Abstract
In this paper, we propose a synthesis of calcium silicate from rice husk and a comprehensive assessment of its physicochemical and adsorption properties. The sorbent was obtained by alkaline extraction of silica contained in rice husk with sodium hydroxide followed by precipitation with calcium chloride. The proposed method ensures rational use of agricultural waste, reduces the burden on the environment and is cost-effective. Microwave irradiation was used in the synthesis, which significantly reduces the process time and increases the efficiency of silica extraction in the form of a sodium silicate solution. To improve the structural and adsorption characteristics of the obtained calcium silicate, the material was subjected to heat treatment in the temperature range of 300-900°C. According to the results, optimal properties were observed at a temperature of 700°C. It was at this temperature that the material showed high adsorption activity for iodine (56%), increased developed porosity and favorable specific surface properties. X-ray diffraction analysis, morphological studies and elemental composition assessment confirmed the structural stability, resistance to processing and high efficiency of the synthesized sample. The structural features of the material contributed to an increase in the adsorption rate and demonstrated its adaptability to water treatment conditions. This additionally contributed to the acceleration of the process and an increase in silica extraction, increased productivity and increased resource efficiency. In general, the obtained results characterize calcium silicate as a promising adsorbent for water purification from organic and inorganic pollutants. The proposed method allows for the wide use of environmentally friendly, technologically simple and accessible raw materials. The results of this scientific study create a solid basis for further applied research aimed at developing effective, inexpensive and stable sorbents and improving water quality.