There is a high iron content in nickel slag that mainly exists in the fayalite phase. Basic oxide can destroy the stable structure of fayalite which is beneficial to the treatment and comprehensive utilization of nickel slag. The research was based on the composition of the raw nickel slag, taking the CaO-SiO₂-FeO-MgO system as the object and CaO as a modifier. The effect of basicity on the melting characteristics, viscosity and structure of the CaO-SiO₂-FeO-MgO system was studied. The relationship between the viscosity and structure of the CaO-SiO₂-FeO-MgO system was also explored. The results show as follows: (1) When the basicity is lower than 0.90, the primary phase of the slag system is olivine phase. When the basicity is greater than 0.90, the primary phase of the slag system transforms into monoxide. When the basicity is 0.90, olivine and monoxide precipitate together as the temperature continues to decrease. At the same time, the liquidus temperature, softening temperature, hemispherical temperature, and flow temperature all reach the lowest value. (2) With the increase of basicity, the critical viscosity temperature of the CaO-SiO₂-FeO-MgO system decreases first and then increases. Critical viscosity temperature is the lowest at the basicity of 0.90, which is 1295 °C. (3) When the slag system is heterogeneous, the viscosity of the molten slag increases rapidly because of the quantity of solid phase precipitated from the CaO-SiO₂-FeO-MgO system. (4) When the slag system is in a homogeneous liquid phase, the molar fraction of O⁰ decreases with the increase of basicity and the mole fraction of O⁻, and O²⁻ increases continuously at the basicity of 0.38~1.50. The silicate network structure is gradually depolymerized into simple monomers, resulting in the degree of polymerization, and the viscosity, being reduced. The mole fraction of different kinds of oxygen atoms is converged to a constant value when the basicity is above 1.20.

In order to reduce the amount of fluorite during the steelmaking process for environmental protection, it is essential to investigate the fluorine-free slag system. Thus, high-basicity CaO–SiO₂–FeO_x–MgO slag with B₂O₃ content from 0% to 15% was designed, and its melting characteristics and viscosity were investigated. The influence of B₂O₃ content on the phase diagram of the slag system was calculated using FactSage 7.3, and the break temperature was determined from the curves of temperature-dependent viscosity. The results show that, with the increase in B₂O₃ content, the melting characteristics of the CaO–SiO₂–FeO_x–MgO/B₂O₃ slag system, including liquidus temperature, flow temperature, softening temperature, and hemispheric temperature, all decreased; the main phase of the slag system transformed from Ca₂SiO₄ into borosilicate, and finally into borate; the viscous flow activation energy reduced from 690 kJ to 130 kJ; the break temperature reduced from 1590 °C to 1160 °C. Furthermore, the melting characteristics and the break temperature of the slag system with 5% and 8% B₂O₃ content were found to be the closest to the values of fluorine-containing steel slag.

A mesoporous polypyrrole/MXene (mPM) composite with multi-layer sandwich-like structures was developed via molecular self-assembly templated by block copolymer micelles, enhancing dielectric loss for superior electromagnetic wave absorption.

A novel and efficient route is proposed to fabricate Fe₃O₄/polypyrrole (Fe₃O₄/PPy) nanotubes via a one‐pot process. The one‐pot strategy involves the synthesis of Fe₃O₄/PPy nanotubes by oxidative polymerization of pyrrole (Py) monomer using Fe³⁺ as an oxidant in the presence of methyl orange (MO) and Fe³⁺ used as iron source to form Fe₃O₄ simultaneously in basic conditions without adding any additional iron source and oxidant. The effects of Fe³⁺ concentration on the morphology and adsorption capacity of the Fe₃O₄/PPy nanotubes were investigated. The Fe₃O₄/PPy nanotubes exhibit a tubular structure. Fe₃O₄ nanoparticles are well dispersed among the PPy nanotubes. The Fe₃O₄/PPy nanotubes exhibit excellent magnetic property, which make them easy to separate from wastewater by magnetic separation. The diameter of the PPy nanotubes decreased with the increase of the Fe³⁺ concentration. The Fe₃O₄/PPy nanotubes showed strong adsorption capability for Cr(VI) with the maximum adsorption capacity of about 451.45 mg·g⁻¹, which is significantly higher than bare Fe₃O₄ nanoparticles. Cr(VI) was adsorbed on Fe₃O₄/PPy nanotubes by ion exchange and chelation, where Cr(VI) was partially reduced to Cr(III) due to the existence of −NH⁺ on the Fe₃O₄/PPy nanotubes. Furthermore, the Fe₃O₄/PPy nanotubes are recyclable, retaining 90% of the initial removal efficiency after 5 adsorption/desorption cycles.