With the advancement of industrial production and urban modernization, pollution from heavy metal ions and the accumulation of solid waste have become critical global environmental challenges. Establishing an effective recycling system for solid waste and removing heavy metals from wastewater is essential. Coal gangue was used in this study as the primary material for the synthesis of a fully coal gangue-based phosphorus-silicon-aluminum (SAPO-5) molecular sieve through a hydrothermal process. The SAPO-5 molecular sieve was characterized through several methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface analysis, Fourier-transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS), to examine its mineral phases, microstructure, pore characteristics, and material structure. Adsorption performance towards wastewater with Cd²⁺ and Pb²⁺ ions was investigated. It was found that the adsorption processes of these ions are well described by both the pseudo-second-order model and the Langmuir isotherm. According to the Langmuir model, the coal gangue-based SAPO-5 molecular sieve exhibited maximum adsorption capacities of 93.63 mg·g⁻¹ for Cd²⁺ and 157.73 mg·g⁻¹ for Pb²⁺. After five cycles, the SAPO-5 molecular sieve retained strong stability in adsorbing Cd²⁺ and Pb²⁺, with residual adsorption capacities of 77.03 mg·g⁻¹ for Cd²⁺ and 138.21 mg·g⁻¹ for Pb²⁺. The excellent adsorption performance of the fully solid waste coal gangue-based SAPO-5 molecular sieve is mainly attributed to its mesoporous channel effects, the complexation of -OH functional groups, and electrostatic attraction.

Carbon dioxide emissions are the primary and most direct contributor to global warming, posing a significant hazard to both the environment and human health. In response to this challenge, there has been a growing interest in the development of effective carbon capture technologies. This study involved the synthesis of 13-X molecular sieve porous materials using solid waste coal gangue as a source of silicon and aluminum. The synthesis process involved the controlled utilization of an “alkali fusion-hydrothermal” reaction system. The resulting materials were characterized for their structure, morphology, and crystal composition using X-ray diffraction and field emission scanning electron microscopy. These 13-X molecular sieve materials were employed as adsorbents to capture carbon dioxide gas, and their adsorption performance was investigated. The findings indicated that the 13-X molecular sieve materials possess uniform pores and complete crystalline morphologies, and they exhibited an adsorption capacity of 1.82 mmol/g for carbon dioxide at 0 °C. Consequently, this study not only converted solid waste gangue into high-value products but also demonstrated effective atmospheric carbon dioxide capture, suggesting that gangue-based 13-X molecular sieves may serve as a potential candidate for carbon capture.

The accumulation of organic pollutants and solid waste is one of the major environmental challenges faced globally. Establishing an efficient recycling system for solid waste and designing cost-effective, high-performance photocatalysts are urgent tasks for the removal of organic pollutants from water. This study utilizes coal gangue as the precursor to synthesize a coal gangue-based phosphorus–silicon–aluminum molecular sieve (SAPO-5) via hydrothermal synthesis. The resulting material was then composited with bismuth oxybromide (BiOBr) to form a novel BiOBr/coal gangue-based SAPO-5 nanocomposite. When the mass ratio of BiOBr to coal gangue-based SAPO-5 molecular sieve is 0.3, the synthesized nanocomposite exhibits excellent adsorption and photocatalytic performance for the removal of methylene blue, achieving a removal rate of 97.8% and the mineralization rate of 57.4% within 30 min. The superior performance can be attributed to the optimal pore size, rapid charge transfer rate, and high photogenerated charge density of the BiOBr/coal gangue-based SAPO-5 nanocomposite. The novel BiOBr/coal gangue-based SAPO-5 molecular sieve nanocomposite catalyst presents a new approach for the harmless treatment of organic dye wastewater and the high-value utilization of coal gangue.