Alkaline Earth Ca Research Articles

The effect of alkaline earth metals Ca, Mg on Cu–Fe catalysts synthesized by solvothermal method and their CO2 hydrogenation performance

Catalytic hydrogenation of CO2 to hydrocarbons reduces carbon emissions and makes better use of CO2 as a C1 resource to supplement chemical feedstocks. Herein, we report the effect of the introduction of Ca on the composition and performance of Cu–Fe catalysts synthesized by hydrothermal methods during the synthesis process. The catalysts were characterized by ICP, SEM, XRD, TEM, H2-TPR, CO2-TPD, N2 adsorption and desorption, and XPS. The results showed that the variation of the Ca (or Mg)Cu feeding ratio causes the change of Cu content in the catalyst. The change in Cu content also caused a change in the catalytic performance of the catalyst. In particular, the Cu content in the catalyst was 3.33% at Ca: Cu = 4:12. At this time, the highest CO2 conversion of 49.37% and C5+ selectivity of 59.89% were achieved with the reaction conditions (320 °C, 3 MPa, 12,000 mL·g-1 cat·h−1, N2/CO2/H2 = 12/12/36, TOS: 8 h) for the Cu–Fe catalyst. Further testing and analysis revealed that the increase in Cu content leads to enhanced Cu–Fe interaction in the catalyst, which is the fundamental reason for the change in catalytic performance.

The effects of dyes and bleaches on the sorption and desorption of trace elements in human hair.

Trace element concentrations and isotope ratios of hair reflect the blood levels at the time of hair formation, but can be affected by external factors such as dyeing, bleaching, and bathing. To investigate the effect of dyeing, bleaching, and bathing on hair, hair was immersed in tap water, and changes in trace element concentrations and the Sr isotope ratio were observed over time. During soaking, alkaline earth metals (Ca, Mg, and Sr) from tap water were gradually absorbed into the hair over time. After about one day, the adsorption capacity of hair reached a maximum and the reverse reaction started to occur. In contrast, alkaline metals (Na and K) behaved in reverse. In dyed and bleached hair, Na was significantly desorbed from the hair and gradually migrated to the water over time. The adsorption and desorption of trace elements were minimal in untreated original hair, but much higher in dyed and bleached hair. Thus, dyeing and bleaching appear to damage the hair surface structure and greatly promote the exchange of trace elements. The rapid exchange of trace elements, including Sr, between hair and tap water observed in this study indicates that hair samples can be easily contaminated during bathing.

Elastic Properties and Hardness of Mixed Alkaline Earth Silicate Oxynitride Glasses.

The incorporation of nitrogen as a second anion species into oxide glasses offers unique opportunities for modifying glass properties via changes in glass polymerization and structure. In this work, the compositional dependence of elastic properties and the nanoindentation hardness of mixed alkaline-earth silicate oxynitride glasses containing a high amount of nitrogen (>15 at.%, c.a. 35 e/o) were investigated. Three series of silicon oxynitride glass compositions AE–Ca–Si–O–N glasses (where AE = Mg, Sr, and Ba) having varying amounts of modifiers were prepared using a new glass synthesis route, in which a precursor powder of metal hydrides was used. The obtained glasses contained high amounts of N (19 at.%, c.a. 43 e/o) and modifier cations (26 at.%, c.a. 39 e/o). Mg–Ca–Si–O–N glasses had high values of nanohardness (12–16 GPa), along with a reduced elastic modulus (130–153 GPa) and Young’s modulus (127–146 GPa), in comparison with the Sr–Ca- and Ba–Ca-bearing oxynitride glasses. Both the elastic modulus and the nanohardness of AE–Ca–Si–O–N glasses decreased with an increase in the atomic number of the AE element. These property changes followed a linear dependence on the effective cation field strength (ECFS) of the alkaline earth (AE) modifier, according to their valences and ionic radii. No mixed alkaline-earth effect was observed in the current investigation, indicating that the properties were more dictated by the nitrogen content.

Green Synthesis of 3-Hydroxybutyraldehyde from Acetaldehyde Catalyzed by La-Ca-Modified MgO/Al2O3

3-hydroxybutyraldehyde (3-HBA) is mainly employed to synthesize 1,3-BDO (1,3-butanediol), which is one of the most important components in cosmetics moisturizers. In this study, a series of composite oxide catalysts were prepared by bringing alkaline earth metal Ca and rare earth metal La to the composite oxide MgO/Al2O3, which were made through the co-precipitation method. These catalysts were applied in the synthesis of 3-HBA through acetaldehyde (AcH) condensation. The structure, texture, and acidic properties of these catalysts were characterized using various characterization methods, and the effects of catalyst composition, reaction temperature, reaction pressure, and residence time on the conversion of AcH were investigated as well. The results showed that the introduction of Ca and La weakened the acidic property and enhanced the basic property, which favored the AcH condensation to synthesize 3-HBA. At a temperature of 20 °C, pressure of 200 kPa, and residence time of 70 min, 0.5%La-2.3%Ca-2MgO/Al2O3 exhibited a better catalytic activity, and the conversion of AcH reached 95.89%. The selectivity and yield of 3-HBA were 92.08% and 88.30%, respectively. The stability test indicated that the high AcH conversion could be maintained for 5 h.

Effect of leaching pretreatment on the inhibition of slagging/sintering of aquatic biomass: Ash transformation behavior based on experimental and equilibrium evaluation

In this study, aquatic biomasses of Ulva lactuca and Hydrilla verticillata were pretreated by water and acid washing. A comprehensive assessment strategy, including systematic experiments and equilibrium calculations, was used to study the migration of elements and transformation characteristics of minerals in aquatic biomass ash before and after leaching pre-treatment. The effect of leaching pre-treatment on slagging inhibition was analyzed. Owing to the different mineral compositions and characteristics of the two types of aquatic biomass, the serious slagging caused by Ulva lactuca was related to the presence of alkali (Na and K) sulfate. In contrast, the presence of silicate/aluminosilicates in Hydrilla verticillata had a greater effect on slagging. The removal of alkali metals (especially Na and K) and Cl from aquatic biomass by leaching pretreatment was conducive to alleviating aquatic biomass slagging. Following leaching pretreatment, the alkali index of the aquatic biomass was reduced to <0.17, and the Cl content was reduced to <0.3%. Furthermore, the abundant alkaline earth metals (Ca and Mg) in aquatic biomass can inhibit slagging by generating high-melting-point alkaline earth metal silicates or phosphates. The removal rate of alkaline earth metal oxides by acid washing was >96% and >78% in Ulva lactuca and Hydrilla verticillata, respectively, while water washing was less effective. Although water and acid washing can alleviate slagging, a comparative investigation showed that water washing of aquatic biomass had better outcomes than acid washing. Therefore, water washing is a better way to comprehensively pre-treat aquatic biomass. The results obtained can help promote the thermochemical utilization of aquatic biomass on an industrial scale.

Ab initio Investigation of the Structural and Electronic Properties of Alkaline Earth Metal - TiO2 Natural Polymorphs

Titanium (IV) oxide (TiO2) has gained much attention due to its application in technologies such as optoelectronics, electronics, sensors, photocatalysts, and sustainable energy generation. However, its optical absorption falls in the ultraviolet part of the electromagnetic spectrum, resulting in a low absorption ratio of solar light. In addition, rapid electron-hole recombination limits its photocatalytic activity. To extend the application range of TiO2, the structural and chemical properties can be modified by adding various dopants to tune its electronic structure for applications within a wider range of the solar energy spectrum and ideally extend towards the visible region, which forms the dominant part of the solar energy spectrum. In this study, the structural and electronic properties of three polymorphs of TiO2 have been studied using density functional theory (DFT) as implemented in the Quantum ESPRESSO simulation package. The exchange-correlation potential has been treated with the generalised gradient approximation (GGA). Cationic substitution with non-toxic alkaline earth metal dopants Mg and Ca has been carried out with the aim of modifying the electronic structure of the polymorphs of TiO2. On 1–4% Mg and Ca cationic substitution, there is a slight expansion of the optimal unit cell volume and modulation of the band gap energy by raising the valence band maximum to higher energies. In addition, dopant inter and intra-band states are observed.

Isolation and Investigation of Natural Rare Earth Metal Chelating Agents From Calothrix brevissima - A Step Towards Unraveling the Mechanisms of Metal Biosorption.

In this study water soluble compounds that form complexes with Rare Earth Elements (REE) and other metals were isolated from Calothrix brevissima biomass with chromatographic methods for the first time. Molecular characterization showed that the isolated compounds are most likely polysaccharides comprised of arabinose, xylose, mannose, galactose and glucose. FT-IR analysis revealed functional groups involved in the binding mechanism of Tb are likely sulfate- and to a lesser extend hydroxyl-groups. The binding specificity of the isolated compounds was investigated with different metal solutions. Here, ions of the alkali and alkaline earth metals Na, K, Mg and Ca showed no competition for Tb-binding even at 10-fold excess concentration. Ions of the elements Co and Pb on the other hand replaced Tb at higher concentrations. Addition of the isolated compounds significantly reduced the precipitation of Eu at pH-values between 6.7 and 9.5, indicating that the interaction between the isolated chelators and Rare Earth Metals is stable even at high pH-values.

Molecular Probing of DOM Indicates a Key Role of Spruce-Derived Lignin in the DOM and Metal Cycles of a Headwater Catchment: Can Spruce Forest Dieback Exacerbate Future Trends in the Browning of Central European Surface Waters?

Peatlands of the Northern Hemisphere and Central European coniferous forests experience significant environmental change. The resultant browning of surface waters, that is, elevated concentrations of dissolved organic matter (DOM) and metals, is of interest in the context of the global C cycle, peatland and forest management, and water treatment. In an attempt to identify the causes of this process in the Harz Mountains (Central Germany), we studied the spatiotemporal variations in DOM molecular composition (thermally assisted hydrolysis and methylation combined with GC-MS) and metal concentrations in headwater stream samples. We found strong relationships between DOM and metals and seasonal variations in the DOM quality and tentatively DOM-metal binding mode: during summer base flow, DOM and metal concentrations are low, and all elements other than the alkali and alkaline earth metals (Ca, Mg, Sr, K, and Na) are positively correlated to DOM, whereas during spring and autumn (high discharge), only metals with strong affinity for DOM (Fe, As, Cu, Cr, Pb, and Ti), but not weakly binding ones (Al, Cd, La, Mn, Ni, Zn, and Zr), are correlated to DOM, indicative of selectivity in DOM-metal interactions. The products of polyphenols are the key ingredients of the DOM-metal complexes. We argue the importance of spruce lignin-derived vanillic acid moieties, which are involved in weak (all seasons) and strong, multidentate and/or colloidal, binding (spring and autumn) of metals. Considering the ongoing spruce forest dieback and climate change acceleration, it is tempting to conclude that spruce necromass and forest soils may release vast amounts of lignin-derived DOM and associated metals to headwater streams. This would have significant implications for forest soil C stocks and the management of connected drinking water reservoirs.

Reduced alkaline earth metal (Ca, Sr) substituted LaCoO3 catalysts for succinic acid conversion

Surface distribution and particle size play a key role in the catalytic activity of substituted La1−xAxCoO3 (A = Ca/Sr, x = 0.2–0.4) perovskites.

Pre-pyrolysis metal and base addition catalyzes pore development and improves organic micropollutant adsorption to pine biochar

Biochars were produced from pine feedstock pretreated with aqueous base, NaOH, at pH 9 and 11, and alkali and alkaline earth metals (AAEMs) Na, K, Ca, and Mg at 10−3 and 1 M. The effects of base and AAEM feedstock pretreatment on biochar surface area, pore size distribution, and adsorption capacity of two organic micropollutants (OMPs), 2,4-dichlorophenoxyacetic acid and sulfamethoxazole, from surface water with background dissolved organic matter (DOM) were evaluated. Base pretreatment significantly increased surface area within micropores (<2 nm diameter). AAEM pretreatment caused pore widening, increasing surface area within pores >2 nm in diameter. The catalytic activity of AAEMs, assessed by generation of non-micropore surface area, decreased in the following order: Ca > K > Na > Mg. All pretreated biochars outperformed untreated biochar for OMP adsorption. Biochar pretreated by aqueous base at pH 11 showed over an order of magnitude increase in OMP adsorption, nearly matching the performance of commercial activated carbon. OMP adsorption from surface water was positively correlated with biochar micropore surface area and negatively correlated with non-micropore surface area, which was linked to higher levels of DOM competition. Base and AAEM pretreatment of biochar feedstocks can increase OMP adsorption for water treatment applications by tuning pore structure and surface area.

Multi-stability modulating of alkaline-earth metal doped LaCoO3 for rechargeable Zn-air batteries

• Alkaline earth mental doped LaCoO 3 (Be, Mg, Ca, Sr, and Ba) with controlled Co 3+ electron spin state and Co-O covalency band. • 2.5 at.% Ca doped LaCoO 3 exhibits remarkable bifunctional ORR/OER stability without any deterioration after multiple electrocatalytic cycling operation. • Doping Ca atoms coupling with oxygen vacancy significantly decreases the energy barrier of LaCoO 3 with the lower theoretical overpotential (0.49 V). • The corresponding rechargeable ZnABs exhibit excellent discharging/charging durability (220 h) and higher specific capacity (793.0 mAh g −1 ). The realization of prominent and permanent electrocatalytic oxygen reduction/evolution reaction activities in perovskites is an intensively demanding and daunting challenge. Herein, a series of LaCoO 3 doped by alkaline earth metal (Ca) with controlled Co 3+ electron spin state and created oxygen vacancies are designed to enhance their super stable bifunctional electrocatalytic activities. Experiments demonstrate that Ca-doped LaCoO 3 exhibits remarkable bifunctional ORR/OER activity with lower potential gap (ΔE=0.89 V), excellent multi-durability in onset overpotential and current density without any deterioration after long-term OER/ORR cycling operations under the same conditions, which is beneficial for the discharging/charging durability (220 h) of rechargeable Zn-air batteries. Density functional theory calculations demonstrate that the intermediate spin state stabilized Co 3+ active sites near oxygen vacancies sufficiently optimize the binding strength between oxygen-related intermediates and the Ca-doped LaCoO 3 surface, simultaneously accelerate the surface charge transfer during electrocatalytic process, giving rise to the low theoretical overpotential (0.49 V) for the formation of OH*. This finding provides a promising strategy for substantially increasing the bifunctional electrocatalytic activity and stability of perovskite oxides.

Anti-Electrostatic Main Group Metal–Metal Bonds That Activate CO2

There has been growing interest in the CO2 capture and reduction by transition-metal-free catalysts. Here we performed a proof-of-concept study using an ab initio valence bond method called the block-localized wave function (BLW) method. The integrated BLW and density function theory (DFT) computations demonstrated that heterobimetallic Ae+/Al(I) (Ae represents alkaline earth metals Mg and Ca) Lewis acid/base combinations without transition metals can facilely capture and activate CO2. There are two remarkable findings in this study. The first concerns the ionic nature of the metal-metal bonds. The experimentally synthesized low valent aluminum compound with a bidentate β-diketiminate (BDI) ligand, or (BDI)Al(I) in brief, is a Lewis base due to the lone pair on the aluminum cation though overall Al(I) is positively charged. Al(I) can form ionic metal-metal bonds with the alkaline earth metals of the positively charged Lewis acids (BDI)Ae+. This type of ionic metal-metal bonds is counterintuitive and antielectrostatic as both metals carry positive charges. The second finding is the CO2 activation mechanism. (BDI)Al(I) can effectively bind and activate CO2 by transferring one electron to CO2, and the resulting complex can be best expressed as [(BDI)Al(I)]+[CO2]-. The participation of (BDI)Ae+ further enhances the capture and activation of CO2 by (BDI)Al(I).

Manganese-mediated hydrochemistry and microbiology in a meromictic subalpine lake (Lake Idro, Northern Italy) - A biogeochemical approach

This study presents the findings from several field campaigns carried out in Lake Idro (Northern Italy), a deep (124 m) meromictic-subalpine lake, whose water column is subdivided in a mixolimnion (~0–40 m) and a monimolimnion (~40–124 m). Hydrochemical data highlight two main peculiarities characterizing the Lake Idro meromixis: a) presence of a high manganese/iron ratio (up to 20 mol/mol), b) absence of a clear chemocline between the two main layers. The high manganese content contributed to the formation of a stable manganese dominated deep turbid stratum (40–65 m), enveloping the redoxcline (~45–55 m) in the upper monimolimnion. The presence of this turbid stratum in Lake Idro is described for the first time in this study. The paper examines the distribution of dissolved and particulate forms of transition metals (Mn and Fe), alkaline earth metals (Ca and Mg), and other macro-constituents or nutrients (S, P, NO3-N, NH4-N), discussing their behavior over the redoxcline, where the main transition processes occur. Field measurements and theoretical considerations suggest that the deep turbid stratum is formed by a complex mixture of manganese and iron compounds with a prevalence of Mn(II)/Mn(III) in different forms including dissolved, colloidal, and fine particles, that give to the turbid stratum a white-pink opalescent coloration. The bacteria populations show a clear stratification with the upper aerobic layer dominated by the heterotrophic Flavobacterium sp., the turbid stratum hosting a specific microbiological pool, dominated by Caldimonas sp., and the deeper anaerobic layer dominated by the sulfur-oxidizing and denitrifier Sulfuricurvum sp. The occurrence in August 2010 of an anomalous lake surface coloration lasting about four weeks and developing from milky white-green to red-brown suggests that the upper zone of the turbid stratum could be eroded during intense weather-hydrological conditions with the final red-brown coloration resulting from the oxidation of Mn(II)/Mn(III) to Mn(IV) compounds.

Effect of alkaline earth metal Ca in rice husk during chemical looping gasification process

As the most abundant trace element in agricultural wastes, Ca can improve the reaction performance, but aggravate the agglomeration and sintering of reaction materials at high temperature during the process of thermochemical conversion. In this paper, the effect of Ca in rice husk was studied in chemical looping gasification (CLG) under different conditions of Ca concentration, Ca solution, temperature and steam/carbon (S/C). The results indicated that Ca would significantly improve the CLG performance, but cause obvious agglomeration and sintering phenomenon at high Ca concentration. Furthermore, the improvement for CLG performance of (CH3COO)2Ca was greater than that of CaCl2. After adding 6% (CH3COO)2Ca, gas yield, carbon conversion efficiency and gasification efficiency increased by 53.30%, 47.06% and 45.61%, respectively. By contrast, they respectively increased by 28.11%, 17.27% and 26.79% after adding CaCl2. Thermogravimetric analysis showed that the presence of Ca was beneficial to reduce the activation energy of the reaction. In the pyrolysis stage, the maximum reduction of activation energy was 37.43%, while in the gasification stage, the maximum reduction of activation energy was 65.36% after adding Ca in the rice husk. Compared with CaCl2, (CH3COO)2Ca decreased more activation energy of CLG process. Moreover, with the increase of temperature and S/C, the CLG performance increased firstly and then decreased after adding 6% (CH3COO)2Ca by impregnation on the pickling rice husk. 800℃ and 6.9 was the optimal temperature and S/C to achieve the best gasification efficiency of 65.03% and gas yield of 0.69 Nm3/kg in the CLG process.

Highly CO selective Ca and Zn hybrid metal-organic framework electrocatalyst for the electrochemical reduction of CO2

A transition metal (Zn) and alkaline earth metal (Ca)-hybridized metal-organic framework (MOF) based electrocatalyst was synthesized using a one-pot process. The as-prepared ZnCa-MOF74 (ZC) catalyst exhibited a low overpotential, an excellent CO selectivity, and high stability in the electrochemical reduction of CO2 (ERC). The Faradaic efficiency of ZC towards CO was as high as 93%, which is two times higher than that of the Zn-MOF74 catalyst. The computational simulation also showed that Ca lowered the activation barrier of the rate-determining step during the ERC.

Alumina‐Supported Alkali and Alkaline Earth Metal‐Based Catalyst for Selective Decarboxylation of Itaconic Acid to Methacrylic Acid

AbstractThe present study focuses on selective decarboxylation of itaconic acid (IA) to methacrylic acid (MAA) using alkali and alkaline earth metals (Na, K, Mg and Ca) supported on Al2O3, prepared by incipient wet impregnation approach. The parent Al2O3, predominantly composed of the boehmite phase, is entirely transformed to γ‐Al2O3 phase upon impregnating calcium, based on XRD analysis, and this is not the case for other metals employed in this study. FTIR analysis corroborates the complete decomposition of nitrate precursor in the case of calcium than other metals (Na, K and Mg). UV‐Vis analysis using diffused reflectance mode suggests that Ca incorporated on to the Al2O3 matrix. Among the catalysts employed, the highest yield of methacrylic acid (MAA) (46.7 %) is achieved with 5 wt % Ca/Al2O3 at 250 °C, 20 bar N2 after 3 h. Moreover, 15.1 % of α‐hydroxyisobutyric acid (α‐HIBA), a hydrated product of MAA, is also obtained, and thus, the combined yield of MAA and α‐HIBA is 61.8 %. The selective decarboxylation of IA to MAA/α‐HIBA can be correlated with the number of basic sites present in the 5 wt % Ca/Al2O3, which possess the highest number of basic sites than other catalysts.

Effect of the Addition of Alkaline Earth and Lanthanide Metals for the Modification of the Alumina Support in Ni and Ru Catalysts in CO2 Methanation

In order to reduce greenhouse gas emissions, which are reaching alarming levels in the atmosphere, capture, recovery, and transformation of carbon dioxide emitted to methane is considered a potentially profitable process. This transformation, known as methanation, is a catalytic reaction that mainly uses catalysts based on noble metals such as Ru and, although with less efficiency, on transition metals such as Ni. In order to improve the efficiency of these conventional catalysts, the effect of adding alkaline earth metals (Ba, Ca, or Mg at 10 wt%) and lanthanides (La or Ce at 14 wt%) to nickel (13 wt%), ruthenium (1 wt%), or both-based catalysts has been studied at temperatures between 498 and 773 K and 10 bar pressure. The deactivation resistance in presence of H2S was also monitored. The incorporation of La into the catalyst produces interactions between active metal Ni, Ru, or Ru-Ni and the alumina support, as determined by the characterization. This fact results in an improvement in the catalytic activity of the 13Ni/Al2O3 catalyst, which achieves a methane yield of 82% at 680 K for 13Ni/14La-Al2O3, in addition to an increase in H2S deactivation resistance. Furthermore, 89% was achieved for 1Ru-13Ni/14La-Al2O3 at 651 K, but it showed to be more vulnerable to H2S presence.

Poisoning Effects of Alkali and Alkaline Earth Metal Doping on Selective Catalytic Reduction of NO with NH3 over the Nb-Ce/Zr-PILC Catalysts

The poisoning effects of alkali metals (K and Na) and alkaline earth metals (Ca and Mg) on catalytic performance of the 2Nb4Ce/Zr-PILC catalyst for the selective catalytic reduction of NOx with NH3 (NH3-SCR) were investigated, and physicochemical properties of the catalysts were characterized by means of the X-ray diffraction XRD (XRD), Brunner−Emmet−Teller (BET), hydrogen temperature-programmed reduction (H2-TPR), X-ray Photoelectron Spectroscopy (XPS), ammonia temperature-programmed desorption (NH3-TPD), and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) techniques. Doping of M (M = K, Na, Ca, and Mg) deactivated the 2Nb4Ce/Zr-PILC catalyst according to the sequence of 0.8 K &gt; 0.8 Na &gt; 0.8 Ca &gt; 0.8 Mg (M/Ce molar ratio = 0.8). The characterization results showed that the decreases in redox ability, NH3 adsorption, Ce3+/Ce4+ atomic ratio, and amount of the chemisorbed oxygen (Oβ) were the important factors influencing catalytic activities of the alkali metal-and alkaline earth metal-doped samples. Consequently, compared with the Mg- and Ca-doped samples, doping of K caused the 2Nb4Ce/Zr-PILC sample to possess the lowest redox ability, NH3 adsorption, and amount of the Oβ species, which resulted in an obvious deactivation effect.

Crystallization behavior, quantitation of Ce3+/Ce4+ and chemical stability analysis of multiple alkaline earths borosilicate glasses for immobilizing simulated tetravalent actinides

A series borosilicate glasses containing three alkaline earth metals (Ca, Mg, Ba) and immobilized with ceria from low content (3 wt%) to exceed the solubility limit (20 wt%) were prepared by the solid-state melt method. The results of phase separation revealed by SEM, XRD and EDX show that simulated waste CeO2 loading was below 13 wt%, and the excess part was tightly connected with glass. The controlled heat treatment of the quenched blocks and the green pellets was conducted to explore the effect of ceria content of the system on the crystalline state. The solidified waste forms with a ratio of Ce3+/Ce4+ close to 1 have the lower leaching rate after 28 d (LRSi=9.84 × 10−4 g m−2 d−1, LRCa=6.68 × 10−4 g m−2 d−1) and LRCe of all samples is always maintained in the order of magnitude of 10−5 g m−2 d−1, suggesting that cerium doped multiple alkaline earths borosilicate glasses have higher chemical stability.

Assessment of groundwater quality using statistical methods in the Isly basin (Horst Belt, Morocco)

The identification of potential sources of groundwater pollution in the Isly basin (North-East Morocco) and the understanding of their spatial variability, in response to certain natural and anthropogenic forcings, were approached through the combined study of ionic ratios and statistical analyses of hydro-chemical data. The results of the Principal Component Analysis (PCA) show that two factors explain nearly 78% of the variance. Factor 1 is mineral salts (Cl and Na), and factor 2 is related to alkaline earth metals (Ca and Mg). The typological structure of the F1 x F2 plan analysis shows four regions according to the nature of pollutants. The contaminations observed for most of the water points could be related to anthropogenic, geological and atmospheric pollution sources.