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The neutron capture cross section for the 164Dy(n,γ)165Dy reaction at 0.0372 eV energy was measured using the horizontal channel (Neutron Diffraction Facility) of Es-Salam nuclear research reactor in Birine-Algeria. The Neutron Activation Analysis (NAA) technique using 197Au(n,γ)198Au as reference reaction was adopted. The γ ray spectra for the Dy2O3 target powder and two thin gold foil were detected for the Germanium Hyper Pure coupled in the Genie 2000 data acquisition software. A resulting σ-value (2198.5 ± 94) b was measured for the thermal neutron cross section after correcting the thermal neutron self-shielding and γ attenuation effects. The measured value was then compared to the evaluated cross sections reported in two different libraries of neutron databases ENDF/B-VIII.0 and JEFF-3.3. The measured data at 0.0372 eV has been extrapolated to the energy of 0.0253 eV assuming 1/ν dependence in the thermal energy region and the result was compared with the fully measured values reported in the literature.

Al, mixed Al-Fe and Al-Cu pillared clays were prepared. The solids were characterized by X-ray diffraction (XRD), N2 adsorption and H2-TPR. The dispersion of the cold clay suspension, before the pillaring, increases the basal spacing and the specific surface area. CWPO of phenol under mild conditions (25 °C, 1 atm) was carried out without correction of pH. Mixed Al-Fe and Al-Cu pillared clays have comparable performances, although they showed some differences in the H2O2 decomposition kinetics. A total conversion of H2O2 is obtained without the complete phenol conversion over mixed Al-Fe pillared clays suggesting the presence of active species in these catalysts. In a slight excess of H2O2, the activity increased for all iron-based clays catalysts with the increase in Fe content. A total conversion of phenol is obtained after 15 h of reaction over Fe/MR-AlFe(10) and after extending the reaction time to 30 h in the presence of Fe/MR-Al. While MR-AlFe(10) only converted 57.12% under the same conditions. MR-AlFe(10) has the greater basal space (17.44 Å) and is more active for H2O2 decomposition than Fe/MR-Al, which certainly allowed greater accessibility of the reactant to the iron species. Iron exchanged and post-pillared clay with mixed (Al-Fe) solution containing 10% of iron expressed as molar percentage {Fe/MR-AlFe (10)} was the most efficient for this reaction combining good catalytic activity with high stability against iron leaching (0.02%). It showed a total phenol degradation, the highest H2O2 decomposition (85.7%) and more than 80% of TOC removal after 15 h of reaction.

During the last decade, there is a growing interest in developing efficient photocatalysts with a visible light sensitivity. Herein, visible-light-driven photoactivity of CrFeO3 prepared by nitrate route was studied. The photocatalysis was evaluated through the Ni2+ reduction. The X-ray diffraction (XRD) is characteristic of a single phase crystallizing in the ilmenite structure with a good crystallinity. It was characterized by the SEM, TEM/HRTEM, FTIR spectroscopy and thermal analysis (TG). The optical and dielectric constants are determined from the diffuse reflectance data. The refractive index (n), extinction coefficient (k), relaxation time (τ), dissipation factor (tan δ) and optical conductivity are extracted. The forbidden band Eg (= 1.65 eV), was computed and confirmed by different methods. The electrical conductivity (σ) augments exponentially with 1000/T and activation energy of 0.22 eV was calculated. The p-type conduction is evidenced from the capacitance measurements with a flat band potential (Efb = −0.38 VAg/AgCl) and a hole concentration (NA = 5.87 × 1018 cm−3). The novel hetero-system CrFeO3/TiO2 showed improved efficiency by 47% compared to CrFeO3. An optimal mass ratio CrFeO3/TiO2 (25%/75%) gives to a Ni2+ reduction of 88% at pH ∼ 7.2 within 4 h irradiation for an initial Ni2+ concentration of 15 mg/L. A first order kinetic was found from the Ni2+ photoreduction with a half photocatalytic life of 61 min−1 and a higher photodegradation under sunlight is obtained. More interestingly, the photocatalyst showed a good stability and recyclability after four runs.

In this study, chromate adsorption onto red peanut skin (RPS) was investigated in a fixed-bed column; FTIR, PZC, SEM, DLS, and BET were used to evaluate its adsorption properties. The experiments were conducted to determine the effect of physical parameters, including the inlet initial Cr(VI) concentration (100–500 mg L−1), bed height (10–20 cm), and feed flow rate (13.59–23.45 mL min−1). They were carried out to predict breakthrough curves. The adsorption capacity coefficients were determined using the most widely used Bohart–Adams model. It was tested to fit experimental data, for a better understand the dynamic behavior, and for further optimize column performance. It was found that the Cr(VI) uptake decreases when increasing the flow rate and that high chromate concentration and bed height consequently increase the column’s life span. A high column adsorption capacity can be achieved with a higher Cr(VI) concentration due to the higher driving force. The results indicated that the Bohart–Adams model provides a good description (R2 > 0.98) of the experimental data of the Cr(VI)’s removal from the aqueous solution on the RPS suggesting that the surface diffusion is the rate-limiting step in the continues adsorption process.. Breakthrough adsorption capacity is crucial for comparing RPS with other similar materials. Indeed, possible mechanisms have been suggested for illustrating adsorption onto RPS. The obtained results showed significant potential of 26.23 mg g−1 of RPS on Cr(VI) elimination at a natural pH of 5.35. Furthermore, this global investigation allowed for the design of a promising low-cost material for the future scale-up of cleaning wastewater polluted by metal and determine the properly conditions for operating column adsorption. This material provides an economical, efficient means of eliminating pollutants, thus meeting the main aims of the UN Sustainable Development Goals (UN SDGs).

This work is devoted to the synthesis, optical and dielectric properties of CuBi2O4 prepared by sol–gel route. The X-ray diffraction analysis shows that CuBi2O4 crystallizes in a tetragonal symmetry (SG: P4/cnn) with lattice parameters: a = 8.5023 A and c = 5.8250 A; the Rietveld refinement reveals a high purity of the spinel. The crystallite size (D = 47.84 nm) was calculated from the Williamson Hall-plot. The presence of Cu–O and Bi-O bonds with Cu2+ tetrahedrally coordinated is confirmed by the Raman spectroscopy. We also report the optical and dielectric properties of CuBi2O4, including the refractive index (nλ), optical (σopt) and electrical (σele) conductivities, extinction coefficient (kλ), dissipation factor (tan δ) and relaxation time (τ). The forbidden band (Eg), measured from the UV–Visible diffuse reflectance spectroscopy, is found in the range (1.50–1.55 eV) and confirmed by these approaches. Furthermore, the as-prepared compound has been successfully tested for the first time for the methyl violet degradation under visible light. The results show a conversion rate of 75% under illumination of 4 h 30 min and that the kinetics follows a first order model.

In this study, we report the photodegradation of a pharmaceutical pollutant namely the tetracycline (TC) onto the spinel ZnAl2O4. The semiconductor ZnAl2O4 was synthesized by chemical route and characterized by X-ray diffraction, scanning electron microscopy and optical analysis. The capacitance potential (C−2–E) measurements showed that the oxide exhibit n-type conduction, supported by a negative thermo-power. The degradation of TC was performed by combined adsorption/photocatalysis processes. The result showed that 30 min of contact time was sufficient to reach 42% of the adsorption capacity; the photodegradation rate of TC was evaluated on ZnAl2O4 under optimal operating parameters pH ~ 4.4, catalyst dose (1 g/L), and initial TC concentration (20 mg/L). The kinetic shows that the TC disappears almost completely (92%) and follows a second order model with a half photocatalytic lifetime of 21 min for a TC concentration of 20 mg/L. The mechanism of the antibiotic tetracycline photodegradation on ZnAl2O4 indicated that the $${\text{O}}_{2}^{ \cdot - }$$ radicals and the holes are mainly responsible for the oxidation of TC. The process can be qualified as clean remediation and is a part of a sustainable development perspective.

The co-precipitation is successfully used for the synthesis of the hetero-junction CuO/ZnO. Thermal analysis, ATR spectroscopy and diffuse reflectance were used to assess the photoactivity of the hetero-system for the hydrogen formation upon visible light. As expected, the X-ray diffraction shows mixed phases of CuO (tenorite) and ZnO (Wurtzite). The specific surface area is around ~7 m2 g−1 with a crystallite size lying between 20 and 49 nm. The diffuse reflectance indicates an indirect transition at 3.13 eV for ZnO and a direct transition at 1.60 eV for the sensitizer CuO. The capacitance-potential (C−2 - E) characteristic of CuO plotted in Na2SO4 electrolyte exhibits p-type comportment with a flat band potential of −0.315 VRHE and a holes concentration of 8.7 × 1018cm−3. The Electrochemical Impedance Spectroscopy exhibits a semicircle characteristic of the bulk material with an impedance of 1725 Ω cm2 which decreases down to 453 Ω cm2 under irradiation, supporting the semiconducting character of CuO. ZnO mediates the electrons transport thanks to its conduction band, formed from Zn2+: 4s orbital (−0.92 VRHE); it is positioned cathodically with respect to the H2O/H2 level (~-0.74 VRHE), producing a H2 evolution under visible light illumination. The performance peaks at pH ~7 on 5% CuO/ZnO for a catalyst dose of 0.25 mg of catalyst/mL of solution in the presence of SO32− as holes scavenger. A liberation rate of 340 μmol h−1 (g of catalyst)−1 is obtained with a quantum efficiency of 0.38% under a photons flux of 2.09 × 1019 s−1.

The aluminate nano-powders Al2XO4 (X = Cd, Ni and Co), crystallizing in a cubic spinel, were prepared by combustion method at 900°C. The effects of cations on the structure, optical properties and distribution of the cations as well as the binding energy of the samples were studied by X-ray diffraction (XRD), UV-Vis diffuse reflectance and FT-IR) spectroscopy. The XRD analysis confirmed the spinel structure of all samples, and showed that the average crystallite size of Al2XO4 increases from 23.89 to 32.72 nm, while the lattice parameter changes from 8.0490 to 8.1066 Å when going from Ni to Co. As expected, the FT-IR spectroscopy of Al2XO4 showed the presence of the fundamental absorption peaks in the region (400–745 cm− 1 ), confirming the formation of the aluminate spinels. The slight shift toward longer wavenumbers is due to the low electronegativity of Cd. The forbidden bands (Eg), determined by diffuse reflectance, were found to be 3.78, 3.82 and 3.75 eV respectively for Al2CdO4, Al2NiO4 and Al2CoO4, assigned to the charge transfer O2−: 2p → X2+: d orbital, making our spinels good candidates for optoelectronic and photocatalytic applications.

The purpose of this research is to evaluate the adsorption kinetics, isotherms and thermodynamic parameters correlating the removal of 60Co2+ radioactive ions from waste water of the primary cooling circuit of the Nuclear Uranium Reactor (Nur / Draria-Algeirs) on Fe(III)-modified Algerian bentonite. Characterization was done using X-ray diffraction, SEM analysis, X-ray Photoelectron Spectroscopy and BET method. The pseudo-second-order kinetic model provided the best fit to experimental data. The two-parameter adsorption model of Langmuir and both of the three-parameter models Langmuir–Freundlich and Toth are the most appropriate for fitting experimental results. The adsorption process was found to be endothermic in nature.

The influence of the concentration of the catalyst zinc oxide (0.01-0.3 g∙L–1) and the initial concentration of the azo dye Solophenyl Brown AGL (SB AGL, 5-75) on the efficiency of its photocatalytic degradation was studied. Almost complete degradation of the pollutant is achieved at a natural pH and catalyst content of 0.05 g∙L–1. The results of kinetic studies correspond to the Langmuir–Hinshelwood model. The efficiency of predicting the yield of photocatalytic degradation of SB AGL using a three-layer neural network with four input neurons, eight hidden neurons, and one output neuron is shown. The treatment of industrial wastewater containing two textile dye, Solophenyl Brown AGL and Cibacete Brown JNH, using a hybrid process (adsorption/solar photocatalysis) was successfully achieved.

The present work aims at the characterization of SrFe12O19 prepared by nitrate route and its photo-electrochemical properties as well as its application for the photodegradation of Basic Red 46 (BR 46), a hazardous and persistent dye. The semiconductor is identified by X-ray diffraction to confirm the single phase. The scanning electron microscopic indicates regular grains with spherical shapes and an average dimension of ~ 0.9 µm. The optical properties were measured by the diffuse reflectance and a direct gap of 2.56 eV was determined. The photo-electrochemistry enables us to determine the conduction type. SrFe12O19 is an n-type semiconductor with a flat band potential of − 0.42 VSCE. The second part of this work is devoted to the BR 46 photodegradation on the hetero-system SrFe12O19/ZnO under visible irradiation. The effect of pH, BR 46 initial concentration, catalyst dose and mass ratio of the hetero-system SrFe12O19/ZnO were studied. The best degradation yield occurs at neutral pH ~ 7 within 90 min with a percentage of 99% for BR 46 concentration of 10 mg/L and a ratio SrFe12O19/ZnO (75/25) and a catalyst dose of 0.75 g/L. The photoelectrochemical properties show that ·OH radicals are responsible for the BR 46 degradation.

Environmental problems on a global scale have become more prominent with the population growth. For the removal of organic contaminants, the solar energy and environmentally friendly photocatalysis are needed to substitute the fossil fuels. In this contribution, we report the synthesis, characterization and photocatalytic capability of CuAl2O4 nanoparticles. The spinel was elaborated by nitrate route and characterized physically and electrochemically for their correlations and application in photocatalysis through the degradation of Basic Red 46 (BR 46), a hazardous dye under visible illumination. The effects of several operational factors like the pH, catalyst dose and initial dye BR 46 concentration were optimized. The results revealed that the photocatalytic performance reached 93% at pH 10, 1 g/L of catalyst dose at a concentration of 10 mg/L of BR 46 within 120 min of irradiation. The quasi-total mineralization was confirmed by the total organic carbon (TOC) and dissolved organic carbon (DOC). Additionally, the prepared photocatalyst possesses a good cyclability with no significant change after five successive photocatalytic cycles. Furthermore, the radical scavenger tests revealed that the specie O2·− and the holes h+ have the significant effects on the removal of BR 46. Based on the latest results, a photocatalytic mechanism was proposed.

In the last years, the development of photocatalysts has gained a growing interest in the photoelectrochemical conversion. Here, we report a hetero-junction organic/inorganic (Polyaniline (PANI)) on n type Silicon substrate prepared by electrophoretic deposition (EPD). ZnO nanorods (NRs) are grown by chemical bath deposition (CBD) on seed layer of ZnO prepared by dip coating onto the PANI layer. The relief and morphological properties are investigated by both atomic force microscope (AFM) and scanning electron microscopy (SEM). The forbidden bands (Eg) of 1.12 and 3.26 eV are obtained for PANI and ZnONRS respectively. The optical and dielectric constants are determined by the diffuse reflectance where the extinction coefficient (k), the refractive index (n), optical conductivity, dissipation factor and relaxation time are extracted. The semi conductivity is highlighted by the capacitance measurement; a flat band potential (Efb = 0.541 V) for ZnONRs-PANI is deduced from the Mott-Schottky plot. The contributions of the bulk and grain boundaries of the electrode are evidenced from the electrochemical impedance spectroscopy (EIS). The as-fabricated samples show improved photoactivity compared to PANI and ZnONRs. Indeed, the hetero-junction exhibits a high stability and recyclability for the photodegradation of Orange II (OII) after six cycling runs. The current research offers a new understanding of designing a high performance of the photocatalyst under solar light based on PANI for the wastewater treatment.

Manganese tungstate (MnWO4) synthesized by hydrothermal method is characterized by many physicochemical techniques. X-ray diffraction pattern (XRD) confirms the formation of the single-phase MnWO4 crystallizing in a monoclinic system. Scanning electron microscopy (SEM) shows a homogeneous grain distribution of the powder. The optical measurements indicate the existence of one direct optical transition and two indirect ones with an Urbach energy tail of 276.82 meV. The textural study, analyzed by the using the Brunauer, Emmett, and Teller (BET), model gives a specific surface area of 23 m2 g-1. The electrical conductivity follows an exponential law, characteristic of a non-degenerate semiconducting with an activation energy of 70 meV. The photo-electrochemical properties of MnWO4 are investigated by using the cyclic voltammetry, chrono-amperometry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS). The results indicate n-type conduction with a flat band potential of -0.41 VSCE. All these results allowed us to construct the electronic energy diagram of the semiconductor/electrolyte junction in the electrochemical scale.

The present work is devoted to the preparation of the hetero-junction of Polyaniline-Zinc oxide nanoparticles (Pani-ZnONps) and its photo-electrochemistry to assess its photocatalytic properties for the water reduction into hydrogen. The semiconducting characterization of the Pani-ZnONps synthetized by in situ chemical oxidative polymerization was studied for the hydrogen evolution reaction (HER) upon visible light illumination. The forbidden bands Eg (= 1.64 eV, Pani) and (3.20 eV, ZnONPS) were extracted from the UV–Visible diffuse reflectance data. The Electrochemical Impedance Spectroscopy (EIS) showed the predominance of the intrinsic material with a bulk impedance of 71 kΩ cm2. The semi conductivity was demonstrated by the capacitance measurements with flat band potentials (Efb = - 0.7 and - 0.3 VSCE) and carriers concentrations (NA = 1.77 × 1019 and ND = 4.80 × 1020 cm−3) respectively for Pani and ZnONPS. The energetic diagram of the hetero-junction Pani-ZnONps predicts electrons injection from Pani to ZnONPS in KOH electrolyte. An improvement of 78% for the evolved hydrogen was obtained, compared to Pani alone; a liberation rate of 61.16 μmol g−1 min−1 and a quantum yield of 1.15% were obtained. More interestingly, the photoactivity was fully restored after three consecutive cycles with a zero-deactivation effect, indicating clearly the reusability of the catalyst over several cycles.

Ca[Fe]2O4 prepared by nitrate route is a narrow band gap semiconductor crystallizing in the normal spinel structure. The direct optical band gap Eg (1.93 eV), determined from the diffuse reflectance, is due to the lifting of degeneracy of Fe3+: 3d orbital, octahedrally coordinated. The semi-logarithm plot of the oxide shows a chemical stability at pH ~ 7 with an exchange current density of 2×10−7 mA cm−2 and a corrosion potential of −0.664 VSCE. The photoelectrochemical properties of CaFe2O4 are investigated for the first time to assess its photocatalytic activity. A flat band potential (Efb) of 0.33 VSCE was obtained from the capacitance measurement in Na2SO4 (0.1 M) solution. The n-type comportment, rare for spinels, is confirmed by the chrono-amperometry and inferred to the metal insertion in the FeO6 octahedra. The electronic concentration ND (7.1 ×1015 cm−3) agrees with a non-degenerate semi-conductivity and a wide space charge region (W ~ 850 nm). The electrochemical impedance spectroscopy (EIS) shows depressed semicircles with the existence of a constant phase element (CPE) and a bulk resistance of 10.89 kΩ cm2 which decreases down to 2.24 kΩ cm2 under visible irradiation. A Warburg diffusion is observed at low frequencies. The valence band (2.09 VSCE) deriving from Fe3+: eg character is more anodic than the potential of H2O/•OH couple. As an application, the Basic Blue 41 (BB 41), a recalcitrant dye, is successfully oxidized; an abatement of 85% is obtained within 3 h under solar light (980 W m−2) and the BB 41 oxidation follows a first-order kinetics with a photocatalytic half-life of 69 min.

International audience; The removal efficiency of the pharmaceutical drug Mebeverine Hydrochloride (MEB) from solutions by an activated carbon (AC) prepared from dates stems was investigated in the present research work. The surface properties of the activated carbon were investigated by elementary analysis, BET surface area, SEM, FTIR and pH(pzc). The operating parameters effect on the MEB adsorption efficiency was investigated by using batch experiments. The adsorption isotherms study indicated that the experimental data were well described by Freundlich and DR isotherms, with the maximum adsorption capacity (q(max)) of 4105 mg/g. This result suggests the multilayer adsorption of MEB on the activated carbon. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40201-021-00658-1.

The crednerite CuMnO2 was synthesized by sol–gel method under N2 flow. The oxide crystallizes in a monoclinic symmetry ascribed to the Jahn–Teller Mn3+ ion and the formation is completed above 600 °C. The XPS analysis confirms the mono and trivalent states of copper and manganese. CuMnO2 exhibits a direct optical gap of 1.70 eV and the p-type conductivity is due to oxygen insertion in the Cu layers. An exchange current density (0.2 mA cm−2) and a corrosion potential (~ -– 0.816 VSCE) indicate a stable compound in neutral solution (pH ~ 7). The flat band potential (Efb = 0.17 VSCE) and the holes density (NA = 7.25 × 1015 cm−3) were determined from the capacitance measurement (C−2 – E). The conduction band made up of Cu-3d orbital is located at (3.43 ± 0.02) eV below vacuum and the electrons can reduce heavy metals to their elemental states. Indeed, CuMnO2 was successfully used for the photodeposition of Cd2+, Pd2+, Zn2+, Ni2+, and Ag+ (30 mg L−1) under visible-light illumination. The best reduction was obtained with Zn2+ (94%) because of the optimal band bending, due to the redox potential of Zn2+ and its adsorption. By contrast, Ag+ (76%) was weakly deposited owing to its positive potential. The metal photodeposition proceeds competitively with the water reduction and decelerates over time. The species showing the high H2 evolution exhibits the lower Mn+ reduction and the medium pH makes the Mn+ deposition easier. The best photocatalytic H2 evolution (1.02 mL g−1 min−1) occurred with Cd2+.

Researchers have used mixed microbial cultures to degrade various pollutants such as domestic effluents, pharmaceuticals, hydrocarbon molecules, etc. The use of a mixed microbial culture induces synergistic associations between different microorganisms by producing multiple enzymes that can effectively degrade refractory molecules such as azo and anthraquinone dyes. It is in this context that we have been interested in the biological decolorization of contaminated water with an anthraquinone dye Remazol Blue Brilliant R (RBBR), by using microorganisms from activated sludge taken at the outlet of the aeration basin of the wastewater treatment plant from Reghaia (Algeria). In order to stimulate the development of the microorganisms responsible for the secretion of ligninolytic enzymes, we have introduced date pedicels cut into small pieces into the bioreactors. These will serve as co-substrate and support for the microorganisms present in the reaction medium. The parametric study is performed by varying the concentration of activated sludge, the concentration of date pedicels, the pH, the temperature and the initial concentration of the Remazol Blue Brilliant R (RBBR) dye. A maximum elimination yield of 82% is obtained. For an activated sludge/pedicel ratio of dates equals 2 at a neutral pH, T = 30°C and an initial dye concentration of 100 mg/L. We also note that this promising technique has achieved a yield of 53% for an initial concentration of Remazol Blue Brilliant R of 3500 mg/L.

The widespread occurrence of drugs in the aquatic environment has raised concerns over the last decades about the mechanisms to be used to remove these emerging contaminants because of their harmful effects on the water quality and human health. This current research was aimed to explore the preparation of an activated carbon from kernel oil treatment residues of Argania Spinosa for the removal of amoxicillin (AMX) from water. The conditions for synthesizing the activated carbon (AC-RS) were used: an impregnation weight ratio of char to KOH 1:1 at activation temperature of 800 °C for 1 h of activation time, which gave a BET surface area and total pore volume of 1618 m2 g−1 and 0.763 cm3 g−1, respectively. The effect of AMX/AC-RS interactions as well as the operating conditions (time, solution pH, initial concentration, and temperature) on the adsorption capacity was also studied. The adsorption of AMX onto AC-RS, with maximum adsorption capacity of 303.03 mg g−1, is much higher compared to several adsorbents reported in the literature. The high amount of AMX absorbed by AC-RS at pH 6 mainly results from the adsorption sites involved in the electrostatic attraction force, π-π hydrophobic interaction, and hydrogen bonding. The regeneration study ascertained the fact that AC-RS was reusable even after four consecutive cycles and the efficiency remains higher than 70%. Therefore, the optimized batch parameters were employed for the AMX removal in real wastewater, a percentage of 77.2% was obtained.

The solid solution NiFe2-xMnxO4 (0 ≤ x ≤ 2) is synthesized by sol gel method and the physical properties are investigated for the first time. The thermal analysis shows that the phases are formed above 400 °C. The oxides crystallize in an inverse cubic spinel whose lattice constant (a: 0.83381–0.83985 nm) increases only slightly up to x = 1.6, according to the Vegard’s law; such result is supported by the FTIR spectra. The UV-Visible spectroscopy shows both direct (1.00–1.56 eV) and indirect optical transitions (0.39–1.65 eV) due to the crystal field splitting of 3d metal. Field-dependent magnetization of the solid solution was measured at 300 K in the region (±20 kOe) and the end member NiFe2O4 exhibits a high magnetism with a saturation magnetization (20 emu/g), comparable to that reported previously. The saturation magnetization varies between 0.5 and 20 emu/g while the coactivity fluctuates between 110 and 239 Oe. The thermal variation of the electrical conductivity indicates a conduction mechanism by low polaron hopping which follows an exponential law with variable activation energies (Ea: 0.12–033 eV). The thermo-power is positive and nearly constant (S300K: 144–130 µVK−1), indicating p type conduction with a mobility more a less constant (1.5–8 × 10−6 V2 cm−1 s−1). The hole densities (NA × 1016: 0.26–2.17) are determined electrochemically from the capacitances measurements in neutral medium (Na2SO4 0.5 M). The flat band potential (Efb: −0.04 to −0.29 V) does not change significantly indicating that the valence band derives mostly from 3d orbital.

The present work has for the main objective the elimination of the textile dye Maxilon Red (MR) by coupling two processes, adsorption on activated clay followed by photocatalysis over the wurtzite ZnO. The influence of the physical parameters like the initial pH, adsorbent dose of the activated clay, MR concentration, and temperature have been studied. The best adsorption yield occurs at neutral pH ~ 7 within 60 min with an adsorption percentage of 97% for MR concentration of 25 mg/L and an adsorbent dose of 0.5 g/L. The data were suitably fitted by the Langmuir model with a maximum adsorption capacity of 175 mg/g. To investigate the adsorption mechanism, the adsorption constants were determined from the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. It was found that the MR adsorption is well described by the pseudo-second-order kinetic. The thermodynamic parameters ΔH˚ = -17.138 kJ/mol, ΔS˚ = 32.84 J/mol.K, and ΔG˚=−6.419 to−7.329 kJ/mol with rising temperature from 25 to 50˚C indicated that the adsorption is exothermic and spontaneous. The second part of this work was devoted to the photocatalytic degradation onto ZnO under solar irradiation of the residual MR concentration, which remained after adsorption. In this respect, the effect of ZnO dose and MR concentration has also been investigated. The photodegradation rate reached 99% under irradiation within 90 minutes under the optimum conditions. The parametric study showed that the elimination is very effective by photocatalysis, based essentially on the in situ generations of free radicals •OH which are non-selective and very reactive. The present study shows that the activated clay is an effective low-cost adsorbent for the removal of Maxilon red from an aqueous solution.

In this work, a potential biosorbent is prepared from agricultural waste material (ash seed) without any treatment. This biomaterial could be successfully used as a low-cost adsorbent for the removal of an anionic dye named Cibacron Blue (CB), under optimal conditions. The prepared adsorbent was characterized by scanning electron microscope (SEM) coupled with EDX, Fourier transforms infrared spectrometer (FTIR), thermogravimetric analysis (TGA), and point of zero charge (pHpzc). The adsorption experiments were carried out in batch mode at room temperature. Results show that the rate of CB dye removal exceeds 95 % using a dose of 2 g/L ash seed at C0 = 25 mg/L and pH = 2.2. The kinetic data were analyzed using the pseudo-first-order, pseudo-second-order, Elovich’s, Bangham, intraparticle diffusion, and Boyd kinetic. Results show that the pseudo-second-order model fits better the experimental data. The isotherm data of the CB dye adsorption were analyzed with several theoretical models (Langmuir, Freundlich, and monolayer model coupled to real gaz (MMRG)). It was found that the adsorption process of the CB dye is well described by monolayer model coupled to real gaz (MMRG) compared to other models. The negative enthalpy (ΔH°) and free enthalpy (ΔG°) indicate the physical and spontaneous nature of CB adsorption. Therefore, the prepared material can serve as a potential adsorbent for removal of CB dye from industrial effluents.

The photocatalytic degradation of the Mebeverine hydrochloride (MEB) by ZnO and the combined ZnO-Activated Carbon (ZnO-AC) under solar light has been investigated in batch mode. The AC was prepared from dates stems using ZnCl2 as chemical activation agent. The effect of some operating parameters on the MEB degradation efficiency such as: photocatalyst dose, solution pH and initial MEB concentration has been examined. The results revealed that the surface reaction on ZnO plays a crucial role in the MEB photo-degradation as confirmed by UV-Visible spectrophotometry. The photocatalytic efficiency of the mixture ZnO-AC is dependent on the mass ratio ZnO/AC, which was optimized for a value of 15 wt%. The MEB degradation kinetics follows a pseudo first order model and the Langmuir-Hinselwood (L-H) model fit adequately the experimental data. Besides, our results show that the combined system (adsorption/photocatalysis) is effective for the MEB degradation than the photocatalysis process alone. A comparative study with the literature indicated the benefits of coupling ZnO-AC under the solar light (93 mW cm−2).

NiFe2−xMnxO4 (0 ≤ x ≤ 2) is prepared by sol–gel route and the physical properties are studied for the first time. The thermal analysis shows that the phases are formed at 600 °C. The oxides crystallize in an inverse spinel with a cubic symmetry whose lattice constant (a: 0.83381–0.83985 nm) augments slightly up to x = 1.6, according to the Vegard’s law; such result is corroborated by the FTIR spectroscopy. The diffuse reflectance shows direct (1.00–1.56 eV) and indirect (0.39–1.65 eV) optical transitions due to the lift of degeneracy of 3d orbital. Field-dependent magnetization of NiFe2−xMnxO4 was measured at 300 K in the range (± 20 kOe) and NiFe2O4 shows a strong magnetism with a saturation magnetization of 20 emu/g. The saturation magnetization varies from 0.5 to 20 emu/g, whereas the coercivity fluctuates between 110 and 239 Oe. The variation of the electrical conductivity with temperature shows a conduction mechanism by small polaron hopping which obeys an exponential law with activation energies (Ea: 0.12–033 eV). The thermo-power is positive and almost constant (S300K: 144–130 µV K−1), indicating p type comportment with a mobility more a less constant (1.5–8 × 10–6 V2 cm−1 s−1). The hole concentrations (NA × 1016: 0.26–2.17) are computed from the capacitances measurements in Na2SO4 solution (0.5 M). The flat band potentials (Efb: − 0.04 to − 0.29 V), determined electrochemically, does not vary significantly indicating that the valence band derives mainly from 3d character.

MoO3 and 5% MoO3/ZnO were prepared by impregnation method using (NH4)6Mo7O24, 4H2O as precursor and ZnO as support. The prepared samples were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), infra red (FTIR) and UV-Vis diffuse reflectance (DRS) spectroscopies and photo-electrochemistry. The XRD pattern showed that the MoO3 powder treated at 700°C is a single-phase crystallizing in an orthorhombic structure with a direct optical transition (2.70 eV). The hetero-junction 5% MoO3/ZnO was photo-electrochemically characterized to assess its feasibility for H2 production under visible light. The capacitance potential (C-2 f(E)) characteristic of MoO3 plotted in Na2SO4, (0.1 M) electrolyte indicates n-type conduction with a flat band potential of -0.54 VSCE. The photocatalytic activity was performed for the photoreduction of water to hydrogen under visible light illumination. The best performance occurs at pH ~ 7 with an evolved volume of 5.9 mL.

The photo-electrochemistry of the hetero-junction Pt/CuCo2O4 synthesized by hydrothermal route was studied to assess its ability for the H2 formation under visible light illumination. The X-ray diffraction is characteristic of mixed phases with narrow lines of the spinel CuCo2O4 and Pt. The sensitizer CuCo2O4 has a forbidden band (Eg) of 1.30 eV, well suited to the sun spectrum and displays p-type behavior. Its conduction band (−0.660 VSCE), deduced from the capacitance – potential (C−2 – E) plot, is more cathodic than the H2O/H2 level (~−0.6 VSCE), thus producing spontaneous H2 evolution under irradiation. The photoelectrons are transferred to Pt clusters, to trigger the water reduction owing to the small H2-over-potential. A quantum conversion yield of 0.65% is obtained under visible light (total flux: 15 mW cm−2, 3.42 × 1018 photons s−1) with H2 evolution rate of ~103 µmol g−1 min−1, higher than that obtained over CuCo2O4 (73 µmol g−1 min−1).

The main goal of the present work is the elaboration of new nanocomposite conducting poly(aniline) with α-Fe2O3 nanoparticles in the presence of zeolite HY acid in aqueous electrolyte by chemical oxidative polymerization. Various formulations of the polymer were synthesized (5, 10, and 20% of α-Fe2O3) and the nanocomposites poly(aniline)/HY/α-Fe2O3 have been characterized by X-ray diffraction (XRD), SEM analysis, and FT-IR spectroscopy. The electrical conductivity and the UV–visible spectroscopy of the nanocomposites were also investigated. In addition, the electrochemical properties were studied by cyclic voltammetry. (CV) and electrochemical impedance spectroscopy. The optimal ratio between α-Fe2O3 and poly(aniline)/HY was found to be 5 wt%. The specific capacitances of poly(aniline)/HY and nanocomposite were found to be be 630, and 1000 F g−1 respectively at a scan rate of 5 mV/s. Besides, the material possesses a high energy density of 88.88 Wh kg−1 and a maximum power density of 1632.3 W kg−1. These electrochemical results indicate that the PANI/HY/α-Fe2O3 nanocomposites is an attractive candidate for the application in the high-performance energy storage systems.

The hematite (α-Fe2O3) nanostructures were synthesized by thermal oxidation of metal at 500 °C under atmospheric pressure. We studied the effect of the electrochemical pretreatment of the substrate before calcinations and its impact on the morphology, crystalline structure, lattice microstructural, and optical properties of α-Fe2O3. Uniform nanosheets were observed on the sample surface after calcination; their dimension and morphology were accentuated by the pretreatment, as confirmed by the SEM images. The characteristics of the nanostructures, analyzed by X-ray diffraction (XRD), revealed a rhombohedral symmetry with the space group R-3c and lattice constants: a = 0.5034 nm and c = 1.375 nm. The average crystallite size and strain, determined from the Williamson-Hall (W-H) plot, showed substantial variations after the substrate pretreatment. The Raman spectroscopy confirmed the changes in the crystal properties of the hematite submitted to pretreatment. The diffuse reflectance allowed to evaluate the optical gap which lies between 1.2 and 1.97 eV, induced by the electrochemical processing. The photocatalytic activity of α-Fe2O3 films was assessed by the degradation of methylene blue (MB) under LED light; 15% enhancement of the degradation for the pretreated specimens was noticed.

Nitrogenous disinfection by-products (N-DBPs) in chlorinated drinking water are receiving increasing attention due to their elevated toxicities. An effective strategy to control N-DBP formation is to reduce their nitrogenous precursors (amino acids) before disinfection. This work was undertaken to study free amino acid l-tyrosine adsorption onto two activated carbons synthesized from date pits. The amino acid is plentiful in low-molecular weight algal organic matter, which helps the formation of nitrogenous and carbonaceous disinfection by-products during water treatment. The equilibrium adsorption of l-tyrosine was studied on well-characterized activated carbons prepared by KOH (ACK) and ZnCl2 (ACZ) activation, possessing textural properties evaluated by SEM analysis, N2 adsorption–desorption isotherms and FT-IR spectroscopy. Batch experiments were conducted to determine the activated carbons’ adsorption capacities. The effect of contact time, initial adsorbate concentration, solution pH, and temperature were studied. The Langmuir model gave the best fit for the experimental data of l-tyrosine with a maximum monolayer adsorption capacity of 178.57 and 102.04 mg·g−1 on ACK and ACZ, respectively. Thermodynamic parameters ΔG°, ΔH° and ΔS° were also estimated for the adsorption study. The adsorption was spontaneous and exothermic, and involved physisorption.

We investigated experimentally the composition of volatile isolates from the leaves and seeds of fraxinus angustifolia Vahl and their antimicrobial activity. The experimental work was supported by a theoretical study, using the Functional Density Theory. The calculations were performed at the B3LYP/6–31 g-d, p), in order to determine the structures of major volatile compounds and the different descriptors of reactivity and biological activity. The chemical composition of the volatile isolates obtained by hydrodistillation of the leaves and seeds are evaluated by the analytical method of gas chromatography-mass spectrometry (GC-MS). We found that the leaves are composed of abundant compounds, specifically, docosane methyl (30.2%), n-Pentacosane (28.5), α-cadinol (9.0%) and T-muurolol (5.9%). Moreover, the isolate from the seeds, is found to be mainly composed of α-cadinol (23.2%) and epi-methyljasmonate (34. 2%). Additionally, we perform antimicrobial activity tests on the volatile isolated using the zone of inhibition (agar disk-diffusion method) of four bacteria strains, mainly, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli. The values of leaves range from 100 to 300 µg of volatile compounds, whereas for the seeds the values lie between 20 and 300 µg. Furthermore, antifungal susceptibility tests are conducted on two yeast strains: Saccharomyces cerevisiae and Candida albicans. The seeds have a better inhibition than the leaves, with 20 and 300 µg respectively. The chemical compositions of the volatile fractions of leaves and seeds are correlated with the antimicrobial results. The reactivity descriptors are calculated to determine stability and microbiological activity of the above compounds. The Isopimaradiene presents the higher microbiological activity and the most stable T-muurololis.

Co-deposited nickel–chromium (Ni–Cr) onto the glassy carbon electrode (GCE) is successfully used as new amperometric sensor for the determination of salicylic acid (SA). SA is detected by a surface catalyzed oxidation, involving nickel(III) oxyhydroxides in alkaline solution. The performance of the biosensor Ni–Cr/GCE is characterized by cyclic voltammetry, chrono-amperometry, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and X-ray diffraction (XRD). The electrochemical behavior of the Ni–Cr alloy is qualitatively similar to that of pure nickel electrode. However, it is proposed that a higher degree of disorder of the oxyhydroxide layer structure is present on the top of the alloy. The electroactivity of Ni–Cr/GCE is studied as a function of the molar fraction (Xf%) of Cr3+ in the deposition bath. The results show that Ni–Cr/GCE exhibits a high electrocatalytic activity for SA oxidation. The Ni–Cr/GCE with 28Xf% Cr3+displays the best activity with a high response signal, a good sensitivity of 71.22 μA mM–1, a low detection limit of 0.1 μM (S/N = 3) and a fast response time (

The corrosion inhibition of mild steel by a drug substance, namely piroxicam, in HCl (1 M) solution was investigated. The Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization technique were used. EIS measurements showed larger capacitive loops in the presence of piroxicam. The inhibition efficiency was found to be dependent on the piroxicam concentration. From the polarization curves the corrosion current density ( $${{i}_{{{\text{cor}}}}}$$ ) decreased from 109.4 to 16.93 μA/cm2. The adsorption mode of the drug obeys to the Langmuir isotherm model. The free energy of adsorption (∆Gads) revealed a spontaneous process with a mixed interaction type i.e. physical and chemical. The kinetic study was conducted using the weight loss technique at the optimal piroxicam concentration (600 ppm). The density functional theory (DFT) method was used to determine the principal species, neutral or ionized drug, involved the inhibition mechanism. Scanning electron microscopy (SEM) was carried out for the surface characterization of the carbon steel after immersion in the aggressive medium in the absence and presence of the drug substance.

In this study, the photodegradation of organophosphorus (OPs) pesticides in the honey medium was evaluated under sunlight irradiation. Some of the 22 samples collected at different sites contained OPs pesticides (Methyl parathion, Coumaphos and Fenitrothion) with an average of 8 ng/g. Moreover, three samples were found with pesticide residue levels exceeding the maximum residue limits (MRL ≥ 50 ng/g) imposed by the standard water (WHO). Gas chromatography (GC) combined with a tritium electron capture detector system was used for the analysis of OPs pesticides in honey. Total degradation of the Methyl parathion was obtained in less than 60 min of irradiation. Moreover, the elimination of the other OPs found in the samples was also effective with a rate of 85% for Coumaphos and Fenitrothion after 50 min of sunlight irradiation. The kinetics of the photodegradation reaction of all OPs pesticides studied followed a pseudo-first order model.

New bio-composites were successfully synthesized from Enteromorpha compressa macro-alga (ECMA) and polyanilic matrix (PANI) through oxidative polymerization. To examine the ECMA effect on the PANI’s characteristics, different weights (5, 10, 15, 20 and 50%) of ECMA powder were incorporated into the polymer matrix. The in situ polymerization of aniline was confirmed by FTIR and UV–Vis spectroscopies which lead to the formation PANI emeraldine base. The XRD analysis showed that the crystallinity of PANI becomes more conspicuous with addition of ECMA as evidenced by the increased peaks intensities. The electrical conductivity measured by the four-probe method averages 10−2 S cm−1. The results showed that ECMA powder has a high ability as reinforcing material in the polymer matrix. As application, PANI–20% ECMA presents the best efficiency for the removal of yellow quinoline from aqueous solutions with an uptake yield of 85%. The adsorption isotherm is well described by the Freundlich model with a capacity of 118.906 mg g−1, and the experimental data were fitted with the pseudo-second-order kinetic models.