Hydration of dicalcium silicate and diffusion through neo-formed calcium-silicate-hydrates at weathered surfaces control the long-term leaching behaviour of basic oxygen furnace (BOF) steelmaking slag

Alkalinity generation and toxic trace metal (such as vanadium) leaching from basic oxygen furnace (BOF) steel slag particles must be properly understood and managed by pre-conditioning if beneficial reuse of slag is to be maximised. Water leaching under aerated conditions was investigated using fresh BOF slag at three different particle sizes (0.5–1.0, 2–5 and 10 × 10 × 20 mm blocks) and a 6-month pre-weathered block. There were several distinct leaching stages observed over time associated with different phases controlling the solution chemistry: (1) free-lime (CaO) dissolution (days 0–2); (2) dicalcium silicate (Ca₂SiO₄) dissolution (days 2–14) and (3) Ca–Si–H and CaCO₃ formation and subsequent dissolution (days 14–73). Experiments with the smallest size fraction resulted in the highest Ca, Si and V concentrations, highlighting the role of surface area in controlling initial leaching. After ~2 weeks, the solution Ca/Si ratio (0.7–0.9) evolved to equal those found within a Ca–Si–H phase that replaced dicalcium silicate and free-lime phases in a 30- to 150-μm altered surface region. V release was a two-stage process; initially, V was released by dicalcium silicate dissolution, but V also isomorphically substituted for Si into the neo-formed Ca–Si–H in the alteration zone. Therefore, on longer timescales, the release of V to solution was primarily controlled by considerably slower Ca–Si–H dissolution rates, which decreased the rate of V release by an order of magnitude. Overall, the results indicate that the BOF slag leaching mechanism evolves from a situation initially dominated by rapid hydration and dissolution of primary dicalcium silicate/free-lime phases, to a slow diffusion limited process controlled by the solubility of secondary Ca–Si–H and CaCO₃ phases that replace and cover more reactive primary slag phases at particle surfaces

Alkaline residues and the environment: A review of impacts, management practices and opportunities

Around two billion tonnes of alkaline residues are produced globally each year by industries such as steel production, alumina refining and coal-fired power generation, with a total production estimate of 90 billion tonnes since industrialization. These wastes are frequently stored in waste piles or landfills, and can be an environmental hazard if allowed to generate dust, or if rainwater infiltrates the waste. This review will focus on the environmental impacts associated with alkaline residues, with emphasis on the leachates produced by rainwater ingress. Many alkaline industrial wastes can produce leachates that are enriched with trace metals that form oxyanions (e.g. As, Cr, Mo, Se, V), which can be very mobile in alkaline water. The management options for the residues and their leachates are also discussed, distinguishing active and passive treatment options. Potential reuses of these materials, in construction materials, as agricultural amendments, and in environmental applications are identified. The mechanisms of carbon sequestration by alkaline residues are assessed, and the potential for enhancing its rate as a climate change off-setting measure for the industry is evaluated. The potential for recovery of metals critical to e-technologies, such as vanadium, cobalt, lithium and rare earths, from alkaline residues is considered. Finally research needs are identified, including the need to better understand the biogeochemistry of highly alkaline systems in order to develop predictable passive remediation and metal recovery technologies

Synthesis of allyl-cyclopropyl alcohols and allyl-1,5-hexadien -3- ols and investigation of their antibacterial and antifungal activities

629-633Two different methods have been used to obtain allyl-cyclopropyl alcohols and allyl-1,5-hexadien -3-ols, starting with various allyl substituted chloromethyloxiranes. While allyl substitued 1,5 - hexad ien - 3 - ols are formed in  reactions occurring with Mg in THF, the unsaturated cyclic alcohols are also formed. However, the reaction carried out with Na in CH3OH gives only 1,5 - dien - 3 - ols. Antimicrobial activity of the synthesised compounds has been tested against 16 microorganisms. The compounds have also been screened for their antibacterial and antifungal activities against bacteria, Yeasts and moulds.</span

A posterior hybrid ML optimization to analyze the relationship between high temperature rheological factors of the Superpave PG and improved PG + asphalt specifications

This study investigated the relationship between the parameters of the Superpave PG asphalt classification method and the improved MCSR PG-Plus asphalt classification method with two hybrid fuzzy models based on deep learning artificial neural network (ANN) and Support Vector Machine (SVM). For this purpose, virgin asphalt was modified with four well-known polymers namely, styrene butadiene styrene (SBS), styrene butadiene rubber (SBR), ethylene vinyl acetate (EVA) and high-density polyethylene (HDPE) at various modification percentages. In order to collect data, a total of 294 high temperature rheological experiments were carried out on neat and modified samples. Complex modulus (), phase angle (), percent recovery () and the non-recoverable creep compliance () were determined at five different temperatures to construct dataset. The relationship between, and factors two models were utilized namely ANN_FL and SVM_FL. Results showed that the ANN based model outperforms the SVM based hybrid model with a value of 0.96 R2 and 0.83 RMSE. The uncertain situation behind road traffic classification were interpreted with the help of FL. Regarding the experimental procedure and machine learning (ML) model results, it has been concluded that the all ML methods were represented the meaningful relation between Superpave PG and MSCR PG-Plus asphalt classification methods. © 2023 Elsevier Lt

Synthesis and in-vitro antimicrobial activity of novel aminophosphinic acids containing cyclobutane and 1,3-thiazole

WOS: 000299727800013The compounds {[4-(3-methyl-3-aryl(mesityl-phenyl-tetralino)cyclobutyl)-1,3-thiazol-2-yl]amino}(aryl)methyl-phosphinic acids 2a-l were prepared by condensation of 2-amino-4-(3-aryl(mesityl-phenyl-tetralino)-3-methylcyclobutyl)thiazoles 1a-c with various aromatic aldehydes and hypophosphorous acid through a one-pot reaction. The characterizations of these compounds were obtained by elemental analyses, infrared (IR) spectra, and H-1, C-13, and P-31 NMR (nuclear magnetic resonance) techniques. The synthesized compounds were tested in vitro against one Gram-positive and two Gram-negative bacterial strains, one mycobacterial strain, and a fungus Candida albicans. Compound 2f showed significant activity against Staphylococcus aureus, whereas the others had no remarkable activity on this strain. Compound 2g was found to be more active than the others against Mycobacterium fortuitum at an MIC (minimum inhibitory concentration) value of 32 mu g/mL. The antibacterial and antifungal activities of 2a-l were also compared with various standard drugs