This article studies the enhancement of methyl orange (MO) adsorption by Mongolian montmorillonite (MMt) modified by the intercalation of the Keggin Al₁₃ complex, followed by calcination during the pillaring process. The properties of MMt, Al-intercalated MMt (P-MMt), and Al-pillared MMt (P-MMt-C) were determined using X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface-area analysis, and a field emission scanning electron microscope (FE-SEM). The MO adsorption by modified MMt was subsequently evaluated. The XRD basal distance (d₀₀₁) and the specific surface area (SSA) increased after the modification of MMt. The TGA results revealed that P-MMt and P-MMt-C had better thermal stability than MMt. The Al-pillared MMt obtained after calcination (e.g., P-MMt-C400) showed a larger basal distance and surface area than that without pillaring. The MO adsorption process of P-MMt-C400 was supposed to be dominated by chemisorption and heterogeneous multilayer adsorption, according to the kinetic and isotherm studies. The maximum adsorption capacity of P-MMt-C400 is 6.23 mg/g. The MO adsorption ability of Al-pillared MMt was contributed by the Keggin Al₁₃ complex attracting MO and the increase in the surface area of macro-, meso- and micro-pores (>1.2 nm). The Al-pillared MMt in this study could be applied as an adsorbent in a water purification system to remove MO or other dye elements.

Phosphorus pollutants are a crucial component of water eutrophication. In this study, montmorillonite modified by Keggin Al₁₃ and hexadecyltrimethyl ammonium (Al₁₃-O-MMt) was used as an adsorbent to remove phosphorus from solutions and thus simulate the practice of a field trial, such as in wastewater. The ammonium molybdate spectrophotometric method was used to determine the concentrations of phosphorus in samples. In the batch experiment, phosphorus was adsorbed by original montmorillonite (MMt) and Al₁₃-O-MMt at various pH values (6–9) to identify the effect of pH during the adsorption process. The batch adsorption results demonstrate that Al₁₃-O-MMt can adsorb up to 93% of phosphorus at pH = 8. Six graduated amounts (0.01–0.25 g) of montmorillonite were tested at three different temperatures to determine the most suitable temperature and the minimum dosage of Al₁₃-O-MMt needed for the adsorption of 200 mg/L phosphorus in a 30 mL solution, which was 0.1 g at 25 °C. Therefore, the adsorption capacity of Al₁₃-O-MMt was found to be 60 mg/g. Subsequently, a column experiment was conducted. The results showed that the optimized dosage of Al₁₃-O-MMt was 6.667 g for phosphorus adsorption with a concentration of 200 mg/L in 2000 mL solution, and the breakthrough time was 4794.67 min.

Metal–organic frameworks (MOFs) have recently received a lot of interest for their use in adsorbing and eliminating hexavalent chromium from water. Obtaining low-cost, biocompatible, and environmentally friendly MOFs for research in this field is vital. One very stable three-dimensional UiO-66-Ce(IV) MOF, Ce-asp, was synthesized with a high yield using an amino acid ligand, DL-aspartic acid. As a result, the adsorption characteristics of the MOF against hexavalent chromium ions in aqueous solution were examined. The effects of time, solution pH, MOF dose, and beginning chromium(VI) content in aqueous solution were investigated on adsorption. More crucially, the adsorption mechanism of this MOF for chromium(VI) was proposed, setting the groundwork for its future use in chromium(VI) removal in real-world waters.

Artificial aquatic habitats including reservoirs, reclamation waters and constructed wetlands undergo dynamic ecological development, marked by continuous community turnover, trophic reorganisation and shifts in ecosystem function. Meanwhile, traditional biodiversity monitoring methods rely on morphological taxonomic surveys and microscopic identification. They are highly time-consuming, labor-intensive, and strongly dependent on taxonomic expertise. These approaches struggle to capture continuous community dynamics across multiple trophic groups and underestimate cryptic and small-sized benthic organisms. Environmental DNA detects DNA fragments released by organisms into the environment, supporting high-throughput and non-invasive surveys of biological communities. This review synthesizes representative published studies concerning eDNA applications in artificial aquatic habitats. We summarise the strengths of eDNA for biodiversity monitoring, and identify practical obstacles specific to engineered aquatic systems, including sampling bias and data correction. We further propose targeted future research prospects in artificial habitat ecological evaluation and restoration management. This review demonstrates that eDNA is a powerful tool for evaluating constructed aquatic ecosystems and highlights future opportunities via multi-technology integration to promote sustainable ecological infrastructure design.