This paper deals with adsorption regularities and mechanisms of nonradioactive Cs(I) and Sr(II) analogs on bentonites of different chemical and mineral composition from solutions of Cs and Sr nitrates with pH 3, 7, and 10 units at constant ionic strength. The bentonites were taken from the deposits Taganskoe (T), Dash-Salakhlinskoe (DS), Zyryanskoe (Z), and 10th Khutor (10H). The pH of bentonite aqueous suspensions, T and DS, exceeded 9 units. A less alkaline reaction was observed in bentonite suspensions Z and T with pH 8.94 and 7.70, respectively. Bentonites T and DS contained significant amounts of nonsilicate iron compounds, 1.0 and 0.5%, respectively. The recovery rate of the studied clays from aqueous solutions of Cs(I) and Sr(II) ions in concentrations from 0.25 to 5 mmol/L varied from 50% to 90% and decreased in the following order: “Ta-ganskoe” > “Dash-Salakhlinskoe” > “Zyryanskoe” > “10th Khutor” in the studied pH range. The main mechanism of Cs(I) and Sr(II) sorption in the studied pH range was cation fixation in the form of outer-sphere complexes on planar surfaces resulting from ion exchange. Increasing pH (pH > 6) enhanced pH-dependent positions, which allowed Cs(I) and especially Sr(II) ions to fix on them more firmly as inner-sphere complexes. At pH 9–10, Sr(II) could precipitate in the form of carbonates. The sorption of Cs(I) + and Sr(II) was accompanied by competitive interactions with proton at pH < 6 and Na⁺, Ca²⁺, Mg²⁺, and K⁺ cations at higher pH values. This competition was more apparent at concentrations of Cs(I)and Sr(II) in initial solutions < 0.5 mmol/L. The ability of bentonite T to sorb Cs(I) and Sr(II) in large amounts compared to the other bentonites was determined by high CEC values and charge of smectite T.

The sorption of Cu²⁺ onto bentonite modified with Al Keggin cations and humic acid from CuCl₂ solutions at pH 4.5 was studied. Modification of Na-bentonite with Al Keggin cations was found to result in an increase in the basal spacing of montmorillonite from 1.29 nm for N-form to 1.85 and 1.78 nm for HAl₁₃ and Al₁₃ forms respectively, in a reduction of CEC (cation exchange capacity) and in the formation of additional sites with a variable charge with pH_PZC 4.2. Al₁₃-bentonite is not affected by heat. Under the conditions of the experiments at pH of 4.5 Na-bentonite adsorbs more Cu²⁺ from CuCl₂ solutions then Al₁₃ forms of bentonites. The main mechanism of copper sorption on Na-bentonite is the cation exchange Cu²⁺–Na⁺. The reduction of CEC of Na-bentonite after modification with Al Keggin cations leads to a decrease in the Cu²⁺ sorption. pH-dependent sorption sites on Al₁₃-bentonites have a pH_PZC of 4.2 and, therefore, under conditions of the experiment have positive charge which prevents Cu²⁺ sorption. Na-bentonite adsorbs more humic acid solution (HA) then Al₁₃-bentonite and the proportion of adsorbed HA remains constant over the entire concentration range. Treatment of the Al₁₃-bentonite with HA leads to the formation of the additional sorption sites. The amount of sorbed Cu²⁺ and the percentage of their extraction from solutions by HAAl₁₃-bentonite is similar to those values for Na-bentonite.

Forms of metals in water and bottom sediments of the Malaya Sen’ga River located in Petushinskii district of Vladimir oblast have been analyzed. It i

The composition of soil, ground litter, and litterfall water extracts was studied for zones affected by gray heron nesting places and for background sites

This paper discusses the composition of soil–water extracts prepared from soils developing within a heterolithic geochemical landscape of the Klyazma

Data on the distribution of Cd species under a possible increase in technogenic load are presented. This research modeled the peculiarities of the redistri