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Herein, a chitosan/polyamide nanofibers (CPN)-based adsorbent is employed to interpret the adsorption mechanism of two dyes, namely Reactive Black 5 (RB5) and Ponceau 4R (P4R), at different temperatures. Based on experimental results, the adsorption isotherms of RB5 and P4R dyes indicate that the separation process tends to a saturation plateau at high concentration, also suggesting that the dyes adsorption process occurs with the formation of a finite number of layers. To provide a reasonable explanation of the dyes adsorption mechanisms, three statistical physics models are used and discussed. The advanced modelling analysis reveals that the adsorption of both dyes occurs by the formation of two different adsorbed layers on CPN surface. Based on the application of the best statistical physics adsorption model, it was deduced that both dyes were anchored with horizontal and non-horizontal positions on CPN surface depending on temperature, which was concluded by investigation the captured number of dye molecules per CPN adsorbent site during the adsorption process. Based on these theoretical results, it was noted that the adsorption capacities at saturation followed this sequence: Q (P4R) > Q (RB5) for all investigated temperatures (i.e., 222.4, 261.3, 352.8, 482.2 mg/g for P4R and 198.6, 267.7, 288.2, 352.5 mg/g for RB5), indicating that CPN adsorbent was more effective for the P4R dye removal. The adsorption energies are studied to explain the difference in the interactions between dyes and adsorbent surface (P4R-CPN, RB5-CPN), and between these dyes (P4R-P4R, RB5-RB5), indicating that the removal of these adsorbates was based on a physisorption mechanism where a desorption process is possible. Comparing the estimated parameters of the best statistical physics model, it was concluded that both steric and energetic factors are mainly responsible for the adsorption of P4R and RB5 dyes on CPN.

International audience; In recent years, the preparation of deep eutectic solvents (DESs) using amines as hydrogen bond donors (HBD) has been reported by several research groups. One of the potential use of this type of DESs is in the field of CO2 capture, where the viscosity of the solvent before and after the absorption is of paramount importance. Since the number of possible combinations of DESs is huge, a mathematical model for the predicting of the viscosity of DESs at different temperatures is very important.In this work, a new mathematical model for the prediction of amine-based DESs viscosities using the quantitative structure property relationships (QSPR) approach is presented. A combination of multilinear regression (MLR) and artificial neural networks (ANN) methods is used for the development of the model. A data set of 108 experimental measurements of viscosity of five amines-based DESs, taken from the literature, is used for the development and subsequent verification of the model. The more appropriate model is determined by a dedicated statistical analysis, in which the most significant descriptors are preliminary determined. The results show that the proposed models are able to predict the DESs viscosities with very high accuracy, i.e. with a R2 value of 0.9975 in training and 0.9863 for validation using the ANN model and R2 value of 0.9305 for the MLR model. The retrieved model can be considered as a very reliable tool for the prediction of DESs viscosity when experimental data are absent. In turn, this can provide useful guidelines for the synthesis of low-viscosity DESs able to minimize energy requirements associated to their processing (e.g. power required for pumps), thus fostering their industrial-scale implementation.

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.

International audience; The removal of a benzodiazepine (clorazepate, CLZ) from aqueous solution by adsorption onto maghnite clay is investigated supported by theoretical simulations. The Fourier-transform infrared (FTIR), Ultraviolet (UV), X-ray diffraction (XRD), and scanning electron microscope (SEM) analyses were used to characterize the adsorbent. To individuate the optimum conditions for adsorption, equilibrium, and kinetic tests are performed to assess the efficiency of this adsorbent to remove CLZ from polluted water in different operating conditions like pH, initial concentration, adsorbent dosage, and contact time. Adsorption is maximum at low pH, and it is mainly driven by electrostatic interactions between the benzenic ring of CLZ molecule and the montmorillonite layer of maghnite adsorbent. The kinetics obeys to the pseudo-first-order kinetic model, while the Freundlich isotherm model was found to better describe the adsorption equilibrium. The maximum observed adsorption amount of CLZ onto maghnite was about 50 mg g−1 at pH 4.66. A complementary theoretical study is performed to quantify the CLZ/maghnite interactions using Monte Carlo simulations. Interestingly, the results show that the CLZ assumes a horizontal position on the maghnite surface upon adsorption, characterized by high energy adsorption.

The present work deals with the Sorption-Enhanced Methane Steam Reforming (SE-MSR), an interesting and energy-efficient hydrogen production route with in situ CO2 capture. A computational fluid dynamics (CFD) model for an industrial-scale fixed-bed reactor, with Ni/Al2O3 as catalyst and CaO as an adsorbent for CO2 capture, is developed taken into consideration also the coke deposition. Temperature is shown to be the key parameter of the SE-MSR chemical process at large scales. H2 production is constant and maximum until the saturation of CaO sorbent occurs, after which the concentrations of all the other compounds start to vary, and the efficiency of the process begins to drop. When the exothermic carbonation reaction stops, an alteration of the thermal regimes is observed. The absence of the contribution of the exothermic carbonation reaction results in a decrease of the temperature, which in turn determines a lower conversion of CH4 and H2O, according to the endothermic reforming reactions. The maximum H2 outlet mole fraction (dry basis) is 0.8, and it occurs in the presence of CO2 sorption; the value drops to 0.42 once the adsorbent reaches its maximum conversion degree. The molar selectivity in hydrogen relative to the quantity of CH4 fed to the reactor is of the order of 1.75 (with CO2-capture) and 0.8 (without CO2 capture). The molar fluxes obtained and the kinetics of the system model show the excellent choice of the operating conditions of the catalyst to produce a large quantity of hydrogen as well as of the adsorbent, which eliminates the CO2 responsible of coke deposition.

In this work, a route is developed to synthesize nanocomposites based on polylactic acid (PLA) and stearic acid-modified TiO2 nanoparticles (TiO2-SA). The nanocomposite is prepared in two steps by solution and melt methods. Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), as well as Thermogravimetric Analysis (TGA) are used to characterize the synthesized materials. Quantum chemical calculations are carried out by means of density functional theory (DFT) calculations, Blends study and AIM analysis, to investigate the role of Stearic Acid (SA) on the nanocomposite PLA/TiO2 at microscopic level. FTIR analysis confirms the functionalization of TiO2 nanoparticles by stearic acid (SA). The DSC results illustrates the overall TiO2 effect in reducing the glass transition temperature Tg (from 58° to 52 °C) and the rise in the crystallinity degree (from 0.19° to 7.18 °C) where the 5% of nanoparticle shows the optimum result. This could be attributed to the fact that TiO2-SA acts as a nucleating agent, as confirmed also by XRD patterns. TGA analysis shows that the thermal stability of PLA decreases by the addition of TiO2-SA and this effect is monothonic with TiO2 content where the 1% nanoparticle shows the most thermally stable formulation. Simulations at atomic level confirmed the dispersion of treated TiO2 in the matrix. In particular, SA plays the role of electron donor with PLA and TiO2, increasing the miscibility between them by a strong hydrogen bond. The main results obtained allow considering SA as a valid option for the functionalization of TiO2 before inclusion in PLA matrix.

Three different activated carbons, namely Aquacarb 207EA (AQ), Organosorb-10 (OR-10) and Organosorb-10AA (OR10-AA) are investigated for carbon dioxide (CO2) adsorption from simulated flue-gas, which is one of the promising approaches to mitigate global warming. Adsorption isotherms are determined at three temperatures (303 K, 323 K and 353 K) and over a wide CO2 partial pressure range (0.03–0.3 bar), in a dynamic lab-scale experimental apparatus. Experimental results show that CO2 adsorption capacity is affected by micropore volume, while the chemical properties (mainly pHPZC and acid functional groups) seem to play a secondary role. The CO2 adsorption isotherms are interpreted by three advanced models derived from statistical physics. The selected model allows retrieving useful information about the sorption process by determining the number of captured CO2 molecules per site (nms), the density of receptor sites (Dsr), the total number of adsorbed layers (Nc) and the energetic parameters (−e1) and (−e2). The modeling analysis suggests that the captured CO2 molecules aggregate upon adsorption and are anchored with a perpendicular position on the adsorbents surface. The total numbers of adsorbed layers range from 3.12 to 5.56 for the three adsorption systems, and the value increases with temperature as if the diminution of active sites available for CO2 capture on adsorbent surface was partially counterbalanced by a multilayer adsorption mechanism. The adsorption energies retrieved from data analysis are in the range from −11.39 to −21.10 kJ/mol, confirming that, for the investigated systems, adsorption is exothermic and based on physisorption. Finally, the site energy distribution is also estimated to corroborate the surface heterogeneity and the physical nature of the adsorbate/adsorbent interactions.

The goal of this work is the study of the adsorption of Diclofenac (DCF) on a magnetic composite made by metal oxide dispersion onto chitosan (ZnFe2O4/CMC). The adsorption isotherms at four temperatures (298, 308,318 and 328 K) and pH = 3 are interpreted in the light of an adsorption model derived from the statistical physics formalism, which includes the calculation of physicochemical parameters with defined physical meaning. Specifically, the adsorption process is interpreted in light of the number of DCF molecules adsorbed per site (n), which increases with temperature, and the density of receptor sites (NM), which shows a similar trend. The values of the calculated adsorption energy (ΔE1 and ΔE2) confirmed that the interaction between the DCF molecules and ZnFe2O4/CMC takes place via physical forces. Overall, the hydrogen bonds are identified as the main bonding interactions of DCF molecules on the ZnFe2O4/CMC surface. Interestingly, thermodynamic potential functions are determined for a complete adsorption characterization, which included also the adsorption energy distribution (AED) determination of DCF adsorption onto the ZnFe2O4/CMC.

Due to the scarcity of data on the industrial use of energy storage technology based on material phase change (PCM), a complete computational assessment is done in this work, where a nano-PCM technique is used to enhance the thermal energy storage in a big-scale shell-and-tube heat exchanger. Four high thermal conductive nano-oxides (i.e., Al2O3, MgO, SiO2, and SnO2) are added at various concentrations (1 to 5% v/v) into the PCM (i.e., paraffin RT82). A two-dimensional mathematical model is used to study the produced nano-PCM systems' heat transfer and melting rate. The model accurately predicted the PCM-melting data's observed behavior, showing that it is adequate for simulating PCM problems. The addition of nano-oxides, for up to 5%, in the PCM solid matrix dramatically enhances heat transmission and melting rate during the first melting stage. However, after a long melting period, the melting performance of the nano-PCMs decreased and became equivalent to that of the pure PCM. Furthermore, increasing the concentration of nanoparticles from 1 to 5% did not significantly improve the temperature and liquid fraction evolutions for the four studied nano-PCMs. Therefore, the use of nano-PCMs in the adopted LTES unit can effectively improve heat recuperation and melting rate, but only for a short charging time during which a part (up to 60%) of the PCM's latent heat is recovered. Consequently, the present paper's data is considered a guideline for increasing the efficacy of thermal energy storage in big-scale shell-and-tube heat exchangers using nano-PCM technology.

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.

Adsorption of two organic pollutants (2-nitrophenol: 2-NRP and ketoprofen: KTP) on activated carbon produced from wastes deriving from a winery industry is investigated in the paper. Experimental data retrieved at T = 298–328 K indicate that, in the investigated equilibrium concentrations, a saturation phenomenon is reached for ketoprofen, while for 2-nitrophenol steeper curves are observed. For both the adsorbates, an increase in temperature determines a reduction of adsorption capacity. A modelling analysis via statistic physics models demonstrates that a double layer model is perfectly suitable to describe the adsorption mechanisms of both the investigated adsorbates. In light of the number of bonded molecules per adsorption site, the inclination of both the molecules upon adsorption is described. The obtained results suggest that they are adsorbed via both parallel and non parallel orientations, depending on the systems and temperature. Adsorption capacity variation is controlled by the number of bonded molecules per adsorption site and the density of receptor sites. Adsorption energy results show that physical interactions are responsible of the adsorption of both the pollutants. Finally, the results demonstrate that our adsorbent has an outstanding adsorption capacity which makes it promising for water depollution.

In the last years, in order to achieve a better treatment of Alzheimer's disease (AD), much focus has been put on the development of cholinesterase (Acetylcholinesterase and Butyrylcholinesterase) inhibitor drugs. Thus, the aim of this study is to discover promising active compounds for Acetylcholinesterase and Butyrylcholinesterase enzymes inhibitors based on QSAR model and drug-likeness evaluation. In this study, a series of DL0410 and its 50 derivatives are accounted for the set up of two QSAR models. This allows an exploration of the main molecular descriptors that control the inhibitory activity of specific compounds towards cholinesterase enzymes: Acetylcholinesterase (AChE) and Butyrylcholinesterase (BuChE). Simultanerously, the models can help to predict the inhibitory activity of new compounds within its applicability domain. A Multiple Linear Regression (MLR) analysis is carried out to derive QSAR models. The results indicate that the QSAR models of Acetylcholinesterase and Butyrylcholinesterase inhibitory activity are robust and have a very good prediction capacity, testified by values of R2 equal to 0.935 and 0.895, respectively. The analysis carried out by adopting the QSAR models succeed in screening 15 potential compounds with higher biological activity. Subsequently, the investigated compounds has been subjected to the drug-likeness evaluation and reactivity study. The results show that most of the compounds do not present any bioavailability problem when administered orally. The results also allow determining the compounds that have not clearance problems, those that are the most stable and the most reactive among those tested. These findings indicate that the newly designed candidate drugs have promising potential toward AChE and BuChE enzyme inhibition and should be experimentally investigated.

Oxidative scrubbing using different oxidizing chemicals (e.g. sodium chlorite, NaClO2) has been proposed since several years for gas emissions control. Although higher performances than conventional after-Treatment process currently in use can be reached, these technologies have not yet found a consolidated application in the power generation and other industrial fields, due to excessive chemical consumption and the formation of some harmful contaminants in the wash water that must be removed with specific treatment systems. This work reports an experimental investigation of an oxidative wet scrubber for NOx removal from a simulated flue-gas containing 1030 ppmv of nitrogen oxides, using a scrubbing liquid doped with sodium chlorite (NaClO2) as oxidizing chemical. The experiments are performed in a packed column operating in countercurrent flow with a constant gas velocity of 1.15 m/s at 60 °C and a liquid-To-gas ratio variable from 1.25 to 4.06 L/m3. The packed column with a DN 100 is equipped with 892 mm of Mellapak 250.X packing. The experimental removal efficiencies of NOx are evaluated in function of the liquid flow rate and NaClO2 loading. These data allow to determine the specific NaClO2 dosage required to achieve a fixed NOx removal. Finally, a predictive correlation for wet oxidative scrubbing is also developed.

Adsorption is an effective technology for wastewater treatment processes. Activated carbons are the adsorbent materials traditionally used in most of the applications but sometimes their use is limited due to the high-cost of synthesis/production and for their partial or difficult regenerability. For these reasons, scientists have turned their interest in synthesizing new and cheaper composites materials with efficient adsorptive properties. In this scenario, layered double hydroxides/biochar composites (LDHs-biochar) have attracted a great interest due to their elevated adsorption performances for a wide spectrum of pollutants, deriving from the synergistic effects arising upon the combination of LDHs with biochar. This review article focuses on the application of LDHs-biochar composites for the removal of pollutants of different nature (i.e. heavy metals, dyes, phosphate, etc.) from aqueous matrixes. Specific emphasis is given to the synthesis and characterization of these materials. Equilibrium and kinetic data are presented together with their modeling analysis and further insights about the thermodynamics of the adsorption are also provided. A specific insight into adsorption mechanisms, including the interpretation of the interactions between the solid matrix and the contaminants, was considered in this review. The review indicated that LDHs-biochar composites are promising materials that can be proficiently applied to wastewater treatment in terms of efficiency and costs demands. However, there is still a need of research efforts in order to establish this class of materials as proficient adsorbents to remove critical contaminants.

In this paper, the antiradical potential of trans-2,4,3′,5′-tetrahydroxystilbene (T-OXY), trans-2,3′,4-trihydroxystilbene (T-RES), cis-2,4,1′,3′-tetrahydroxystilbene (C-OXY) and cis-2,1′,4-trihydroxystilbene (C-RES) is investigated by BDE (E0) and ETS-NOCV calculations, in water, benzene, DMSO, and ethanol. The study of solubility by the COSMO-RS model demonstrates that the compounds are very soluble in DMSO. The hydrogen atom transfer (HAT), sequential proton loss electron transfer (SPLET), and single electron transfer followed by proton transfer (SET-PT) mechanisms are explored as possible oxidation paths of these compounds using the DFT calculations at B3LYP/6-311++G(2d,2p) level of theory in DMSO. For all the studied compounds, the HAT was found to be the thermodynamically dominant mechanism, indicating that the investigated compounds can be classified according to their antiradical activity in the following sequence order T-OXY˃T-RES˃C-OXY˃C-RES. The evaluation of ΔHBDE reaction enthalpies, ΔHIP, and ΔHPA linked to the three mechanisms with certain radicals (HO·, HOO·, CH3O· and CH3OO·, NO·, and NO2·) are determined. The results indicate the HAT and SPLET mechanisms are competitive in inhibiting those species. QTAIM calculations reveal the existence of critical points in the two conformers. The Diels-Alder intramolecular cyclization of (C-OXY) leads to two new tautomers: trans-cycle-OXY (T-CYCLE-OXY) and cis-cycle-OXY (C-CYCLE-OXY) with a significant improvement in the antioxidant activity. In conclusion, T-OXY and T-CYCLE-OXY are identified as the best antioxidant candidates among those tested.

Flue-Gas Desulphurization (FGD) is a fundamental process commonly adopted for the treatment of exhausts deriving from both stationary and mobile sources. The removal of SO2 from flue gasses can be made through different technologies and absorption offers the highest versatility for a large spectrum of applications. The data presented in this paper derive from FGD experiments carried out in a pilot wet scrubber equipped with a structured packing (Hastelloy C-22, Mellapak 250.X). The experiments aim to determine the SO2 removal efficiency from a simulated flue-gas in different operating conditions, similar to those observed in common wet FGD processes. Experimental data are reported in terms of gas velocity, concentration of SO2 in the flue-gas, liquid/gas feed ratio, fluids temperature and pressure. The dataset also includes the measurements of several working parameters, i.e. pressure drops in the column, wash water pH, relative humidity of the outlet gas and temperatures of gas and liquid flowing out of the FGD unit. The collection of these data could be useful in future studies and in the analysis of FGD units, also to design/improve large-scale absorption columns with structured packing, using various scrubbing liquids and in different operating conditions.

Preparation, characterization, and application of activated olive residue (ROA) and their novel biocompatible bio-composite beads (ROA/AS) are investigated. The adsorbents are characterized by FTIR, XRD, and SEM and subsequently tested to remove methylene blue (MB) taken as a probe-pollutant. Experimental results show a marked enhancement in the adsorptive removal of MB by ROA/AS bio-composite beads as compared to ROA. When statistical physics theory is used to describe the dye removal process, the best match for experimental adsorption isotherms is a monolayer isotherm model coupled with real gas law (MMRG model). Quantum chemical descriptors including frontier orbital energies (EHOMO and ELUMO), gap energy (ΔE), dipole moment (μ), and Fukui index have also been computed and discussed. All the examined systems' adsorption and interaction energies are estimated using Monte Carlo and molecular dynamics simulations. To summarize, integrated experimental and computational calculations have shown to be unique and robust techniques for in-depth investigations of physical processes such as adsorption, providing crucial insights at the molecular level to elucidate the adsorption mechanism.

Effective landfill management and operation require an accurate evaluation of the occurrence and extent of odour emission events, which are among the main causes of resident complaints and concerns, in particular in densely urbanised areas. This paper proposes a fuzzy optimal protection system (FOPS) based on fuzzy logic to manage odour production from a municipal solid waste (MSW) landfill. The case study is a MSW landfill in an old quarry site located 6 km north-west of Naples city centre (Italy). The aim is to reduce the odour nuisance in the area surrounding the landfill where there are several sensitive receptors. FOPS is based on logical relationships between local atmospheric dynamics, number and intensity of odour pollution events detected by certain fixed receptors and odour emission rate via an optimal fuzzy approach. Such system allows to start, in real time, established mitigation actions required to further reduce the odorous emissions from the landfill itself (e.g. spraying of perfumed substances and activation of extraction wells), especially when weather conditions might not be favourable and cause by causing a higher odour perception. The fuzzy system was coupled with the air pollutant transport software CALPUFF to simulate the odour dispersion in the considered area taking into account both different odour emission rates and local weather conditions. FOPS results show that this approach can be very useful as, by measuring the odour concentrations, a significant reduction of the odour exceedances over the thresholds fixed, to minimise the olfactory harassment, was observed in the whole area studied.

Waste of Mytella falcata shell was used as low-cost adsorbent to remove the biocide Basic Green 4 (BG4) from water. Shells were collected form trash nearby the lagoon were Mytella falcata is fished. After clean, dry and crushed, the powder was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), and X-ray dispersive energy spectroscopy (EDS). Both kinetic and equilibrium adsorption tests are carried out. Adsorbent regenerability was tested during adsorption/desorption cycles, using a UV photo-regeneration process. The maximum adsorption capacity reached 539.24 mg.g-1 (60 °C), which was higher than those retrieved for other materials with similar origin. The kinetic results indicated that the process followed pseudo-second order model. Equilibrium data indicate an increase in BG4 adsorption capacity with temperature and Sips model had better fit for all the investigated temperatures (30, 40, 50 and 60 °C). The regeneration/reuse test indicated that the adsorbent is able to assure a BG4 removal above 70 % during five adsorption/desorption cycles evaluated. Thermodynamic parameters suggested that adsorption is spontaneous, endothermal, governed by chemisorption and with structural changes in the solid surface upon adsorption.

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.

An advanced model is applied to analytically explore the adsorption mechanism of Indigotine blue dye (IBD) onto a CoFe2O4/chitosan magnetic composite (CoFe2O4/CMC). Contrary to the classical adsorption models, the model is defined starting from the statistical physics theory and it is a generalized model containing numerous parameters having a defined physical meaning. Experimental evidences based on equilibrium data at four temperatures (298−328 K) are analyzed for a useful analytical interpretation. The analysis of the data via the advanced model indicates that the number of IBD linked per CoFe2O4/CMC active site (n) varied from 3.65 to 3.83, also demonstrating that the orientation (adsorption geometry) of the IBD dye on CoFe2O4/CMC surface is angled and affected by the temperature. Based on these values, it can be deduced that the adsorption mechanism at all the investigated temperatures is a multi-molecular process. It is also demonstrated that an increment in the temperature leads to a positive evolution of the adsorption capacity (Qsat) from 224.81 mg/g at T = 298 K to 289.87 mg/g at T = 328 K, testifying that the adsorption process is overall endothermic. This theoretical evidence is corroborated by the estimation of the adsorption energies ( Δ E 1 a and Δ E 2 a ), which indicated that physical interactions between IBD molecules and the CoFe2O4/CMC receptor sites and among IBD-IBD molecules take place. Finally, three thermodynamic parameters are determined for a further insight into the interpretation of the adsorption mechanism. The adsorption configurational entropy (Sad) evolution allows confirming the occurrence of different adsorbed layers (NC = 1+N2), while the Gibbs adsorption free energy (Gad) confirmed that the process is spontaneous.