Fluorine sorption by aluminosilicate-modified diatomite from highly concentrated fluorine solutions: 1. Adsorption equilibrium

摘要: The adsorption capacity of natural (D1) and chemically structure-modified diatomite (DMA) in the removal fluorine ions from highly concentrated solutions (up to 0.3 mol/L) under static conditions at room temperature is studied. effect different parameters—solution pH, initial concentration, sorbent weight, particle surface charge density—is examined determine properties DMA process conditions. It shown that solution pH plays a crucial role solutions. An efficient occurs 4.5–5.5. Under equilibrium conditions, upon saturation with ions, achieves 58 mmol/g sorbent; this value 5.5 times higher than unmodified D1. Fluorine isotherms for samples are derived; data modeled using twostage Langmuir model; it experimental calculated on good agreement: correlation coefficient R2 D1 0.9952 0.9687, respectively. mechanism X-ray diffraction chemical analyses, FTIR spectroscopy, potentiometric titration, adsorption–desorption experiments reveal diatomite–NaF–H2O system characterized by occurrence not only physical ion exchange but also bonding active sites surface, i.e., formation weakly soluble compounds Al Ca (AlF3, Na3AlF6, СаF2).