Perlite Composites Research Articles

Comparative study on adsorptive removal of Cu, Pb, Zn heavy metals by modified perlite composites

Comparative study on adsorptive removal of Cu, Pb, Zn heavy metals by modified perlite composites

PREPARATION OF TiO2/PERLITE COMPOSITES BY USING 23-1 FRACTIONAL FACTORIAL DESIGN

Successive impregnation and calcination process was performed in order to produce TiO 2 /perlite composites. 2 3-1 fractional factorial design was first applied to optimize the production conditions of TiO 2 /perlite photocatalysts. Seven TiO 2 /perlite composites (including three central point experiments) were produced by manipulating three process parameters (amount of TiO 2 used in impregnation process, particle size of perlite and calcination temperature). Prepared TiO 2 /perlite photocatalysts were characterized by X-Ray Diffraction Spectrometer and SEM. XRD patterns indicated that anatase was the main crystalline phase for all produced samples. Degradation capacities of produced TiO 2 /perlite composites were investigated in methylene blue degradation process. The linear models of TiO 2 loading (%) and methylene blue degradation (%) of TiO 2 /perlite composites were developed by regression analysis of the experimental data. As a result of analysis of variance, it was found that developed models were statistically significant with the p-value of 0.0040 and 0.0003, for TiO 2 loading (%) and methylene blue degradation (%), respectively. According to the coefficient of determination (0.9821 and 0.9970 for the models of TiO 2 loading and methylene blue degradation, respectively) and error analysis, developed models fit well to the experimental data. Effect of process parameters was investigated by using response surface plots. Amount of TiO 2 and particle size were found as the most effective parameters on both TiO 2 loading (%) and degradation efficiency (%). Calcination temperature did not affect TiO 2 loading but methylene blue degradation capacity.

ELECTRORHEOLOGICAL PROPERTIES OF BIODEGREDABLE CHITOSAN/EXPANDED PERLITE COMPOSITES

In this study, chitosan (CS)/expanded perlite (EP) composites with different chitosan fractions (10%, 20% and 50%) were prepared by absorbing chitosan into porous networks of expanded perlite, as a new hybrid smart electrorheological (ER) material. Structural and morphological characterizations of the composites were carried out by FTIR and SEM-EDS techniques. Also, apparent density, particle size, and conductivity of the CS/EP composites were determined. Finally, the effects of electric field strength ( E ), shear rate, shear stress, and temperature onto ER behavior of the CS/EP/silicone oil system were investigated. The CS/EP/SO ER fluid system showed reversible electrorheological activity when subjected to external electric field strength by showing shear thinning non-Newtonian viscoelastic behavior. The yield stress value reached to 1250 Pa under E = 3 kV/mm for CS/EP3 composite.

Simulation of adsorption of antimony on zero-valent iron nanoparticles coated on the industrial minerals (kaolinite, bentonite and perlite) in mineral effluent

Antimony is one of the most toxic pollutants existing in the industrial and mineral effluents threatening human and other creatures’ life. Removal of antimony has been performed using various methods. One of the methods of removing antimony from mineral effluent is surface adsorption. We simulated the absorption of antimony in the presence of nano-zero-valent iron (nZVI) coated with industrial minerals such as kaolinite, bentonite, and perlite from mineral effluent using VISUAL MINTEQ 3.1 software. Our aim was to determine the factors affecting the absorption of antimony from mineral effluent by applying simulation. The simulation was performed using an adsorption of diffuse layer model. The results of simulation indicated that the nZVI concentration and pH factor are effective in the absorption of antimony. The simulation presented by increasing the pH from 1 to 2 and by rising the concentrations of nZVI from 7.5 to 12.5 mg/l causes the rate of antimony absorption to increase. The absorption capacity for nZVI coated with kaolinite, bentonite, and perlite were 3.92, 2.46, and 3.1 milligrams per gram of absorbent and the greatest amount of antimony removal was associated with perlite composite. In all cases, the coefficient of determination (R2) between laboratory results and model predictions was more than 0.9.

Research on the preparation and properties of lauric acid/expanded perlite phase change materials

In this study, a form-stable lauric acid/expanded perlite (LA/EP) composite was prepared by absorbing paraffin into porous networks of expanded perlite. The form-stable composite was characterized by using Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM) techniques, durability and leakage test. Leakage test results showed that optimum and maximum mass fraction of LA contained in the composite without leakage is 70wt.%. The FT-IR results revealed that there were physical interactions between the expanded perlite and the lauric acid. In addition, SEM images showed that LA can be quite evenly dispersed in the porous skeleton of EP. The melting temperature and latent heat of the form-stable EP/PA composite containing 70wt.% lauric acid were determined as 43.2°C and 105.58J/g, presenting its suitable phase transition temperature, sufficient latent heat, good thermal stability for application as composite phase change materials (PCMs). The durability test showed that the leakage problems of PCMs composite can be greatly prevented because of the interaction between the expanded perlite and the LA. All the results suggested that the form-stable EP/PA composite has great potential in building applications for thermal energy storage.

Novel mechanical behaviour of perlite/sodium silicate composites

A novel mechanical behaviour of perlite/sodium silicate composites is studied with the benefits of a new manufacturing method based on the perlite particle buoyancy. The objective was to develop perlite composites and to understand their quantitative relations between manufacturing parameters, volume fractions of constituents, and properties. For the composites development, sodium silicate dehydration behaviour was characterised with phases formed during dehydration i.e. liquid, gel, and solid phases. The water loss–time curve for dehydration was found to have three distinctive parts – linear part at an early stage for liquid phase, followed by non-linear part during a period between commencements of gel and hydrated solid phase formations, and then another linear part for hydrated solid phase. Foams as composites were manufactured with diluted sodium silicate binder for a density range of 0.2–0.5g/cm3. One of practical milestones achieved for composite properties without reinforcement was a density of 0.3g/cm3 at a compressive strength of 1MPa. Manufactured perlite/sodium silicate composites are analysed/discussed for understanding from three different perspectives i.e. manufacturing parameters (i.e. binder content, compaction pressure, and compaction ratio), properties (i.e. particle size, density, compressive strength, and modulus), and volume fractions of constituents. A rule of mixtures applicable for perlite composites for a constant compaction ratio was developed in comparison with that for particulate composites with non-compaction. It may be a basis for further development for variable compaction ratio in the future.

Synthesis, structural characterization and evaluation of floating B-N codoped TiO2/expanded perlite composites with enhanced visible light photoactivity

Floating photocatalysts of boron-nitrogen codoped TiO2 grafted on expanded perlite (B-N-TiO2/EP) were prepared by a facile sol–gel method. The catalysts were characterized by N2 adsorption–desorption (BET), scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (UV–vis–DRS). The results revealed that the physicochemical properties of the photocatalysts, such as BET surface area, porosity and pore size could be controlled by adjusting the calcination temperature and EP dosage. XRD patterns were mainly influenced by calcination temperature and the transformation of anatase to rutile occurred at 650°C. Uniform TiO2 loading, higher surface area and absorption in visible light region were obtained for B-N-TiO2/EP calcined at 550°C with 3.0g EP addition. Moreover, photocatalytic activity for RhB destruction under visible light irradiation was slightly influenced by TiO2 loading in the range of 1–3g EP dosage. BNTEP550 showed the highest photocatalytic activity indicating to be a promising photocatalyst employed to remediate contaminated waters using solar irradiation.

Preparation of energy efficient paraffinic PCMs/expanded vermiculite and perlite composites for energy saving in buildings

This paper deals with the preparation, characterization, thermal properties and thermal reliability of form-stable composite phase change materials (PCMs), composed of n-octadecane, expanded vermiculite, and perlite for thermal energy storage. The composite PCMs were prepared by incorporation of liquid n-octadecane within the expanded vermiculite (eVMT) and expanded perlite (ePLT), using a vacuum impregnation method. The microstructures of n-octadecane/expanded vermiculite and pearlite were characterized by scanning electron microscopy (SEM). Analysis of Fourier transform infrared spectroscopy (FT-IR) of the prepared composite PCMs showed good compatibility between n-octadecane and the expanded vermiculite and pearlite. The thermal conductivities of composites were reduced, based on the TCi results. Differential scanning calorimetry (DSC) analysis indicated that the n-octadecane/eVMT and n-odtadecane/ePLT composites maintained their large latent heat capacity and original phase change temperatures, due to large surface area and good dispersion of the eVMT and ePLT. TGA analysis revealed that the prepared composite PCMs had good thermal durability in the working temperature ranges. Therefore, n-octadecane based composite PCMs can be considered as suitable candidates for latent heat thermal energy storage, with high thermal performance.

A Model of Foam Density Prediction for Expanded Perlite Composites

Multiple sets of variables associated with expanded perlite particle consolidation in foam manufacturing were analyzed to develop a model for predicting perlite foam density. The consolidation of perlite particles based on the flotation method and compaction involves numerous variables leading to the final perlite foam density. The variables include binder content, compaction ratio, perlite particle size, various perlite particle densities and porosities, and various volumes of perlite at different stages of process. The developed model was found to be useful not only for prediction of foam density but also for optimization between compaction ratio and binder content to achieve a desired density. Experimental verification was conducted using a range of foam densities (0.15 - 0.5 g/cm 3 ) produced with a range of compaction ratios (1.5 - 3.5), a range of sodium silicate contents (0.05 - 0.35 g/ml) in dilution, a range of expanded perlite particle sizes (1 - 4 mm), and various perlite densities (such as skeletal, material, bulk, and envelope densities). A close agreement between predictions and experimental results was found.

Structures and thermal properties of fatty acid/expanded perlite composites as form-stable phase change materials

Capric acid/expanded perlite (CA/EP) and capric-stearic acid/expanded perlite (CA-SA/EP) composites were prepared. The composite phase change materials (PCMs) were characterized by scanning electron microscopy (SEM) and Fourier transformation infrared spectroscopy (FT-IR). The thermal properties and thermal reliability of the composites were determined by differential scanning calorimetry (DSC), melting-freezing test, polarization microscope equipped with hot stage. Results show that the form-stable composite PCM has an optimal mass ratio of 50% fatty acid. The fatty acid is impregnated into EP by physical attraction. The measured latent heat values of CA/EP composites are 87.3J/g for the melting process and 89.0J/g for the freezing process. The corresponding values of the CA-SA/EP are 82.1J/g and 82.6J/g, respectively. The DSC, FTIR, and thermal cycling test results show that the thermal reliability of the composite PCMs imperceptibly changes. All of the conclusions indicate that the composites have good thermal and chemical stability.

One-Step Synthesis of TiO2/Perlite Composites by Flame Spray Pyrolysis and Their Photocatalytic Behavior

TiO2/perlite composites were prepared via facile one-step flame spray pyrolysis (FSP) route. Titanium alkoxide (TIPO) and expanded perlite were used as Ti source and substrate, respectively. Precursor TIPO-ethanol solutions containing homogeneously dispersed perlite particles were processed through FSP setup at different experimental conditions regarding the gas flow and precursor supply rates. The structure, morphology, and the composition of the obtained powders were investigated. The porosity and the light absorbance of the TiO2/perlite composites were examined and their photocatalytic activity in NO oxidation was evaluated. Commercial titania powder P25 was also FSP processed and investigated for comparison. The XRD analysis revealed that biphased titania with different anatase-rutile ratio and particles size 20–40 nm was synthesized onto the perlite which according to microscopy results was covered by neck-connected TiO2nanoparticles. The anatase-rutile interplay was also demonstrated by the Raman spectra where presence of Si-O-Ti vibrational modes was observed for some samples. The UV-Vis diffuse reflectance spectra of the TiO2/perlite composites revealed up to 70% reflection that was connected to the presence of the gray perlite and superficial carbon. The best photocatalytic activity of the composites was connected to almost equal anatase-rutile ratio and possible synergetic effect of the two TiO2phases.

Effects of pH, concentration and temperature on radionuclides sorption onto polyhydroxyethyl methacrylate-expanded perlite composite

Poly (hydroxyethylmethacrylate-expanded perlite) [P(HEMA-EP)], was synthesized and its adsorptive features were investigated for natural radionuclides (TI+, Ra2+, Bi3+, Ac3+ and Pb2+) in aqueous media at differing initial pH, initial radionuclides concentration and adsorption thermodynamics. The amounts of natural radionuclides at equilibrium were determined by gamma spectrometry. The Langmuir adsorption capacities (XL) were found to be in the order of 212Pb (0.4 MBq kg−1) > 228Ac and 208Tl (0.3 MBq kg−1) > 226Ra and 212Bi (0.2 MBq kg−1). These findings indicated that P(HEMA-EP) adsorbed natural radionuclides with high affinity. It was also demonstrated that the adsorption mechanism was spontaneous (ΔG 0). The composite was reused for four more times after regeneration without any detectable changes either in its structure or adsorptive capability.

Colon-specific drug delivery behavior of pH-responsive PMAA/perlite composite.

The preparation, characterization, and in vitro release of 5-aminosalicylic acid (5-ASA) from methacrylic acid (MAA)/perlite composites (APC) prepared via a sol–gel route are reported. The free-radical graft polymerization of methacrylic acid (MAA) onto perlite particles was studied experimentally. The grafting procedure consisted of surface activation with 3-(trimethoxysilyl) propyl methacrylate (TSPA), followed by free-radical graft polymerization of methacrylic acid (MAA) in ethyl acetate with 2,2′-azobisisobutyronitrile (AIBN) initiator. The composition of the composites hybrid materials was determined by FTIR spectroscopy. Equilibrium swelling studies were carried out in enzyme-free simulated gastric and intestinal fluids (SGF and SIF, respectively). The dried composites were immersed in a saturated solution of 5-ASA in water overnight and dried over a period of three days at room temperature and the in vitro release profiles were established separately in both (SGF, pH 1) and (SIF, pH 7.4). The 5-ASA concentration of the solution was measured using a UV-Vis spectrophotometer (205 nm) at different time intervals. The in vitro drug release test revealed that the release rate of 5-ASA in buffer solutions increased with the silica content in the composites; on the contrary, the increase of the content of 3-(trimethoxysilyl)propyl methacrylate (TSPA), a coupling agent, decreased the drug release rate.

Preparation and characterization of novel conducting polyaniline–perlite composites

AbstractThe development of composites displaying electrical conductivity has attracted significant research attention over the last decade due to the possibility of new applications. For the first time, we describe the preparation of composites in which perlite particles have been combined with the well‐known conducting polyaniline (PAni). Such composites have been prepared by the in situ deposition of a thin coating of chemically synthesized polyaniline onto perlite particles (diameter <250 µm). These composite materials have been characterized by FT‐IR spectroscopy, scanning electron microscopy, thermogravimetric analysis and four‐point probe conductivity measurements. In addition, the effects of reaction time, perlite particle size and type of protonic acid medium on the conductivities of the composites have been investigated. Their conductivities were also compared to those of mechanical blends of polyaniline and perlite. Copyright © 2005 Society of Chemical Industry

Preparation and characterization of conductive latex based on polyaniline–perlite composite

AbstractThe development of polymers with high electrical conductivity has attracted significant research interest because of the possibility of new applications. Electrically conductive latexes have drawn the attention of scientists over the last few years. The present work reports the preparation of composites in which polyaniline was deposited onto perlite particles by oxidative polymerization. Electrically conductive latex was prepared by homogeneously mixing submicron conductive composites with poly(vinylacetate‐co‐butylacrylate‐co‐butylversitate) resin in a desirable ratio. The conductivity of composites and latex was measured by a standard four‐point probe. Morphology of composites was studied by scanning electron microscopy. Adhesion and electroactivity of the latex were also investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2528–2531, 2004

Failure modes in low density aluminous cement bonded composites

Acoustic emission analysis showed that the failure of some low density aluminous cement bonded perlite composites cannot be explained adequately using the classical Griffith type approach in which it is assumed that failure is caused by the catastrophic propagation of the most severe flaw. It was found that the general concept of cumulative weakening could be applied to the failure of these composites. A change in failure mode from that of cumulative weakening to Griffith type fracture occurred when the bulk density of the composite was greater than about 1.6 lb/bd ft and/or the cement content of the material was greater than approximately 30%. In addition, microscopic examination showed a change in fracture surface morphology from primarily interparticle failure at low density or low cement contents to primarily transparticle failure at high density or high cement content.