Abstract
Removal of mixed contaminants, including heavy metal ions and aromatic hydrocarbons, from water systems requires the development of efficient and selective adsorbents. This study presents a comparative investigation of the adsorption properties of silicon oxide with different purity levels (80% and 100%) toward Cu2+ ions and aromatic hydrocarbons (benzene, ethylbenzene, m, p-xylenes). Adsorption kinetics were examined, and the porous structure of the materials was characterized using low-temperature nitrogen adsorption-desorption analysis.The results revealed a paradoxical advantage of technical silicon dioxide (80%) over the high-purity sample (100%) in copper ion adsorption. The maximum sorption degree reached 36.90% compared to 32.37%, while equilibrium was achieved within 10 min versus 30 min, respectively. In contrast, high-purity SiO2 demonstrated superior selectivity toward aromatic hydrocarbons, particularly benzene, with removal efficiency increasing from 17% to 79% within 40 min, accompanied by partial desorption of bulkier molecules.Pore structure analysis showed a 4.75-fold reduction in micropore volume after purification, together with significant redistribution of mesopores: pores in the 5-10 nm range disappeared, while a new maximum emerged at 40-60 nm. Benzene adsorption on technical SiO2 followed a pseudo-second-order kinetic model (R2 = 0.992), indicating a chemisorption mechanism. The findings establish a clear relationship between pore architecture and adsorption selectivity, enabling rational adsorbent selection depending on pollutant type and supporting cost-effective design of adsorption materials without additional feedstock purification.