Carbonation of steel slag at low CO2 concentrations: Novel biochar cold-bonded steel slag artificial aggregates.

Carbonation technology resolves the volume expansion of steel slag by combining CO2 with f-CaO, but the previous stringent carbonation conditions (99%vol) significantly limit the application prospect of steel slag. To achieve the carbonation of steel slag at lower CO2 concentrations, a novel cold-bonded artificial aggregates (CASSAs) based on steel slag and biochar is produced in this paper. The carbon capture capacities of CASSAs with different biochar contents (5 wt%, 10 wt%, and 15 wt%) are investigated in a low-CO2 concentration environment (10.79 % vol) and natural environment using the porosity and CO2 adsorption capacity of biochar. The changes in the performance of CASSAs before and after carbonation are investigated at different curing ages (7 d and 28 d). The results reveal that biochar increases the pores of the CASSAs. At 7 d, B15 achieves complete carbonation at low concentrations and can uptake 6.5 wt% of CO2. CO2 adsorption capacity by biochar in the natural environment facilitates the diffusion of CO2 in CASSAs. Regarding mechanical properties, the addition of biochar makes B15 at 7 d half as strong as B0, but B15 exhibits long-term strength development. B15 at 7 d has a strength of 8.49 MPa after carbonation, which is almost the same as B0. In addition, B15 achieves a net CO2 emission of -39.9 kg/ton. This study combines biochar with CASSAs to provide a potential method to carbonate steel slag at low CO2 concentrations. A new methodology was also used to quantitatively assess the ability of biochar CASSAs to solidify CO2 under low concentration conditions and natural environments from a macroscopic perspective. Biochar CASSAs have great potential to realize resource utilization and carbon capture from steel slag.

Co-disposal of municipal solid waste incineration bottom ash (MSWIBA) and steel slag (SS) to improve the geopolymer materials properties.

In previous studies, municipal solid waste incineration bottom ash (MSWIBA) exhibited low compressive strength when made into geopolymer materials due to the lack of active Ca. The introduction of steel slag (SS) not only supplements MSWIBA with active Ca, but also enables further treatment of SS, an underutilized solid waste. In this study, mechanical properties, XRD, TGA, FTIR and MIP are the means to evaluate this binary geopolymer. The heavy metal leaching concentration of this geopolymer was used as a basis for assessing its environmental impact. The results show that the introduction of SS helps to improve the compressive strength of geopolymers. The introduction of SS supplements the active Ca and promotes the production of C-(A)-S-H gels. Increasing the alkali doping on this basis contributes to the dissolution of active substances in MSWIBA and SS and promotes the generation of silica-aluminate gels, which likewise contributes to the development of compressive strength of geopolymers. The activation of MSWIBA by alkali can be used as an aluminum removal process, which can reduce the volume of harmful pores in the geopolymer. The solidification efficiency of heavy metals after the introduction of SS can be>90%.

Synthesis of geopolymer using municipal solid waste incineration fly ash and steel slag: Hydration properties and immobilization of heavy metals.

In this study, a novel method for the disposal of municipal solid waste incineration fly ash (MSWIFA) was proposed. By applying geopolymer technology, steel slag (SS) and MSWIFA were used together as precursors to synthesize a cementitious material with sufficient strength that is useable in construction. The effects of the dosages of SS and alkaline activator on the properties of the geopolymer were investigated. Compressive testing was used to characterize the mechanical properties of the geopolymer. X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used for microscopic analysis. Leaching tests were performed to assess the immobilization effect of the geopolymer on heavy metals. The results showed that the compressive strength of the geopolymer reached 23.03 MPa at 56 d with 20% SS and 11% Na2O admixture. Highly polymerized hydration products, such as C-(A)-S-H gels and N-A-S-H gels, contributed to the compact microstructure, which provided mechanical strength and limited the migration and leaching of heavy metals in the geopolymer matrix. In terms of the results, this work is significant for the development of MSWIFA management.

Exploring the carbon capture and sequestration performance of biochar-artificial aggregate using a new method.

To achieve the ambitious goal of carbon neutrality, more carbon sequestration channels need to be developed. In this study, we tried to combine biochar with cold-bonded artificial lightweight coarse aggregate (ALCA) which is made from municipal solid household waste incineration bottom ash (MSWIBA).The strong carbon capture ability of biochar was used to attract external CO2 into the interior of ALCAs, which combined with CaO in MSWIBA to form CaCO3 to achieve the effect of chemical carbon sequestration. The total carbon sequestration and carbon sequestration rate of biochar-ALCAs were quantified by a self-designed CO2 concentration change test box, the physical and mechanical properties of biochar-ALCAs were investigated, as well as the changes before and after carbonization. The results showed that biochar and ALCAs had good synergistic carbon sequestration ability. The total carbon sequestration of biochar-ALCAs could reach 30.58-33.06 kg/ton. The carbon sequestration efficiency could reach 70.2 % and 84.9 % at 28 d/56 d in a low CO2 concentration environment (0.05 % VOL). In addition, the water absorption of biochar-ALCAs decreased by 4.3 %-13.9 %, the apparent density increased by 0.9 %-2.8 %, and the strength increased by 4.3 %-7.0 % after carbon sequestration, and the physical and mechanical properties were significantly improved. The purpose of this paper is to investigate the synergistic carbon sequestration of biochar in combination with ALCAs and to quantitatively assess its ability to solidify low concentrations of CO2 in the natural environment. A new test apparatus and test method were designed for this purpose. This paper may contribute for an important advance on the preparation of recyclable cement-type composites able to capture and solidify CO2 from the natural environment.

Resource utilization of municipal solid waste incineration fly ash - cement and alkali-activated cementitious materials: A review.

The increase in municipal solid waste (MSW) production has led to an increase in MSW incineration fly ash (MSWIFA) production. MSWIFA contains toxic and harmful substances such as heavy metals and dioxins, which can cause harm to the environment if not treated properly. Only a few MSWIFAs will be landfilled directly, and the rest will need to be treated by other methods. The treatment of MSWIFA can be divided into three types: separation, stabilization/solidification (S/S), and thermal treatment, which are either not fully developed or too costly. Resource utilization is a sustainable means of treating MSWIFA. MSWIFA is used in the production of cement and alkali-activated cementitious materials as a means of resource utilization with significant advantages. This can alleviate the consumption of nature and reduce greenhouse gas emissions in conventional cement production. Compared with MSWIFA cement, MSWIFA alkali-activated cementitious material can be achieved with almost no consumption of natural resources, which is worthy of further research to realize the large-scale application of MSWIFA. At the end of the paper, the perspective of separation of dioxins from MSWIFA, co-processing of MSWI ash, and production of "MSWIFA green materials" is presented.

CsPb(Br/Cl)3 Perovskite Nanocrystals with Bright Blue Emission Synergistically Modified by Calcium Halide and Ammonium Ion.

Colloidal cesium lead halide (CsPbX3, X = Cl, Br, and I) perovskite nanocrystals (NCs) demonstrate supreme optical properties in the spectra region of infrared, red, and green. High-performance blue-emitting counterparts are still eagerly required for next-generation full-color displays. However, it is challenging to obtain efficient blue perovskite NCs, especially in a deep blue region with an emission wavelength of around 460 nm or shorter. Herein, calcium halide and ammonium ions are applied simultaneously to modify the CsPb(Br/Cl)3 NCs in situ to reduce surface defects, finally remarkably enhancing the photoluminescence quantum yield (PLQY) from 13% to 93% with an emission peak at 455 nm and the Commission Internationale de l'Eclairage (CIE) coordinates at (0.147, 0.030), which is close to the requirement of the Rec.2020 standard and also meets the requirement of blue emission in DCI-P3. Bright white emission and a wide color gamut are also achieved by combining the commercial red-emitting and green-emitting phosphors. The combination of time-resolved PL spectra and femtosecond transient absorption results discloses the reason for PLQY improvement as suppressing the nonradiative recombination.

Valorization of municipal solid waste incineration bottom ash (MSWIBA) into cold-bonded aggregates (CBAs): Feasibility and influence of curing methods.

The municipal solid waste incineration bottom ash (MSWIBA) contains amounts of hazardous elements or composition, and its disposal to landfills may pose a serious threat to the ground water and soil. To reduce the environmental impact of MSWIBA, a novelty application into the utilization of MSWIBA for the manufacture of cold-bonded aggregates (CBAs) was investigated in this study. This study explored the impacts of curing systems on the comprehensive properties of CBAs. Furthermore, the hydrating phases of the designed CBAs were studied by X-ray diffractometer, and the micro characteristics of CBAs was analyzed by Scanning Electron Microscopy. The results show that CBAs produced from the MSWIBA had good properties with density of 1.75-1.98 g/cm3, moisture content of 0.78-16.48 %, water absorption of 3.99-14.02 % and compressive behavior of 1.6-4.8 MPa. Moreover, the heating water curing environment can significantly improve the comprehensive properties of CBAs. Specifically, the compressive strength of the CBAs under the 80 °C curing condition was increased by 74 %-113 %, and the water absorption rate was reduced by 3.4 %-8 %, compared with other curing regimes. Additionally, the XRD analysis showed that there are spinel phases in the CBAs compounds, which is beneficial to solidify the hazardous metals. Also, low-carbon CBAs also greatly reduce the amount of Cu and Pb leaching, which meets the limit requirements in the Chinese standards. Overall, application of MSWIBA as admixture in CBAs is an effective approach to recycle waste and replace natural aggregates. Meanwhile, this work can provide an insight for the production of eco-friendly LWAs.

Novel recycling application of high volume municipal solid waste incineration bottom ash (MSWIBA) into sustainable concrete.

Since municipal solid waste incineration bottom ash (MSWIBA) contains some heavy metals that are harmful to the groundwater and soil, this study proposes an effective and new approach to deal with high-volume MSWIBA. Selecting 70% MSWIBA, 10% ordinary Portland cement (OPC), 10% fly ash/ground granulated blast furnace slag (FA/GGBFS), and 1% volume of polypropylene (PP) fiber as the raw materials, this project designed and manufactured cold-bonded fiber aggregates (CBFAs) and applied them into sustainable concrete. It was found that the water absorption of CBFAs was between 12 and 14%, the bulk density was between 900 and 1100 kg/m3, and the compressive strength of single particle was greater than 1.8 MPa. And it was found that the mechanical strength and bulk density of CBFAs were positively correlated, while the mechanical strength and water absorption were negatively correlated. The leaching behaviors of CBFAs on Cu, Pb, Cd, and Cr were successfully suppressed to less than 1% of that originally from MSWIBA, which can be in line with the Chinese standards. Additionally, it is also found that the green concrete with adding GGBFS-CBFAs has higher overall fluidity and better mechanical properties than the concrete with FA-CBFAs. The mechanical properties of concrete were the best under the replacement rate of 60% of CFBAs, and the strength of green concrete added with GGBFS-CBFAs reached 96% of that of ordinary concrete. In this study, the rapid chloride ion penetration test, mercury intrusion and electron microscope tests found that the bonding effect between the CBFAs and the green concrete matrix was better, and the pore structure in the transition zone of the surrounding interface was refined. The proportion of transition pores in the pore structure was up to 59%. This shows that the concrete added with CBFAs has better resistance to chloride ion diffusion, and has some improvement on the durability. This research suggests that CBFAs including high volume MSWIBA has the potential to be successfully applied as the alternative to natural aggregates in sustainable concrete, and this can also advance waste recycling, and solidify high volume heavy metals in infrastructures.

Expanded Graphite-Based Materials for Supercapacitors: A Review.

Supercapacitors have gained e wide attention because of high power density, fast charging and discharging, as well as good cycle performance. Recently, expanded graphite (EG) has been widely investigated as an effective electrode material for supercapacitors owing to its excellent physical, chemical, electrical, and mechanical properties. Based on charge storage mechanism, supercapacitors have been divided into symmetric, asymmetric, and hybrid supercapacitors. Here, we review the study progress of EG-based materials to be electrode materials. Furthermore, we discuss the application prospects and challenges of EG-based materials in supercapacitors.

Application of expanded graphite-based materials for rechargeable batteries beyond lithium-ions.

New types of rechargeable batteries other than lithium-ions, including sodium/potassium/zinc/magnesium/calcium/aluminum-ion batteries and non-aqueous batteries, are rapidly advancing towards large-scale energy storage applications. A major challenge for these burgeoning batteries is the absence of appropriate electrode materials, which gravely hinders their further development. Expanded graphite (EG)-based electrode materials have been proposed for these emerging batteries due to their low cost, non-toxic, rich-layered structure and adjustable layer spacing. Here, we evaluate and summarize the application of EG-based materials in rechargeable batteries other than Li+ batteries, including alkaline ion (such as Na+, K+) storage and multivalent ion (such as Mg2+, Zn2+, Ca2+ and Al3+) storage batteries. Particularly, this article discusses the composite strategy and performance of EG-based materials, which enables them to function as an electrode in these emerging batteries. Future research areas in EG-based materials, from the fundamental understanding of material design and processing to reaction mechanisms and device performance optimization strategies, are being looked forward to.

Efficient and Reabsorption-Free Radioluminescence in Cs3Cu2I5 Nanocrystals with Self-Trapped Excitons.

Radioluminescent materials (scintillators) are widely applied in medical imaging, nondestructive testing, security inspection, nuclear and radiation industries, and scientific research. Recently, all-inorganic lead halide perovskite nanocrystal (NC) scintillators have attracted great attention due to their facile solution processability and ultrasensitive X-ray detection, which allows for large area and flexible X-ray imaging. However, the light yield of these perovskite NCs is relatively low because of the strong self-absorption that reduces the light out-coupling efficiency. Here, NCs with self-trapped excitons emission are demonstrated to be sensitive, reabsorption-free scintillators. Highly luminescent and stable Cs3Cu2I5 NCs with a photoluminescence quantum yields of 73.7%, which is a new record for blue emission lead-free perovskite or perovskite-like NCs, is produced with the assistance of InI3. The PL peak of the Cs3Cu2I5 NCs locates at 445 nm that matches with the response peak of a silicon photomultiplier. Thus, Cs3Cu2I5 NCs are demonstrated as efficient scintillators with zero self-absorption and extremely high light yield (≈79 279 photons per MeV). Both Cs3Cu2I5 NC colloidal solution and film exhibit strong radioluminescence under X-ray irradiation. The potential application of Cs3Cu2I5 NCs as reabsorption-free, low cost, large area, and flexible scintillators is demonstrated by a prototype X-ray imaging with a high spatial resolution.

Characterization and spatiotemporal expression analysis of nine bone morphogenetic protein family genes during intermuscular bone development in blunt snout bream.

Intermuscular bones (IBs) only exist in the myosepta of lower teleosts and its molecular mechanism remains to be clarified. Bone morphogenetic proteins (BMPs) have been demonstrated to be involved in various physiological processes, including bone and cartilage formation. In this study, we firstly obtained and characterized nine bmp genes for Megalobrama amblycephala, which belongs to Cyprinidae and have a certain amount of IBs. Sequence alignment and phylogenetic analysis both documented that the mature proteins of M. amblycephala bmp genes were highly conserved with other corresponding homologs, respectively, indicating that the function of each bmp gene has been conserved throughout evolution. As a step to characterize potential involvement of bmp genes in IB formation and development, spatiotemporal expressions of nine bmp genes (bmp2a, bmp2b, bmp3, bmp4, bmp5, bmp7b, bmp8a, bmp14 and bmp16) were investigated during the key development stages of IBs. During the ossification process from stage I (the IBs haven't emerged) to stage IV (all of the IBs ossified in the tail with the mature morphology), the expression profiles revealed that bmp16 was the most abundant transcript while bmp4 had the lowest abundance. The mRNA levels of bmp3, bmp4, bmp5 and bmp8a increased significantly at stage II, suggesting their roles in stimulating IB formation. The expression of bmp7b reached the highest level at stage III (the rapid period of IB development), suggesting potential involvement of bmp7b in promoting osteoblast differentiation. With the exception of bmp7b and bmp16, most bmp genes appeared a significant increase at IB maturation phase (stage IV), which means that they may play important roles in maintenance of IB morphogenesis. Spatial tissue distribution of bmp genes showed that most bmp genes were observed at the highest level in developing IBs at one year old fish. Spatiotemporal expression patterns suggest the potential key roles of these bmp genes in IBs formation and maintenance in fish, being as possible promoters or inhibitors.

Dynamic mRNA and miRNA expression analysis in response to intermuscular bone development of blunt snout bream (Megalobrama amblycephala).

Intermuscular bone (IB), which occurs only in the myosepta of lower teleosts, is attracting more attention because they are difficult to remove and make the fish unpleasant to eat. By gaining a better understanding of the genetic regulation of IB development, an integrated analysis of miRNAs and mRNAs expression profiling was performed on Megalobrama amblycephala. Four key development stages were selected for transcriptome and small RNA sequencing. A number of significantly differentially expressed miRNAs/genes associated with bone formation and differentiation were identified and the functional characteristics of these miRNAs/genes were revealed by GO function and KEGG pathway analysis. These were involved in TGF-ß, ERK and osteoclast differentiation pathways known in the literature to affect bone formation and differentiation. MiRNA-mRNA interaction pairs were detected from comparison of expression between different stages. The function annotation results also showed that many miRNA-mRNA interaction pairs were likely to be involved in regulating bone development and differentiation. A negative regulation effect of two miRNAs was verified through dual luciferase reporter assay. As a unique public resource for gene expression and regulation during the IB development, this study is expected to provide forwards ideas and resources for further biological researches to understand the IBs' development.

Mitochondrial Genome Variation after Hybridization and Differences in the First and Second Generation Hybrids of Bream Fishes.

Hybridization plays an important role in fish breeding. Bream fishes contribute a lot to aquaculture in China due to their economically valuable characteristics and the present study included five bream species, Megalobrama amblycephala, Megalobrama skolkovii, Megalobrama pellegrini, Megalobrama terminalis and Parabramis pekinensis. As maternal inheritance of mitochondrial genome (mitogenome) involves species specific regulation, we aimed to investigate in which way the inheritance of mitogenome is affected by hybridization in these fish species. With complete mitogenomes of 7 hybrid groups of bream species being firstly reported in the present study, a comparative analysis of 17 mitogenomes was conducted, including representatives of these 5 bream species, 6 first generation hybrids and 6 second generation hybrids. The results showed that these 17 mitogenomes shared the same gene arrangement, and had similar gene size and base composition. According to the phylogenetic analyses, all mitogenomes of the hybrids were consistent with a maternal inheritance. However, a certain number of variable sites were detected in all F1 hybrid groups compared to their female parents, especially in the group of M. terminalis (♀) × M. amblycephala (♂) (MT×MA), with a total of 86 variable sites between MT×MA and its female parent. Among the mitogenomes genes, the protein-coding gene nd5 displayed the highest variability. The number of variation sites was found to be related to phylogenetic relationship of the parents: the closer they are, the lower amount of variation sites their hybrids have. The second generation hybrids showed less mitogenome variation than that of first generation hybrids. The non-synonymous and synonymous substitution rates (dN/dS) were calculated between all the hybrids with their own female parents and the results indicated that most PCGs were under negative selection.

The complete mitochondrial genome of the hybrid of Megalobrama terminalis (♀) × Megalobrama amblycephala (♂).

In this study, the complete mitochondrial genome of the hybrid of Megalobrama terminalis (♀) × Megalobrama amblycephala (♂) was determined. The total length of the genome was 16,622 bp in accordance with the female parent, and the overall base composition was 31.13% A, 24.94% T, 27.72% C and 16.21% G, with a slight A + T bias. The genome contained 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and 2 main non-coding regions (the control region and the origin of the light strand replication). The 99.48% sequence identity between the hybrid and its female parent, M. terminalis, confirmed the maternal inheritance pattern followed by the mitochondrial genome of the hybrid bream; however, it was interesting to find a total of 86 mutation sites in 12 genes or regions. The phylogenetic analysis indicated that the studied hybrid was relatively more close to M. terminalis, and the result was in agreement with their conventional taxonomic relationship. The genome information reported here may provide important information for further studies on the mitochondrial inheritance mechanisms in hybrids.