Home – Home – Jornals – Chemistry for Sustainable Development 2017 number 2

Potassium sorption processes from aqueous solutions of KH₂PO₄, K₂HPO₄, K₃PO₄, KCl, and KNO₃ by porous substrates of bast and birch bark were studied. The effect of the nature of the salts on potassium sorption was found. It was demonstrated that the investigated salts by their capacity to potassium sorption could be placed in the following row: K₃PO₄ > К₂HPO₄ > KCl > KNO₃ > KH₂PO₄. Comparison of sorption of potassium and phosphates from solutions of phosphorus-containing salts was made. The effect of pH of solutions and the background electrolyte on potassium sorption from various salt solutions was studied. It was found that the application of the background electrolyte exerted a positive effect on potassium sorption from solutions of KH₂PO₄, KCl and KNO₃. It was demonstrated on an example of potassium chloride and potassium nitrate that an increase in the pH of solutions of the salts to 10.7 led to a larger increase in potassium sorption in comparison with the effect reached in the presence of the background electrolyte. It was found that the highest sorption of potassium (А_∞) was reached from solutions of K₃PO₄ and KCl (рН 10.8) and amounts to 32.55 и 30.20 mg/g, respectively. Potassium sorption isotherms obtained under various conditions, for which values of the constant К_L and the limiting sorption А_∞ were determined according to the Langmuir equation, are given. Potassium sorption values were calculated using these significations and compared with the experimental data. It was demonstrated that porous substrates of bast and birch bark showed close sorption activities in relation to potassium. The substrates investigated exceed activated carbon of birch wood.