The structure of halloysite nanotubes (Hal) from different mines was investigated by Small-Angle Neutron Scattering (SANS) and Electric Birefringence (EBR) experiments. The analysis of the SANS ...curves allowed us to correlate the sizes and polydispersity and the specific surfaces (obtained by a Porod analysis of the SANS data) of the nanotubes with their specific geological setting. Contrast matching measurements were performed on patch Hal (from Western Australia) in order to determine their experimental scattering length density for a more precise analysis. Further characterization of the mesoscopic structure of Hal was carried out by Electric Birefringence (EBR), which allowed to study the rotational mobility of Hal. From the obtained rotational diffusion coefficients of the different Hal we deduced their length via the Broersma theory, which compares well to TEM data. The analysis of both SANS and EBR data provided a bulk average information on the Hal structure in water, which, for instance, documented the markedly higher degree of well-definedness of the PT-Hal and the thinner tube walls present here. The attained systematic structural knowledge represents a step forward for the robust structural description of halloysites selected from four geological deposits and shows that Hal of different origin differ very markedly with respect to their mesoscopic structure.
A Fe3O4/activated montmorillonite (Fe3O4/Mt) nanocomposite was prepared by a coprecipitation method. The morphology and structure of the Fe3O4/Mt nanocomposite are explored using X-ray powder ...diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption isotherm and scanning electron microscopy. The adsorption capacity of Fe3O4/Mt for methylene blue (MB) was evaluated. Within 25min, the Fe3O4/Mt nanocomposite (0.5g) removed 99.47% of the MB from a 120mgL−1 solution at 293K and at an original solution pH of 7.37. The experimental adsorption data followed a pseudo-second-order kinetic model and Langmuir isotherm. The reusability of the Fe3O4/Mt was tested and still over 83.73% color removal of MB was obtained after five cycles. The Fe3O4/Mt nanocomposite has good stability and reusability.
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•A Fe3O4/Mt nanocomposite was prepared by a coprecipitation method.•The adsorption capacity of Fe3O4/Mt for methylene blue was evaluated.•The adsorption followed pseudo-second-order kinetic model and Langmuir isotherm.•The Fe3O4/Mt nanocomposite has good stability and reusability in MB removal.
The oily wastewater is one of the major waste streams generated due to industrialization. The membrane technology has prominent advantages in the field of oily wastewater treatment. In present ...investigation, halloysite nanotubes (Hal) and polydopamine (PDA) were utilized to synergistically modify MXene followed by the fabrication of a series of Hal@MXene-PDA two-dimensional (2D) composite membranes by vacuum filtration. Observing the morphology of the membrane and exploring the change in interlayer space by scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray diffraction (XRD), it was confirmed that, the composite membrane was successfully modified. The results revealed that, the Hal@MXene-PDA composite membrane exhibits higher hydrophilicity compared to the virgin membrane. The pure water flux using the composite membrane was found to be 5036.2 L·m−2·h−1·bar−1, and the rejections of petroleum ether and lubricating oil were evaluated as 99.8%. The modified membrane(M6) also shows good anti-fouling ability in the anti-fouling cycle test and hence can be considered as a potential candidate for oil-water separation.
•Hal@MXene-PDA composite membrane was fabricated by vacuum-assisted self-assembly.•The co-modification improved the hydrophilicity of membrane dramatically.•The membrane possessed high flux and excellent rejection for oil/water separation.•The application scopes of MXene-based membrane have been expanded.
A novel material for the deacidification and protection of paper has been designed by using MgO filled halloysite nanotubes (Hal). The ability of MgO loaded nanotubes to control the acidic conditions ...was evaluated by pH measurements in aqueous solvent. Afterwards, paper was impregnated into hydroxypropyl cellulose dispersions containing the consolidating material. A simulation of strong acidic conditions allowed us to evaluate the deacidification effect of the composite material on the samples. In particular, the paper reaches a pH of 7.7 after 1 h exposition to HNO3 vapours when MgO-Hal nanoparticles are added to the impregnation mixture at a concentration of 10 wt% and it remains still neutral after 12 h. Dynamic mechanical analysis showed that the tensile strength of the consolidated paper is improved, since the stress at breaking increase of ca. 8% for the samples treated with MgO-Hal compared to the untreated paper. Due to the presence of halloysite loaded with the alkaline reservoir, the acidic degradation of cellulose is neutralized as suggested by the stored energy which is similar to the pristine paper without any chemical attack. Therefore, the mechanical performances of the paper are preserved during the aging together with its macroscopic aspect, as suggested by colorimetric analysis. The proposed consolidation protocol represents a further step for the self-healing and long-term protection of cellulose based artworks.
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•MgO was loaded within halloysite nanotubes (Hal) by electrostatic interactions.•Paper was treated using hydroxypropyl cellulose/MgO-Hal aqueous dispersions.•MgO-Hal act as deacidifying fillers of cellulose.•The morphology, pH and tensile properties of the treated paper were investigated.•Treatment by 10 wt% MgO-Hal provides a paper protection from acidic aging.
In the present study, industrial wastes such as Granulated Blast Furnace Slag (GBFS) and Basic Oxygen Furnace Slag (BOFS) activated with calcium oxide (CaO) and medium reactive magnesia (MgO) are ...used for chemical stabilization of a soft clay. This environmentally friendly approach can eliminate the hazards associated with improper waste disposal and reduce greenhouse gas emissions generated by cement production. To this end, various amounts of additives (ranging from 2.5 to 20%) with the activator:slag ratio of 1:3 are added to kaolinite clay and cured at two temperatures of 20 and 45°C. A series of laboratory tests, including pH, Electrical Conductivity (EC), one-dimensional consolidation, Unconfined Compressive Strength (UCS), are conducted on the stabilized samples. The increasing temperature causes a faster formation of cementitious products and a higher UCS value, as confirmed by the SEM micrographs and XRD analysis, particularly in the case of MgO-BOFS (MB) and CaO-BOFS (CB) samples with the UCS values of 4 and 4.7 MPa after 90 days of curing, respectively. Furthermore, the MB- and CB-stabilized clay samples show a better compressibility characteristic compared to the MgO-GBFS (MG) and CaO-GBFS (CG) blends. To further enhance the activity of the additives and to prepare a slag-clay based geopolymers, two types of alkaline solutions at various Na2SiO3:NaOH ratios are added to the mixtures at the final step. In addition, the energy absorption capacity (Eu) and the secant modulus (E50) of the optimum blends are determined to assess the toughness and stiffness of the samples. The results indicate that the UCS values of the MB and CB samples increase up to 7.41 MPa and 8.44 MPa after 90 days of curing, respectively, when the Na2SiO3:NaOH ratio is 80:20. Generally, the use of slag-clay based geopolymers, particularly BOFS, is very effective to address the problems associated with the soft soil and the optimum mixtures are successful in decreasing settlements and enhancing compressive strength of the soft soil, which can be considered for use as a pavement base material.
•Soft clays can be satisfactorily treated when GBFS and BOFS are activated by CaO and MgO.•Increasing temperature can give rise to the faster formation of cementitious products, particularly in MB and CB samples.•The clay-BOFS based geopolymers show the highest increase on the UCSs of the samples in the Na2SiO3:NaOH ratio of 80:20.•The MB- and CB-treated samples represent a better compressibility compared to the MG and CG treatment.
Biomass-derived amorphous carbon has received considerable attention in recent decades. In this paper, carbon/montmorillonite (CMt) nanocomposites were synthesized by a hydrothermal carbonization of ...cellulose and montmorillonite (Mt), and the adsorption properties were evaluated by the removal of methylene blue (MB) from aqueous solutions. The CMt was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Nitrogen adsorption-desorption isotherm, Scanning electron microscopy, and Thermal analysis. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data and the Langmuir, Freundlich, Redlich-Peterson and Sips models were applied to describe the adsorption isotherms. The results showed that the equilibrium adsorption data was found to fit better to the Redlich-Peterson adsorption model, and the adsorption capacity for the removal of MB on CMt was 138.1 mg·g−1. The kinetic process of adsorption could be described by the pseudo-second-order model. The porous structure of CMt was responsible for the adsorption of MB. But the adsorption ability could be improved by increasing pH. Lastly, the adsorption mechanism was obtained.
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•Carbon/montmorillonite (Mt) composite (CMt) was synthesized by cellulose and Mt.•CMt was effective adsorbent for methylene blue (MB) wastewater.•The porous structure of CMt was responsible for the adsorption of MB.•The adsorption ability could be improved by pH of the solution.•The kinetics and isotherm of the adsorption process were studied.
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.
Herein, graphene oxide intercalated montmorillonite nanocomposites were prepared by a facile chemical route and then used for the adsorption of crystal violet dye from contaminated water. Structural ...characterization of the nanocomposites were performed using Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy, zeta potential, X-ray diffraction, specific surface area and pore volume measurements. The isothermal data obtained using batch adsorption technique were fitted using Langmuir and Freundlich equations and it was found that the experimental data is well described by the Langmuir isotherm model with a very high adsorption capacity of 746.27 mg g−1. The kinetics of the adsorption process showed rapid dynamics and conformed to pseudo-second-order model with a correlation coefficient of R2 > 0.99. The influence of interaction time and initial dye concentration on the adsorption efficiency were also investigated. Additionally, thermodynamic studies revealed that the adsorption process was spontaneous and endothermic. Further, the results indicated that the synthesised nanocomposites adsorb crystal violet dye efficiently (∼96%) with a small decrease in removal efficiency even after five cycles of adsorption and could be employed in wastewater treatment for the removal of cationic dyes.
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•Graphene Oxide intercalated montmorillonite (MtGO) nanocomposite was used as adsorbent for the removal of crystal violet dye.•Adsorption of crystal violet dye onto MtGO nanocomposite was spontaneous and endothermic in nature.•The adsorption process followed Langmuir isotherm model with a very high adsorption capacity of 746.27 mg g-1.•The reaction mechanism of the adsorption process conformed to pseudo-second-order kinetic model.•The prepared MtGO nanocomposite is stable and shows good recyclability.
The aim of this study is the design and preparation of Mater-Bi/halloysite nanocomposite materials that could be employed as bioplastics alternative to the petroleum derived products. The ...biocomposite materials at variable halloysite content (from 0 to 30 wt%) were prepared by using the solvent casting method. We investigated the mechanical behaviour and the thermal properties of the prepared nanocomposites in order to estimate their suitability as biocompatible packaging materials. The thermo-mechanical characteristics were correlated to the nanocomposites' morphologies, which were studied by Scanning Electron Microscopy (SEM). As a general result, the physico-chemical performances of Mater-Bi were improved by the presence of small amounts of nanotubes, which evidenced a homogenous distribution in the polymer matrix. The strongest enhancements of the thermal stability and tensile properties were achieved for Mater-Bi/halloysite 10 wt%. A further addition of nanotubes determined the worsening of both thermal stability and mechanical behaviour.
The attained knowledge represents the starting step for the development of packaging films composed by Mater-Bi and halloysite nanotubes.
•Mater-Bi/halloysite nanocomposite films with variable filler content were prepared by casting methods•The thermal and mechanical properties of the nanocomposites were affected by their specific composition•Mater-Bi/halloysite 10 wt% evidenced the most promising performances in agreement with its uniformity•Mater-Bi/halloysite 30 wt% exhibited lower mechanical and thermal performances respect to pure Mater-Bi
This research investigates strength development and the carbon footprint of Calcium Carbide Residue (CCR) and Fly Ash (FA) based geopolymer stabilized marine clay. Coode Island Silt (CIS), a soft and ...highly compressible marine clay present in Melbourne, Australia was investigated for stabilization with the CCR and FA geopolymers. CCR is an industrial by-product obtained from acetylene gas production, high in Ca(OH)2 and was used as a green additive to improve strength of the FA based geopolymer binder. The liquid alkaline activator used was a mixture of sodium silicate solution (Na2SiO3) and sodium hydroxide (NaOH). The influential factors studied for the geopolymerization process were Na2SiO3/NaOH ratio, NaOH concentration, L/FA ratio, initial water content, FA content, CCR content, curing temperature and curing time. The strength of stabilized CIS was found to be strongly dependent upon FA content and NaOH concentration. The optimal ingredient providing the highest strength was found to be dependent on water content. Higher water contents were found to dilute the NaOH concentration, hence the optimal L/FA increases and the optimal Na2SiO3/NaOH decreases as the water content present in the clay increases. The maximum strength of the FA geopolymer (without CCR) stabilized CIS was found at Na2SiO3/NaOH=70:30 ratio and L/FA=1.0 for clay water content at liquid limit (LL). The role of CCR on the strength of FA geopolymer stabilized CIS can be classified into three zones: inactive, active and quasi-inert. The active zone where CCR content is between 7% and 12% is recommended in practice. The 12% CCR addition can improve up to 1.5 times the strength of the FA geopolymer. The carbon footprints of the geopolymer stabilized soils were approximately 22%, 23% and 43% lower than those of cement stabilized soil at the same strengths of 400kPa, 600kPa and 800kPa. The reduction in carbon footprints at high strength indicates the effectiveness of FA geopolymer as an alternative and effective green soil stabilizer to traditional Portland cement.
•Soft Coode Island Silt (CIS) was investigated for stabilization with the CCR and FA geopolymer.•CCR, an industrial by-product obtained from acetylene gas production, was used as a green additive.•Effects of Na2SiO3/NaOH, NaOH, L/FA, water content, FA, CCR, curing temperature and time are investigated.•UCS and carbon footprints between geopolymer and cement stabilization are compared.