ИСТИНА

The development of cost-effective and sustainable sorbents for the removal of organic contaminants from wastewater remains a significant challenge. Organic pollutants such as p-cresol are commonly found in industrial and municipal wastewater, posing threats to environmental and human health [1]. Meanwhile, the global production of approximately 140 million tons of rice husk (RH) annually results in a largely underutilized agricultural waste product, causing environmental harm when burned or discarded [2]. In this study, sorbents derived from RH ash, including carbon and silica materials, were prepared and characterized. The synthesis involved the separation of RH ash into silica and carbon fractions, followed by modification of carbon sorbents using hydrothermal treatment with ammonia to introduce nitrogen- containing functional groups. The sorbents were evaluated for their efficiency in removing p-cresol and indoxyl sulfate from aqueous solutions. Carbon sorbents demonstrated high adsorption capacities (e.g., maximum adsorption capacity of 67 mg/g for p-cresol), while silica sorbents showed negligible adsorption under the studied conditions. The introduction of nitrogen-containing groups on carbon surfaces significantly enhanced their adsorption performance for indoxyl sulfate, as evidenced by improved adsorption isotherms and kinetic behavior. The kinetics of p-cresol adsorption were studied on carbon sorbents derived from RH ash. Theoretical calculations were performed based on diffusion equations and pseudo-first-order and pseudo-second-order models, confirming the applicability of the latter. The findings highlight the potential of RH-derived sorbents, particularly modified carbon materials, for addressing the pressing need for cost-effective and sustainable solutions in water purification. Future work will focus on optimizing these sorbents for broader applications, including pilot-scale studies in wastewater treatment.