Diatomite as a natural sorbent for water treatment: A modern review and prospects for application

Diatomite is a naturally occurring siliceous sedimentary material characterized by high porosity, low density, developed pore architecture, and favorable adsorption properties, making it a promising low-cost sorbent for water and wastewater treatment applications. This review critically analyzes recent advances in the use of natural and modified diatomite for the removal of heavy metals, petroleum hydrocarbons, dyes, and emerging organic contaminants from aqueous systems. A systematic analysis of peer-reviewed literature indexed in Scopus and Web of Science was conducted, with emphasis on the physicochemical properties of diatomite, pollutant sorption mechanisms, and the influence of thermal and chemical activation methods on adsorption performance. The review demonstrates that the adsorption efficiency of natural diatomite is governed by its mineralogical composition, surface hydroxyl groups, pore accessibility, and environmental conditions such as pH, ionic strength, and temperature. Various modification approaches, including calcination, acid and alkaline activation, hydrothermal treatment, and surface functionalization, significantly improve the specific surface area, pore distribution, and density of active adsorption sites. Recent studies indicate that modified diatomite-based materials exhibit enhanced adsorption capacity and selectivity toward heavy metal ions, dyes, oils, and phenolic compounds compared with raw diatomite. Particular attention is given to thermo-chemical activation and composite materials incorporating magnetic phases, metal oxides, and biopolymers, which improve regeneration ability and practical applicability in real wastewater matrices. Despite the significant potential of activated diatomite, challenges remain regarding the heterogeneity of natural deposits, variability of experimental conditions, regeneration efficiency, and large-scale implementation. Overall, the review highlights diatomite as an environmentally sustainable and technologically versatile sorbent platform with considerable prospects for advanced water treatment technologies and circular environmental applications.

کلیدواژه ها:

Sorbent ، Wastewater ، Diatomite ، Thermal modification ، Water treatment