The capacity of an Algerian Tertiary sedimentary palygorskite to remove methylene blue was studied. The raw material was characterized using X-ray diffraction, infrared spectroscopy, and chemical, ...granulometric and micotextural analyses. Kinetic experiments were carried out to study the effect of contact time, stirring speed, initial dye concentration and adsorbent mass on the adsorption processes. The palygorskite-rich material mainly consists of this fibrous clay (72%) and calcite (19%) with minor amounts of dolomite (5%), illite (2%) and quartz (2%). After 5 min contact time at room temperature, the adsorption reaction of a 50 mL solution containing 10 ppm of methylene blue on 50 mg of Cal-Pal as adsorbent reached equilibrium, and 97% of cationic dye was fixed. Temperature did not have a significant influence on methylene blue adsorption. The obtained adsorption isotherm indicates high affinity between the adsorbent and the adsorbate. The use of the studied Algerian palygorskite-rich sediment may have great potential for the elimination of textile dyes.
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•Adsorption capacity of methylene blue on Algerian palygorskite is estimated to be 97%.•Methylene blue adsorption on palygorskite is spontaneous and an endothermic process.•Acidic surface of palygorskite is favorable for the basic dye adsorption.
•LC3 prepared using calcined Hal exhibits high early compressive strength.•Hydration simultaneously occurs in the inner and outer lumen of nanosized tubular calcined Hal.•Hal calciend at 650°C-850°C ...is conducive to the mechanical properties development of LC3.•Overdose (≥ 2 wt%) gypsum changes the composition of LC3 and negatively affects its mechanical properties.•A decrease in water/binder ratio densifies the microstructure of LC3 and enhances its compressive strength.
Halloysite is a clay mineral that has a nanosized tubular morphology and high pozzolanic activity, and its calcination product can be used as a supplementary cementitious material in limestone calcined clay cement (LC3). In this study, the effects of the calcination temperature of halloysite, gypsum content, and water/binder (W/B) ratio on the mechanical properties and microstructures of LC3 were evaluated. The results demonstrated that halloysite calcined at the temperature of 650°C–850°C exhibited high pozzolanic activity: LC3 prepared using halloysite calcined above 650°C exhibited a shorter setting times and higher compressive strengths than those prepared with halloysite calcined at 550°C. This is attributable to the formation of more additional calcium aluminate silicate hydrate gel, and a larger amount of hemicarboaluminate and monocarboaluminate at higher temperatures than at lower temperatures, which results in more filling of pores in LC3 under the former conditions than the later conditions. The results also indicated that the optimum content of additional gypsum for LC3 was between 0 wt% and 2 wt%, and overdose gypsum did not substantially alter their setting times but decrease their compressive strengths. In contrast, a decrease in the W/B ratios decreased their setting times, total porosity, and increased their compressive strengths. Overall, in this study, LC3 prepared using halloysite calcined at 750°C, with a W/B ratio of 0.40 and without additional gypsum, exhibited the highest compressive strengths, which were 42.6, 51.7, and 57.1 MPa after 3, 7, and 28 days of curing, respectively. These findings deepen the research on the hydration mechanism of LC3 prepared with calcined halloysite and provide basic data for the wide application of this approach.
Three types of palygorskite nanoparticles for the retention of the herbicide linuron in water were tested: purified palygorskite (Pur Pal), palygorskite modified by magnetic iron oxides (FeO Pal1) ...and this one synthesized by hydrothermal treatment (FeO Pal2). The adsorbents were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), electron microscopy (TEM) and chemical analysis (XRF). XRD patterns indicate the presence of a magnetic Fe2O3 compound, and TEM images evidence how these crystals cover the palygorskite fibers' surface with different crystallite sizes (7–15 nm in FeO Pal1 and 30-50 nm in FeO Pal2). The adsorbent mass, the contact time, the initial adsorbate concentration and the effect of temperature were evaluated for linuron retention. Adsorption kinetics revealed that adsorption followed a pseudo-second order equation. Adsorption isotherms were better fitted to the Freundlich than to the Langmuir equation. Removed linuron amounts were ranged as FeO Pal2 (83%) > FeO Pal1 (55%) > Pur Pal (27%). The adsorbents could be used as a cheap alternative for pesticide removal in environmentally-contaminated waters.
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•The purified palygorskite was already capable of adsorbing linuron at low rates.•The palygorskites' surface was modified as confirmed by XRD and FT-IR analysis.•Magnetic palygorskites were able to efficiently remove the herbicide linuron.•Linuron adsorption capacity was even tripled on modified magnetic palygorskites.
Schiff bases are proved to possess numerous biological activities. Clay minerals on another hand are known for their bio-compatibility and therapeutic properties. The present work aimed to ...synthetize, characterize and assess the antibacterial activity of two new Clay-Schiff base materials by functionalizing two different types of clay minerals, Montmorillonite (Lalithe) and Palygorskite (Sif Pal) with the N-salicylideneaniline Schiff-base for the formation of the N-Salicylideneaniline modified montmorillonite named HSA- Lalithe and modified palygorskite named HSA- Sif Pal compounds.
The new modified materials were characterized using X-ray diffraction (XRD) and Fourier transform Infra-Red (FT-IR). The antibacterial activity was evaluated against gram positive bacteria, Staphylococcus aureus and Staphylococcus aureus (MRSA+) and gram negative bacteria, Escherichia coli and Pseudomonas aeruginosa through the agar dilution method (Muller-Hinton agar, MHA). The results of the minimum inhibitory concentration (MIC) demonstrated moderate antibacterial activity with the four strains of bacteria. HSA-Lalithe shows a better performance against Staphylococcus aureus and Pseudomonas aeruginosa compared to solid HSA- Sif Pal, which could be due to the swelling structure, and or the existence of the HSA Schiff base in the interfoliar space of the Lalithe material.
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•Fixation of the Salicylidenaniline Schiff base on both Lalithe and Sif Pal.•The Schiff base's presence within both structures confirmed through XRD and FT-IR.•Mild antibacterial activity against GRAM+ and GRAM- bacteria.•Organomodified Lalithe showed a greater efficiency than Sif Pal against resistant bacteria.
Recently, magnetic adsorbents have aroused a significant attention because of their excellent adsorption capacity. An Algerian palygorskite/magnetic iron oxide was prepared by chemical ...co-precipitation and characterized using infrared spectroscopy, X-ray diffraction and X-ray fluorescence. The results prove the formation of a red brick powder, with magnetic character, showing a high percentage of iron oxide on palygorskite. To verify the ability of the magnetic palygorskite for retaining organic pollutants, three different samples were evaluated for the adsorption of the fungicide fenarimol from aqueous samples: sifted palygorskite, purified palygorskite and Fe2O3/palygorskite. The effects of different variables were assessed: adsorbent mass, reaction time, initial pesticide concentration and desorption stability. Fenarimol adsorption kinetics followed a pseudo-second order model. The adsorption rates were 11%, 50% and 70%, for sifted, purified and Fe2O3/palygorskite, respectively. Both Langmuir and Freundlich models could be used to describe fenarimol adsorption on sifted and purified palygorskites. However only the Freundlich model could fit the adsorption data on Fe2O3/palygorskite, probably due to the adsorbent heterogeneity. Stability of fenarimol desorption from the three samples, where the fungicide had been previously preadsorbed, showed that the extent of desorbed fenarimol from Fe2O3/palygorskite remained constant along the studied period (15days).
•Cheap adsorbents are required for the removal of pollutants from water sources.•Algerian palygorskite modified with iron oxides represents a promising alternative.•Different mathematical equations have been used to explain fenarimol adsorption.•The fungicide fenarimol in water was efficiently removed by the modified adsorbents.
A natural Algerian palygorskite (Sif Pal) was purified (Pur Pal) and modified with tin by the hydrolysis method (SnO2 Pal) to create a novel adsorbent. The three types of palygorskite were ...characterized by infrared spectroscopy, X-ray fluorescence analysis, X-ray diffraction, scanning electron microscopy and N2-BET analysis. Adsorption studies were conducted to evaluate how the different types of palygorskite would retain two commonly consumed antibiotics (spiramycin and metronidazole) from polluted water. It was found that Pur Pal was more efficient at removing spiramycin (up to 89.2%) than Sif Pal (up to 73.2%), while SnO2 Pal was able to retain up to 98.8% of the metronidazole initially present. Adsorption of both antibiotics fitted better with a pseudo-second-order kinetic model, but other models were also examined. The Langmuir and Temkin equations provided more acceptable explanations than the Freundlich model for the adsorption of spiramycin on Sif and Pur Pal, with a maximum adsorption capacity of 10.2 mg g−1 for Pur Pal, which was double that of Sif Pal. However, the adsorption data of metronidazole on SnO2 Pal were better explained by the Freundlich and Temkin models, suggesting that adsorption could occur as a multilayer. This study shows that selection of the correct adsorbent material will depend on the target pollutant. The modification of the palygorskite with tin did not improve the retention of spyramicin, while adsorption of metronidazole was enhanced up to 1000 times, probably through the formation of a complex with SnO2.
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•Antibiotics, emerging pollutants, should be eliminated from environmental ecosystems.•Palygorskite, natural or modified, may be an efficient adsorbent in antibiotic removal.•Purification (Pur Pal) of raw palygorskite (Sif Pal) enhanced spiramycin removal.•Modification of Pur Pal with tin successfully improved the retention of metronidazole.
Beads are versatile spherical drug delivery units that can be coated, filled into capsules or compressed as tablets to be orally administered. Crosslinking of chitosan (CS) and polyanions such as ...tripolyphosphate (TPP) results in beads with mechanical properties that could be improved by the addition of clay mineral particles to the bead network. Hybrid systems of palygorskite and chitosan have been shown to have advanced properties in biomedical applications as a result of the synergic effects of their combination. In this paper chitosan was intercalated with palygorskite (Pal) and the resultant hybrid was loaded with diclofenac, an anti-inflammatory drug. Chitosan (CS) beads crosslinked with sodium tripolyphosphate (TPP) were prepared and their properties compared to palygorskite/Chitosan (Pal/CS) beads. The synergic effects resulting from the clay/polymer hybrids were evaluated by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning transmission electron microscopy (SEM) and thermal analysis (thermogravimetric analysis, TGA, and differential scanning calorimetry, DSC). The results showed that chitosan and palygorskite interaction took place. Diclofenac sodium (DFNa) was used as model drug to reveal the effects of Pal within the bead structure. DFNa was successfully loaded into beads and FTIR analyses confirmed its presence. A drug release test was carried out in phosphate buffer medium (pH. 6.8). The results indicated that only 33% (w/w) of total drug was released from DFNa-Pal/CS compared to 66% (w/w) from DFNa-CS. The total amount of drug released fell significantly with the addition of palygorskite to the chitosan matrix. Pal/CS beads crosslinked with TPP were shown to be able of carrying diclofenac sodium, meaning they could possibly be used as drug carriers.
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•TPP crosslinked Palygorskite/Chitosan and Chitosan beads were synthesized.•Diclofenac sodium was successfully loaded into Pal/CS and CS beads.•Pal/CS is a promising material as carrier for drug delivery.
A palygorskitic-rich Algerian clay (Sif Pal) has been selected as Si source to synthesize zeolite LTA through a hydrothermal treatment by using sodium aluminate. Sif Pal is activated under reflux ...using hydrochloric acid solutions at different concentrations (4, 6 and 7 mol.L−1) in a ratio of 50 g.L−1 and then analysed using XRD, SEM and XRF analysis. The selected product (PalH1) is mixed with NaOH solutions at different concentrations (1, 2, 3, 4 and 5 mol.L−1), diverse NaAl2O3 quantities (1, 2, 3 and 5 g) and analysed after several nucleation (1, 2, 3 and 5 h) and crystallization (6, 18 and 24 h) times to check the influence of these parameters on the synthesis of zeolite LTA. To obtain almost pure (> 98%) zeolite LTA, the better experimental conditions were: 3 mol.L−1 of NaOH solutions, 3 g of sodium aluminate, 3 h for nucleation and 24 h for crystallization.
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•Palygorskite is a natural fibrous clay available in the Est of Algeria.•Use of palygorskite as natural silica source.•Identification of key parameters involved for the synthesis of zeolite LTA.•Synthesis of zeolite LTA requires moderate quantity of reagents.
