TS-1 zeolite and a series of Zr-modified samples (TS-1/xZr) were synthesized and systematically characterized to investigate the influence of zirconium incorporation on structural, textural, and photocatalytic properties. The structural and textural properties of the samples were examined by XRD and nitrogen adsorption isotherms. Elemental analysis (EDXRF, SEM/EDS) and FTIR confirmed successful incorporation of Zr into the TS-1 framework. Photocatalytic tests under white light irradiation using crystal violet (CV), methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) dyes revealed enhanced degradation efficiency for the Zr-containing samples, particularly TS-1/10Zr. Kinetic modeling using pseudo-first-order (PFO) and pseudo-second-order (PSO) approaches indicated that dye degradation followed mainly PSO kinetics. Reusability studies demonstrated sustained stability and recyclability of the catalysts. The improved photocatalytic performance is attributed to synergistic electronic effects between Ti and Zr species, which enhance charge separation and light absorption.

In this study, Zirconium‐modified Engelhard Titanium Silicate 4 (Na−K‐ETS‐4/xZr) catalysts were synthesized and evaluated for their photocatalytic efficiency in degrading crystal violet (CV) and methylene blue (MB) in aqueous solutions. The catalysts were characterized using XRD, FTIR, SEM, WDXRF, and nitrogen adsorption/desorption isotherms. The results confirmed the successful incorporation of Zr into the ETS‐4 framework, with the highest Zr content reaching 9.2 wt %. The photocatalytic performance under visible light irradiation was studied at varying pH levels. The Na−K‐ETS‐4/6.3Zr catalyst exhibited the highest photodegradation efficiency for CV (76.6 %), while Na−K‐ETS‐4/8.9Zr achieved 86.6 % efficiency for MB. A combination of Engelhard Titanium Silicate 10, Na−K‐ETS‐10/6.3Zr and Na−K‐ETS‐4/8.9Zr significantly enhanced dye degradation, achieving up to 96.5 % efficiency for MB. Kinetic studies indicated that the degradation process follows a non‐linear pseudo‐first‐order model. The catalysts also demonstrated excellent reusability, with minimal efficiency loss after five cycles, and full recovery after an ethanol wash. These findings suggest that Na−K‐ETS‐4/xZr is a promising candidate for environmental water treatment applications due to its efficient photodegradation performance and stability.

This study documents the formation of optically anomalous biaxial apatite resulting from partial fluid-mediated metasomatic alteration of pegmatitic apatite containing a britholite component. The optical anomaly was identified using a refractometer. SEM and EDX data constrain alteration conditions to interaction with acidic, oxidizing, highly saline, Si-bearing fluids at temperatures below 400–500 °C, accompanied by elevated fluorine activity. Pervasive partial metasomatic modification produced patchy compositional zoning and increased porosity within the apatite crystals. Microscale variations in F, OH, and Cl define compositional domains with differing proportions of fluorapatite, hydroxylapatite, and chlorapatite end members. These chemical differences result in variable light propagation velocities and refractive indices, giving rise to anomalous biaxial optical behavior. Single-crystal X-ray diffraction shows that all crystals retain the hexagonal apatite structure (P6₃/m). At the same time, fluid-induced apatite alteration generated non-uniform channel-site occupancies, accompanied by substitution of apatite by britholite along with the formation of vacancies in the calcium positions, and local structural distortions without symmetry lowering. The integration of optical, structural, and chemical data demonstrates that microscale compositional heterogeneity, produced by fluid–apatite interaction, is responsible for the observed optical anomaly.

AgBr-modified Zr-containing titanium silicalite-1 (TS-1) composites were prepared and evaluated for methyl orange (MO) removal under white-light irradiation. AgBr modification markedly enhanced the visible-light response of the Zr-containing TS-1 materials, resulting in MO removal efficiencies of up to 98.6% after 50 min of irradiation. Structural and textural characterization confirmed preservation of the MFI framework after modification, while diffuse-reflectance measurements showed that the visible-light absorption of the composites is predominantly governed by the AgBr component. The composites retained substantial activity over five consecutive cycles, and scavenger experiments indicated a possible contribution of hydroxyl radicals to MO removal. These results demonstrate that AgBr modification is an effective strategy for enhancing the visible-light activity of Zr-containing TS-1 materials.