Sorption purification of solutions from silicon ions using aluminum oxyhydroxide modified with manganese and copper ions

The sorption process of silicon ions from a sodium silicate solution by two sorbents has been investigated. The first sorbent with a specific surface area of 219 m2/g was obtained by modifying aluminum oxyhydroxide with manganese ions in a solution with the 0.4 % concentration of manganese ions. The second sorbent with a specific surface area of 204 m2/g was obtained by modifying aluminum oxyhydroxide with in a solution with the 0.4 % concentration of copper (II) ions. The modification process was carried out simultaneously with the reaction of thermal hydrolysis for the formation of nanofibrous aluminum oxyhydroxide at 60 ˚C. It has been determined that an increase of the copper ions concentration in the solution leads to increasing fraction of unreacted metallic aluminum and formation of reduced metallic copper. The degree of silicon ion extraction is 50% for the first sorbent and 44% for the second one at an initial silicon ion concentration 25 mg/L in its solution. It has been shown that the modification of aluminum oxyhydroxide with manganese ions and copper (II) ions increases the extraction degree of silicon ions by 10% and 3%, respectively, compared to the unmodified sorbent. The value of the maximum sorption capacity with respect to silicon ions is 44 mg/g for the first sorbent, 39 mg/g for the second one, respectively. The groundwater study has shown that the sorbent modified with manganese ions is more effective than the sorbent modified with copper (II) ions at the post-treatment stage. The use of the first sorbent leads to a decrease in the concentration of silicon ions from 16.2 to 7.9 mg/L and iron content decreases from 4.6 to 0.9 mg/L.