Nitrite ions sorption on strongly basic anion exchanger Purolite A-400 modified with Cr(III)-containing compounds

It is shown that in the same conditions the sorption of nitrite ions on strongly basic anion exchanger Purolite A-400 modified with Cr(III)-containing compounds, especially from solution with pH >4, is much higher as on Purolite A-400(Cl). Sorption on Purolite A-400 (Cl) essentially depends on solution pH and on Purolite A-400(Cr) almost does not depend on solution pH. Nitrite ions sorption isotherm on Purolite A-400 (Cl) may be described by Langmuir sorption model, but on Purolite A-400 (Cr) – by the type III isotherms of the BET classification. The influence of NaNO2, KCl, K2SO4 concentration, pH, temperature and duration of Purolite A-400 (Cr) contacting with solution on NO2- removal has been studied using method of statistical mathematics. Optimizing of NO2- ions removal has been studied too. It is shown that NO2- ions removal from solution by Cr(III)-containing compounds polymer takes place through the three processes: ion exchange, NO2- coordinate with Cr3+ in the polymer phase and NO2- decomposition (in a low-acid medium). Modified with Cr(III)-containing compounds strongly basic anion exchanger becomes a selective sorbent for NO2- ions sorption.