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Pollution by dyes is one of the main pollutions of industrial effluents. This research examined Moroccan diatomite as a low-cost adsorbent to remove one of the dangerous dyes, malachite green (MG). Brunauer–Emmett–Teller analysis, scanning electron microscopy, pHpzc and X-ray diffraction were used to characterise diatomite. The studies were carried out at different levels of pH, diatomite masses and MG concentrations at a temperature of 25°C. Equilibrium, kinetics and thermodynamic characteristics were also studied. The results show that the diatomite consisted of an integrated and nearly circular sieve plate with many small ordered pores, giving it a high specific surface area of 17.36 m2/g. The ideal pH was found to be 7, with a saturation period of 90 min. The results indicate that MG removal increased accordingly as the pH increased and also as the adsorbent mass increased. The results of the isotherms showed that the Langmuir model is the most adequate, while the adsorption of MG is better characterised as monolayer adsorption. The maximum adsorption capacity obtained from the Langmuir model is about 22.17 mg/g at 25°C. Kinetic studies indicated the pseudo-second-order model as the most adequate model. It was also revealed that intraparticle diffusion is not the only rate-controlling step. From the thermodynamic data, it was concluded that the adsorption is endothermic – that is, the adsorption is more favourable at high temperatures. The research confirmed the applicability of diatomite as an effective and inexpensive adsorbent for removing hazardous materials.

The current work describes the synthesis of carbonaceous composites via pyrolysis, based on CMF, extracted from Alfa fibers, and Moroccan clay ghassoul (Gh), for potential use in heavy metal removal from wastewater.

Water pollution with copper (Cu) has a significant impact on the environment and human health. Within this context, the present study aims to synthesize a composite bead based on Moroccan natural clay from Chaouia (CH) and sodium alginate (Na-AL) as adsorbents to remove copper ions from aqueous solution. The adsorbents were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy coupled with Energy Dispersive X-ray (SEM-EDX) and Thermogravimetric Analysis (TGA). The effect of adsorbent dose, kinetic time, initial concentration of copper ions and temperature were investigated. Nonlinear regression was applied to fit the isothermal and kinetic models. The results showed that the clay is composed of kaolinite and quartz and the SEM confirmed the successful incorporation of sodium alginate into the clay. The adsorption process follows the Langmuir isotherm with a maximum adsorption capacity of 48.24 and 92.44 mg.g−1 for the clay (CH) and the beads composite designated as (CH@AL), respectively. Pseudo-second-order model best described the kinetic data. Moreover, the thermodynamics of the adsorption was spontaneous and endothermic. All of these results proved that the used adsorbents are eco-friendly and efficient for the adsorption of Cu(II) ions.

In this study, the removal of methyl violet by natural clays was investigated. Rhassoul-clay, A-clay, E-clay, R-clay, and Y-clay were sampled from different sites in Morocco. Their surface properti...

New environmentally, friendly, inorganic rare earth elements are now being offered as possible alternatives to chromate and lead compounds for metals protection and were evaluated as corrosion inhibitors of brass in 3% NaCl medium. The purpose of this research is to study the corrosion inhibition performance of a beforehand swelling clay, Stevensite labeled ST, intercalated by lanthanum ions. XRD and ICP-AES technics were used to confirm the Stevensite exchange by Na+ and La3+. The basal spacing d001 of Na+-ST (14.2 A) increases to 16.2 A (La3+-ST). The inhibition efficiency of La3+-ST was carried out by the polarization and the electrochemical impedance spectroscopy (EIS) measurements. The performance of the smart inhibitor La3+-ST is due to the progressive release of lanthanum ions in the corrosive medium. Corrosion products were analyzed by SEM-EDS technique.

Pyrolytic conversion of biomass stands as one of the most promising sustainable routes to carbon-based nanostructures, including carbon dots (CDs). Yet, molecular composition of functionalized carbon dots is limited to heteroatom doping and the incorporation of few single metal precursors. Besides, most of these modifications were undertaken by strenuous post-grafting procedures, requiring organic solvents for carbon dispersion and excluding a large library of potential reactants because of incompatible experimental conditions. In a significant divergence from the well-established literature, we herein disclose an innovative and highly versatile approach for enriching carbon dot functionalities. This straightforward method merges chitosan as carbon precursor and metal alkoxide as ceramic precursor and explores a twin growth of two dissimilar "metal oxide@carbon dots" phases through hydrothermal conversion of the carbohydrate solution. Owing to the structure-directing effect of chitosan toward metal alkoxide precursors, a set of crystalline metal oxides including titanium dioxide, germanium oxide, and iron oxide clusters were intimately fused within the in situ formed nitrogen-containing carbon framework. Distinctively, the following approach uses water as solvent and renewable biomass as carbon source and is expected to shed light on the hidden talent of discarded bio-waste for engineering functional nanomaterials.

Clay materials combined with other compounds are intensely used in several fields. The present study focuses on the synthesis of organoclays and nanocomposites based on the intercalation of surfactant and biopolymer into swelling Moroccan clay. The produced materials were used in the removal of glyphosate from the aqueous medium. The organoclay was obtained by the intercalation of cetyltrimethylammonium bromide (CTAB) in the interlamellar space of stevensite, and the nanocomposite was fabricated by the direct interaction between the stevensite and chitosan. These materials were characterized by mean X-Ray Diffraction, Fourier Transform Infra-Red Spectroscopy (FTIR), Thermal Analysis and Transmission Electron Microscopy (TEM). The results showed that the stevensite is the dominant clay mineral of Ghassoul and confirmed that the nanocomposite has an intercalated clay structure. The batch mode was accomplished to quantify the glyphosate removal capacity from aqueous solution by these materials. The enhancement of hydrophobic properties has promoted the retention of the herbicide. The pseudo-second-order kinetic model of adsorption was the most suitable to describe the process of adsorption and the Freundlich isotherm equation fitted satisfactory the adsorption isotherm data. The capacity of adsorption was more outstanding for the nanocomposite chitosan/Ghassoul and reached a significant value of 159.10 mg.g-1. The nanocomposites based on chitosan/Ghassoul could be considered as promising materials for treatments of pesticide-contaminated water.

Corrosion control of copper alloys such as brass is of great interest to researchers and scientists. Clays become materials of choice as corrosion inhibitors and as their reservoir in corrosive environments. The effect of Rhassoul on the corrosion of Cu-36Zn alloy in 3% NaCl solution has been studied. Electrochemical techniques showed that the optimum concentration was 1g/L showing the highest inhibition efficiency (82%). This concentration was evaluated at five different temperatures. In order to determine the influence of purification, this result was compared to that of the homoionic clay labeled Na+-ST and to the pure calcite. Chemical composition of the brass specimen and solutions were done by inductively coupled plasma atomic emission spectrometry (ICP-AES) and atomic absorption (AA) respectively. The effectiveness of this clay against the dissolution of Zinc reached 61%. XRD technique demonstrated the homoionization of this clay by shifting the basal spacing d001.

Different natural Moroccan clays were used as adsorbents for the removal of lead from aqueous solution. The study was performed not only employing the starting clays in the form of powder but also after their extrusion as honeycomb monoliths, this representing the major novelty of this work respect to the current state-of-art. The experiments were done in batch conditions with continuous stirring and using a recirculated flow, respectively. In addition to an exhaustive characterization of the clays by means of X-ray fluorescence, X-ray diffraction, thermogravimetric analysis, laser granulometry, N2 physisorption, infrared spectroscopy, SEM-EDS and evaluation of the cation exchange capacity, special attention was paid to the influence on the lead adsorption of variables such as adsorbent dosage, pH, contact time with the adsorbate and initial concentration of lead. Considering the cheap and abundant character of the raw materials, their easy processing (no additives were required for their extrusion) and the time and energy save due to no need for further modification through chemical/thermal activation, the obtained results (with retention over 90% for 30 ppm of lead) demonstrated the potential of the proposed design as low cost solution that may be competitive versus other technologies for water depollution, especially in developing regions.

The present work describes the production of novel highly hydrated cellulose microfibrils (CMFs) with unique morphology from coffee pulp waste using specific chemical treatments. The as-produced CMFs were successfully characterized and then used as an adsorbent for removal of methylene blue (MB) from concentrated aqueous solutions. Surprisingly, it was found that the novel CMFs display high water-uptake ability, with a maximum swelling ratio of 265%, and that they form an entangled hydrated network gel in water. The morphological observation and nitrogen adsorption measurement demonstrated that the extracted CMFs exhibit an average fibril diameter of 11.5 µm and mesoporous structure with an average pore size of 6.37 nm. These special features make the as-produced CMFs excellent candidates to be used as adsorbents for removal of MB from concentrated solutions. The performed adsorption studies determined that the adsorption equilibrium was reached within 90 min. The adsorption kinetics data were well fitted to the pseudo-second-order kinetic model, and the adsorption isotherms were well described by the Freundlich isotherm model. In addition, the maximum adsorption capacity was 182.5 mg/g, much higher than that determined for other previously reported cellulose-based adsorbents. Through this study, we have demonstrated a possible strategy to give an added value to the coffee pulp waste, a by-product of the coffee processing industry, which is rich in cellulose, inexpensive and renewable source. Indeed, the extracted CMFs are very attractive for developing a sustainable and economically viable bio-sourced material for future growth of cellulose use in advanced applications.

Along with water scarcity and the new risks related to climate change, pollution is a major issue affecting this vital resource globally. To face the challenge of treating large volumes of pollutants-loaded municipal wastewaters and industrial effluents, researchers have been investigating the application of different biological, physical, and (electro)chemical water treatment technologies. In this context, the application of adsorption for the removal of toxic or undesirable compounds from (waste)water is widely recognized as a versatile decontamination procedure, which is able to deal with a wide range of pollutants under various process configurations and operating conditions. In this chapter, relevant and recent research investigations conducted in North African countries (Libya, Tunisia, and Morocco) are presented and discussed, including diverse sorbents, adsorption systems, and targeted pollutants. Overall the main objective of this chapter is to showcase the current situation and prospects for the production and utilization of conventional and advanced sorbents for water depollution in North Africa.

The aim of this work was the synthesis of a mesoporous geopolymer material based on Moroccan clay rich in kaolinite. For developing the porosity of the geopolymer material, we have followed three different ways to create mesoporosity in the studied material which are; use of Cetyl trimethylammonium bromide (CTAB) organic surfactant, hydrogen peroxide (H2O2) addition to CTAB solution during synthesis and finally no use of CTAB surfactant and H2O2 blowing agent; only optimizing the geopolymerization temperature at 70 °C as well as the formulation ratios: H2O/Na2O = 15, Si/Al = 2 and Na/Al = 1.5. Our started and prepared materials were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Thermal Gravimetric Analysis (TGA), nitrogen adsorption-desorption isotherm analysis (BET and BJH methods) and Scanning Electron Microscopy (SEM). The prepared materials present a very interesting specific surface area witch reached 128 m2/g and homogeneous mesoporosity equal about 0.14 cm3/g. It has been tested in the retention of methylene blue as cationic dye model. The maximum amount retained was drastically improved from 60 to 183 mg/g.

Graphene oxide (GO) has recently captured tremendous attention, but only few functionalized graphene derivatives were used as fillers, and insightful studies dealing with the thermal, mechanical, and biological effects of graphene surface functionalization are currently missing in the literature. Herein, reduced graphene oxide (rGO), phosphorylated graphene oxide (PGO), and trimethylsilylated graphene oxide (SiMe3GO) were prepared by the post-modification of GO. The electrostatic interactions of these fillers with chitosan afforded colloidal solutions that provide, after water evaporation, transparent and flexible chitosan-modified graphene films. All reinforced chitosan&ndash, graphene films displayed improved mechanical, thermal, and antibacterial (S. aureus, E. coli) properties compared to native chitosan films. Hemolysis, intracellular catalase activity, and hemoglobin oxidation were also observed for these materials. This study shows that graphene functionalization provides a handle for tuning the properties of graphene-reinforced nanocomposite films and customizing their functionalities.

The objective of this work was the characterization and valorization of new clay materials in the elimination of a model dye, namely methylene blue (MB) from aqueous solutions. The clays were sampled in the Assa-Zag region, located north of the Moroccan Sahara. Adsorption technique was selected to study the retention properties of the clays. This method is known by its simplicity and efficiency. Five samples were collected from different sites, then purified and characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) coupled with an Energy Dispersive X-rays Spectroscopy (EDXS) elemental compositions analyzer. All the samples are very rich in kaolinite and muscovite as phyllosilicates clay minerals and contain also a few amounts of quartz and calcite as associated minerals. The raw and purified clays have been tested in the retention of MB cationic dye from aqueous solution. The maximum amount retained was 70 mg/g and 82 mg/g respectively for TIFL sample.

Heterogeneous Fenton-like reactions on pillared clays were investigated for the degradation of 4-Nitrophenol (4-NP). A Box–Behnken Design coupled with response surface methodology (RSM) was applied to evaluate and optimize the important variables. In this process, copper-pillared clays were prepared by intercalation of a Moroccan Bentonite and tested in the catalytic wet peroxide oxidation of 4-NP. The prepared catalysts were characterized by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Inductively coupled plasma atomic emission spectroscopy (ICP-AES). A significant quadratic model (P-value < 0.0008, R2 = 0.9526) was derived using analysis of variance (ANOVA), which was adequate to perform the process variables optimization. More than 90% of 4-NP was experimentally degraded after 4 h of reaction time under the optimum conditions. The model predicted maximum removal of 98.66% of 4-NP under the optimum conditions of operational parameters (9.48 mM peroxide concentration, 0.325 g L−1 catalyst dose and 51 ℃).

49 paginas, 5 tablas, 3 figuras, 2 figuras suplementarias. -- The definitive version is available at http://www.elsevier.com

Normetanephrine is a marker for pheochromocytoma, a rare catecholamine-secreting and neuroendocrine tumor, that arises from sympathetic and parasympathetic paraganglia. In this work, a novel carbon/chitosan electrode paste was used for sensitive voltammetric determination of normetanephrine and dopamine in the presence of ascorbic acid and uric acid. The modified electrode has shown an increase in the effective area of up to 68%, well-separated oxidation peaks, and an excellent electrocatalytic activity. The electrochemical response characteristics were investigated by cyclic and differential pulse voltammetry. Interestingly, high sensitivity and selectivity in the linear range of normetanephrine, dopamine, ascorbic acid, and uric acid concentrations were observed. The present method was applied in the urine sample and satisfactory results were obtained showing that this electrode is very suitable in pharmaceutical and clinical preparations.

In this study, carboxy-functionalized spherical cellulose nanoparticles have been produced from Alfa plant-derived cellulose microfibers (CMF) using ultrasonic-induced cellulose fragmentation process. CMF, with fiber diameter of 7.26 µm and crystallinity of 87%, were firstly produced from Alfa plant fibers and then subjected to surface carboxylation using TEMPO-mediated oxidation process. The as-resulted TEMPO-oxidized CMF (T-CMF), with an average diameter of 2.72 µm, a crystallinity of 89% and carboxyl groups content of 1032 mmol COO-/Kg cellulose, were then exposed to ultrasonication treatment for 45 min, resulting in the formation of cellulose nanospheres (CNS) with an average diameter of 33.96 ± 7.01 nm and a crystallinity of 76%. The carboxyl groups content on the surface of CNS was measured at 945 mmol COO-/Kg cellulose. This study demonstrated the importance of the ultrasonication process as a green method for producing CNS with interesting properties, which can be used in various potential functional applications.

Several clay minerals as inorganic fillers were incorporated to aliphatic polyester by various procedures. The target of enhancing the physicochemical properties of the resulting composite material leading thereby to overcome the limitations of neat polyesters. Still, bentonite (Bnt) as a clay mineral has been relatively unexplored as a reinforcing agent of the poly(e-caprolactone) (PCL). In this study, a bio-nanocomposite based on poly(e-caprolactone) & bentonite nanofiller was prepared by in-situ ring opening polymerization (ROP) of e-caprolactone (e-CL) under open air using tin-based catalyst. The obtained bio-composites (PCL-OBnt) were fully characterized to examine their structural interactions, thermal stability, mechanical, and morphological properties. Finally, the antimicrobial activity against S. epidermidis and S. aureus of the prepared bio-composites materials was evaluated.

The present work describes the production of carboxymethylcellulose (CMC) -hydroxyethyl cellulose (HEC) hydrogel films using citric acid as a non-toxic crosslinking agent, for a potential application in wastewater treatment. After their synthesis, all films were then characterized through Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), UV-Visible spectroscopy (UV-Vis) and swelling study. During these measurements, the successful crosslinking of the hydrogel film was validated; films also possess good thermal stability, a high transmittance under the visible light region, confirming their transparency, and excellent swelling ability in neutral and in acidic media. Therefore, the as-produced films were then used as a potential adsorbent for the removal of cadmium (Cd) and methylene blue (MB) from concentrated aqueous solutions. The adsorption ability of each film was evaluated thanks to thermodynamic and kinetic studies showing that the adsorption equilibrium was reached within 1h for Cd and 3h for MB. Furthermore, the analysis of the adsorption kinetics highlights that all the data could be fitted by a pseudo-second order model, and the adsorption isotherms could be sufficiently described by Langmuir isotherm model for the two studied pollutants. From this analysis, the maximum adsorption capacities, determined by Langmuir model, are close to 126.58 and 769.23 mg/g for Cd and MB, respectively. Moreover, the sorption capacities of Cd and MB in films both increase with the temperature. According to the thermodynamic parameters, cadmium and methylene blue adsorption processes using tested films are favorable, spontaneous, and endothermic.

natural Moroccan illite–smectite was used as an adsorbent for the removal of methylene blue (MB) from aqueous solutions. The clay was characterized by FTIR spectroscopy, TGA, SEM–EDS, X-ray fluorescence, XRD and N2 physisorption. The influence of pH, temperature and time on the MB adsorption by the clay was investigated. The maximum equilibrium adsorption capacity was 100 mg g−1 at 45 °C. The kinetic behavior and the isotherms better-fitted with the pseudosecond- order and Langmuir models, respectively. Clay honeycomb monoliths (50 cells cm−2) were obtained by means of extrusion from the starting material without any additive except water. The structured filters exhibited better performance under dynamic conditions than the powdered clay, adding value to the application of this low-cost adsorbent.

International audience; Five different functional phosphorus motifs were trivially installed within graphene oxide (GO) sheets to provide water-dispersible and thermally-stable phosphorus graphene oxide materials (PGO). The presence of exogenous phosphorus heteroatoms on the surface of the tiny carbon sheets was harnessed for the anchoring and growth of metal oxide clusters, exemplified herein by titanium dioxide, and for the chelation and stabilization of small gold nanoparticles. Unexpectedly, both GO and PGO promoted crystallization in a low-temperature liquid-phase medium without thermal annealing treatment. However, the fingerprint of the surface chemistry is illustrated through the formation of different species; while discrete anatase nanoparticles were selectively formed on the surface of GO sheets, a biphasic mixture of anatase and rutile was grown on PGO. The latter provides a more stable material owing to the robustness of the interfacial P–O–Ti bridges. Strong coordination to gold nanoparticles was also observed for PGO due to the presence of P[double bond, length as m-dash]O(OH)2 fragments, compared to the weakly coordinating oxygenated functions in GO. Lastly, the possible delamination of PGO sheets associated with their improved thermal stability renders them promising nanosized fillers for carbohydrate-based bioplastics.

The properties of copper-based pillared clays (Cu-PILBen) have been studied and compared with those of Aluminum-based clays (Al-PILBen) in the catalytic wet hydrogen peroxide oxidation (CWPO) of model phenolic compound 4-nitrophenol (4-NP) without pH adjustment. The parameters like temperature (40–60 °C), peroxide dosage (8–12 mM) and initial 4-NP concentration (50–100 mg/L) were optimized using a three-factor Box–Behnken Design (BBD) of response surface methodology (RSM). The results of this study showed that more than 90% of 4-NP was experimentally degraded using Cu-PILBen after 4 h of reaction time under optimum conditions of temperature and initial concentrations of H2O2 and 4-NP, which was in a good agreement with the BBD model’s prediction of a 97% maximum degradation at 52 °C, initial 4-NP concentration of 50 mg/L and peroxide dosage of 10 mM.

North of Morocco is becoming one of suppliers of tourism sites and agricultural products for Europe. Thus, environmental risks from this region are important for the future of these activities. The presence of pesticides in soils and waters can become a serious environmental problem. Clay minerals can be used for mitigation of this problem. In this work, the adsorption of two fungicides, metalaxyl and tricyclazole, on natural Northern Moroccan clays was investigated using the batch equilibration method and several techniques, such as, X-ray diffraction (XRD), thermal analysis (TGA/DSC), and surface area measurement (BET) were used for clay characterization. The data from kinetic and adsorption studies were fitted to different models. The adsorption kinetics of these fungicides followed a pseudo-second-order model. Adsorption data, higher for metalaxyl than for tricyclazole, were fitted the Freundlich model. A natural stevensite was the clay with the highest adsorption capacities for both fungicides.

The disappearance of two phenylurea herbicides, chlorotoluron (CHL) and isoproturon (IPU), in two Mediterranean soils, an agricultural calcareous soil (S5) and an organic forest soil (S2), was assessed under irrigation with high- and low-quality water. Irrigation with wastewater, as opposed to irrigation with high-quality water, increased the degradation rate of both herbicides in both soils. For each soil, the decay rate of IPU was always higher than that of CHL, and both pesticides disappeared more rapidly from S5 with lower clay and organic carbon content than from S2. The degradation rate was inversely related with pesticide sorption on soil, because increased sorption would reduce pesticide bioavailability for decomposition. In most cases the residual concentration in soil of both phenylurea herbicides was better fitted to a bi-exponential decay model than to first-order or first-order with plateau models. Dehydrogenase activity, used as an indication of microbial activity, was very high in S2 in comparison with S5, but was not related to pesticide disappearance.

In this study, the improvement of cadmium ions retention from aqueous medium by alginate beads was investigated. Two drying methods were performed, namely, air-drying and freeze-drying. The physical and chemical properties of the beads were characterized by different techniques (SEM, BET, FTIR, TGA/DTG). The microscopic observations show that the freeze-dried beads (AL-FD) have a smoother surface compared to the air-dried beads (AL-AD); besides, they have practically conserved their initial size. The specific surface areas were found to be 0.039 m2/g and 56.83 m2/g for AL-AD and AL-FD, respectively. Furthermore, the influence of pH and adsorbent dosage, as well as the kinetic, equilibrium and thermodynamic studies, were carried out in order to elucidate the adsorption process. Results obtained showed that the kinetic sorption process follows the non-linear fitting of Avrami fractionary order model and the sorption rate decreases when decreasing the pH of the medium. The equilibrium data were well fitted by the Langmuir non-linear model for AL-AD, and described by both Langmuir and Freundlich equations in the case of AL-FD. The uptake of AL-FD was greater than AL-AD, with maximum adsorption capacities of 60.98 mg/g and 83.06 mg/g for AL-AD and AL-FD, respectively. Moreover, the computed thermodynamic parameters, i.e., Δ G ∘ , Δ H ∘ , and Δ S ∘ , suggested that the adsorption of Cd(II) onto alginate beads is an endothermic, spontaneous, and physical adsorption process.

Alginate (AL)-based composite beads filled with bentonite (BE) and phosphate washing sludge (PS) have been prepared and used as low-cost adsorbents for removal of cadmium (Cd) from aqueous solution. Such composite beads were prepared by solvent mixing technique followed by a crosslinking reaction. The obtained humid beads were dried using two approaches, namely air drying (AD) and freeze-drying (FD) and then separately used as adsorbents. All the materials investigated in this study were analyzed in terms of their structural, textural, morphological, thermal properties as well as their chemical composition and size distribution. The adsorption capacities of the as-prepared freeze-dried and air-dried composite beads toward Cd ions were evaluated in batch experiments. To optimize the adsorption conditions, the effect of adsorbent dosage, equilibrium time, Cd concentration, initial pH and temperature was evaluated and compared. It was found that the adsorption capacities of BE- and PS-filled composite beads are higher than those determined with BE and PS. The performed adsorption studies showed that the adsorption equilibrium was reached within 180 min. The pseudo-second order model can be effectively used to evaluate the adsorption kinetics and the adsorption isotherms can also be well described by the Langmuir isotherm model with a maximum adsorption capacity of 54.27 and 53.24 mg/g for PS- and BE-filled composites, respectively. Moreover, Cadmium recovery was enhanced with temperature increase and the thermodynamics studies revealed that the adsorption processes were spontaneous and endothermic in nature.

Two natural Moroccan clays, an illite-smectite (O) and a stevensite (ST), were used to manufacture honeycomb monoliths for the removal of cadmium from aqueous solution. This goal was based on their easy extrudibility without additives and good performance for organic dyes and lead removal in previous studies. First, the influence of adsorbent dosage, time, pH and initial Cd(II) concentration was studied through batch experiments with the clay powders. Then, flow recirculation tests with the clays conformed as structured filters were performed. These confirmed the kinetics and adsorptive model, pseudo-second order and Langmuir, respectively, no matter the linear or non-linear character of the regression followed to fit the experimental data. With both experimental and sample designs, ST exhibited better performance than O. This could not be attributed to an exchange with Mg(II) overlapping the adsorption, despite its greater content in this element. Clay honeycombs behaved also better than packed columns charged with the same amount of powdered clay in similar experiments. Their maximum adsorption capacity (4 mg/g) ensures complete depuration of a solution containing 150 ppm of Cd(II) after recirculation through a 10 cm long and 3 cm-diameter monolith with the help of a centrifugal pump for less than 10 h.

This study aims to develop and characterize the active corrosion protection properties of lanthanum ions intercalated through cation exchange with the clay fraction of stevensite which has been previously saturated with sodium. The corrosive medium was 3% NaCl solution, while the immersion time was 24 h. To improve these properties, the pigment was incorporated into an alkyd resin coating and tested for 240 h. This additive guarantees on the one hand a progressive release of the inhibitor and on the other hand it does not cause holes or defects in the polymer film over time. The two stevensite clay samples: homoionic (Na+-ST) and intercalated (La3+-ST) were characterized by mean X-ray diffraction (XRD) technique. The basal spacing d001 increased from 14.2 A (Na+-ST) to 16.2 A (La3+-ST), confirming the exchange of La3+ with Na+. The kinetic release of La3+ from the exchanged clay was followed during its dispersion in the studied medium. The cation exchange capacity (CEC) was about 73 meq/100 g. Electrochemical measurements revealed effective protection against corrosion. This property was improved by incorporating the before-hand intercalated stevensite into a paint system and compared to that of the commercial corrosion inhibitor (TPA), pigmented in the same type of coating. Corrosion products and the protective layer were analyzed by using SEM-EDS and optical microscope techniques. The results showed that it was possible to replace a large volume of TPA with a very small amount of lanthanum ions.

Metal-organic frameworks (MOFs) are versatile nanostructured materials that find applications in different fields, spanning from separation, adsorption, sensing and catalysis to health care and nanomedicine. Their association with (bio)polymers has been recognized as a milestone for their processing into scalable devices, well-suitable for applied technologies. Herein, we investigated the templating growth of HKUST-1 and ZIF-8 in a colloidal solution of different molecular weight chitosan biopolymers under various reaction conditions. Besides isolating nanostructured polysaccharide-MOF hybrids with hierarchical porosity, we also succeeded in shaping the material body as flexible films, porous monoliths and self-standing microspheres. This templating route was successfully expanded to binary chitosan-alginate and chitosan-starch colloidal solutions, which result in flexible films with enhanced molecular diversity. The preliminary assessment of Red Congo dye removal from contaminated water revealed that open-porous chitosan-MOF nanohybrids outperform microporous MOF and marginally porous chitosan. These findings open novel opportunities for the use of such functional carbohydrates as bio-based adsorbents and chemical scavengers.

The aim of this work was to study arsenic adsorption behavior onto clayey materials from Morocco. Five samples were investigated: R-clay and Y-clay from Oued Laou (Tetouan region), E-clay and A-clay from Tetouan City and Rhassoul-clay from the East side of the Middle Atlas Mountains, in the Moulouya Valley, approximately 200 km away from Fes. A thorough characterization of these five samples was performed. Adsorption studies were conducted in batch system as a function of time, pH and initial As concentration. The effect of the pH on the adsorption of As for the 5 clays indicated that the arsenic adsorption was most favorable in the acidic pH range for R-clay, A-clay and E-clay. For Rhassoul-clay and yellow clay, no significant adsorption was found in the whole pH range considered. Langmuir and Freundlich isotherms were used for the interpretation of sorption isotherms data. Langmuir model provided the best fit with the experimental adsorption isotherm data obtained with R-clay. The adsorption onto E-clay and A-clay could be described both by the Langmuir and Freundlich models. For Y-clay and Rhassoul-clay, the sorption efficiency was too low and it was therefore not possible to determine the favorable models. R-clay is the most effective adsorbent with a maximum adsorption capacity of 1.076 mg·g− 1. Therefore, the R-clay is an efficient and economical adsorbent and could be used for the removal of arsenic from water.

A commercially available acid-activated montmorillonite clay catalyst, K10 montmorillonite, was tested for the catalytic oxidation of cyclic ketones in the presence of molecular oxygen under mild conditions (343 K and atmospheric pressure). K10 montmorillonite catalyzed the oxidative cleavage of C C bonds in 2-methylcyclohexanone, 2-phenylcyclohexanone, 2-hydroxylcyclohexanone and 1,2-cyclohexanedione with good activity and excellent selectivity toward the formation of the corresponding ketoacids and diacids. The effects of acidity, amount of catalyst, temperature and solvent on the catalytic activity were investigated. Furthermore, this catalyst was reusable without any appreciable loss in activity and selectivity.

The retention values of two herbicides, chlorotoluron and isoproturon, in five Mediterranean soils were assessed by two different approaches, a dynamic method, using a batch technique (BT) and a static method, using a soil saturated paste (SP). The SP method led in all cases to lower herbicide sorption when compared with BT, although pesticide distribution constants from both methods were linearly related for the set of used soils (R2 ⩾ 0.99) showing that both methods similarly reflected the behaviour of the different soils. Low-quality water, evaluated by employing recycled urban wastewater, did not modify herbicide sorption when compared with high quality water, in any soil and with any method.

The hydrotalcite-like compounds with [Mg 3Al(OH) 8][CH 3(CH 2) 10CH 2SO 4]·nH 2O (HT-DDS) and [Mg 2Al(OH) 8] 2[OOC(CH 2) 8COO] nH 2O (HT-SEB) chemical formula were studied to investigate their potential adsorption properties for the uptake of the widely used non polar pesticide Linuron from water. Adsorption experiments were carried out under different experimental conditions, such as pH, contact time and pesticide concentration. Results show the efficiency of HT-DDS and HD-SEB for Linuron adsorption which was quick, pH independent and higher for HT-SEB than for HT-DDS. The adsorbents and the adsorption products were characterized by XRD technique, FT-IR spectroscopy and TG analysis confirming the presence of Linuron in the adsorption products., This work has been financed by the Spanish by Ministerio de Ciencia e Innovación (Project AGL2008-04031-CO2-02) and also by Junta de Andalucía through Research Groups FQM-214 and RNM-214. D. Chaara acknowledges the Ministerio de Asuntos Exteriores y Cooperación (Spain) for a grant from the AECID to research in Universidad de Cordoba.

A comparative adsorption study of linuron, diazinon and myclobutanil, representing three classes of pesticides, by sewage sludge (SS), grape marc (GM) and spent mushroom substrate (SMS) and soils a...

This work was partially funded by Spain's Ministerio de Asuntos Exteriores y de Cooperacion (AECI) through the PCI-Mediterraneo Projects A/4879/06 and A/8191/07, by Ministerio de Ciencia e Innovacion (AGL2008-04031-CO2-02) and also by Junta de Andalucia through Research GroupFQM-214.

The adsorption of the slightly hydrophobic herbicide ethofumesate (Kow = 2.70) by a bentonite and a common clay from Morocco was studied in water and in the presence of different cosolvents (methanol, hexane and dissolved organic matter (DOM)). The bentonite (SC) and the clay (NSC) were used in both a raw and modified state by the addition of long-chain quaternary ammonium ions (tetramethylammonium TMA, octyl trimethylammonium OTMA and octadecyl trimethylammonium ODTMA). The Freundlich adsorption coefficients (Kf) of ethofumesate by TMA- and OTMA-clays in water increased significantly (8.5–93 fold (SC) and 2–12 fold (NSC)) in relation to raw clays. This was more evident for ODTMA-clays (1100 fold (SC) and 290 fold (NSC)). The adsorption capacities were lower for modified NSC and increased with the organic carbon content. Different interactions between adsorbate–solvent and adsorbate–adsorbent were established with cosolvents, but when they were present in the clay–water system a decrease in adsorption was seen in general. Adsorption decreased 4–7-fold (TMA-clays), 3.2-fold (OTMA-clays) and 2.4–2.8-fold (ODTMA-clays) in the presence of methanol. No significant change was seen in the adsorption by ODTMA-clays in presence of hexane, although a marked decrease occurred in this system for the adsorption by TMA-clays (no adsorption) and OTMA-clays (22-fold). No significant variation in adsorption was observed in the presence of DOM. The results indicated that the enhanced adsorption of ethofumesate by organic cation-exchanged clays in water can be significantly changed in the presence of different cosolvents. This has serious environmental implications for pesticide adsorption by modified bentonites and clays in the presence of organic solvents.