Review on physical performance, modification mechanisms, carbon emissions and economic costs of recycled aggregates modified with physical enhancement technologies

With the continuous advancement of urban renewal, the application of recycled aggregates (RA) is a win-win measure to solve the treatment of construction waste and provide the required building materials. However, the existence of a large amount of old adhesive mortar (OAM) makes it difficult for RA to equivalently replace natural aggregates (NA) due to their higher water absorption and crushing index, as well as a lower apparent density. From the published literature on enhancing RA, the most mature and easiest method for construction is physical enhancement technology. Therefore, through a review of recent related researches, this article summarizes and compares the modification effects of mechanical grinding technology, traditional heating and grinding technology, and microwave heating technology on the physical properties of RA, including water absorption, apparent density, and crushing value. The related modification mechanisms were discussed. Additionally, the impacts of different physical enhancement technologies on the environment and economy effects are assessed from the perspectives of carbon emissions and cost required during processing. Based on multi-criteria analysis, microwave heating technology is more efficient and cleaner, which is the most recommended in the future.

AC/off-grid photovoltaic powered open-source ball mill

Ball milling is used for comminution by rotating a drum to grind materials using balls with specific diameters. Ball milling advantages include the potential for high capacity, predicted fineness in a specific amount of time, reliability, safety, and simplicity, but has disadvantages of high weight, energy consumption and costs, which limit accessibility. To overcome these limitations this study applies the free and open source hardware approach coupled to distributed digital manufacturing to fabricate a ball mill with a simple, customizable design that can be used in a wide range of scientific applications and circumstances including those without access to reliable grid electricity. The highly-customizable design reduces the cost to <US$130 for an AC powered version and <US$315 for a switchable power that enables off-grid operation with a solar module and battery. Using a solar photovoltaic energy source not only improves the power reliability, but also makes it easier to move the ball mill for use in field environments. The open source ball mill is capable of reducing silicon particle sizes from the millimeter scale down to the nanometer scale.

Mechanochemically interlocked cubane copper complex interface for WOLED

In the rapid development of organic light-emitting diodes (OLEDs), phosphorescent transition metal complexes have played a crucial role as the most promising candidates for next generation display and lighting applications. However, most devices are fabricated using iridium and platinum-based complexes which are expensive and available in very limited quantities, whereas using relatively abundant organometallic complexes for fabrication results mostly in inefficient performance results. To overcome these issues, we have synthesized tetra copper iodide with tetra triphenyl cage like structure (denoted as CIPh) as an emerging class of luminescent material by mechanochemical grinding followed by thermal treatment for application in white OLED. The CIPh complex exhibits considerable quantum yield and a millisecond decay lifetime. Phosphorescent OLEDs were fabricated using CIPh complex as emitter shows a remarkable performance with external quantum efficiency and current efficiency of 5.28 % and 22.76 cd/A, with a high brightness of 4200 cd m^-2, respectively. White OLEDs were also fabricated with a fluorescent blue and phosphorescent red emitted with (CIPh) as green emitter and achieved an impressive CRI of 82 with an EQE of over 3 %. This is the first ever attempt at fabricating WOLEDs using organocopper complex.

Manufacturing nano novel composites using sugarcane and eggshell as an alternative for producing nano green mortar

The purpose of this study is to demonstrate the impact of incorporating two different types of green nanomaterials (sugarcane and eggshell) on destructive and non-destructive properties of mortar. Nano sugarcane (NSC) was manufactured by calcining sugarcane at temperatures of 600 °C for 3 h. On the other hand, nano eggshell (NES) was manufactured by calcining eggshell at temperatures of 600 °C for 6 h. The sugarcane ash and eggshell ash were then milled to nano size. The final nano-sized product replaced Portland cement with different dosages of 2, 4 and 6%. Sixteen mortar mixtures were designed and prepared using only NSC or only NES or a combined hybrid of NSC and NES. Consistency, compressive strength, flexural strength and microstructure analysis (scanning electron microscopy and energy-dispersive X-ray) tests were conducted to investigate the influence of replacement materials on the performance and properties of mortars. The results showed that the use of nano sugarcane and nano eggshell enhanced the compressive strength and reduced permeability of green mortar due to the micropore structure. At the ages of 7 and 28 days, mortars containing a replacement ratio of 2% (0.5% NSC + 1.5% NES) had remarkably improved mechanical properties, and the improvement in compressive strength reached 21.3% and flexural strength to 10.08% when compared to the control sample. The efficiency of NSC and NES in increasing mortar strength was also confirmed by microstructure analysis.

Mechanofluorochromism with Aggregation-Induced Emission (AIE) Characteristics: A Perspective Applying Isotropic and Anisotropic Force

Organic mechanofluorochromic (MFC) materials (that change their emission under anisotropic and isotropic pressure) have attracted a great attention in recent years due to their promising applications in sensing pressure, storage devices, security inks, three-dimensional (3D) printing, etc. Stimuli-responsive organic materials with aggregation-induced emission (AIE) characteristics would be an interesting class of materials to enrich the chemistry of MFC compounds. A diamond anvil cell (DAC) is a small tool that is employed to generate high and uniform pressure on materials over a small area. This article discusses the relationship between the chemical structure of AIE compounds and the change in emission properties under anisotropic (mechanical grinding) and isotropic (hydrostatic) pressure. The luminescent properties of such materials depend on the molecular rearrangement in the lattice, conformational changes, excited state transitions and weak intermolecular interactions. Hence, studying the change in luminescent property of these compounds under varying pressure will provide a deeper understanding of the excited-state properties of various emissive compounds with stress. The development of such materials and studies into the effect of pressure on their luminescence properties are summarized.

Green synthesis of graphitic nanobiochar for the removal of emerging contaminants in aqueous media

This study reports the preparation of nanobiochar (NBC) via top-down approach of bioenergy waste-derived dendro biochar through mechanised grinding in order to assess its capacity to remove emerging contaminants, such as antibiotics, agrochemicals, and potentially toxic elements from aqueous media. Preconditioned biochar was disc milled in ethanol media, and the resulting colloidal biochar was dispersed in water to obtain the NBC fraction by centrifugation. Adsorption edge and isotherm experiments were carried out at pH 3 to 8 and NBC dosages of 0.5 g/L for oxytetracycline (OTC), glyphosate (GL), hexavalent chromium (CrVI), and cadmium (CdII). NBC was characterised by scanning electron microscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area, and Fourier transform infrared spectroscopy, which demonstrated the flakey and graphitic nature of the NBC particles with a surface area of 28 m²/g and the presence of different functional groups, such as OH, CO, NH, and CH₃. The best pH for OTC and Cd(II) was 9, whereas the best pH levels for GL and Cr(VI) were 7 and 4, respectively. Isotherms depicted a positive cooperative adsorption mechanism by providing the best fit to the Hills equation, with high removal capacities for four contaminants. Dendro NBC showed the best performance, demonstrated by the high partition coefficient for the removal of OTC, GL, Cr(VI), and Cd(II) over various types of adsorbents. The overall results indicated that graphitic NBC produced by mechanical grinding of dendro biochar is a promising material for the removal of OTC, GL, Cr(VI), and Cd(II) from aqueous media.

Improvement of sugar yields from corn stover using sequential hot water pretreatment and disk milling

Efficient pretreatment is essential for economic conversion of lignocellulosic feedstocks into monosaccharides for biofuel production. To realize high sugar yields with low inhibitor concentrations, hot water or dilute acid pretreatment followed by disk milling is proposed. Corn stover at 20% solids was pretreated with hot water at 160-200°C for 4-8min with and without subsequent milling. Hot water pretreatment and disk milling acted synergistically to improve glucose and xylose yields by 89% and 134%, respectively, compared to hot water pretreatment alone. Hot water pretreated (180°C for 4min) and milled samples had the highest glucose and xylose yields among all hot water pretreated and milled samples, which were comparable to samples pretreated with 0.55% dilute acid at 160°C for 4min. However, samples pretreated with 1% dilute acid at 150°C for 4min and disk milled had the highest observed glucose (87.3%) and xylose yields (83.4%).