Clay Minerals Palygorskite Research Articles

Tailoring LLDPE properties with modified palygorskite fillers: A comprehensive study

AbstractLinear low‐density polyethylene (LLDPE) is a polyolefin known for its superior low‐temperature heat seal ability, low‐temperature tolerance, and bag‐tear resistance which are important features for the polymeric packaging sector. In this work, to improve the mechanical properties and expand the range of applications of LLDPE, the microfibrillar clay mineral palygorskite (PAL) was added. However, the use of PAL as a reinforcing agent for polymers depends on its purification process to extract accessory minerals such as calcite, dolomite, and quartz. In addition to this purification process, two surface modifications were used on the purified PAL (PALp) to improve interactions with LLDPE: silanization with aminosilane (PALs) and organophilization by incorporating an organic compound (PALo). The PAL were characterized according to their morphological properties using transmission electron microscopy (TEM), X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT‐IR). The films of LLDPE/PAL, with varying levels (1, 3, and 5 wt%) and types of PAL (raw PAL, PALp, PALs, and PALo), were prepared by an extrusion process, and films were prepared by compression molding, without preferred orientation. The films were characterized by rheological analyses, tensile tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and water vapor permeability. Incorporating modified PAL was significant in enhancing the mechanical properties of the nanocomposites. LLDPE/PALs with the addition of 3 wt% PALs showed a 14% increase in elastic modulus (281.08 ± 8.25 MPa) compared to the nanocomposite with 3 wt% of raw PAL (243.43 ± 15.01 MPa).Highlights The PAL is a clay mineral with a fibrous morphology and has a low cost. The technique to purify PAL is a quick, simple, and inexpensive technique. Comparison between of two technique surface modification of PAL. The effectiveness of modifications of PAL was confirmed in LLDPE films. The surface modification with silanization was more effective.

Optimization and characterization of sustainable geopolymer mortars based on palygorskite clay, water glass, and sodium hydroxide

Abstract The synthesis of ambient-cured sustainable geopolymer mortars (GMs) was studied throughout this work. To reduce carbon dioxide emissions, new materials must be used in the production of sustainable concrete and mortars. Many types of binders are used in the synthesis of GM and concrete (GPC), especially clay minerals. These clay minerals are considered sources of alumina and silica in GM and concrete. The geopolymerization process relies on the alkaline solution activating the alumino-silicate to produce geopolymer gel products. The palygorskite (PA) clay mineral, sodium hydroxide (NaOH), and sodium silicates (Na2SiO3) were chosen as a binder (solid material) and alkaline activator solution to synthesize GM at ambient temperature. PA was thermally treated at 550, 650, 700, and 750°C, respectively, to convert into high-reactive PA (HRP) HRP550, HRP650, HRP700, and HRP750, respectively. The characteristics of PA clay, HRP powders, and HRP-based GM were evaluated using compressive strength (CS) testing, X-ray fluorescence analysis, carbon footprint analysis, X-ray diffraction (XRD) diffractograms, Fourier transform infrared spectroscopy (FTIR) spectroscopy, scanning electron microscopy (SEM) images, and energy-dispersive X-ray spectroscopy (EDS) analysis. The maximum CS of 25.1 MPa was acquired for geopolymer synthesis utilizing HRP700-based GM cured at 30°C for 28 days. FTIR spectroscopy demonstrated that HRP-based GM showed the presence of Si–O, Al–O, and O–C–O bonds stretching vibrations in the alumino-silicate network. The results showed that the CO2 emissions had a reduction in the HRP-based GM compared with the reference mix of ordinary Portland cement mortar (OPM). The percentage of reductions was 14.1, 13.7, 13.1, and 12.4 for HRP550, HRP650, HRP700, and HRP750, respectively, compared with the OPM mixture. SEM images/EDS analysis and XRD diffractograms confirmed the presence of sodium alumino-silicate hydrates, magnesium silicate hydrate, and calcium silicate hydrate gels with high quantities particularly in the HRP700-based GM than that in HRP550, HRP650, and HRP750, respectively. The results indicate the suitability of HRP calcined at 700°C (HRP700) in the synthesis of the GM.

Computational and experimental assessment of efficient dye adsorption method from aqueous effluents by halloysite and palygorskite clay minerals.

The removal of dyes from effluents of textile industries represents a technological challenge, due to their significant environmental impact. The application of halloysite (Hal) and palygorskite (Pal) clay minerals as adsorbents for the removal of Congo red (CR) and methylene blue (MB) was evaluated in this work. The materials were applied both in natural and acid-treated forms, and characterized by XRD, XPS, SEM-EDS, FTIR, and N2 adsorption-desorption isotherm techniques to identify their properties and main active sites. The adsorbents showed potential to remove CR (> 98%) and MB (> 85%) within 180min, using 0.3g adsorbent and initial dye concentration of 250mg L-1. Semi-empirical quantum mechanical calculations (SQM) confirmed the interaction mechanism between dyes and the adsorbents via chemisorption (- 69.0kcalmol-1 < Eads < - 28.8kcalmol-1), which was further observed experimentally due to the high fit of adsorption data to pseudo-second order kinetic model (R2 > 0.99) and Langmuir isotherm (R2 > 0.98). The use of Pal and Hal to remove dyes was proven to be economically and environmentally viable for industrial application.

Palygorskite-supported ruthenium catalysts for the efficient selective oxidation of 5-hydroxymethylfurfural to 2, 5-diformylfuran

The oxidation of 5-hydroxymethylfurfural (HMF) to 2, 5-diformylfuran (DFF) is an important reaction for the conversion of renewable biomass into feedstock chemicals. In this work, palygorskite (Pal)-supported ruthenium (Ru) catalysts were developed for the efficient selective oxidation of HMF to DFF. Using natural clay mineral palygorskite as the support enabled the immobilization and dispersion of Ru nanoparticles. A 100% HMF conversion, 98% DFF yield, and 98% DFF selectivity were obtained over Ru(III)/Pal catalyst after 4.5 h under the optimal reaction conditions at 110 °C and 10 bar of O2 in toluene. Ru nanoparticles and palygorskite synergistically achieve the excellent catalytic performance of the catalyst. The Ru metal active sites facilitate the activation of the reactants or intermediates, accelerating the formation of DFF. Furthermore, due to their different particle sizes and Ru species, the Ru(III)/Pal catalyst exhibits higher catalytic activity than the Ru(0)/Pal catalyst for the oxidation of HMF to DFF. The palygorskite-enhanced dispersion effect on Ru nanoparticles augments the catalytic activity. Moreover, the palygorskite-supported Ru catalyst showed good stability and was reused for at least five times consecutive cycles without significant loss of its catalytic activity.

Clay microparticles for the enhancement of bone regeneration: in vitro studies.

Humans develop osteoporosis as they age, a disease characterized by the slow and consistent reduction in bone mass and the subsequent risk of fractures. Due to aging, the mesenchymal stem cells within the bone marrow niche, show a shift in differentiation from osteogenesis to adipogenesis. The challenge of osteoporosis treatment is being met with advances in nanotechnology and tissue engineering. In this study , we evaluatedthe potential of palygorskite clay mineral microparticles for the promotion of the osteogenic differentiation in human mesenchymal stem cells (hMSCs) in vitro. Alkaline phosphatase (ALP) activity and Alizarin red staining showed that osteogenic differentiation of hMSCs is enhanced in the presence of palygorskite clay. Although, gene expression analysis did not reveal upregulation of several osteogenic markers in the presence of the clay microparticles, another interaction mechanism resulted in the enhanced osteogenic differentiation of hMSCs. The charged surfaces of the palygorskite clay particles interact with the stem cells using their high adhesion characteristics, leading to complete bridging, adherence, and enveloping of the stem cells' cadherins and integrins with their environment. This restoration of the adhesion among the stem cells and their environment most probably promotes/restores the osteogenic differentiation of hMSCs. Therefore, palygorskite clay microparticles are a promising candidate for further in vivo studies on bone regeneration.

Chemical and mechanical model to analysis wellbore stability

Wellbore instability problems mainly contribute to increased nonproductive time (NPT) through drilling operation developments in the Southern Iraq oilfield. This work aims to study the impact of drilling fluid chemicals on shale formation based on lab tests. At the same time, a mechanical earth model (MEM) constructs for the wellbore failure analysis, which simulates the mechanical effect on the shale formation. The Lab tests showed that the shale formation is of many types, including illite, kaolinite, palygorskite clay mineral, montmorillonite, and non-clay minerals quartz and calcite, where kaolinite was a dominant clay mineral of the shale. The shale samples swelled slightly when sodium silicate was used with polymer mud, but they had significant swelling when potassium chloride was applied with polymer mud. The MEM showed that the leading cause of those problems is using unsuitable mud weight (10.4 ppg) during the drilling of the Tanuma formation. Thus, the model indicates that an equivalent mud weight of 11 ppg for vertical wells will be required to stabilize the Mishrif and Tanuma shale formations. This work was unique in studying chemical and mechanical effects to analyze the wellbore stability and develop the optimum solutions.

Study of the fillers influence on the organosilicon polymers resistance to high temperatures

Organosilicon varnishes, such as polymethylphenylsiloxane and polyaluminomethylphenylsiloxane, filled with modified clay minerals are the object of research The most vulnerable place of the organosilicon coating is insufficient mechanical properties (hardness, impact strength, etc.) and low adhesive strength of the film to the surface, especially when operating at elevated temperatures. Various oxides, ceramic compounds, natural and synthetic silicate materials are introduced into organosilicon compositions to improve the specified properties. But only individual units can comprehensively improve both the mechanical and heat-resistant properties of organosilicon compounds although the range of such materials is quite wide. The clay minerals palygorskite, which is classified as an intermediate type between strip and layered silicates, and montmorillonite from the subclass of layered silicates, which have a natural high dispersion, were used as fillers during the study. The choice of palygorskite and montmorillonite is explained by the sufficient study of their behavior in organic environments by a number of scientists, availability and economic advantages for introduction into production. Existing clay minerals, which are traditionally used to solve the problem of improving the physical and mechanical properties of organosilicon coatings, are not sufficiently active due to the hydrophilic properties of the particles surface. Based on this, a modifier that has proven itself well in this field was used for the study. A number of compositions of heat-resistant organosilicon varnishes with modified fillers based on the above-mentioned clay minerals were obtained. It was established that the introduction of modified forms of natural aluminosilicates contributes to the increase of temperature resistance in filled coatings, compared to coatings made of pure polymer. At the same time, the best effect is achieved when using montmorillonite. This is related with the fact that the proposed compositions of polymethylphenylsiloxane varnish and montmorillonite have a number of features, in particular, the highest comprehensive result of simultaneous improvement of the physical, mechanical and thermal properties of the specified coatings. It is possible to obtain compositions with stable physico-mechanical properties, as they withstood heat treatment at 400 °C for 100 hours without visible changes in integrity, due to the introduction of the optimal amount of modified montmorillonite into organosilicon varnishes KO-08K and KO-921. Compared to similar heat-resistant polymethylphenylsiloxane varnishes, longer service life at elevated temperatures is ensured.

UiO-66/Palygorskite/TiO2 Ternary Composites as Adsorbents and Photocatalysts for Methyl Orange Removal

Metal–organic frameworks are recognized as a new generation of emerging porous materials in a variety of applications including adsorption and photocatalysis. The present study presents the development of ternary composite materials made through the coupling of UiO-66 with palygorskite (Pal) clay mineral and titanium dioxide (TiO2) applied as adsorbent and photocatalyst for the removal of methyl orange (MO) from aqueous solutions as a typical anionic dye. The prepared materials were characterized using XRD, ATR, DR UV/Vis, and TGA analysis. Detailed kinetic experiments revealed that the presence of the clay at low amounts in the composite outperformed the adsorption efficiency of pure UiO-66, increasing MO adsorption by ca. 8%. In addition, coupling Pal/UiO-66 with TiO2 for the production of ternary composites provided photocatalytic properties that resulted in complete removal of MO. This was not observed in the pure UiO-66, the Pal/UiO-66 composite, or the pure TiO2 material. This study presents the first example of clay mineral/MOF/TiO2 composites with improved performance in removing dyes from aqueous solutions and highlights the importance of coupling MOFs with low-cost clay minerals and photocatalysts for the development of multifunctional advanced composites.

Adsorption of Methyl Orange on a Novel Palygorskite/UiO-66 Nanocomposite

Herein, a novel composite material containing UiO-66 and palygorskite (Pal) clay mineral was prepared using a facile one-pot synthesis process. The material was studied using a variety of techniques and applied as did not affect the structure of the metal-organic framework (MOF) part, but induced a small increase in specific surface area. The developed Pal/UiO-66 composite presented excellent adsorption efficiency against MO removal, as evidenced by detailed kinetic and isotherm experiments. An impressive maximum adsorption capacity at equilibrium was evidenced; 340 mg g−1 at pH = 5 and T = 25 °C. This corresponds to a 34.5 % increase compared with pure UiO-66, considering only the MOF content. Furthermore, the Pal/UiO-66 composite was proven stable and highly recyclable, losing less than 9% of the removal capacity after five consecutive cycles. The study highlights the synergistic effect of the coupling of MOF structures with low-cost and abundant clay minerals for the development of advanced absorbents.

Interfacial ionic transport in natural palygorskite-Na0.60CoO2 nanocomposite mineral materials

Natural clay minerals have been applied to various energy fields due to their low cost, good stability, and abundance of resources, but few of them have been investigated for fuel cell application. Proton ceramic fuel cell, one of the most promising sustainable-energy-conversion technologies, has attracted a lot of attentions because it possesses high ionic conductivity at relatively low temperatures (<600 °C). However, the characteristics of expensive construction cost and high temperature operation hinder the development and industrialization of fuel cell. In this paper, natural clay minerals palygorskite (PAL) and Na0.60CoO2 (NCO) nanosheets composite were synthesized via an electrostatic adsorption method, and used as the electrolyte of fuel cell. NCO/PAL demonstrated a high conductivity of 0.27 S∙cm−1 at 550 °C and the maximum power output of 641 mW cm−2 was achieved for NCO/PAL cell. The mechanism of proton transport at the interface of NCO/PAL semiconductor-insulator composite was discussed.

Base-free oxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid over palygorskite-supported bimetallic Pt–Pd catalyst

Aerobic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2, 5-furandicarboxylic acid (FDCA) is an important reaction for producing green and sustainable chemicals. Herein, natural clay mineral palygorskite (Pal)-supported bimetallic Pt–Pd catalyst for the oxidation of HMF to FDCA in water without the addition of any bases was developed. The 1Pt9Pd1/Pal catalyst with Pt/Pd molar ratio of 9/1 exhibited excellent catalytic performance, and 100% HMF conversion and 99% FDCA yield were obtained under optimum reaction conditions after 12 h, which was mainly attributed to the synergy between palygorskite and bimetallic Pt–Pd nanoparticles. Palygorskite used as support realized the immobilization and dispersion of bimetallic nanoparticles, increasing the catalytic activity. The basicity of palygorskite and alloying effects between Pt and Pd facilitated the formation of FDCA by synergistically catalyzing the oxidation of alcohol and aldehyde groups in the reactants and intermediates. Furthermore, this catalyst showed good stability and reusability. The present work provides a highly efficient, cost-effective, and environmentally benign catalyst for the base-free oxidation of HMF to FDCA in practical industrial applications.

Removal of total organic carbon from olive mill wastewater using palygorskite clay mineral

Removal of total organic carbon from olive mill wastewater using palygorskite clay mineral

Using raw and thermally modified fibrous clay minerals as low concentration NH4+-N adsorbents.

Raw and modified fibrous clay minerals palygorskite (Pal) and sepiolite (Sep) were tested for their ability to remove ammonium from ammonium polluted water. Palygorskite and sepiolite underwent thermal treatment at 400°C (T-Pal and T-Sep respectively). Raw and thermally treated samples were characterized using XRD, SEM, BET, FTIR, TGA, zeta potential, and XRF. The techniques verified the effect of thermal treatment on sample structures and the enhancement of negative charge. Both raw and thermally activated materials were applied in batch kinetic experiments, and found to be efficient adsorbents in their raw forms, since Pal and Sep achieved 60 and 80% NH4+-N removal respectively within 20 min of contact for initial NH4+-N concentration of 4 mg/L. Similar removal rates were gained for other concentrations representative of contaminated aquifers that were examined, ranging from 1 to 8 mg/L. Results for the modified T-Pal and T-Sep minerals showed up to 20% higher removal rate. Saturation tests indicated the positive effect of thermal treatment on the minerals since T-Pal and T-Sep removal efficiency reached 85% and remained stable for 24 h. However, competitive ions in real water samples can influence the NH4+-N removal efficiency of the examined samples. At almost all the examined samples, the nonlinear Freundlich isotherm and linear pseudo-second kinetic models showed better fitted all examined samples thus indicating heterogeneous chemisorption.

Interactions among TiO2 and palygorskite revealed: Boost for stability of well-known photocatalyst

Anatase, is widely used in photocatalysis because it is environmentally friendly, low-cost and presents good catalytic activities. Nevertheless, the anatase nanoparticles tend to agglomerate resulting in degradation of catalysis efficiency. The agglomeration problem can be resolved, using the fibrous clay mineral palygorskite via TiO2 particles dispersion on its fibers. Hence, it should be possible the efficient photocatalytic activity to derive from the strong interactions among the initial compounds. Palygorskite–TiO2 nanocomposites were synthesized and characterized by X-ray diffraction, Fourier transform-infrared spectroscopy and transmission electron microscopy, while the exact interactions and possible spontaneous bonding between palygorskite and the anatase sphere were investigated by molecular simulations. Three different supercells of palygorskite were built, which were further interacted with the TiO2 sphere with suitable surfaces. The optimal TiO2-palygorskite connection takes place among the Ti atoms of the curved TiO2 part with the O atoms from palygorskite’s fibers surface via electrostatic interactions and the potential strong covalent bonds. The molecular simulations results are in good agreement with transmission electron microscopy data. Based on simulation we can see the curved part of anatase which interacts with the Ti atoms and is connected to the palygorskite fibers through several types of its surfaces via the O atoms.

Microwave-assisted hydrothermal synthesis of CuWO4-palygorskite nanocomposite for enhanced visible photocatalytic response

CuWO4-Pal nanocomposite formed by copper (II) tungstate nanoparticles with palygorskite clay mineral (Pal) was synthesized via coprecipitation method followed by microwave-assisted hydrothermal technique and applied in the photodegradation of the antibiotic ciprofloxacin (CIP) using visible-light irradiation. The formation of CuWO4-Pal nanocomposite was confirmed by XRD, Raman spectroscopy and DRIFT studies. X-ray photoelectron spectroscopy (XPS) and photoelectrochemical studies of the nanocomposite showed structural changes, which induced the formation of oxygen vacancies and better charge carrier mobility. Field emission scanning electron microscopy (FE–SEM) and transmission electron microscopy (TEM) images revealed the fibrous morphology of Pal as well as the control of CuWO4 crystal growth with the formation of the nanocomposite. The CIP photodegradation was influenced by the adsorption power and the pH solution. CuWO4-Pal exhibited 92% of CIP photodegradation and 50% of total organic carbon (TOC) removal using an initial concentration of 8 mg L−1 at pH 10 after 90 min. Together with the photoelectrochemical study, the scavengers used indicated that the hole (h+) is the main oxidative species in CIP photodegradation.

Mechanistic insights into ethidium bromide removal by palygorskite from contaminated water

Ethidium bromide (EtBr)-containing wastewater can be hazardous to biodiversity when released into the soil and water bodies without treatment. EtBr can mutate living microbial cells and pose toxicity to even higher organisms. This work investigated the removal of EtBr from aqueous solutions by a naturally occurring palygorskite (PFl-1) clay mineral via systematic batch adsorption experiments under different physicochemical conditions. EtBr existed in an undissociated form at pH ~7, and was adsorbed on PFl-1 obeying the Freundlich isotherm model. The maximum EtBr adsorption capacity was 285 mmol/kg. The best fitted kinetic model for EtBr adsorption was the pseudo-second order model. The amounts of exchangeable cations desorbed from PFl-1 during EtBr adsorption was linearly correlated to the amounts of EtBr adsorbed, with a slope of 0.97, implying that a cation exchange-based adsorption mechanism was dominating. Additionally, dimerization of EtBr molecules via bromide release assisted an increased EtBr removal by PFl-1 at high adsorbate concentrations. Detailed x-ray diffraction, Fourier transform infrared, scanning electron imaging and energy dispersive x-ray analyses confirmed that EtBr adsorption occurred dominantly on the surface of palygorskite which mineralogically constituted 80% of the bulk PFl-1 adsorbent. A small portion of EtBr was also adsorbed by PFl-1 through intercalation onto the smectite impurity (10%) in PFl-1. This study suggested that PFl-1 could be an excellent natural material for removing EtBr from pharmaceutical and laboratory wastewater.

Antimicrobial efficacy of building material based on ZnO/palygorskite against Gram-negative and Gram-positive bacteria

This study investigated ZnO nanoparticles immobilized in palygorskite clay mineral (Pal) that acted as an inorganic antimicrobial agent in a commercial mortar aiming to control microorganisms and improve safety and stability for building applications. ZnO/Pal nanocomposites were obtained by sol-gel methods at pH 7 and 11 and were calcined at 250 °C and 400 °C to evaluate different synthesis parameters. The mortar/ZnO/Pal composite was obtained using 5% (by weight) ZnO/Pal hybrid mixed with a commercial mortar. The results show that pH and calcination temperature influenced the properties of ZnO/Pal. ZnO was observed in the ZnO/Pal samples during the wurtzite phase by analyzing the XRD patterns. FTIR spectra illustrated the interactions between ZnO nanoparticles and the fibrous clay mineral. TG-DTG analysis showed the thermal events of Pal before and after zinc incorporation. Scanning electron microscopy (SEM) evaluated ZnO morphology as spherical in shape and dispersed on the fibers of the clay minerals, which presented needle-like morphology. ZnO/Palygorskite showed a possible antibacterial effect when used in mortar formulation. The mortar/ZnO/Pal composites were effective against Escherichia coli and Staphylococcus aureus bacteria when tested by the direct contact method in darkness and in visible light and could be an alternative antimicrobial material for building surfaces.

Oxide-Clay Mineral as Photoactive Material for Dye Discoloration

Titanium and zirconium oxides (TiO2 and ZrO2, respectively) were obtained from alkoxides hydrolyses, and then deposited into palygorskite clay mineral (Pal) to obtain new materials for photocatalytic applications. The obtained materials were characterized by structural, morphological, and textural techniques. X-ray diffraction (XRD) results confirmed the characteristic peaks of oxides and clay transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of the modified palygorskite with both oxides showed that the clay was successfully modified by the proposed method. The increase in the specific surface area of the clay occurred when TiO2 and ZrO2 were deposited on the surface. The photocatalytic activity of these materials was investigated using the Remazol Blue anion dye under UV light. The evaluated systems presented high photocatalytic activity, reaching approximately 98% of dye discoloration under light. Thus, TiO2–Pal and ZrO2–TiO2–Pal are promising clay mineral-based photocatalysts.

Novel application for palygorskite clay mineral: a kinetic and thermodynamic assessment of diesel fuel desulfurization

Palygorskite (Pal) is a low-cost clay mineral material and was investigated in this study as a novel material for adsorptive desulfurization of petroleum refining fractions from the Clara Camarao Potiguar Refinery (RPCC) in Brazil. This clay mineral was characterized by X-ray fluorescence, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry, zeta potential ($$\zeta$$) and N2 adsorption/desorption isotherm analyses. Palygorskite textural properties (specific surface area 156 m2 g−1, total pore volume 0.36 cm3 g−1) and specific surface chemistry activity with several metals were crucial to efficient adsorption, proposing that an interaction between adsorbate/adsorbent involves π-complexation mainly with Fe species. This material was used in raw and thermally activated forms to evaluate the adsorption capacity. Several kinetic and equilibrium models were used to assess the experimental data. The results showed high correlation to the pseudo-second order kinetic model for both adsorbents (R2 > 0.99), suggesting a chemisorption process as the determining step. Isotherm data were used to evaluate the equilibrium experimental data. Maximum adsorption capacity calculated from the Langmuir isotherm (R2 > 0.97) was 6.25 mg g−1 for raw-Pal at 318 K. The adsorption thermodynamic assessment of S-compounds indicated an endothermic process, and there was consequently an increase in spontaneity at higher temperatures. The adsorbent raw-Pal displayed good potential in the adsorption of sulfur compounds in real diesel fuel. Palygorskite stands out for being an abundant clay mineral in nature, environmentally safe, and with high possibility of its applications in adsorption and catalysis processes.

Design of solid foams for flame retardant based on bionanocomposites systems

Bionanocomposites are hybrid materials obtained from the interaction between two or more components. The construction of this type of material comes from a continuous phase, usually organic, and the dispersed phase, usually inorganic. Both phases are naturally occurring and at least one of them has a nanoscale structure. The bionanocomposites in this work were synthesized from the biopolymers rice starch and pectin reinforced by the clay mineral palygorskite. During synthesis, the freeze-drying method was used for production of low-density solid foams. Spectroscopic techniques were applied in order to identify the interaction mechanism established between the inorganic fibers and the polysaccharide chains, which is established between the hydroxyl groups in the biopolymers and the silanol groups at the external surface of the palygorskite fibers. Besides, X-ray diffraction showed that the structure of palygorskite was not affected during the synthesis and Energy-Dispersive X-ray spectroscopy (EDX) revealed a good dispersion of palygorskite on biopolymers. Horizontal burning tests were carried out based by ASTM D4986–03 for a preliminary study of flame-retardant materials, revealing that bionanocomposite foams based on rice starch with palygorskite content > 5% behave as auto-extinguishable materials.