Adsorption of emerging pollutants on lignin-based activated carbon: Analysis of adsorption mechanism via characterization, kinetics and equilibrium studies

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 worldwid

Modélisation et interprétation des isothermes d'adsorption binaire de deux liquides ioniques et de l'ibuprofène sur un tissu du carbone activé

National audienc

Binary adsorption isotherms of two ionic liquids and ibuprofen on an activated carbon cloth: simulation and interpretations using statistical and COSMO-RS models

International audienc

Simulation et interprétation des isothermes d'adsorption simple et binaire de deux liquides ioniques et de l'ibuprofène sur un tissu du carbone activé

National audienc

Application of statistical physics formalism to the modeling of adsorption isotherms of ibuprofen on activated carbon

International audienc

Experimental and theoretical studies of adsorption of ibuprofen on raw and two chemically modified activated carbons: new physicochemical interpretations

International audienc

Adsorption of methylene blue on comminuted raw avocado seeds: Interpretation of the effect of salts via physical monolayer model

In this work, the effect of salts on the adsorption of a textile pollutant (Methylene blue: MB) on comminuted raw avocado seeds (CRAS) was interpreted via a physical monolayer model (PMM). To this aim, ten MB adsorption isotherms were determined at 25 °C and pH 10 in the presence of the next salts: NaCl, Na2CO3, Na2SO3, NaHCO3, C6H5Na3O7, NaHSO3, Na2B4O7·10H2O, Na2S2O3, NaNO2 and Na2HPO4. Under the same experimental conditions, a further adsorption isotherm was also determined without any salt addition and taken as reference data. In order to achieve a theoretical interpretation of the experimental data and to address the effect of salts on adsorption mechanism, a physical monolayer model (PMM) was applied to all the retrieved data. The model showed that Na2CO3, NaHCO3, Na2B4O7, Na2S2O3, and NaNO2 salts have no effect on the adsorption of MB dye, while the presence of NaCl, Na2SO3, C6H5Na3O7, NaHSO3 and Na2HPO4 salts in the solution caused a slight decrement of MB adsorption capacity due to a competitive effect between MB dye and salts on CRAS adsorption site. The modeling analysis showed that MB was adsorbed with a mixed parallel and non-parallel orientation on CRAS adsorbent surface. Moreover, the adsorption energies varied from 19.44 to 22.36 kJ/mol in tested systems. Adsorption energy values revealed that the process evolved via a physical adsorption, regardless the salt present in solution. All the investigated salts did not functionalize the CRAS adsorbent surface and also did not change the interaction energy between MB molecules and the adsorbent receptor sites. The interpretation of all the model parameters contributed to explain the adsorption mechanism of MB dye on CRAS. Specifically, the effect of salt on the reduction of MB adsorption capacity seems to be likely due to both steric hindrance effect and to MB molecule aggregation hindrance exerted by the salts, which prevented the formation of subsequent MB adsorbed layers, thus limiting its overall adsorption capacity