STUDY OF THE PROCESS OF ADSORPTION OF METHYLENE BLUE BY THE SURFACE OF POTASSIUM TITANATE

Abstract

Clean natural drinking water is necessary for every aspect of human life. In recent years, the problem of the quality of drinking water has become quite acute. Pollution of the environment by emissions from various industries leads to a number of negative consequences that are reflected in the vital activities of all living organisms. Accordingly, wastewater treatment remains an urgent problem today. There are a significant number of water purification methods, but adsorption methods are the most widely used. Their use is especially promising for compounds that are not biodegradable, in particular for artificial dyes. Adsorption efficiency depends on many factors, one of the most important being the chemical nature of the adsorbent. Among the group of adsorbents, titanium compounds are quite promising. The paper investigates the process of methylene blue adsorption from an aqueous solution. As an adsorbent, potassium titanate was used, which was synthesized by the method of alkaline leaching of ilmenite concentrate of the Irshan group of potassium hydroxide deposits. It was established that the maximum degree of extraction of methylene blue, more than 44%, is achieved when using potassium titanate weighing 0.005 g within 10 minute s from the beginning of contact between the adsorbent and adsorbate surfaces. It was determined that the experimental kinetic curves of methylene blue adsorption on the surface of potassium titanate are adequately described by the pseudo-second-order (Ho-McKay) kinetic equation. This adsorptio n mechanism simultaneously takes into account the interaction at the “adsorbate-adsorbent” interface and intermolecular interactions of adsorbed substances on the surface. It is calculated that the initial rate of adsorption is 2.81 mg/h·min. It was established that the adsorption capacity of potassium titanate for methylene blue dye is 21.92 mg/g. Under these conditions, the partition coefficient between the dye solution and the surface of potassium titanate reaches 3346.57 ml/g, which indicates a significant affinity of the adsorbent surface for methylene blue molecules. It is shown that the adsorption process is satisfactorily described by the Tiomkin isotherm model, i.e. dye molecules are adsorbed on potentially heterogeneous surfaces with a uniform distribution of adsorption centers. The calculated value of the adsorption energy indicates the physical nature of the interaction at the “adsorbateadsorbent” separation boundary. The perspective of using potassium titanate as an adsorbent of methylene blue from an aqueous solution is shown.