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• The work discusses a sustainable alternative to landfilling of hazardous spent adsorbents by introducing the spent ZIF-8@GO-COOH, into cement production for safe disposal. • Adding spent ZIF-8@GO-COOH as an additive to cement production increases the compressive strength of cement as the amount of spent adsorbent increases. • The TCLP experiments results show that the method of cement solidification is an effective way to reduce the leaching of heavy metal ions in spent adsorbents. Spent adsorbents often contain harmful substances, which may have an impact on the ecological environment if these substances enter the environment. This study mainly introduces a safe treatment method for solid waste formed after heavy metal ions are adsorbed by an efficient adsorbent, ZIF-8@GO-COOH. This work mainly discusses the impact of solidifying the spent adsorbent in the cement system on the cement mechanical properties and hydration process. The experimental results showed that when the dosage of the spent adsorbent was 0.01%, 0.02%, 0.03%, and 0.04%, respectively, the compressive strength of 28 d was increased by 4.24%, 6.16%, 7.19%, and 8.87%, respectively, compared with the cement without spent adsorbent. Introducing spent ZIF-8@GO-COOH in the cement production process does not have a negative impact on the cement mechanical properties, and can refine the cement pore structure and dense microstructure, thereby improving the compressive strength. The Toxicity Characteristic Leaching Procedure (TCLP) results showed that solidifying the spent adsorbent with cement can effectively reduce the leaching of heavy metal ions in the spent adsorbent. This study solidifies the spent ZIF-8@GO-COOH nanoadsorbent material into the cement system as a sustainable alternative to landfilling. This treatment method has certain economic benefits and safety, and has some reference significance for promoting the development and improvement of spent adsorbents and improving their safe treatment and reuse. [ABSTRACT FROM AUTHOR]

Water pollution caused by severe heavy metal contamination poses a significant threat to freshwater resources and aquatic ecosystems, necessitating effective removal strategies. This study focuses on the synthesis of highly crystalline ZIF-8 particles using an energy-efficient, cost-effective in-situ self-assembly method. The resulting particles exhibit exceptional specific surface area (1663.413 m2/g) and particle sizes ranging from approximately 60 to 80 nm. We conducted batch adsorption experiments using Cu(II) and Pb(II) solutions as representative models of water pollution to evaluate ZIF-8's adsorption capacity for these heavy metal ions. Remarkably, ZIF-8 demonstrated a significantly higher maximum adsorption capacity for Cu(II) (378.5 mg/g) compared to Pb(II) (92.74 mg/g) under identical experimental conditions. By employing adsorption kinetics and isotherm models, as well as density functional theory calculations, we elucidated that Cu(II) removal from water by ZIF-8 relies on ion exchange and coordination interactions, whereas Pb(II) elimination primarily occurs through surface adsorption due to ZIF-8's elevated micropore structure and specific surface area. Moreover, we proposed a sustainable solution by solidifying the waste ZIF-8 adsorbent into cement-based materials, offering an innovative and environmentally friendly alternative to landfill disposal. This methodology not only demonstrates noteworthy economic effectiveness but also ensures harm-free treatment and repurposing of waste adsorbents, providing valuable insights into secure and sustainable heavy metal removal strategies. [Display omitted] • ZIF-8 with small volume and high specific surface area were synthesized by one-step method for adsorption of Cu(II) and Pb(II) in water. • The experimental results show that ZIF-8 has different adsorption mechanisms for Cu(II) and Pb(II). • Doping the waste ZIF-8 with cement at 0.10% content, the compressive strength increased by 7.76% at 28 d. [ABSTRACT FROM AUTHOR]

• Steel-PVA -CW hybrid fiber improves the strength of mortar after elevated temperatures. • MSFRC has better high temperature resistance than concrete, RPC and ECC. • Digital camera and optical microscope are useful to evaluate changes of fiber at high temperature. By experimental research on the steel- polyvinyl alcohol (PVA) fibers- calcium carbonate whisker (CW) multi scale fiber-reinforced cement-based composites (MSFRC) after exposure of temperatures up to 900 °C, the flexural, compressive strength, and microstructures of multi scale fibers were investigated in this paper. The incorporation of steel-PVA fibers-CW can effectively improve the flexural and compressive strength of mortar after elevated temperatures. Compared with normal concrete, hybrid fiber reactive powder concrete (RPC) and engineered cement-based composites (ECC), the MSFRC present better capacity of high temperature resistance. The flexural and compressive strength increase first and then decrease with the increasing temperature, and the critical temperatures are 200 °C and 400 °C respectively. Models for describing the relationship between strength, CW content and temperature are proposed. The good high temperature resistance of MSFRC relates to the hybrid effect of melt of PVA fiber, good heat conduction of steel, and the phase transformation from aragonite to calcite of CW. Comprehensive morphology observations by digital camera and optical microscope are simple and useful way to evaluate the changes of fibers and CW at high temperature. This research is very beneficial for the applications of MSFRC in construction project with fire risk. [ABSTRACT FROM AUTHOR]

Limestone is commonly used in cement concrete due to its unique nature and type. It has physical effects (nucleation effect and dilution effect) and chemical effects on the hydration process of cement. This paper reviews the effects of three representative limestone materials on the hydration process, hydration products, and hydration kinetics. In the hydration process, the reaction was delayed by limestone powder with a particle size larger than 20 μm and calcium carbonate whiskers due to their dilutive effect. On the other hand, limestone powder with a particle size smaller than 20 m and calcium carbonate nanoparticles facilitated the reaction through nucleation and chemical effects. Limestone has a similar effect on hydration products, promoting the production of C-S-H through nucleation. The mechanism of action for this nucleation effect depends on the differences in crystalline form and particle size of the three types of micro- and nano-calcium. Chemical effects impact the amount of AFt produced, with the generation of new products being the main reaction influenced by the limestone admixture.

Portland cement (PC) is ubiquitously used in construction for centuries, yet the elucidation of its early-age hydration remains a challenge. Understanding the initial hydration progress of tricalcium aluminate (C 3 A) at molecular scale is thus crucial for tackling this challenge as it exhibits a proclivity for early-stage hydration and plays a pivotal role in structural build-up of cement colloids. Herein, we implement a series of ab-initio calculations to probe the intricate molecular interactions of C 3 A during its initial hydration process. The C 3 A surface exhibits remarkable chemical activity in promoting water dissociation, which in turn facilitates the gradual desorption of Ca ions through a metal-proton exchange reaction. The dissolution pathways and free energies of these Ca ions follow the ligand-exchange mechanism with multiple sequential reactions to form the ultimate products where Ca ions adopt fivefold or sixfold coordination. Finally, these Ca complexes reprecipitate on the remaining Al-rich layer through the interface-coupled dissolution-reprecipitation mechanism, demonstrating dynamically stable inner-sphere adsorption states. The above results are helpful in unmasking the early-age hydration of PC and advancing the rational design of cement-based materials through the bottom-up approach., (© 2024. The Author(s).)

The enhanced photocatalytic properties of Z-Scheme Bi@BiOCl/C 3 N 4 -DPY heterojunction materials were successfully prepared by the ultrasonic-assisted coprecipitation method. The Bi@BiOCl/C 3 N 4 -DPY heterojunction exhibited remarkable photocatalytic activity under visible light irradiation, and the degradation rate of methyl orange (MO) was about 90.6% in 180 min. This impressive efficiency is mainly due to the Z-Scheme charge transfer mechanism in Bi@BiOCl/C 3 N 4 -DPY, resulting in the efficient separation of charge carriers and an increase in the REDOX potential of photogenerated electrons and holes. C 3 N 4 was modified with a π-deficient conjugated pyridine ring, which caused the light absorption redshift, promoted the formation of oxidizing • O 2 - , and improved the photocatalytic activity. At the same time, a well-aligned heterojunction is formed at the interface between C 3 N 4 -DPY and BiOCl, facilitating the seamless transfer of light-induced electrons from the LUMO of C 3 N 4 -DPY to the CB of BiOCl. In addition, the addition of Bi introduces a unique band gap reduction effect, resulting in a change in the density of the band states, which further promotes charge transfer and separation. It is worth noting that the introduction of metallic bismuth (Bi) brings about a unique band gap reduction effect, resulting in a change in the density of states within the band, which ultimately promotes charge transfer and separation. The Z-scheme charge migration inside Bi@BiOCl/C 3 N 4 -DPY further promotes the efficient separation of photogenerated electron-hole pairs, greatly improving the overall efficiency of the material. The Z-structured photocatalyst developed in this study has great application potential in various fields of photocatalysis.

Background: Clinical breast cancer subtypes are categorized basing on the expression of hormone receptors and overexpression of the human epidermal growth factor receptor 2 (HER2). It is still unclear whether parity impact the risk of different breast cancer subtypes., Methods: We searched eight mainstream databases for published epidemiologic studies that assessed the relationship between parity and risk of breast cancer subtypes up to January 12, 2021. Parity number were unified into nulliparity and ever parity. The random-effects or fixed-effect models were used to calculate the pooled odds ratios (ORs) and 95% confidence intervals (CIs) among different subtypes. Restricted cubic spline analysis with four knots was applied to determine the relationship of parity number and risk of breast cancer subtypes., Results: We pooled sixteen case-control and four cohort studies, and performed an analysis including 7795 luminal A, 3576 luminal B, 1794 HER2-overexpressing, and 5192 triple-negative breast cancer cases among 1135131 participants. The combined ORs for ever parity versus nulliparity indicated a 34% reduction in luminal A risk (OR=0.66, 95% CI: 0.56-0.78), and a 29% reduction in luminal B risk (OR=0.71, 95% CI: 0.63-0.81), there was no significant association in HER2-overexpressing or TNBC risk. In the dose-response analysis, we observed a potentially non-linear and gradually increasing protective relationship between the number of parity and luminal breast cancer risk., Conclusions: The effect of parity on breast cancer seems to vary among breast tumor subtypes, and it plays a protective role in luminal breast cancer., (Copyright © 2021 Elsevier Ltd. All rights reserved.)