Comprehensive Investigation of Cu2+ Adsorption from Wastewater Using Olive-Waste-Derived Adsorbents: Experimental and Molecular Insights.

This study investigates the efficacy of adsorbents from locally sourced olive waste-encompassing olive skins, leaves, and pits, recovered from the initial centrifugation of olives (OWP)-and a composite with sodium alginate (OWPSA) for the removal of Cu2+ ions from synthetic wastewater. Experimental analyses conducted at room temperature, with an initial Cu2+ concentration of 50 mg/L and a solid/liquid ratio of 1 g/L, showed that the removal efficiencies were approximately 79.54% and 94.54% for OWP and OWPSA, respectively, highlighting the positive impact of alginate on adsorption capacity. Utilizing statistical physics isotherm models, particularly the single-layer model coupled to real gas (SLMRG), allowed us to robustly fit the experimental data, providing insights into the adsorption mechanisms. Thermodynamic parameters affirmed the spontaneity and endothermic nature of the processes. Adsorption kinetics were interpreted effectively using the pseudo-second-order (PSO) model. Molecular modeling investigations, including the conductor-like screening model for real solvents (COSMO-RS), density functional theory (DFT), and atom-in-molecule (AIM) analysis, unveiled intricate molecular interactions among the adsorbent components-cellulose, hemicellulose, lignin, and alginate-and the pollutant Cu2+, confirming their physically interactive nature. These findings emphasize the synergistic application of experimental and theoretical approaches, providing a comprehensive understanding of copper adsorption dynamics at the molecular level. This methodology holds promise for unraveling intricate processes across various adsorbent materials in wastewater treatment applications.

Exploring the Efficiency of Algerian Kaolinite Clay in the Adsorption of Cr(III) from Aqueous Solutions: Experimental and Computational Insights.

The current study comprehensively investigates the adsorption behavior of chromium (Cr(III)) in wastewater using Algerian kaolinite clay. The structural and textural properties of the kaolinite clay are extensively characterized through a range of analytical methods, including XRD, FTIR, SEM-EDS, XPS, laser granulometry, N2 adsorption isotherm, and TGA-DTA. The point of zero charge and zeta potential are also assessed. Chromium adsorption reached equilibrium within five minutes, achieving a maximum removal rate of 99% at pH 5. Adsorption equilibrium is modeled using the Langmuir, Freundlich, Temkin, Elovich, and Dubinin-Radushkevitch equations, with the Langmuir isotherm accurately describing the adsorption process and yielding a maximum adsorption capacity of 8.422 mg/g for Cr(III). Thermodynamic parameters suggest the spontaneous and endothermic nature of Cr(III) sorption, with an activation energy of 26.665 kJ/mol, indicating the importance of diffusion in the sorption process. Furthermore, advanced DFT computations, including COSMO-RS, molecular orbitals, IGM, RDG, and QTAIM analyses, are conducted to elucidate the nature of adsorption, revealing strong binding interactions between Cr(III) ions and the kaolinite surface. The integration of theoretical and experimental data not only enhances the understanding of Cr(III) removal using kaolinite but also demonstrates the effectiveness of this clay adsorbent for wastewater treatment. Furthermore, this study highlights the synergistic application of empirical research and computational modeling in elucidating complex adsorption processes.

The potential role of Epstein-Barr Virus in breast cancer development.

We are looking into viral components that may contribute to breast cancer in order to find possible therapeutic targets. The Epstein-Barr virus (EBV), which has been found to cause nasopharyngeal carcinoma and Burkitt lymphoma, is thought to play a role in breast cancer. Our series' patients had a median age of 49, with nearly half being under the age of 49. T2 tumors (two to five centimeters in size) make up the vast majority of our collection (60%). Six percent of our patients showed lymph node involvement, with roughly the same number in the N1 and N2 stages (41.17% each). Only 17.64% of people are at the N3 stage. SBR II tumors were the most common (90%). Only 20% of patients have HER2 overexpression, whereas 73.33% have ER expression. EBV was found in 23.33% of breast carcinomas (7 cases/30) after oncoprotein LMP1 expression, but normal surrounding tissues tested negative. We discovered that overexpression of the HER2 protein is inversely related to the two HRs' expression. They have no relationship with EBV infection and, consequently, LMP1 expression. LMP1 expression was not shown to be linked with patient age, tumor grade, tumor size, or lymph node invasion.

Identification of the Contamination Sources by PCBs Using Multivariate Analyses: The Case Study of the Annaba Bay (Algeria) Basin.

Persistent Organic Pollutants (POPs), particularly the indicator polychlorinated biphenyls (PCBs), were first quantified in water and sediments of two wadis, Boujemaâ and Seybouse, as well as in the effluents from a fertilizer and phytosanitary production industrial plant (Fertial). Since these contaminated discharges end in Annaba Bay (Algeria) in the Mediterranean Sea, with a significant level of contamination, all the potential sources should be identified. In this work, this task is conducted by a multivariate analysis. Liquid-liquid extraction and gas chromatography/mass spectrometry (GC-MS) methods were applied to quantify seven PCB congeners, usually taken as indicators of contamination. The sum of the PCB concentrations in the sediments ranged from 1 to 6.4 µg/kg dw (dry weight) and up to 0.027 µg/L in waters. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used for the multivariate analysis, indicating that the main sources of PCB emissions in the bay are urban/domestic and agricultural/industrial. The outfalls that mostly contribute to the pollution of the gulf are the Boujemaâ wadi, followed by the Seybouse wadi, and finally by the Fertial cluster and more precisely the annex basin of the plant. Although referring to a specific site of local importance, the work aims to present a procedure and a methodological analysis that can be potentially applicable to further case studies all over the world.

Multitask Quantum Study of the Curcumin-Based Complex Physicochemical and Biological Properties.

Density functional theory (DFT), time-dependent density functional theory (TDDFT), quantum theory of atoms in molecules (QTAIM), and extended transition state natural orbitals for chemical valence (ETS-NOCV) have all been used to investigate the physicochemical and biological properties of curcumin and three complexes, i.e., Cur-M (M = Ni, Cu, and Mg). Based on DFT calculations, the enolic form (Cur-Enol) is more stable than the anti-diketone form (Cur-Anti diketone) favored for complexation. This enolic form stability was explained by the presence of three intramolecular hydrogen bonds according to the QTAIM analysis. Furthermore, the ETS-NOCV technique revealed that the enolic form had more significant antioxidant activity compared with the anti-diketone form. The calculations from the COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) showed that the dimethyl sulfoxide (DMSO) solvent could dissolve all the curcumin tautomers Cur-Enol, Cur-Anti-diketone and Cur-Cu, Cur-Mg, and Cur-Ni complexes in contrast to benzene, acetone, octanol, ethanol, methanol, and water. Furthermore, except for Cur-Mg, which had a relatively low solubility (14 g/L), all complexes were insoluble in water. Cur-Anti-diketone was considerably more soluble than Cur-Enol in the examined solvents.

Mechanisms of Methylparaben Adsorption onto Activated Carbons: Removal Tests Supported by a Calorimetric Study of the Adsorbent⁻Adsorbate Interactions.

: In this study, the mechanisms of methylparaben adsorption onto activated carbon (AC) are elucidated starting from equilibrium and thermodynamic data. Adsorption tests are carried out on three ACs with different surface chemistry, in different pH and ionic strength aqueous solutions. Experimental results show that the methylparaben adsorption capacity is slightly affected by pH changes, while it is significantly reduced in the presence of high ionic strength. In particular, methylparaben adsorption is directly dependent on the micropore volume of the ACs and the π- stacking interactions, the latter representing the main interaction mechanism of methylparaben adsorption from liquid phase. The equilibrium adsorption data are complemented with novel calorimetric data that allow calculation of the enthalpy change associated with the interactions between solvent-adsorbent, adsorbent-adsorbate and the contribution of the ester functional group (in the methylparaben structure) to the adsorbate⁻adsorbent interactions, in different pH and ionic strength conditions. It was determined that the interaction enthalpy of methylparaben-AC in water increases (absolute value) slightly with the basicity of the activated carbons, due to the formation of interactions with π- electrons and basic functional groups of ACs. The contribution of the ester group to the adsorbate-adsorbent interactions occurs only in the presence of phenol groups on AC by the formation of Brønsted⁻Lowry acid⁻base interactions.

New insights into single-compound and binary adsorption of copper and lead ions on a treated sea mango shell: experimental and theoretical studies.

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.

Adsorption of Cd (II) on Modified Granular Activated Carbons: Isotherm and Column Study.

In this work, equilibrium and dynamic adsorption tests of cadmium Cd (II) on activated carbons derived from different oxidation treatments (with either HNO3, H2O2, or NaOCl, corresponding to GACoxN, GACoxP, and GACoxCl samples) are presented. The oxidation treatments determined an increase in the surface functional groups (mainly the acidic ones) and a decrease in the pHPZC (except for the GACoxCl sample). A slight alteration of the textural parameters was also observed, which was more significant for the GACoxCl sample, in terms of a decrease of both Brunauer-Emmett-Teller (BET) surface area and micropore volume. Adsorption isotherms were determined for all the adsorbents and a significant increase in the adsorption performances of the oxidized samples with respect to the parent material was observed. The performances ranking was GACoxCl > GACoxP > GACoxN > GAC, likely due to the chemical surface properties of the adsorbents. Dynamic tests in a fixed bed column were carried out in terms of breakthrough curves at constant Cd inlet concentration and flow rate. GACoxCl and GACoxN showed a significantly higher value of the breakpoint time, likely due to the higher adsorption capacity. Finally, the dynamic tests were analyzed in light of a kinetic model. In the adopted experimental conditions, the results showed that mass transfer is controlled by internal pore diffusion, in which surface diffusion plays a major role.

Effect of Solution pH on the Adsorption of Paracetamol on Chemically Modified Activated Carbons.

Paracetamol adsorption in acidic, neutral and basic media on three activated carbons with different chemistry surfaces was studied. A granular activated carbon (GAC) was prepared from coconut shell; starting from this sample, an oxidized activated carbon (GACo) was obtained by treating the GAC with a boiling solution of 6 M nitric acid, so to generate a greater number of oxygenated surface groups. In addition, a reduced activated carbon (GACr) was obtained by heating the GAC at 1173 K, to remove the oxygenated surface groups. Paracetamol adsorption was higher for GACr due to the lower presence of oxygenated surface functional groups. Moreover, adsorption was highest at neutral pH. The magnitude of the interactions between paracetamol molecules and activated carbons was studied by measuring the immersion enthalpies of activated carbons in solution of paracetamol at different concentrations and pH values and by calculating the interaction enthalpy. The highest value was obtained for GACr in a paracetamol solution of 1000 mg L-1 at pH 7, confirming that paracetamol adsorption is favoured on basic activated carbons at pH values near to neutrality. Finally, the Gibbs energy changes confirmed the latter result, allowing explaining the different magnitudes of the interactions between paracetamol and activated carbons, as a function of solution pH.

Assessment of CO2 adsorption capacity on activated carbons by a combination of batch and dynamic tests.

In this work, batch and dynamic adsorption tests are coupled for an accurate evaluation of CO2 adsorption performance of three different activated carbons (AC) obtained from olive stones by chemical activation followed by physical activation with CO2 at varying times (i.e., 20, 40, and 60 h). Kinetic and thermodynamic CO2 adsorption tests from simulated flue gas at different temperatures and CO2 pressures are carried out under both batch (a manometric equipment operating with pure CO2) and dynamic (a lab-scale fixed-bed column operating with a CO2/N2 mixture) conditions. The textural characterization of the AC samples shows a direct dependence of both micropore and ultramicropore volume on the activation time; hence, AC60 has the higher contribution. The adsorption tests conducted at 273 and 293 K showed that when CO2 pressure is lower than 0.3 bar, the lower the activation time, the higher CO2 adsorption capacity; a ranking of ω(eq)(AC20) > ω(eq)(AC40) > ω(eq)(AC60) can be exactly defined when T = 293 K. This result is likely ascribed to the narrower pore size distribution of the AC20 sample, whose smaller pores are more effective for CO2 capture at higher temperature and lower CO2 pressure, the latter representing operating conditions of major interest for decarbonation of flue gas effluent. Moreover, the experimental results obtained from dynamic tests confirm the results derived from the batch tests in terms of CO2 adsorption capacity. It is important to highlight the fact that the adsorption of N2 on the synthesized AC samples can be considered to be negligible. Finally, the importance of proper analysis for data characterization and adsorption experimental results is highlighted for the correct assessment of the CO2 removal performance of activated carbons at different CO2 pressures and operating temperatures.

Theoretical Exploration of Enhanced Antioxidant Activity in Copper Complexes of Tetrahydroxystilbenes: Insights into Mechanisms and Molecular Interactions.

A theoretical investigation was conducted using DFT/PW91/TZP/DMSO calculations on a complete set of exhaustive lists of 18 compounds resulting from the complexation of trans-2,4,3',5'-tetrahydroxystilbene (T-OXY) and cis-2,4,1',3'-tetrahydroxystilbene (C-OXY) with copper metal cations (Cu+ and Cu2+). The ligand-binding sites are the critical points of Quantum Theory of Atoms in Molecules (QTAIM) analysis on neutral and deprotonated ligands. Various mechanisms, including hydrogen atom transfer (HAT), sequential proton loss electron transfer (SPLET), single electron transfer followed by proton transfer (SET-PT), and bond dissociation energy (BDE(E0)) calculations, were employed to quantify the antioxidant activity. The BDE(E0) mechanism emerged as the most suitable approach for such analyses to evaluate the departure of hydrogen atoms since the results show the HAT mechanism is the most likely occurring. Particularly intriguing were the anionic Cu+ complexes with ligands adopting trans configurations and deprotonated conformations, displaying superior antioxidant activity compared to their counterparts. Remarkably, a single ligand within the Cu+ complex exhibited exceptional antioxidant prowess, yielding a BDE(E0) value of 91.47 kcal/mol. Furthermore, a complex involving two deprotonated ligands demonstrated antioxidant activity of 31.12 kcal/mol, signifying its potential as a potent antiradical agent, surpassing T-OXY by a factor of 3.91 and even surpassing the antioxidant efficiency of Vitamin C.

Removal of textile pollutants from aqueous medium using biosynthesized CuO nanoparticles: Theoretical comparative investigation via analytical model.

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.

Elimination of aspirin and paracetamol from aqueous media using Fe/N-CNT/ß-cyclodextrin nanocomposite polymers: theoretical comparative survey via advanced physical models.

The main purpose of this research is to theoretically investigate the adsorption of two pharmaceutical molecules, i.e. aspirin and paracetamol, using two composite adsorbents, i.e. N-CNT/ß-CD and Fe/N-CNT/ß-CD nanocomposite polymers. A multilayer model developed by statistical physics is implemented to explain the experimental adsorption isotherms at the molecular scale, so as to overpass some limitations of the classical adsorption models. The modelling results indicate that the adsorption of these molecules is almost accomplished by the formation of 3 to 5 adsorbate layers, depending on the operating temperature. A general survey of the number of adsorbate molecules captured by the adsorption site (npm) suggested that the adsorption process of pharmaceutical pollutants is multimolecular and that each adsorption site can capture several molecules simultaneously. Furthermore, the npm values demonstrated the presence of aggregation phenomena of aspirin and paracetamol molecules during adsorption. The evolution of the adsorbed quantity at saturation confirmed that the presence of Fe in the adsorbent enhanced the removal performance of the investigated pharmaceutical molecules. In addition, the adsorption of the pharmaceutical molecules aspirin and paracetamol on the N-CNT/ß-CD and Fe/N-CNT/ß-CD nanocomposite polymer surface involved weak physical type interactions, since the interaction energies do not overcome the threshold of 25 000 J mol-1.

Explaining the adsorption mechanism of the herbicide 2,4-D and the drug ketoprofen onto wheat husks Fagopyrum esculentum treated with H2SO4.

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.

Highlighting the adsorption mechanism of dyes onto activated carbon derived from sludge by theoretical physical analysis.

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.

Adaptation of advanced physical models to interpret the adsorption isotherms of lead and cadmium ions onto activated carbon in single-compound and binary systems.

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.

Application of a multilayer physical model for the critical analysis of the adsorption of nicotinamide and propranolol on magnetic-activated carbon.

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.

Theoretical interpretation of the adsorption of amoxicillin on activated carbon via physical model.

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.

Pump-and-treat configurations with vertical and horizontal wells to remediate an aquifer contaminated by hexavalent chromium.

Pump-and-treat technology is among the most used technologies for groundwater remediation. While conventional, vertical wells (VRWs) are well-known and used from long time, horizontal wells (HRWs) have been explored for remediation technologies only in last few decades. HRWs have shown to outperform vertical wells in terms of versatility, productivity and clean-up times under certain conditions. In this paper, the efficacy of an innovative pump-and-treat (P&T) configuration for groundwater remediation obtained by adopting either VRWs or HRWs technology is comparatively tested. A 3D transient finite element model of an unconfined aquifer containing a hexavalent chromium (Cr(VI)) contamination plume is considered to compare a single horizontal well configuration vs a range of spatially-optimised arrays containing vertical wells. A sensitivity analysis aimed at finding the best configuration to minimise the remediation time and the related cost is carried out by comparing different well diameters, D, pumping rates, Q, and position of wells. A comparative cost analysis demonstrates that, for the examined case-study, a single HRW achieves the clean-up goals in the same time span as for a greater number of vertical wells, but at higher price due to the excavation costs.

Ternary adsorption of cobalt, nickel and methylene blue on a modified chitin: Phenomenological modeling and physical interpretation of the adsorption mechanism.

The simultaneous adsorption of three pollutants cobalt (Co), methylene blue (MB) and nickel (Ni) on a modified chitin surface from ternary systems was investigated. Multicomponent experimental adsorption data were determined at 298-328 K and pH 6. These experimental studies indicated that Ni adsorption was higher than those obtained for Co and MB. The multicomponent adsorption mechanism of this ternary system was analyzed with statistical physics theory where a set of new models with different hypotheses was developed and tested. Results showed that an adsorption model assuming that the pollutants Co, MB and Ni were adsorbed on three different types of modified chitin receptor sites was the most appropriate. This model was also utilized to calculate the corresponding adsorption energies to describe the possible interactions between these adsorbates and the surface of modified chitin. A general analysis of trends and magnitude of the model parameters provided a deeper understanding of the ternary adsorption mechanism at molecular level. Macroscopically, the ternary adsorption mechanism was interpreted via a calculation of three thermodynamic functions.