A new strategy has been innovatively proposed for wrapping the Ni-incorporated and N-doped carbon nanotube arrays (Ni-NCNTs) on porous Si with robust Ni–Si interfacial bonding to form the ...core–shell-structured NCNTs-Ni2Si@Si. The hierarchical porous silicon core was first fabricated via a novel self-templating synthesis route based on two crucial strategies: in situ thermal evaporation of crystal water from the perlite for producing porous SiO2 and subsequent magnesiothermic reduction of porous SiO2 into porous Si. Ni-NCNTs were subsequently constructed based on the Ni-catalyzed tip-growth mechanism and were further engineered to fully wrap the porous Si microparticles by forming the Ni2Si alloy at the heterojunction interface. When the prepared NCNTs-Ni2Si@Si was evaluated as the anode material for Li-ion batteries, the hierarchical porous system in the Si core and the rich void spaces in carbon nanotube arrays contributed to the remarkable accommodation of volume expansion of Si as well as the significant increase of Li+ diffusion and Si utilization. Moreover, the Ni2Si alloy, which chemically linked the Ni-NCNTs and porous Si, not only provided good electronic contact between the Si core and carbon shell but also effectively prevented the CNTs’ detachment from the Si core during cycling. The multifunctional structural design rendered the whole electrode highly stable and active in Li storage, and the electrochemically active NCNTs-Ni2Si@Si electrode delivered a high reversible capacity of 1547 mAh g–1 and excellent cycling stability (85% capacity retention after 600 discharge–charge cycles) at a current density of 358 mA g–1 (0.1 C) as well as good rate performance (778 mAh g–1 at 2 C), showing great potential as an efficient and stable anode for high energy density Li-ion batteries.
In this work, silver nanoparticles (Ag NPs) were loaded on the surface of perlite using Hamamelis virginiana leaf extract as a reducing and stabilizing agent. The immobilization of Ag NPs was ...confirmed by FT-IR, XRD, FESEM, EDS and TEM. According to TEM analysis, the average size of Ag NPs on perlite before and after the reduction reaction was in the range of 8–35 nm. The prepared Ag NPs/perlite was a highly active catalyst for the reduction of 4-nitrophenol (4-NP) and Congo red (CR). It can be recovered and reused several times without losing of its catalytic activity.
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•Facile and green approach to prepare Ag NPs/perlite by extract of the leaves of Hamamelis virginiana.•Ag NPs/perlite was characterized by FT-IR, XRD, FESEM, EDS and TEM.•Catalytic reduction of 4-nitrophenol and Congo red.•High recycling efficiency of Ag NPs/perlite in reduction reactions.
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•Sulfamethoxazole was degraded using a floating photocatalyst under UV irradiation.•The photocatalyst was obtained by supporting TiO2 onto expanded perlite.•The mechanism of ...sulfamethoxazole photodegradation in water was proposed.•The photodegradation rate of sulfamethoxazole is greater at higher pH.
Photocatalytic degradation of an antibiotic, sulfamethoxazole (SMX), in aqueous solution using a novel floating TiO2-expanded perlite photocatalyst (EP-TiO2-773) and radiation from the near UV spectral range was studied. The process is important considering that SMX is known to be a widespread and highly persistent pollutant of water resources. SMX degradation was described using a pseudo-first-order kinetic equation according to the Langmuir–Hinshelwood model. The products of the SMX photocatalytic degradation were identified. The effect of pH on the kinetics and mechanism of SMX photocatalytic degradation was explained.
This paper investigates the effect of temperature on the microstructure, failure mechanism and compressive mechanical properties of newly developed ZA27 syntactic foams. Two different types of filler ...particles are considered, i.e. expanded perlite (P) and expanded glass (G). Metallic syntactic foam (MSF) has been produced via a counter-gravity infiltration process of packed particle beds, followed by controlled thermal exposure. Quasi-static compressive tests were carried out on cylindrical samples at five different in-situ testing temperatures between 25 °C and 350 °C. At all considered temperatures, P-MSF exhibits superior mechanical properties compared to G-MSF. The mechanical properties of both foam types decrease significantly with increasing testing temperature. For comparison, solid ZA27 samples were compressed at the same testing temperatures. Due to microstructural changes, a significant strength degradation of solid ZA27 was observed starting at 100 °C. Comparison of results indicates that the temperature-dependent mechanical properties of P-MSF and G-MSF are strongly controlled by the matrix material. However, the addition of particles decreased the relative reduction of plateau stress and volumetric energy absorption of ZA27 MSF at elevated temperatures.
A porous supporting matrix, expanded perlite (EP) is composited with a salt hydrate mixture of CaCl2·6H2O and SrCl2·6H2O (98:2 in mass ratio), to develop a nonflammable thermal storage material for ...building use. The salt hydrate is uniformly adsorbed on sheets of EP, and a maximum absorption capacity test shows EP can contain as high as 55 wt% the salt hydrate and keep the stable form. It is shown that the melting temperature of the composite PCM is 27.38 °C, close to that of CaCl2·6H2O, and its latent heat is 87.44 J/g, equivalent to the calculated value based on the mass fraction of CaCl2·6H2O in the composite. EP further reduces the salt hydrate thermal conductivity by over 70% to enhance its thermal insulation, and suppresses the supercooling. A 1000 heating-cooling cycles test verifies the CaCl2·6H2O/EP composite possesses good thermal reliability. The CaCl2·6H2O/EP composite is then fabricated into a board for replacing the foam board employed as the core in a commercial foam insulating brick to obtain a PCM brick. It is found that, when applied as the roof of a test room, the PCM brick has the function of decreasing the indoor peak temperature and causing the hysteresis in the indoor temperature rise, compared with the foam insulation brick. The nonflammability along with good thermal storage and insulation properties makes the CaCl2·6H2O/EP composite PCM show great promises for use in building energy conservation.
•A novel form-stable CaCl2·6H2O/EP composite PCM with nonflammability was prepared.•Composite PCM has low thermal conductivity, little supercooling, low cost and good thermal reliability.•Composite PCM has great thermal characteristics and insulation properties.•Composite PCM shows great potentials to be applied in building energy conservation.
•A novel phase change material (PCM) wallboard with grooves has been fabricated.•Solar thermal system was coupled with PCM wallboard through capillaries.•The hybrid system has reduced the indoor ...temperature fluctuation.•PCM wallboard extended the service time of solar thermal system.•The coupling use of PCM and solar energy enhanced building energy efficiency.
Building is a significant contributor to high energy consumption and its associated environmental effects. Hence, there had been a continuous drive towards alternative active and passive options for creating a thermally comfortable environment at lower energy penalty. The incorporation of phase change material (PCM) with building envelope appears as one of passive techniques for building energy efficiency. Solar thermal energy, a renewable energy, has an unsteady problem that restricts its application on the space heating. Therefore, PCM wallboard (passive option) coupling with solar thermal system (active option) to form a hybrid system can enhance the thermal performance of building envelope and meanwhile maintain a comfortable indoor thermal environment with a sustainable and cleaning energy supply under the winter condition. In this study, a novel expanded perlite-based composite phase change material wallboard has been fabricated and then combined with solar thermal system by capillaries. Strategy experiments were comparatively conducted in two real scale experimental rooms (PCM room and reference room). PCM wallboards coupling with solar thermal system have been installed on the internal surface of PCM room, and the reference room is the same as PCM room, except that there is no PCM wallboard. The results showed that PCM wallboards with excellent mechanical ability and thermal property performed well in their integration with solar thermal system, and this hybrid system has reduced daily energy consumption by 44.16%. Therefore, it can be concluded that the novel hybrid system composed of PCM wallboard and solar thermal system has a significant application potential on maintaining a comfortable indoor environment and enhancing building energy efficiency.
•The paper presents an experimental study on thermal conductivity enhancement.•Thermal conductivity of composite PCMs is enhanced by adding CuP and CF.•Method of mixing TCE with PCM is better than ...implanting TCE into matrix material.•Composite PCMs have good thermal property for thermal energy storage.
In this study, form-stable tetradecanol (TD)/expanded perlite (EP) composites by adding Cu powder (CuP) and carbon fiber (CF) to enhance thermal conductivities have been prepared via vacuum impregnation method. The thermal conductivity enhancer (TCE) is introduced by two methods of mixing TCE with phase change materials (PCMs) and implanting TCE into matrix materials. The result demonstrates the former is better than the latter in aspects of thermal property, thermal conductivity and controllability, moreover, adding ratio of TCEs gather in more appropriate interval from 2.5% to 3% suitable for the former. For CPCMs, FT-IR results indicate it is no chemical interaction among raw materials but physical combination via two methods. CPCMs prepared by the method of mixing TCE with PCMs have better phase change latent heat and thermal stability by DSC and TGA, while thermal cycling measurements show that form-stable composite PCMs have adequate stability even after being subjected to 200 melting/freezing cycles. Therefore, the method of mixing TCE with PCMs has better thermal property and controllability than that of implanting TCE into matrix materials and the prepared CPCM has great application prospect in solar energy utilization, building material, indoor cooling instrument and so on for thermal energy storage.
A major challenge in extrusion‐based additive manufacturing is the lack of commercially available materials compared to those in well‐established processes like injection molding or extrusion. This ...study aims at expanding the material database by evaluating the feasibility of polypropylene, which is one of the most common and technologically relevant semicrystalline polymers. Expanded‐perlite‐filled polypropylene and ternary blends with amorphous polyolefins are evaluated to establish an understanding of their processability and their printability. A detailed study on the shrinkage behavior, as well as on the thermal, mechanical, morphological, and warpage properties is performed. It is found that smaller sized fillers result in a tremendous warpage and shrinkage reduction and concurrently improved mechanical properties than compounds filled with bigger sized fillers. Based on the optimal properties profile, a ternary blend that can overcome the shrinkage and warpage of printed parts is suggested.
The semicrystalline nature of polypropylene usually results in undesirable shrinkage and warpage, especially when parts are produced by extrusion‐based additive manufacturing. The present work aims at addressing this issue by offering a simple strategy for producing dimensionally stable 3D‐printed polypropylene. Therefore, ternary blends containing amorphous polyolefins and spherical perlite fillers are compounded, characterized, and successfully printed.
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•F-Ce-TiO2/EP floating photocatalysts were prepared by a facile sol-gel method.•F-Ce-TiO2/EP achieved efficient alga destruction under visible light irradiation.•MC-LR and organic ...metabolin were also oxidized during the photocatalytic process.•F-Ce-TiO2/EP photocatalysts have good reusability and stability.
A series of efficient solar light-driven F-Ce-TiO2/expanded perlite (EP) floating photocatalysts were successfully synthesized using a facile sol-gel method and applied as algaecides in eutrophic waters. The as-synthesized photocatalysts were characterized by means of XRD, FESEM/EDX, TEM, N2 adsorption/desorption, XPS, UV–vis DRS and PL spectrum. The results show that F-Ce-TiO2/EP has a honeycomb-like structure with F-Ce co-doped TiO2 particles distributed on EP surface. Calcination temperature can greatly affect the doping status, specific surface area and photoelectric properties of F-Ce-TiO2/EP. Among the synthesized photocatalysts, those calcined at 450°C (i.e., F-Ce-TiO2/EP450) exhibited the highest photocatalytic activity. The photocatalytic destruction process could be described by the modified Chick–Watson kinetic model and Hom kinetic model. F-Ce-TiO2/EP450 can achieve the algal cells removal rate of 98.1% within 9h. The algal cell walls obviously damaged in this process. Following the damages, the electron transfer in water-water cycle was also inhibited, thereby accelerating the death of algal cells with the accumulation of the reactive oxygen species (ROS). In addition, microcystin-LR (MC-LR) and metabolic products proved to be effectively removed by photocatalytic oxidation during the algal destruction process. After three consecutive cycles, the removal rate of algal cells can still achieve 88.7% by F-Ce-TiO2/EP450, indicating the F-Ce-TiO2/EP photocatalyst has good reusability and stability.
There are many factors affecting the filtration of drilling fluid into the drilled formation. The adverse impact of the filtration on the well productivity calls for concerted research effort towards ...developing promising solutions to minimize the volume of mud filtration and solid invasion. This study investigates the potentials of perlite as a filtration control agent under high pressure conditions. Perlite is an amorphous volcanic glass that occurs naturally and abundantly. Perlite was added to a high-density barite weighted drilling fluid at different concentrations. For the different perlite concentrations, fluid loss test was conducted to form filter cakes. NMR measurements were performed before and after fluid invasion and filter cake deposition to evaluate the amount and particle size distribution of the solids that invaded the core samples. The results showed that the drilling fluid formulations containing perlite controlled filtration loss and mud particles invasion better than standard barite weighted fluids.
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•Introduce “perlite” as new drilling fluid additive•Reduction in filter cake thickness by 30%, and filtration volume by 40% as consequence of perlite addition.•The cutting carrying capacity and sealing properties were improved due to the perlite addition.
