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This work investigates the synthesis of Mg-Fe layered double hydroxides intercalated by sulphate (Mg-Fe-SO4) or dodecylsulfate (Mg-Fe-SDS) and their capacity to adsorb methyl orange (MO), as a mode...

The aim of this study is to evaluate the Mg-Al layered double hydroxides (LDHs) containing dodecyl sulfate and carbonate ions in the removal of methyl orange (MO) from aqueous solution. The prepared materials (Mg-Al-CO3 and Mg-Al-Ds) were characterized by XRD, TEM and FT-IR methods. XRD patterns of the two materials show the interlayer type structure with (00 l) reflections. TEM analysis showed that the LDH samples have nanoscale structures. FTIR spectroscopy confirmed the presence of the desired anions in the interlayer space. The results of the adsorption experiences for MO were performed as a function of solution pH and contact time. The adsorption ability of MO onto Mg-Al-CO3 was practically influenced by pH solution. However, the adsorption capacity of MO by Mg-Al-Ds appears stable at the different values of solution pH. The maximum adsorption capacities were 185.06 and 97.5 mg/g for Mg-Al-Ds MB and Mg-Al-CO3, respectively. The adsorption tests recommend the use of organic LDHs as potential adsorbents for azo dye treatment in a wide range of pH.

This work involved the removal of textile dyes by synthesized Ni-Fe-SDS and Ni-Fe-SO4 layered double hydroxides (LDH). The adsorbent was synthesized using co-precipitation method at room temperature. Samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and inductively coupled plasma (ICP). The obtained materials were used for the removal of methyl orange (MO) as a model anionic dye. Adsorption experiments were carried out under different solution pH and contact time. XRD analyses indicate low degree of crystallinity when using SDS as an intercalating anion in the LDH structure. Experimental results indicate rapid adsorption process with maximum adsorption capacity occurred in acidic medium. The maximum adsorption capacities were 105.36 and 82.45 mg/g, respectively for Ni-Fe-SDS and Ni-Fe-SO4 samples.

The objective of the present study is to investigate the spatiotemporal variation analysis of water quality and identification of water pollution sources in Oum Er Rbia river. To evaluate the water quality of river, physico‐chemical analysis of water samples taken from eight stations in dry and in wet seasons along the Oum Er Rbia river were studied. These stations were monitored for 20 parameters; water temperature, potential Hydrogen, dissolved oxygen, electrical conductivity, total Hardness, turbidity, complete alkalimetric title, organic matter (oxidizability), chlorides, sulphates, nitrates, nitrites, ammonium, iron, copper, lead, cadmium, nickel, chromium and zinc. Results of water samples were compared with Moroccan Standards for drinking water and permitted values recommended by World Health Organization. Results indicated that the water quality parameters are over Moroccan Standards for drinking water in some stations. Seasonal variation was observed in the physicochemical composition of water in the wet compared to the dry period. Water quality index (WQI), which is an important and unique rating to represent the overall water quality in a single term that is useful to determine the suitability of water for human consumption, was also estimated. The water quality index method was used to evaluate water quality classification for drinking purpose; it is calculated for each sampling station studied using 19 parameters. Based on 19 parameters; the range obtained without including the heavy metals for calculation of WQI was from 75.92(S1) to 243.12 (S6) and from 79.05 (S1) to 464.34 (S6) indicating a good to very poor quality and a good to unsuitable for drinking in dry and wet period respectively. When the calculation of the WQI to assess the water quality along the river was included the heavy metals, it observed that all the WQI values exceeded the limit of 300 in all stations indicating the water unsuitable for drinking in the river. This study indicates that the water of Oum Er Rbia River is potentially dangerous to health of the users and signaled the necessity to treat industrial and municipal wastewater and to encourage sustainable agricultural practices to avoid adverse health effects.

The main objective of this study is the use of Fourier transform mid-infrared (FTIR) spectroscopy for discrimination of samples of Argan kernels from three Moroccan regions. The content of Argan oil extracted from the kernel depends on the plant genotype and on the environmental conditions. The origin of argan kernel samples could be distinguished combining the IR spectra measurement and chemometric tools for discriminant analysis. A multivariate analysis procedure based on the combined use of Hierarchical Cluster Analysis (HCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) was tested for this purpose. HCA showed three distinct clusters related to the Moroccan regions and suggested the usefulness of IR spectroscopy to distinguish among kernel origins. Afterwards, PLS-DA was used for the discrimination and classification of the origin of the various argan kernels and good classification models and validation results were obtained. For 9 new unknown samples we attribuate 100% these samples by external validation. The results demonstrated that the combined use of FTIR and chemometric analysis (cluster analysis and discrimination by PLS- DA) can be used to rapidly and simply determine the origine of argan kernels, a relevant task for the agroalimentary Moroccan industry.

In this work, a promising photocatalyst was prepared and investigated for the photocatalytic degradation of caffeine as a model pharmaceutical pollutant. Mg-doped ZnO-Al2O3 heterostructure with different content of Mg (1, 3 and 5 wt%) was prepared from Zn-Al-CO3 layered double hydroxides precursors using ceramic process. The synthesized catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) coupled with energy dispersive X-ray analysis (EDX) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic activity of the catalysts was evaluated for the degradation of caffeine in aqueous solutions under UV irradiation. Detailed experiments based on the effect of doping amount, irradiation time, photocatalyst dose, initial solution pH, caffeine concentration and reuse were performed and discussed in this study. The 1%Mg-ZnO-Al2O3 sample showed the highest photocatalytic activity with a degradation efficiency of 98.9% after 70 min of irradiation. This catalyst showed significantly higher degradation efficiency compared to undoped, pure ZnO and standard Degussa P-25 titanium dioxide. The photocatalyst showed good stability after three regeneration cycles.

In this paper Ca/ZnO-Al2O heterojunction photocatalysts was prepared in two steps. First, Zn-Al-CO3 layered double hydroxides (LDH) precursor was synthesized by co-precipitation method. Second, Ca at various content (1, 3 and 5 wt%) was incorporated on LDH structure using solid state reaction at 500 °C. Samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) coupled with energy dispersive X-ray analysis (EDX) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic activity of the catalysts was evaluated in the degradation of caffeine as a model of pharmaceutical pollutants in aqueous solutions under UV irradiation. The Ca-doped ZnO-Al2O3 materials showed significantly higher photocatalytic activity compared to undoped, pure ZnO and standard Degussa P-25 titanium dioxide. This behavior was attributed to increased adsorption capacity, crystallinity of the catalysts and surface morphology. The maximum degradation rate (98.5 ± 0.5%) was obtained in 70 min by 5%Ca-ZnO-Al2O3 photocatalyst. Furthermore, the effect of different parameters such as irradiation time, photocatalyst amount, caffeine concentration, initial pH and reuse on the resulting photocatalytic activity was investigated. The photocatalytic degradation of caffeine was increased with an increase in the Ca-loaded amounts. This work demonstrates that the prepared Ca doped ZnO-Al2O3 nanoparticles are promising material for the photocatalytic degradation of pharmaceuticals pollutants.

The focus of this study is the investigation of removal ability of methylene blue (MB) and malachite green (MG) dyes from aqueous solution by raw maize corncob (RMC) and H3PO4 activated maize corncob (AMC). Maize corncobs were carbonized at 500 °C for 2 h, and then impregnated at a phosphoric acid to maize corncob ratio of 2.5 g/g. The impregnated maize corncob was activated in a tubular vertical furnace at 450 °C for 2 h. Samples were characterized by different methods. Adsorption experiments were carried out as a function of solution pH, adsorbent dosage, contact time, initial concentration of dyes and the temperature. Experimental results show that the activation of maize corncob boosts four times the adsorption performance for the selected dyes. The adsorption process is very rapid and was pH dependent with high adsorption capacities in the basic range. The kinetic data were fitted with the pseudo-second-order kinetic model. The best fit of equilibrium data was obtained by the Langmuir model with maximum monolayer adsorption capacities of 75.27 and 271.19 mg/g for MB, 76.42 and 313.63 mg/g for MG, respectively, in the case of RMC and AMC. The temperature did not have much influence on the adsorption performance.

In this study, Mg/Fe and Ni/Fe layered double hydroxides (LDHs) with molar ratio (M 2+ /Fe 3+ ) of 3 and intercalated with carbonate ions were synthesized by co-precipitation method. The as-synthesized materials and their calcined products (CLDHs) were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric and differential thermal analyses (TGA–DTA), transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (TEM-EDX), inductively coupled plasma (ICP) and elemental chemical analysis CHNSO. The materials were used as adsorbents for the removal availability of textile dyes from aqueous solution. Methylene blue (MB) and malachite green (MG), representative of cationic dyes, and methyl orange (MO) representative of anionic dyes were used as model molecules. Adsorption experiments were carried out under different parameters such as contact time, temperature, initial dyes concentration and solution pH. Experimental results indicate that CLDHs had much higher adsorption capacities compared to LDHs. Adsorption kinetic data fitted well the pseudo-second order kinetic model. The process was spontaneous, endothermic for cationic dyes and exothermic for the anionic dye. Equilibrium sorption data fitted the Langmuir model instead of Freundlich model.

The aim of this work is to study the removal ability of cadmium(II) and cobalt(II) ions from aqueous solution by raw and chemicly treated carob shells as an ecofriendly and sustainable biosorbents. The biosorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis (CHNOS), scanning electron microscopy (SEM), Boehm titration and the point of zero charge (pH PZC ). Biosorption experiments were carried out as function of solution pH, biosorbents dosage, contact time, initial metal ions concentration and temperature. The effect of some major inorganic ions including Na + , K + , Ca 2+ , Mg 2+ and Al 3+ on the biosorption efficiency was also investigated. From this studies it can be concluded that chemical pretreatment of the raw carob shells with NaOH strongly enhances its biosorption potential for the selected metals. Experimental results show that maximum biosorption capacity occurred at neutral pH medium. Kinetic data were best fitted with pseudo-first-order kinetic model instead of pseudo-second-order. Biosorption isotherms were best correlated with Langmuir model than with Freundlich model. The temperature doesn’t have much influence on the biosorption yield. Based on this preliminary study, full factorial experimental design with two levels (2 4 ) was used for the optimisation of the process. Four independent variables, including solution pH, biosorbents dosage, initial metal concentration and treating agent were investigated. Thus, the optimal conditions for high biosorption of cadmium(II) and cobalt(II) were achieved at pH = 6, biosorbent dosage of 1 g/L, initial metal concentration of 50 mg/L for NaOH treated carob shells.

This work aims to treat olive mill wastewater (OMWW) by infiltration percolation in different columns containing filtration sand, granular activated carbon, and lime, and thus followed by biological treatment using the soil microorganisms to the treatment that will give the best results. The optimum removal efficiency was obtained using granular activated carbon column mixed with 15% of lime with percentages removal of 39.33, 60.28, 53.17 and 88.74% for biological oxygen demand (BOD5), chemical oxygen demand (COD), polyphenols and suspended matter respectively. Aerobic treatment 30 days of OMWW obtained from the column of activated carbon mixed with 15% of lime, neutralized and diluted 15 times with distilled water was investigated. The results showed a significant percentage reduction of 79.78, 69.43, and 60.67%, respectively, for BOD5, COD, and polyphenols. The global removal percentages after the two successive treatments were 87.86% for COD, 87.39% for BOD5 and 81.59% for polyphenols compounds. Fourier Transformed Infrared spectroscopy analysis of crude OMWW, infiltrated percolated and biologically treated, showed a difference between the spectra that manifests by the reduction of the spectrum intensity bands after each treatment stage, which confirmed the analytical results. Soil microorganisms have shown their biodegradation efficiency of organic matter and polyphenols of these much-polluted effluents under aerobic conditions. The results indicated that the pretreatment of raw olive mill wastewater could be realized before biological treatment to obtain a satisfactory reduction.

The objective of the present study is to investigate the spatiotemporal variation analysis of water quality and identification of water pollution sources in Oum Er Rbia river. To evaluate the water quality of river, physico-chemical analysis of water samples taken from eight stations in dry and in wet seasons along the Oum Er Rbia river were studied. These stations were monitored for 20 parameters; water temperature, pH, dissolved oxygen, electrical conductivity, total Hardness, turbidity, tomplete alkalimetric title, organic matter (oxidizability), chlorides, sulphates, nitrates, nitrites, ammonium, iron, copper, lead, cadmium, nickel, chromium, and zinc. Results of water samples were compared with Moroccan norms for drinking water and permitted values recommended by World Health Organization. Results indicated that the water quality parameters are over Moroccan norms for drinking water in some stations. Seasonal variation was observed in the physicochemical composition of water in the wet compared to the dry period. The water quality index (WQI) method was used to evaluate water quality classification for drinking purpose. This study indicates that the water of Oum Er Rbia River is potentially dangerous to health of the users and signaled the necessity to treat industrial and municipal wastewater and to encourage sustainable agricultural practices to avoid adverse health effects., Journal of Applied Surfaces and Interfaces, Vol 5, No 1-3 (2019)

Zn/Al layered double hydroxides (LDHs) intercalated by dodecylsulfate and carbonate were synthesized using a hydrothermal method without calcination. The prepared material was used as adsorbents for the removal of the anionic azo dye, methyl orange (MO), from aqueous solution. The Zn/Al LDHs containing carbonate (Zn-AlCO3) and an anionic surfactant, sodium dodecylsulfate (SDS) (Zn-AlDs) were characterized by XRD, TEM, FT-IR, elemental analysis and TGA-TDA techniques. XRD patterns of Zn-AlDs and Zn-AlCO3 had a possibility to intercalate into the interlayer structure with a basal spacing of 1.262 and 0.758 nm, respectively. TEM observation showed that the LDHs displayed nanoscale particles. The presence of the desired anion in gallery space was confirmed by FTIR analysis. Adsorption tests for MO were performed as a function of solution pH, initial dye concentration, and contact time. The adsorption comportment onto Zn-AlCO3 was practically influenced by solution pH. However, the adsorption capacity of MO by Zn-AlDs was stable at the different varieties of pH solution. As the MO concentration increased, the form of a curve of removal capacity became L-type onto carbonate-containing LDHs and the S-type for organic LDH. XRD and FTIR analyses after MO retention indicates that the adsorption behavior for the organic compound was suggested by the dissolution of MO in a hydrophobic structure (adsolubilization). The adsorption results proposed that organic LDHs could be used as potential adsorbents for azo dye treatment in a wide range of pH. Keywords: Layered double hydroxide, Methyl orange, Adsorption, Dodecylsulfate

In this work, Zn–Al layered double hydroxides intercalated with carbonate, nitrate, chloride and sulphate ions were synthesised via a co-precipitation method at a constant solution pH. The as-synthesised samples were characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and simultaneous thermogravimetric/differential thermal analysis (TGA-DTA). The XRD patterns showed that Zn-Al-SO 4 had the greatest interlayer spacing, followed by Zn-Al-Cl, Zn-Al-NO 3 and Zn-Al-CO 3 . The FTIR spectra clearly confirmed the presence of intercalated anions in the structure of the LDHs. Batch experiments for methyl orange (MO) adsorption onto synthesised samples were investigated under various conditions such as contact time, initial dye concentration and solution pH. The experimental results show that pH is the most influencing factor. The effective pH range for the MO removal was found to be 3.5–4.5. The kinetics data can be described accurately by a pseudo-second-order kinetic model instead of a pseudo-first-order model. The equilibrium data were analysed using the Langmuir, Freundlich and Dubinin–Radushkevich models. The results showed that the Langmuir and Dubinin–Radushkevich isotherm models fit well to the experimental data. The Zn-Al-LDH samples exhibited exceptional Langmuir maximum adsorption capacities of 2758, 2455, 2270 and 1684 mg/g for Zn-Al-SO 4 , Zn-Al-Cl, Zn-Al-NO 3 and Zn-Al-CO 3 , respectively.

The presence of certain pharmaceutical compounds in ground and surface waters may constitute a serious environmental problem, even at low concentrations. The removal of these compounds is a trending research topic that implies a wide variety of disciplines. To provide clear insight into this field of research, a Systematic Mapping Study review (SMS) has been conducted. We investigated studies reported from 1993 to 2019 in ScienceDirect library. 4164 articles have been analyzed resulting in 172 primary relevant studies and revealing the treatment of 174 molecules. This paper aims to review the existing and recent trends in techniques for the removal of pharmaceuticals present in varied aqueous matrices and also presents a brief overview of the different classes of pharmaceutical compounds investigated. Findings of this study can help the scientists to identify potential techniques aiming to reduce the impact of pharmaceuticals present in wastewater discharge and into surface water bodies. It was revealed that, antibiotics and analgesics/anti-inflammatories are the most commonly investigated, since the highest risk is posed by these classes. The biological processes were found to be the most commonly used techniques in these field of research, and the diclofenac is the most extensively compounds examined. Recent advances in the field of the combination of AOPs with biological water treatment processes for the degradation of pharmaceuticals are discussed. Finally, advantage and limitations of methods used for the elimination of target compounds are addressed.

This study aimed to use the Attenuated Total Reflectance-Fourier transform mid-infrared (ATR-FTIR) spectroscopy coupled with chemometrics, as an alternative method for the qualitative-quantitative determinations of flocculent quality. To the best of our knowledge, there is no work that has treated the properties of flocculants by direct spectroscopic methods. The quality of the flocculent was ensured by the determination of two parameters namely, sedimentation rate (VS) and solid rate (TS), during the coagulation/flocculation process. Firstly, spectral and reference data of 36 samples from three different lots of flocculent, were analyzed by principal component analysis (PCA), Partial Least Squares Regression (PLSR) and results were used to establish calibration models. PLSR models revealed the best calibration models for predicting VS and TS values for studied samples, with the coefficient of determination (R2) of 0.99. In addition, cluster analysis (CA) and linear discriminant analysis (LDA) were adopted as differentiation methods of studied samples. On the basis of CA, three distinctive clusters were recognized. The model built by LDA could classify the samples with an accuracy value of 100%. Hence, it can be concluded that ATR-FTIR spectroscopy combined multivariate analysis can be used for the rapid prediction of flocculent quality.

Mg–Al, Zn–Al, and Ni–Al layered double hydroxides (LDH) materials with molar ratio (M2+/Al3+) of 3 were synthesized via co-precipitation method. The as-synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and simultaneous thermogravimetric–differential thermal analysis (TGA/DTA). XRD analyses showed that Zn–Al-SO4 had the greatest lattices parameters followed by Mg–Al-SO4 and Ni–Al-SO4. FTIR confirmed clearly the presence of sulfate anions in the structure of LDHs with the presence of carbonate impurity in the interlayer. TGA/DTA analysis indicates a better thermal stability of Zn–Al-SO4 vs. Ni–Al-SO4 and Mg–Al-SO4. The capability of the materials for textile dye removal was investigated using methyl orange (MO) as a model dye and an industrial textile effluent. Experimental results showed that pH is the most affecting factor in dye removal. The effective pH range for dye removal was between 3.5 a...

Titanium dioxide was synthesized by the sol–gel method and platinum supported on titanium dioxide were prepared by a wet impregnation chemical process at different platinum contents. The prepared samples were dried over night at 110 °C and then calcined at 500 °C for 4 h. Structural and morphological characterization has been carried out by means of X-ray diffraction (XRD), differential scanning calorimetry–thermogravimetric analysis (DSC–TGA), Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller surface area measurement (BET) and transmission electron microscopy coupled to the energy dispersive spectroscopy (TEM/EDX). The adsorption performance and photocatalytic activity of the samples were investigated using two chlorophenoxy herbicides: 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-(2,4-dichlorophenoxy) propionic acid (2,4-DP) as models of organic pollutants in water. The obtained results show that Pt/TiO 2 exhibited higher photocatalytic activity than TiO 2 particles for the degradation of the two selected herbicides. The photocatalytic activity increases by increasing the platinum yield in the catalyst.

In this study, Zn-Al, Mg-Al and Ni-Al layered double hydroxides were successfully synthesized via co-precipitation method. Samples were characterized by XRD, FTIR, TGA-DTA, TEM and pHPZC analysis. XRD patterns showed a basal spacing increase in the order of Zn-AlNO3 (8.85Å)> Mg-AlNO3 (7.95Å)> Ni-AlNO3 (7.82Å). TEM images indicated that the Zn-AlNO3 presents circular to shaped particles with an average particle size of approximately 30 to 40 nm. Small plates assigned to sheets with hexagonal form were observed in the case of Mg-AlNO3.Ni-AlNO3 display nanostructured sphere in diameter between 5 and 10 nm. The materials were used for the removal of methyl orange (MO), as a model dye and for the treatment of a real effluent generated by a textile factory. Maximum adsorption was occurred in acidic pH solution. Kinetic data were tested using pseudo-first-order, pseudo-second-order kinetic and intra-particle diffusion models. The best fit was obtained with the pseudo-second-order kinetic model. Equilibrium data were correlated to Langmuir, Freundlich, Sips and Redlich–Peterson isotherm models. The best conditions for color and COD removal from the textile effluent sample were obtained at lower values of pH. Reduction of COD to limits authorized by Moroccan standards was obtained with 0.5g/L of LDH dosage., Journal of Applied Surfaces and Interfaces, Vol 2, No 1-3 (2017)

Being categorized as high strength wastewater, landfill leachate is a complex mixture of organic and inorganic matters many of which are toxic and harmful. The composition of leachate depends on landfill age, percolation, precipitation and type of solid waste (Narayanasamy et al. in Environ Sci Technol 33(2):482–489, 2014; Kochany and Lipczynska-Kochany in J Hazard Mater 166(1):248–254, 2009).

This work focuses on the development of zinc/aluminum layered double hydroxides (LDHs) phases intercalated by carbonates ions (Zn-Al-CO3) and their use in the removal of pharmaceutical pollutants. The materials were synthesized by the co-precipitation method at different Zn/Al molar ratios (r = 1, 3 and 5). Each synthesized material was calcined at 300, 400, 500 and 600 °C to increase their performance. Samples were characterized by various physicochemical techniques including XRD, FTIR, ICP-AES and TEM-EDX. The as-synthesized and calcined products were used for the removal of salicylic acid (SA) as a model of pharmaceutical pollutants. The results obtained show that the Zn/Al molar ratios and calcination temperatures have a great influence on the adsorption capacity. The optimum adsorption efficiency was found to be 94.59% for Zn/Al molar ratio of 3 and a calcination temperature of 300 °C. Kinetics of the adsorption takes place in two steps; the first fast rapid step can be interpreted by the adsorption on the external surface of the crystallites, while the second slow step could be due the reconstruction phenomenon of LDHs structure “memory effect”. After the adsorption processes, XRD patterns show that the calcined product (r = 3, T = 300 °C) was reconstructed by a salicylic acid. The adsorption performance was slightly decreased with regeneration cycles. Keywords: Layered double hydroxides, Reconstruction, Pharmaceutical pollutants, Regeneration, Wastewater treatment