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Co/TiO2 catalysts with different cobalt loadings (3.8, 7.5 and 15 wt%) were prepared by impregnation method of Co(NO3)2 6H2O over titania. Samples containing Co(NO3)2·6H2O and TiO2 in stoichiometric proportions in order to obtain CoTiO3 and Co2 TiO4 phases were also synthesized. The effect of the calcination treatment at two different temperatures, 550 and 1150 °C, was investigated. Characterizations by several techniques, such as XRD, UV–vis–NIR, DRS, Raman and XPS, were carried out. XRD showed the coexistence of three phases: CoTiO3; Co2TiO4 and Co3O4 after calcination at 550 °C, while calcination at high temperature (1150 °C) led to single-phase systems (CoTiO3 or Co2TiO4). Diffuse reflection and XPS spectroscopy showed that divalent cobalt occupies octahedral sites in the ilmenite phase, and both tetrahedral and octahedral sites in the spinel phase. The catalytic performances of the prepared catalysts were evaluated in the oxidative dehydrogenation reaction (ODH) of ethane to ethylene, as a function of the Co content for Co/TiO2 catalysts and as a function of the calcination temperatures for the CoTiO3 and Co2TiO4 phases. Co(7.5)/TiO2 was the most active, although the conversion of ethane decreased in the first 150 min of the reaction, reaching values comparable to those of Co2TiO4 and CoTiO3; however, Co(7.5)/TiO2 was confirmed as having the best selectivity to ethylene in comparison with the bulk phases, CoTiO3 and Co2TiO4. The influence of the reaction mixture composition, specifically the presence of water, at different percentages, was investigated. There is a decrease in the overall ethane conversion and an increase in the ethylene selectivity when the percentage of water increases. This behavior can likely be attributed to an increase in the surface concentration of hydroxyl species (OH), resulting in heightened surface acidity.

One of the main challenges of photocatalysis is to find a stable and effective photocatalyst, that is active and effective under sunlight. Here, we discuss the photocatalytic degradation of phenol as a model pollutant in aqueous solution using NUV-Vis (>366 nm) and UV (254 nm) in the presence of TiO2-P25 impregnated with different concentrations of Co (0.1%, 0.3%, 0.5%, and 1%). The modification of the surface of the photocatalyst was performed by wet impregnation, and the obtained solids were characterized using X-ray diffraction, XPS, SEM, EDS, TEM, N2 physisorption, Raman and UV-Vis DRS, which revealed the structural and morphological stability of the modified material. BET isotherms are type IV, with slit-shaped pores formed by nonrigid aggregate particles and no pore networks and a small H3 loop near the maximum relative pressure. The doped samples show increased crystallite sizes and a lower band gap, extending visible light harvesting. All prepared catalysts showed band gaps in the interval 2.3–2.5 eV. The photocatalytic degradation of aqueous phenol over TiO2-P25 and Co(X%)/TiO2 was monitored using UV-Vis spectrophotometry: Co(0.1%)/TiO2 being the most effective with NUV-Vis irradiation. TOC analysis showed ca. 96% TOC removal with NUV-Vis radiation, while only 23% removal under UV radiation.

Aims: The present study was carried out to evaluate the quality and quantity of lipids and fatty acids in Mauritanian sardines (Sardinella aurita) and Moroccan sardines (Sardina pilchardus). Methods: Gas chromatography/mass spectrometry (GC/MS) and Fourier transform infrared (FTIR) analyses were adopted thereof. Results: The studied samples were found to be very rich in lipids: 17 – 26 % for Mauritanian sardinella and 45 – 48 % for Moroccan sardine. Thus, GC/MS analyses revealed that the fatty acids contents in both samples were subdivided into three essential groups: polyunsaturated, monounsaturated and saturated fatty acids. The semi-quantitative analysis results, calculated using chromatographic peak areas, have shown that Moroccan sardine is very rich in polyunsaturated fatty acids (mainly docosahexaenoic (DHA) and ecosapentaenoic (EPA) acids) and monounsaturated fatty acids (mainly oleic acid), compared to Mauritanian sardinella, who is very rich in monosaturated fatty acids (mainly palmitoleic acid). Conclusion: The lower valuable lipid content of sardinella was probably due to sampling conditions realized during the reproduction period. On the other hand, the omega-6/omega-3 ratio is higher in Mauritania sardinella than in Moroccan sardine. result: the studied samples were found very rich in lipids: 17 – 26 % for Mauritanian sardinella and 45 – 48 % for Moroccan sardine conclusion: The lower valuable lipid content of sardinella was probably due to sampling conditions realized during the reproduction period.

The present work is the first investigation of the electrocatalytic performances of ZrP

Ag-based semiconductors have attracted significant attention as promising visible-light photocatalysts for environmental purification. In this study, electronic and photocatalytic properties of AgTi2(PO4)3 NASICON-type phosphate, have been addressed in detail, combining experimental results and theoretical calculations. The as-prepared sample was characterized for its morphological, structural and optical properties by various techniques. The generalized gradient approximation by Perdew-Burke-Ernzerhof (GGA-PPE) within density functional theory (DFT) was used to investigate the electronic structure. We have applied corrective Hubbard U terms to Ti 3d orbitals in order to better reproduce the experimental band gap of 2.6 eV. The photocatalytic activity has then been performed for rhodamine B dye degradation under visible light illumination. Efficient dye degradation up to 97.2% was achieved in 120 min. In addition, the catalyst exhibited good stability over four consecutive cycles. Finally, combining experimental and theoretical findings, the origin of the photocatalytic activity was identified and a photodegradation mechanism was proposed.

In this work, we have reinvestigated the thermal degradation kinetics of synthetic gypsum (CaSO4·2H2O) using a novel approach based on peak deconvolution followed by the application of Model-Free isoconversional method. Gypsum was prepared using wet chemical route and characterized by conventional X-ray diffraction, in situ high-temperature X-ray diffraction (HT-XRD), infrared spectroscopy (IRTF-ATR), simultaneous thermal gravimetry, and differential thermal technique (TG/DTA). The physicochemical analysis showed that gypsum thermally degrades into calcium sulfate anhydrite (γ-CaSO4; anhydrite III) via an intermediate phase formed by calcium hemihydrate (CaSO4·0.5H2O; bassanite). HT-XRD analyses revealed the difference between the bassanite and anhydrite III phases, although they have a similar structure. The thermal kinetics of gypsum indicated a complex behavior of overall process mechanism consisting of overlapping contributions, which were separated into two individual ones using a mathematical deconvolution of Fraser Suzuki function. The separate thermal processes were analyzed using Model-Free isoconversional and Malek’s methodology. The kinetic results showed that both processes may be represented by Johnson–Mehl–Avrami [JMA(n)] equation which corresponds to nucleation and growth mechanisms, with n > 1. The first process corresponding to the partial dehydration of gypsum into bassanite was carried out by a two-dimensional JMA mechanism, while the second process, attributed to the complete dehydration of gypsum, was performed according to a three-dimensional JMA. Calculations of thermodynamic parameters have shown that the dehydration process of gypsum is accompanied by endothermic effects and requires heat, in agreement with the thermal analysis data.

A series of silver nanoparticles (Ag-NPs) loaded onto new mesoporous silica (MS), produced from natural cheap pumice was prepared via wet impregnation and characterized by means of several analytical techniques. Catalysts Ag–x/MS with x = 3, 10 and 20 wt% have been investigated in the gas conversion of isopropyl alcohol (IPA) under N2 and air atmospheres and exhibit a particular catalytic behavior different from conventional crystalline and supported silver-based catalysts. In N2 atmosphere, Ag–x/MS catalysts provide propene by dehydration process with selectivity greater than 95% whereas under the air atmosphere at low temperature (≤ 423 K), the reaction only produces acetone by oxidative dehydrogenation. This bifunctionality was due to special textural properties of MS support, characterized by high specific surface area (423 m2 g−1) and Bronsted acidic sites which are formed by bridged siloxanes (≡Si–O–Si≡) and silanols groups (≡Si–OH) leading to the formation of propene and on the other hand, to the high dispersion and redox properties of Ag-NPs under air atmosphere giving rise to “Ag-Ox” species which are selectively active for acetone production. The selective oxidative dehydrogenation toward acetone was confirmed by the non-detection of total oxidation products (CO/CO2) suggesting that the MS support preserves Ag-NPs against agglomeration and the redox properties of surface active “Ag-Ox” during the long-time service. The exceptional surface characteristics of MS produced from pumice and its promoting effect in the dispersion of active metal elements in the conversion of IPA exceeds broadly those obtained on various silica supports reported in the literature.

New mesoporous nano-silica with special physicochemical properties was successfully produced from silica-rich rocks using alkaline-based chemical treatment and low temperature. Pumice is a high quality silica-rich rock and used as raw material. An experimental design based on Response Surface Methodology (RSM) combined to Central Composite Design (CCD) was chosen to model and optimize the process parameters using three major independent variables that affect the production yield of nano-silica (reaction temperature, reaction time and molar ratio (n = nNaOH/nSilica). From analysis of variance (ANOVA), the three chosen variables were recognized as the influential factors for the silica production yield. The mesoporous nano-silica produced under optimum reaction conditions was characterized by various techniques. The chemical composition of nano-silica products is confirmed by X-Ray Fluorescence (XRF) and Energy Dispersive Spectroscopy (EDS) and the amorphous nature by X-Ray Diffraction (XRD). The microstructural analysis reveals that the nano-silica exhibits a mesoporous structure with an average pore diameter around 5.5 nm and an irregular distribution of nanoparticles as agglomerated clusters with an average value of 8 nm and very high specific surface area (422 m2 g−1) compared to the conventional silica (257 m2 g−1). The mesoporous nano-silica obtained here is economically inexpensive by comparison with other existing methods.

In the present work, a newly synthesized hybrid β-chitin/dicalcium phosphate anhydrous (DCPA) loaded with copper nanoparticles Cu(NPs) was investigated as an antibacterial agent using various strains. The hybrid β-chitin/DCPA was obtained via a mechano-chemical route and the Cu(NPs) supported over β-chitin/DCPA matrix was successfully synthesized from Cu(II) ions using the ultrasound-assisted method followed by in situ chemical reduction with sodium borohydride. All the prepared materials were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectroscopy (DRS), simultaneous thermogravimetry/differential thermal analysis (TG/DTA), and scanning electron microscopy (SEM-EDS). The localized surface plasmon resonance (LSPR) of Cu(NPs) after the reduction process was identified by the optical absorption spectroscopy, in the visible light region around 600 nm. The antibacterial activity of Cu-based materials was investigated against series of Gram-positive bacteria (S. aureus, L. monocytogenes) and Gram-negative (E. coli, P. aeruginosa) strains, using the microtitration assay by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Among the materials tested, Cu(NPs)/β-chitin/DCPA exhibited a high antibacterial effect exceeding CuII-β-chitin/DCPA and many others reported antibacterial agents, with a MIC value of 125 μg.mL−1 (6 μg.mL−1 of copper). The excellent antibacterial result was related to high dispersion properties of the hybrid support (β-chitin/DCPA) which avoid the aggregation of Cu(NPs) via various surface bonds with β-chitin biopolymer. Copper-based materials synthesized here exhibit promising antibacterial activities which can be explored in more details in others bacterial strains.

Silver based-nanoparticles (Ag NPs) have been recently shown to be promising catalysts for the degradation of toxic organic dyes in wastewater despite the challenges of recycling. In this paper, self-supported Ag NPs were obtained at the surface of AgTi2(PO4)3 NASICON-type phosphates through in situ chemical reduction by sodium borohydride (NaBH4). The adopted approach enables the self-growth of zero-valent Ag NPs on the NASICON matrix, and concomitantly leads to the formation of Ag1−xNaxTi2(PO4)3. The crystalline structure, morphology and phase composition of the Ag nanocomposite has been characterized by several techniques. The catalytic performance of the as-fabricated Ag NPs/Ag1−xNaxTi2(PO4)3 has then been verified in the reduction of methylene blue (MB) and methyl orange (MO) dyes, chosen as target pollutants. Our findings reveal a good catalytic activity with an efficiency and time of reaction of respectively ∼ 96.30% and 320 s in the case of the MB reduction and ∼ 94.60% and 270 s in the case of the MOreduction. Additionally, the initial AgTi2(PO4)3 phase can be regenerated via simple calcination route and recycled up to five times with no appreciable loss of catalytic activity.

This study focused on a detailed examination of the thermal behavior of Brushite-based calcium phosphate (CaHPO 4 .2H 2 O, DCPD) to identify and characterize the intermediate phases which have been the subject of previous several controversies. For that, in situ high-temperature X-ray diffraction supported by infrared spectroscopy, thermal analysis, and scanning electron microscopy analysis were used and the results showed that the progressive thermal stress of DCPD in air resulted in a heterogeneous formulation consisting of dibasic calcium phosphate anhydrous (CaHPO 4 , DCPA) and an amorphous phase, which appears at low temperatures (~160 °C) and persists up to 375 °C. The deep examination of the amorphous phase by infrared spectroscopy revealed that its chemical composition is similar to that of disordered calcium pyrophosphate (Ca 2 P 2 O 7 , CPP) with the appearance of a characteristic band δ(P-O-P), located at 740 cm -1 . This IR band is shifted to low frequencies (725 cm -1 ) as the temperature is increased, indicating the crystallization of the amorphous phase into γ-CPP. The high temperature treatment (≥ 375 °C) leads to b-CPP polymorph. According to the present characterization results, obtaining pure DCPA from the thermal dehydration of DCPD is not effective and leads to biphasic materials including an amorphous phase.

In this study, the essential oil of Origanum vulgare was evaluated for putative antibacterial activity against six clinical strains and five reference strains of Aggregatibacter actinomycetemcomitans, in comparison with some antimicrobials. The chemical composition of the essential oil was analyzed, using chromatography (CG) and gas chromatography&ndash, mass spectrometry coupled (CG&ndash, MS). The major compounds in the oil were Carvacrol (32.36%), &alpha, terpineol (16.70%), p-cymene (16.24%), and Thymol (12.05%). The antimicrobial activity was determined by an agar well diffusion test. A broth microdilution method was used to study the minimal inhibitory concentration (MIC). The minimal bactericidal concentration (MBC) was also determined. The cytotoxicity of the essential oil (IC50) was &lt, 125 &micro, g/mL for THP-1 cells, which was high in comparison with different MIC values for the A. actinomycetemcomitans strains. O. vulgare essential oil did not interfere with the neutralizing capacity of Psidium guajava against the A. actinomycetemcomitans leukotoxin. In addition, it was shown that the O. vulgare EO had an antibacterial effect against A. actinomycetemcomitans on a similar level as some tested antimicrobials. In view of these findings, we suggest that O.vulgare EO may be used as an adjuvant for prevention and treatment of periodontal diseases associated to A. actinomycetemcomitans. In addition, it can be used together with the previously tested leukotoxin neutralizing Psidium guajava.

In this work, the mineralogical characteristics and the assessment of the petroleum potential of organic carbon-rich sedimentary rock (CK sample) originating from the western part of the Central Kongo were the subject of a preliminary analysis and the results were compared with those of Moroccan oil shales. The mineralogical characterization was carried out using X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Fourier Transform Infra-Red (FTIR) spectroscopy, Thermal Gravimetry/Differential Thermal Analysis (TG/DTA) and Scanning Electronic Microscopy (SEM-EDX). The results show that the examined sedimentary rock contain a significant part of minerals, about 80%, consisting of quartz, clays and pyrite, similar to those frequently found in oil shales. The pyrolysis also indicates the presence of volatile matter between 250 and 580°C, attributed to the Organic Matter (OM) disseminated within the sedimentary rock as was shown in several carbon-rich materials. The detection of pyrite in the CK sample reveals the existence of a reducing environment during the preservation period of OM in the source rock. The assessment of the petroleum potential using the basic Rock-Eval method associated with the elemental analysis and 13C Cross Polarization/Magic Angle Spinning Nuclear Magnetic Resonance (13C CP/MAS NMR) spectroscopy indicated a very good organic richness (TOC=10.77%), very good petroleum potential (S2=80.4 mgHC/g rock) with the sapropelic OM described as type I kerogen (H/C molar ratio of 1.71) characterized by high hydrogen index (HI=746 mgHC/g TOC) and low oxygen index (OI=13 mgCO2/g TOC) values. The Rock-Eval results were confirmed by 13C CP/MAS NMR spectroscopy which shows the exclusive presence of aliphatics. The mineralogical and petroleum characteristics of CK sample show a great resemblance with those of known oil shales such as Moroccan oil shales and its kerogen is probably related to a marine or lacustrine environment which formed in anoxic sedimentary rocks and with a thermal evolution that has just reached the early stage of the oil window

Certain reservations regarding the high energy costs needed for Portland cement production and eco-friendliness of the cement synthesis process are pointed out. Belite clinker synthesis offers an effective alternative approach capable of addressing these reservations by producing cements at reduced temperatures/CO2 emission. The present study suggests a new method to synthesize belite clinkers at even lower temperatures by incorporating the natural fluorite (CaF2) into a mixture of limestone and alumina sludge originated from the water purification plants. The obtained clinkers and their respective cements are characterized by free lime contents, X-ray fluorescence, X-ray diffraction, scanning electron microscopy, refusal, Blaine fineness and mechanical resistance analyses. The obtained results reveal that the synthesized belite cement possesses mechanical strength similar to that of ordinary belite cement. In addition, the introduction of CaF2 into the clinkers not only lowers their preparation temperatures but also facilitates the formation of crystalline phases which eventually leads to inproved hydraulic properties of the cement.

A green and efficient synthesis of new sulfonamide-1,2,3-triazoles 5 in heterogeneous conditions has been developed. The procedure involved one-pot four-component tandem sulfonamidation/azidation/1,3-dipolar cycloaddition (1,3- DC ) reactions under a cooperative effect of ultrasound irradiation and Cu (II) supported on amorphous mesoporous silica [mSiO2-Cu (II)] catalysis at room temperature in aqueous medium. In addition, the 1,4-disubstituted 1,2,3-triazoles 5 were synthesized by regioselective and chemoselective methods to afford the pure products in excellent yields and short reaction times under ultrasonic irradiation. The supported catalyst has been prepared from copper (II) nitrate by simple method using ultrasound activation and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method and Barrett-Joyner-Halenda (BJH) method. Also, the catalyst is easily prepared, stable, efficient, selective, and reusable under ultrasonic conditions.

This study focused on a detailed examination of the thermal behavior of Brushite-based calcium phosphate (CaHPO4•2H2O, DCPD) to identify and characterize the intermediate phases which have been the subject of previous several controversies. For that, in situ high-temperature X-ray diffraction (HT-XRD) supported by Fourier transform infrared spectroscopy (FTIR), simultaneous thermal gravimetry and differential thermal analysis (TG/DTA), and scanning electron microscopy (SEM) analysis were used and the combination of results showed that the progressive thermal stress of DCPD in air resulted in a complex heterogeneous formulation consisting of dibasic calcium phosphate anhydrous (CaHPO4, DCPA) and an amorphous calcium phosphate, which appears at low temperatures (~160 °C) and persists up to 375 °C. This amorphous phase was identified as a disordered calcium pyrophosphate (Ca2P2O7, CPP) by the appearance in FTIR spectra of a characteristic band δ(P—O—P) of pyrophosphate groups, located at 740 cm−1. This band is shifted to low frequencies (725 cm−1) as the temperature is increased, indicating the crystallization of the amorphous CPP material into γ-CPP. The high temperature treatment (≥ 375 °C) leads to β−CPP polymorph. The quantification of the amorphous CPP phase by HT-XRD analysis depends on the heating rate of the decomposition of DCPD and presents a maximum at 300 °C for 10 °C min−1. According to the present characterization results, obtaining pure DCPA from the thermal dehydration of DCPD is not effective and leads to biphasic materials including a disordered calcium pyrophosphate phase.

The kinetic analysis of the complex process of Moroccan Rif oil shale pyrolysis was studied in detail by thermogravimetric (TG) analysis and its derivative (DTG) under non-isothermal conditions. The investigated pyrolysis region, located between 325 and 600 °C, is formed by partially overlapping peaks and it was successfully separated into three discrete processes using the mathematical Fraser-Suzuki algorithm that accommodates asymmetric functions. For each separated process, the isoconversional differential and integral Model Free methods were used to evaluate activation energy and two Master plots fitting methods were explored to get reliable kinetic models. The main pyrolysis step of Moroccan Rif oil shale involves the devolatilization of organic matter including bitumen and kerogen respectively and subsequent decomposition of pyrite mineral FeS 2 . The first process represents the principal pyrolysis kinetic in accordance with dominance of bitumen products in the studied oil shale. By applying the nonlinear least square analysis to kinetic data, it was found that all processes were well described by n-th order kinetic equations, with n ≈ 1, for the first and third processes and n ≈ 1.67 for the second process. Besides, the thermodynamic functions of activated complexes (ΔS*, ΔH* and ΔG*) for the pyrolysis step of studied oil shale were calculated and discussed.

This paper presents a comparative study about the evaluation of antioxidant activity and corrosion inhibition in Kenitra, Marrakesh and Taiz. An interesting topic, indeed polyphenols can improve or help to reduce oxidative stress in the treatment of digestive problems, weight management difficulties, diabetes, hypertension, arteriosclerosis and damage fatty tissue. Therefore, the authors deal with the measurement of polyphenol content and evaluation of the antioxidant activity of lemon peels in Kenitra , Marrakesh and Taiz.The authors performs empirical analyzes on lemon peels. The total polyphenol contents of the ethanolic extract of lemon peels were measured. It was to be 30. 23, 26. 346 and 20.961 mg/CE/g in Kenitra, Marrakech, and Taiz, respectively. Moreover, the DPPH radical scavenging activity of ethanolic extract of dried lemon peels was higher than 200μg/ml concentration. They were 73.47%, 47.36%, and 32.09in Kenitra, Marrakech, and Taiz, respectively. Also, the IC50 values of ethanolic extracts calculated from the percentage inhibitions at the same concentration. Inhibition (IC50) which obtained in Kenitra was 123.089 μg/ml. It was lower compared to the ethanol extract of Marrakech and Taiz that were 197.418, 276.750μg/mL, respectively. Therefore, the extract which is containing a high amount of phenolic is showed high radical scavenging activity. In addition, the maximum inhibition efficiencies for 2 mL L-1 of the inhibitor at 298 k were 98, 12% and 84, 85 % in Kenitra and Taiz, respectively. These values obtained through polarization curve measurements.

In this paper, we have employed multi-stage parallel reaction approach and Fraser–Suzuki distribution method to fit the non-isothermal TG/DTG curves resulting from oxidation of Moroccan Timahdit (X-layer) oil shale. The kinetic study was conducted to overcome the insufficiencies of the previous works, which oversimplified the oxidation processing having complex behaviors. The differential curves (DTG) of thermal oxidation of Timahdit organic matter were separated into two independent reactions. Based on the results of the deconvolution method, the kinetic mechanism was obtained using Malek’s procedure, followed by the determination of the apparent activation energy Eα using isoconversional model free methods of Friedman, Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS). The obtained values of Eα show that the first oxidation process is more energetic than the second. This behavior is correlated to nature of organic matter including in Timahdit oil shale. The kinetic modeling results for each individual peak showed that the thermal oxidation process is controlled by nth order reaction mechanism with n > 1, unlike to simple first order mechanism predicted by fitting methods.

In this contribution, we are presenting the study of structural and thermal decomposition kinetics of synthesized calcium hydroxyzincate dihydrate CaZn2(OH)6·2H2O (CZO). The characterization of the prepared and calcined precursors was done by X-ray diffraction and Fourier Transform Infrared techniques and indicates that CZO exhibits a monoclinic structure with space group P2 1 /c. Calcining this material at 200 °C leads to a heterogeneous mixture composed of ZnO, Ca(OH)2, and an amorphous Zn(OH)2. When the temperature is >400 °C, only ZnO and CaO phases were detected by XRD analysis. The thermal decomposition kinetics of CZO was evaluated by thermogravimetry and derivative thermogravimetry in N2 atmosphere under non-isothermal conditions. The kinetic parameters such as the activation energy (E α ) and reaction model (f(α)) revealed the complex nature of the decomposition process, consisting of several steps. The separation of overlapped peaks was performed by applying the Fraser–Suzuki procedure to the experimental DTG data and the activation energy was then calculated for each individual peak by Friedman method confirming the fair single-step mechanism of the first three processes. On the basis of kinetic results, a thermal decomposition mechanism of CZO material has been proposed and correlated to structural nature and stability of the resulting phases. The CaO∙ZnO based catalyst is formed according to a limited nucleation and growth mechanism at low temperatures and three complex processes occur afterwards when the structure cleaves.

In this study, we have synthesized and performed the thermal decomposition kinetics of anhydrous calcium phosphate monetite CaHPO4 under air atmosphere by TG/DTG and DTA techniques using non-isothermal experiments. The prepared and calcined products at 500 °C were characterized by powder X-ray diffraction, infrared spectroscopy, transmission electron microscopy and X-ray microanalysis. The degradation of CaHPO4 was observed between [425–490 °C] and leads to the formation of calcium pyrophosphate by condensation of orthophosphate groups. The kinetic parameter results achieved by the isoconversional methods combined to Malek’s procedure showed that the thermal dehydroxylation is a single-step process which related to crystal nucleation and growth mechanism, according to JMA (n) model, with n = 1.37 and an activation energy of Friedman E α = 299.4 ± 2.1 kJ mol−1. The thermodynamic functions (ΔS*, ΔH* and ΔG*) of the thermal dehydroxylation step were calculated using the activated complex theory. The obtained values showed that the reaction is directly related to the introduction of heat and is non-spontaneous process.

Pyrolysis is a promising way to upgrade large amounts of residues from olive oil processing into charcoal. Pyrolysis of the stone and pulp fractions needed to be investigated before conclusions could be drawn. We subjected the olive stone fraction, the pulp fraction, and a mixture of the two to dynamic pyrolysis and isothermal pyrolysis at 360°C. We characterized the charcoals resulting from isothermal pyrolysis at 360°C for different durations in terms of the fixed-carbon content (FCC), carbon content (CC), and high heating value (HHV). We found that charcoal yield from the pulp was higher than that from the stones, which were 38.1% and 32.9%, respectively, after pyrolysis for 360 min. This seemingly unexpected result was due to the high contents of ash (6.22%) and extractives (13%) in the pulp, which remained completely and partially undecomposed, respectively, in the charcoals and are accounted for when calculating yields. However, charcoals obtained from the stones were of higher quality than charcoals from the pulp, with lower ash content and higher FCC, CC, and HHV. In particular, the FCC, CC, and HHV after pyrolysis for 360 min were 73.2%, 74.4%, and 30.2 MJ/kg for the stones and only 61.8%, 63.2%, and 25.9 MJ/kg for the pulp, respectively. Depending on the required quality of the final charcoal, our results help decide whether to pyrolyse the entire olive residues or only one of the two fractions, more likely the stones.

In this study, we have reinvestigated the thermal decomposition kinetics of iron(III) phosphate dihydrate FePO 4 ∙2H 2 O in air atmosphere by TG/DTG and DTA techniques using non-isothermal experiments. The apparent activation energy E α was determined by the differential and integral isoconversional methods and suggested that the decomposition reaction is complex and follows multi-step processes. A mathematical deconvolution technique using Fraser–Suzuki equation was applied to the DTG curves and allowed the separation of two distinct processes. The apparent activation energies determined by the isoconversional Friedman’s method were 93.05 ± 3.80 kJ mol −1 and 73.41 ± 3.14 kJ mol −1 for the first and second process respectively. Using Malek’s procedure for each process, the characteristics of y ( α ) and z ( α ) functions showed that the kinetic reaction follows the Johnson–Mehl–Avrami model (JMA( n )). One-dimensional nucleation and growth mechanism occurred firstly with f ( α 1 ) = 1.272(1 − α 1 )[−ln(1 − α 1 )] (1 − 1/1.272) and pre-exponential factor A 1 = 9.11 × 10 10 min −1 . After 27% of total conversion, a two-dimensional nucleation and growth mechanism becomes predominant with f ( α 2 ) = 2.306(1 − α 2 )[−ln(1 − α 2 )] (1 − 1/2.306) and A 2 = 1.28 × 10 8 min −1 . It was concluded that the two decomposition processes of FePO 4 ∙2H 2 O are closely interrelated and thus neglected the first process leads to incoherent results.

Pumice is a porous volcanic rock containing a significant proportion of silica and alumina, and which has a low iron content. This natural, silica-rich material attracts wide attention because of its applications in adsorption processes, heterogeneous catalysis and nanotechnology. In this contribution, the white amorphous silica nanoparticles were extracted using an optimized alkaline treatment and an acid-precipitation process using grey pumice powder. The isolated amorphous silica SiO2 was characterized via X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electronic Microscopy (TEM-EDS), N2 adsorption/desorption measurements and simultaneous Thermal Gravimetry/Differential Thermal Analysis (TG/DTA). The obtained results indicated that the nanosilica powder was successfully prepared via the acid-base route with a predominantly amorphous mesoporous structure having a high surface area (422m2/g). The TEM images exhibited relatively homogeneous dispersed nanosilica particles with small sizes about 5–15 nm, in accordance with XRD data. Thermal analysis of the silica powder under air atmosphere showed total mass losses of 6.5%, with endothermic effects corresponding to the removal of water molecules and the OH of silanol groups contained in the material. The investigations performed in this work have indicated that there is great scope for pumice exploitation as a raw material in the production of amorphous silica nanopowder on large scale.