition of vanadium species remains unclear on the surface of the biochars. Initially, H3V2O7-, H2VO4-, and HVO42- species were electrostatically attracted by the oxygen-based functionalities, then V(V) species was partially reduced to VO2+ by the oxygen, nitrogen, and sulfur functionalities in different ratios. Finally, H3V2O7-, H2VO4-, and HVO42- species produced Pb5(VO4)3Cl and Pb2V2O7 which co-precipitate with Pb(II), but VO2+ does not generate any form of precipitates. The above-explained technique supports the treatment of vanadium mining groundwater with valuable vanadinite (Pb5(VO4)3Cl) mineral.
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A theoretical assessment of the o-nitrophenol adsorption on layered double hydroxides containing different metallic species (Ca-Al, Ni-Al and Zn-Al) was performed. Experimental o-nitrophenol adsorption isotherms obtained at different adsorption temperatures with these layered double hydroxides were analyzed using a statistical physics monolayer model. Model calculations showed that the o-nitrophenol aggregation could occur with a high degree. It was estimated that the o-nitrophenol adsorption implied a non-flat orientation on all adsorbent surfaces and this process was multi-molecular. It was also demonstrated that there was no significant difference on the o-nitrophenol adsorption capacities of tested adsorbents, which varied from 77 to 135, 95 to 122 and 74 and 130 mg/g for Ca-Al, Ni-Al and Zn-Al layered double hydroxides, respectively. This finding suggested that the incorporation of Ca-Al, Ni-Al and Zn-Al in the layered double hydroxide structure played a similar role to adsorb o-nitrophenol molecules from aqueous solution. Calculated adsorption energies and thermodynamic functions confirmed an exothermic adsorption with the presence of physical-based interaction forces. This paper highlights the importance of reliable theoretical calculations based on statistical physics theory to contribute in the understanding of the adsorption mechanisms of a relevant water pollutant using layered double hydroxides as promising adsorbents for industrial applications.
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Hidróxidos , Nitrofenoles , Adsorción , Cinética , Modelos Teóricos , ZincRESUMEN
The statistical physics modeling is a reliable approach to interpret and understand the adsorption mechanism of both organic and inorganic adsorbates. Herein, a theoretical study of the adsorption mechanism of anionic dyes, namely reactive blue 4 (RB4), acid blue 74 (AB74), and acid blue 25 (AB25), on bone char was performed with a multilayer statistical physics model. This model was applied to fit the equilibrium adsorption data of these dyes at 298-313 K and pH 4. Results indicated that the global number of formed dye layers on the bone char varied from 1.62 to 2.24 for RB4, AB74, and AB25 dyes depending on the solution temperature where the saturation adsorption capacities ranged from 0.08 to 0.12 mmol/g. Dye molecular aggregation was also identified for these dyes where dimers and trimers prevailed at different operating conditions especially for adsorbates RB4 and AB74. Adsorption mechanism of these dyes was multimolecular and endothermic with adsorption energies from 10.6 to 20.8 kJ/mol where van der Waals interactions and hydrogen bonding could be present. This investigation contributes to understand the physicochemical variables associated to dye adsorption using low-cost adsorbents as bone char.
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Colorantes , Contaminantes Químicos del Agua , Adsorción , Aniones , Concentración de Iones de Hidrógeno , Cinética , FísicaRESUMEN
The paper describes a theoretical analysis of the adsorption of amoxicillin (AMX) onto two activated carbons pyrolysed at either 600 or 700 °C (PAC-600 and PAC-700). Series of experimental data are carried out at different temperatures ranging from 10 to 45 °C, as this is the first key factor to explain the adsorption mechanism of this pollutant. AMX adsorption capacity varied from 275 to 450 mg/g and between 276 and 454 mg/g for PAC-600 and PAC-700, respectively. It can be deduced that the pyrolysis temperature does not play a crucial role in AMX removal capacity of the adsorbents. A comparison with literature data shows that the retrieved adsorption capacities of both the adsorbents are very competitive for an effective water treatment. Physical models are applied to the two experimental data sets showing that a monolayer model with single energy is the best option to explain the AMX adsorption mechanism on both PAC-600 and PAC-700 adsorbents. The interpretation of the theoretical results points out that the AMX was not aggregated during the adsorption process. Under these experimental working conditions, it is noted that AMX is adsorbed almost via a parallel orientation on PAC-600 and PAC-700 adsorbents, reflecting that the adsorption is a multi-interaction mechanism. The model provides an estimation of the adsorption energy that allows the quantification of the interactions between the AMX and both PAC-600 and PAC-700 adsorbent surfaces; in both the cases, physical bindings are involved in AMX adsorption.