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.

Partially replacing cement with superhydrophobic fly ash (FA-PFDS), cellulose nanofibers (CNF) and synthetic fibers (SYN) is a promising route to combine mechanical performance and water resistance in polymer-modified cementitious composites. However, current studies rarely quantify the dosage sensitivity under the complex interactions of multiple polymers, which often results in trade-offs between mechanical strength and impermeability. This study employs an L₃₆(6³) orthogonal experimental design combined with least absolute shrinkage and selection operator (LASSO) regression to analyze macroscopic performance data, supported by X-ray diffraction (XRD), scanning electron microscopy (SEM) and a simplified hydro-mechanical slope model to discuss possible mechanisms and structural responses. The LASSO models predicted that a mixture of 20% FA-PFDS, 1% SYN and 0.4% CNF by mass of cement replaced would reach a 7-day compressive strength of 18.20 MPa with a water absorption of 8.15% and a consistency of 16.3 mm while reducing cement consumption by 21.4%. XRD and SEM observations are consistent with capillary pore filling by CNF and crack bridging by SYN, but the proposed mechanism remains to be verified. The slope model suggests that a modified surface layer with reduced permeability would delay rainfall breakthrough of a thin surface layer and keep stresses well below the assumed 20 MPa load. Overall, this study provides empirical evidence on how the dosage of multiple polymers affects the trade-off of strength and impermeability, and a data-driven starting point for mix design in slope-protection applications, pending experimental validation.