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The present study focuses on the effect of experimental parameters (pH, temperature, gel mass, metal concentration, contact time) on the performance of lead adsorption by polyacrylamide hydrogels. The results obtained showed that the retention of Pb2+ ions is closely linked to these parameters. The adsorbent gels equilibrate with the metal solution after 180 minutes, and the maximum adsorption capacity is 442.31 mg/g. In addition, the adsorption obeys the pseudo-second-order kinetics and Langmuir isotherm. Desorption of the micropollutant retained by the hydrogel was also studied using 0.1 M of HCl solution. The desorption was rapid, and the efficiency exceeded 90% after a contact time of 90 minutes.

In this work, we study the elimination of three bivalent metal ions (Cd2+, Cu2+, and Pb2+) by adsorption onto natural illitic clay (AM) collected from Marrakech region in Morocco. The characterization of the adsorbent was carried out by X-ray fluorescence, Fourier transform infrared spectroscopy and X-ray diffraction. The influence of physicochemical parameters on the clay adsorption capacity for ions Cd2+, Cu2+, and Pb2+, namely the adsorbent dose, the contact time, the initial pH imposed on the aqueous solution, the initial concentration of the metal solution and the temperature, was studied. The adsorption process is evaluated by different kinetic models such as the pseudo-first-order, pseudo-second-order, and Elovich. The adsorption mechanism was determined by the use of adsorption isotherms such as Langmuir, Freundlich, and Temkin models. Experiments have shown that heavy metals adsorption kinetics onto clay follows the same order, the pseudo-second order. The isotherms of adsorption of metal cations by AM clay are satisfactorily described by the Langmuir model and the maximum adsorption capacities obtained from the natural clay, using the Langmuir isotherm model equation, are 5.25, 13.41, and 15.90 mg/g, respectively for Cd(II), Cu(II), and Pb(II) ions. Adsorption of heavy metals on clay is a spontaneous and endothermic process characterized by a disorder of the medium. The values of ΔH are greater than 40 kJ/mol, which means that the interactions between clay and heavy metals are chemical in nature.

The anticorrosive performance of two acrylic polymers (PANa) and (PAA) on smild steel in the 0.1 M hydrochloric acid medium was investigated using numerous techniques, such as weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Scanning electron spectroscopy (SEM), Energy-dispersive X-ray Analysis (EDAX), and DFT simulation. The obtained results through all tested methods are in good agreement. The polarization curves revealed that PANa and PAA belonged to mixed-type inhibitors. The influence of temperature on the corrosion of mild steel in 1.0 M HCl was also studied. The adsorption of PANa and PAA on mild steel surface in the studied medium follows the Langmuir isotherm. Scanning electron spectroscopy and Energy-dispersive X-ray analyses were carried out in order to study the mechanism which controls the corrosion inhibition of mild steel. Theoretical calculations realized using density functional theory (DFT), molecular dynamic (MD), and Monte Carlo (MC) simulations explored the most reactive sites of the investigated polymers.

The adsorption of methyl orange (MO) dye by artificial zeolites beads, used previously in the removal of heavy metal through the ionic exchange process, has been studied. The effect of several parameters such as temperature, MO concentration, and zeolite mass on MO adsorption was tested in order to determinate optimal conditions. All results have shown that the adsorption process was influenced by the studied parameters. The kinetic data concerning the study of temperature effect was modeled through pseudo-first-order and pseudo-second-order to determinate the adsorption mechanism. Thermodynamic parameters were calculated using the Van’t Hoff equation. Also, they have shown that the studied process has an endothermic, stable and spontaneous nature.

The present work aims the elimination of an organic dye Methylene Blue (MB) by adsorption on the polyacrylamide (PAAM) hydrogel. Several experiments series were then carried out in order to study the influence on the adsorption capacity of certain parameters such as the mass of the adsorbent, the pH, the contact time, the initial dye concentration and the temperature. The maximal capacity is 1620 mg/g it was obtained at T = 25°C, pH = 6, [BM] = 200 ppm and 0.013g of the adsorbent. The adsorption kinetics of the dye on the support is well described by the first-order model. The adsorption isotherms of the adsorbent/adsorbate systems studied are satisfactorily described by the Langmuir mathematical model. On the other hand, the thermodynamic study revealed that adsorption is spontaneous and endothermic.

Coriandrum Sativum seeds (CSS), were tested as a new eco-friendly adsorbent of copper ions from aqueous solutions. Hence, the effect of the most influencing experimental parameters such as initial concentration of Cu (II) and the temperature was studied upon the adsorption process in order to use its results in following studies. Lagergren pseudo-first-order, pseudo-second-order, and Intraparticle diffusion models were used to describe the biosorption kinetics. The adsorption process was also analyzed by Langmuir, Freundlich and Temkin models and the maximum monolayer biosorption capacity of CSS was found to be 33,5 mg. g −1 by using the Langmuir model. So as to investigate the thermodynamic properties of the adsorption process, the Gibbs free energy ( Δ G°), enthalpy ( Δ H°), and entropy ( Δ S°) values in the temperature range of 25-55 C ° were also calculated in order to conclude the process characteristics. SEM and EDAX analysis were effectuated in order to study the surface morphology of CSS before and after the adsorption process.

Coriandrum sativum seeds (CSS) were investigated as a new eco-friendly and economic biosorbent for the removal of methylene blue (MB) dye from synthetic solutions. First, the spectroscopic analyses were effectuated using FTIR and SEM to confirm the possibility of CSS to remove MB dye from aqueous solutions. The study of the influence of different parameters, such as contact time, CSS mass, solution pH, MB concentration, and temperature was realized and proved the rapid and efficient power adopted by CSS as a removal of the studied dye. Also, the regeneration study was effectuated for four cycles with excellent adsorption rates. The modeling studies revealed that the studied process obeys the pseudo-second-order model and Langmuir isotherm model. The adsorption amount was found to be 107.53 mg/g. Finally, the determination of thermodynamic parameters indicated the exothermic and spontaneous type of the removal process of MB onto CSS.

In the present study, the performance of sodium polyacrylate beads on the removal of trivalent chromium Cr (III) from aqueous solutions was evaluated using several techniques such as Fourier Transformed Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX), Inductively Coupled Plasma (ICP) and Atomic Adsorption Spectroscopy (AAS). On one hand, the characterization of dry PANa beads was carried out through FTIR and the surface morphology was analyzed by SEM and EDAX methods in order to show the loading of heavy metal on PANa beads. On the other hand, the effect of contact time, initial pH solution, initial Cr(III) concentration, adsorbent mass and temperature on the adsorption capacity of PANa was studied. All results have shown that the adsorption equilibrium was reached at about 60 minutes with an adsorption efficiency close to 90 %. Also, the study of the reliability of PANa beads was effectuated using 0.01 M nitric acid solution through six cycles of adsorption/desorption which were determined in order to study the reliability of PANa over time and to test their efficiency in industrial applications. Finally, the obtained thermodynamic parameters (ΔG°, ΔH° and ΔS°) indicate that the adsorption process is spontaneous and endothermic.

The present work aimed to investigate the potential power of coriander seeds to remove dyes from contaminated solutions. The characterization of the adsorbent before and after the adsorption of indigo blue and methyl orange have shown that they have a porous structure rich in active sites, which constitutes a very important seat to fix organic pollutants. Then, the study of the adsorption of indigo blue and methyl orange by CS was highlighted through parametric study, thermodynamic study, mathematical modelling and spectroscopic analysis. The optimal contact time for the biosorption performance of CS are 20 and 35 min for IB and MO, respectively. Then, the biosorption capacity of coriander seeds powder increases from 9 to 124 mg.g−1 and from 8.23 to 42 mg.g−1 for IB and MO, respectively. Further, The elimination yield values of the biosorption capacity of coriander seeds are 92 and 83 % for IB and MO, respectively. Further, global quantum chemical descriptors (GQCDs) namely EHOMO, ELUMO, energy gaps, electronegativity, hardness, electrophilicity, fractions of electron transferred between cellulose that is the major component of coriander seeds and both of studied dyes IB and MO were performed through density functional theory (DFT) method at M06-2x functional with 6-311G(d,p) basis set and were also examined and more discussed. All the obtained results were in a good correlation with experimental, spectroscopic, mathematical modelling and thermodynamic studies.

The adsorption of chromium ions Cr3+ using two forms of a superabsorbant polymer PANa from aqueous solution was investigated. On one hand the equilibrium pH with the distilled water and the pH of point of zero charge have been studied in order to characterize the acid-base behavior of both of PANa forms. On the other hand, the effect of contact time between PANa and the metallic solution and stirring speed of aqueous solution on the adsorption rate were established to highlight the importance of PANa as an efficient adsorbent of chromium ions Cr3+.

The adsorption of copper ions Cu2+ by Coriandrum Sativum seeds (CSS) from aqueous solution was studied in order to highlight the importance of coriander seeds as a potential tool in the treatment of wastewaters containing heavy metals. The kinetic studies of adsorption of Cu (II) were discussed using the spectroscopic technique “Inducting Coupled Plasma” (ICP). The effects of initial copper ion concentration and contact time were determined. All results show that coriander seeds have, over their culinary and medicinal benefits, a significant adsorbent power of copper ions.