Synthetic ferripyrophyllite: preparation, characterization and catalytic application

Boosting peroxymonosulfate activation via Fe-Cu bimetallic hollow nanoreactor derived from copper smelting slag for efficient degradation of organics: The dual role of Cu

Valorization of iron-rich metallurgical slags in the construction of Fenton-like catalysts has an appealing potential from the perspective of sustainable development. For the first time, copper smelting slag (CSS) was utilized as the precursor to synthesize hollow sea urchin-like Fe-Cu nanoreactors (Cu1.5Fe1Si) to activate peroxymonosulfate (PMS) for chlortetracycline hydrochloride (CTC) degradation. The hyper-channels and nano-sized cavities were formed in the catalysts owing to the induction and modification of Cu, not only promoting the in-situ growth of silicates and the formation of cavities due to the etching of SiO2 microspheres, but also resulting the generation of nanotubes through the distortion and rotation of the nanosheets. It was found that 100 % CTC degradation rate can be achieved within 10 min for Cu1.5Fe1Si, 75 times higher than that of Cu0Fe1Si (0.0024 up to 0.18 M-1‧min-1). The unique nanoconfined microenvironment structure could enrich reactants in the catalyst cavities, prolong the residence time of molecules, and increase the utilization efficiency of active species. Density functional theory (DFT) calculations show that Cu1.5Fe1Si has strong adsorption energy and excellent electron transport capacity for PMS, and Fe-Fe sites are mainly responsible for the activation of PMS, while Cu assists in accelerating the Fe(II)/Fe(Ⅲ) cycle and promotes the catalytic efficiency. The excellent mineralization rate (83.32 % within 10 min) and efficient treatment of CTC in consecutive trials corroborated the high activity and stability of the Cu1.5Fe1Si. This work provides a new idea for the rational design of solid waste-based eco-friendly functional materials, aiming at consolidating their practical application in advanced wastewater treatment.

Ultrathin Two-dimensional Layered Composite Carbosilicates from in situ Unzipped Carbon Nanotubes and Exfoliated Bulk Silica

A key task in today's inorganic synthetic chemistry is to develop effective reactions, routes, and associated techniques aiming to create new functional materials with specifically desired multilevel structures and properties. Herein, we report an ultrathin two-dimensional layered composite of graphene ribbon and silicate via a simple and scalable one-pot reaction, which leads to the creation of a novel carbon-metal-silicate hybrid family: carbosilicate. The graphene ribbon is in situ formed by unzipping carbon nanotubes, while the ultrathin silicate is in situ obtained from bulk silica or commercial glass; transition metals (Fe or Ni) oxidized by water act as bridging agent, covalently bonding the two structures. The unprecedented structure combines the superior properties of the silicate and the nanocarbon, which triggers some specific novel properties. All processes during synthesis are complementary to each other. The associated synergistic chemistry could stimulate the discovery of a large class of more interesting, functionalized structures and materials.

Characterization and reuse of waste from the magnesium nitrate fertilizer industry

Currently, liquid fertilizers are considered strategic products in the sector, particularly those with nitrogen and magnesium in their composition. During their synthesis, the generated muddy and sticky residue is usually managed as a toxic waste because its properties and feasible valorization methods have not yet been studied. For the first time, this residue has been thoroughly characterized, and, on the results obtained, its possible reuse options have been discussed. This material, with 47 % moisture content, a neutral pH, and a specific density of 0.85, still contains 35 % dry weight of nitromagnesite. These findings, together with a high cation exchange capacity and the presence of iron, aluminium, calcium and silicon as minority components, make its reintroduction into the manufacturing process of fertilizers the most viable option for its valorization, having two alternatives for this purpose. The first is to use it as a feedstock for the production of solid fertilizers by adding 30 % quicklime to the residue to improve its mechanical properties, thus obtaining a fertilizer with 5.7 %, 5.0 % and 24.3 % (dry weight) of magnesium, nitrogen and calcium, respectively. The second option, which focused on obtaining a liquid fertilizer, allowed the recovery of approximately 86 % of the remaining nitromagnesite in the residue by washing it with nitric acid, reducing its initial dry mass by 77 %. Then, the resultant liquid phase, with 16 % magnesium nitrate, could be enriched to the 35 % concentration demanded by liquid fertilizer consumers by a subsequent acid attack of the raw rock.