In this paper, the influence of calcium on coal gangue and fly ash geopolymer is explored, and the problem of low utilization of unburned coal gangue is analyzed and solved. The experiment took uncalcined coal gangue and fly ash as raw materials, and a regression model was developed with the response surface methodology. The independent variables were the CG content, alkali activator concentration, and Ca(OH)₂ to NaOH ratio (CH/SH). The response target value was the coal gangue and fly-ash geopolymer compressive strength. The compressive strength tests and the regression model obtained by the response surface methodology showed that the coal gangue and fly ash geopolymer prepared with the content of uncalcined coal gangue is 30%, alkali activator content of 15%, and the value of CH/SH is 1.727 had a dense structure and better performance. The microscopic results demonstrated that the uncalcined coal gangue structure is destroyed under an alkali activator’s action, and a dense microstructure is formed based on C(N)-A-S-H and C-S-H gel, which provides a reasonable basis for the preparation of geopolymers from the uncalcined coal gangue.

Rare earth metal–organic frameworks (RE-MOFs) are mainly composed of rare earth ions and organic ligands, taking advantage of the strengths of both metal–organic frameworks (MOFs) and rare earth ions. Rare earth ions have the unique feature of unfilled 4f electron shells, which endows them with higher coordination numbers, unique luminescence properties, larger Stokes shifts, longer fluorescence lifetimes, and higher luminescence quantum efficiency. The MOFs combined with a variety of organic ligands can effectively guide the antenna effect to sensitize the rare earth ions and thus enhance the photon emission, making RE-MOFs a promising material in the field of fluorescent probes. In this paper, the recent advances in design principles, strategies, synthesis means, and monitoring mechanisms of RE-MOF materials for pollutant monitoring are presented. The intrinsic correlation between the luminescence performance of RE-MOFs, the detection of contaminants and the selection of organic ligands, and the adjustment of the MOF backbone structure is systematically and comprehensively discussed. Finally, the future development direction and application prospects of RE-MOF materials are summarized and discussed.

Coal gangue and aluminum ash emerge as quintessential constituents within the ambit of coal-derived solid waste and industrial residue, respectively. Leveraging coal gangue as a primary substrate and aluminum ash as an adjunct aluminum source, molecular sieves can be synthesized through hydrothermal means. By modulating the dosage of aluminum ash, molecular sieves with varying crystalline structures can be obtained. The synthesized LTA-type molecular sieves manifest in two distinct morphologies: regular tetrahedral and stratified spherical stacking, evincing commendable Cu²⁺ adsorption efficacy. The Cu²⁺ adsorption phenomenon predominantly transpires via chemisorption, albeit with ancillary manifestations of physical adsorption. The valorization of coal gangue and aluminum ash towards the synthesis of molecular sieves not only underscores the elevation of industrial solid waste towards high-value utility, but also underscores the praxis of waste remediation through upcycling.