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.
•Paraffinic PCMs/expanded vermiculite and perlite composites were prepared for efficient thermal energy storage.•The composite PCMs were prepared by incorporation of liquid n-octadecane using a vacuum impregnation method.•The composite PCMs showed good dispersion and compatibility.•The composite PCMs maintained good thermal properties.
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•EP particles as a novel bacteria carrier on crack-healing in concrete was studied.•EP particles exert more positive effects on the healing capacity over EC particles.•Microstructures ...of the mineral precipitations on the crack surface were analyzed.•Completely healed crack widths were maximized in EP-B specimens.
Immobilization has been reported to be an efficient approach for bacteria-based self-healing concrete to maintain the high-efficiency mineral-forming capacity of incorporated bacteria over a period of time. However, the relatively high-cost, local unavailability, and low adsorption capacity of the current bacteria carriers make them impractical for potential implementation in large-scale concrete structures. In this study, the feasibility of expanded perlite (EP) as a novel bacteria carrier on quantifying cracks-healing in concrete via immobilization of Bacillus cohnii was demonstrated. The effects of two other self-healing techniques, i.e., direct introduction of bacteria and expanded clay (EC) immobilized bacteria, on the efficiency of crack-healing were also investigated. Experimental results showed that specimens incorporated with EP-immobilized bacteria exhibited the most efficient crack-healing after each healing time. The values of completely healed crack widths were up to 0.79mm after 28days of healing, which is larger than the value of 0.45mm for specimens incorporated with EC-immobilized bacteria. Field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) analysis confirmed that mineral precipitations on their crack surfaces are calcite crystals. The findings obtained in this study may provide a scientific basis for the potential implementation of expanded perlite, as a new microorganism carrier, in bacteria-based self-healing concrete.
•Paraffin/hydrophobic coated expanded perlite PCM composite was developed.•PCM leakage in the thermal energy storage system was prevented.•Microstructural and mechanical properties of PCM integrated ...concrete were investigated.•Thermal performance of PCM integrated concrete panel was studied.
In this study, a novel thermal energy storage composite was developed by impregnating paraffin into hydrophobic coated expanded perlite (EPO) granules. A paraffin/uncoated expanded perlite (EPW) phase change composite was also prepared to study and compare the stability when integrated into cementitious composites. Paraffin/EPW, containing 35% by weight of paraffin, showed significant leakage of phase change material (PCM) during integration into concrete. However, no PCM leakage was observed for novel paraffin/EPO containing 50% by weight of paraffin in the composite. Microstructural and mechanical properties were studied for the compatibility of hydrophobic coated PCM composite in concrete. The thermal behaviour of a concrete panel incorporating PCM was studied and compared with the reference panel. The results revealed that incorporation of the developed PCM composite into concrete significantly improved the thermal inertia and thermal energy storage.
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•Novel demulsifier of EP@APTES-Fe3O4 with amphiphilic and magnetic porous structures was prepared.•EP@APTES-Fe3O4 has good demulsification efficiency.•EP@APTES-Fe3O4 can be reused for ...4 times.•There exists a strong electrostatic attraction between EP@APTES-Fe3O4 and oil.
Oily wastewater has become a serious environmental problem and attracted global concern. Traditional methods are limited by their low separation efficiency, complicated instrument setup and high energy usage. Therefore, it is imperative to develop cost-effective materials or technologies for treating emulsified oil wastewaters. In this study, the expanded perlite (EP) was firstly modified by 3-aminopropyl triethoxysilane (APTES) to form the EP@APTES, and then magnetic Fe3O4 nanoparticles (NPs) were further grafted onto the surface of EP@APTES to synthesize the novel composite of EP@APTES-Fe3O4. The synthesized EP@APTES-Fe3O4 was employed as an environmentally friendly and recyclable demulsifier for treating emulsified oil wastewaters and its demulsification performance was evaluated. Especially, the effects of pH, demulsifier dosage and salt concentration on oil separation efficiency have been studied detailedly. The demulsification mechanism was also explored. Results showed that synthetic EP@APTES-Fe3O4 has favorable demulsification performance. The oil absorbance in the aqueous phase decreased to the lowest value when 500 mg/L of EP@APTES-Fe3O4 was added into the emulsified wastewaters. Besides, the demulsification efficiency has little difference at different salt concentrations, suggesting the favorable salt resistance of EP@APTES-Fe3O4. What’s more, the EP@APTES-Fe3O4 can be recycled up to 4 cycles without showing significant decrease in emulsion separation efficiency, which can be ascribed to the facts that the EP@APTES-Fe3O4 has good amphiphilicity and can reach the oil-water interface to contact the molecules of asphaltenes and resins; besides, it was positively charged under the conditions of pH 2.0, 4.0 and 6.0, and oil droplets could be effectively attached to the EP@APTES-Fe3O4 via electrostatic attraction. In conclusion, EP@APTES-Fe3O4 can be easily synthesized and recycled, providing a promising and cost-effective demulsifies to remove oil from the emulsified oil wastewater.
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•Green synthesis of Cu NPs/perlite composite.•Catalytic reduction of 4-nitrophenol to 4-aminophenol.•Catalyst was characterized using XRF, XRD, SEM, EDS, TEM, TG–DTA, BET, and ...FT-IR.•Catalyst can be easily recovered and reused.
We report the facile synthesis of environmentally benign Cu NPs/perlite composites without employing any toxic reductants or capping agents. Renewable natural Euphorbia esula L. not only functioned as a reductant, but also served as a stabilizer for the formation of Cu NPs. Cu NPs synthesized using aqueous extract of the leaves of E. esula L. was immobilized on perlite by a very simple and inexpensive method. The structural investigation was performed using XRF, XRD, SEM, EDS, TEM, TG–DTA, BET and FT-IR. The Cu NPs/perlite shows favorable activity and separability on the catalytic reduction of 4-nitrophenol, and can be reused several times without a decrease in the catalytic activity. Their reaction rate constant was calculated according to the pseudo-first-order reaction equation.
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•Sludge-based activated carbon HNO3-impregnated for 4 h at 90 °C removed 98% of Pb2+.•This sorbent removed 99% Cu, 43% Zn and 35% Al from complexed acid rock drainage.•Removal was ...likely due to carboxyl groups (R-COO−) on activated carbon surface.•After 24-h desorption of pH 3 solution, 0.90% (mass) of sorbed Pb2+ had leached.•This sorbent had greater and faster Pb2+ removal than other sorbents tested.
Sewage sludge has the potential to be utilised as a sorbent for dissolved pollutant removal. This study investigated metal removal efficiency of carbonised sewage sludges obtained via pyrolysis at 500 °C: biochar/carbonised sludge (CS), ZnCl2-activated sludge-based active carbon (SBAC), and three SBACs modified by nitric acid at different concentration and temperature (MSBACs). Batch adsorption kinetic tests indicated that the Pb2+ adsorption equilibrated in <5 min. Efficiencies of these sludge-based sorbents for Pb2+ adsorption followed the order MSBAC > SBAC > CS. Metal leachabilities were low or negligible for the SBAC and MSBACs. A comparison of 5-min adsorption of the best-performing MSBAC with different sorbents indicates that performance followed the trend MSBAC > grundite (illite) > zeolite (clinoptilolite) > commercial activated carbon (CAC) > kaolinite > perlite. Furthermore, MSBAC achieved 98.9%, 42.6%, and 34.6% removal of Cu, Zn, and Al, respectively, from spiked natural acid rock drainage in <5 min. The modified sludge-based activated carbon is an effective and sustainable sorbent for removing metals from aqueous environments.
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•A g-C3N4/TiO2 floating photocatalyst was prepared via a facile sol-gel method.•M. aeruginosa and Microcystin-LR were simultaneously removed under visible light.•Photoinduced holes ...and OH are the reactive species involved in photocatalysis.•Microcystin-LR was gradually degraded with oxidation of the Adda chain occurring.•The floating photocatalyst can be readily recovered for reuse.
Harmful algal blooms (HABs) have increasingly occurred worldwide causing human and ecological health risks. In this study, we report on an effective alternative to inactivating Microcystis aeruginosa under visible light irradiation with the use of a floating heterojunction photocatalyst. The photocatalyst (CTAE for short) is made of graphitic carbon nitride (g-C3N4) and TiO2 that are loaded on Al2O3-modified expanded perlite via a facile sol-gel method. The N/C doping in TiO2 and the interaction between TiO2 and g-C3N4 enhanced the generation of h+ and OH independent of O2 activation, which could facilitate applications in oxygen-deficient waters. Consideration was given to the impacts of different mass ratios of g-C3N4 to TiO2. The photocatalysts were characterized by XRD, N2 adsorption/desorption isotherms, FESEM/EDS, TEM, XPS, UV–vis absorption and Photoluminescence spectroscopy. Results showed that different contents of g-C3N4 had an influence on the crystal structure, specific surface area and pore volumes of the photocatalysts. The use of 2 g/L of 0.03CTAE (i.e., the theoretical mass ratio of g-C3N4 to TiO2 = 0.03) photocatalyst could simultaneously remove 88.1% of M. aeruginosa at an initial concentration of 2.7 × 106 cells/mL and 54.4% of Microcystin-LR at an initial concentration of 50 μg/L following 6-h of visible light irradiation. Microcystin-LR was gradually degraded with oxidation of the Adda chain occurring. Following each treatment, the floating g-C3N4/TiO2 photocatalyst could be readily recovered from the solution, demonstrating a great potential for in situ remediation of eutrophic waters.
•Surface modification methods were developed for preventing PCM leakage.•Granular PCM composites were compared with microencapsulated PCMs.•Absorption mechanisms were proposed for expanded perlite ...and paraffin.
In this study, granular phase change material (PCM) composites were developed by absorbing paraffin into the pores of expanded perlite particles with two grades of particle size. Because of the different particle sizes and pore structures, the absorption mechanisms of the expanded perlite particles were found to differ. A significant amount of paraffin leakage was found when the PCM composites were applied directly into the cement mixture. To prevent such leakage, a new method by using hydrophobic silane was investigated as surface modification for the PCM composites. The method was then compared with nanosilica deposition method. Although both methods prevented leakage effectively, cement composites incorporating silane-modified PCM composites had lower compressive strength than those incorporating nanosilica modified PCM composites. Thermal performances of expanded perlite/paraffin composites were compared with that of microencapsulated PCM and the results showed expanded perlite/paraffin composites were superior under certain conditions.
Abstract
When propagating tall blueberries by lignified cuttings, the optimal type of substrate and the method of preparing cuttings for rooting have been established. It has been experimentally ...proven that lignified cuttings before planting for rooting are effectively furrowed (wounding in the lower part of the cuttings along the shoot axis), treated with Ukorzeniacz B
aqua
growth powder (0.2%) and rooted in a substrate consisting of high peat. At the same time, the rooting rate of the
Bluecrop
variety was 69% versus 47% in the control rooted on high-moor peat and against 37% in the control rooted on a mixture of high-moor peat with perlite. And in the
Northland
variety-79% versus 59% in the control rooted on high-moor peat and against 52% in the control rooted on a mixture of high-moor peat with perlite (1:1).
Various adsorbents have been used to remove different types of dyes and heavy metal ions from wastewater especially those that are harmful to mankind. Activated carbons, plant or lignocellulosic ...wastes, clays and biopolymers are among the common adsorbents used. Chitosan, a type of biopolymer, is a good adsorbent to remove various kinds of anionic and cationic dyes as well as heavy metal ions. Chemical modifications that lead to the formation of chitosan derivatives, grafting chitosan and chitosan composites have gained much attention, extensively studied and widely reported in the literatures. This review provides relevant literature of the past ten years on the application of chitosan composites for removing dyes and heavy metal ions. A list of chitosan composites with their adsorption capacity and the experimental conditions has been compiled. This review also includes the mechanisms that might be involved during adsorption process.
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