Adsorption of aromatic nitro and amino compounds with modified bentonite

Abstract

Wastewater of many types of industries contribute to the entry into open water bodies of toxic organic compounds, the concentrations of which in some cases exceed the Maximum Permissible Concentration for Water in Commercial Fishery Reservoirs. Typical representatives of toxic organic pollutants in the aquatic environment are aromatic nitro and amino compounds. Currently, a significant number of wastewater treatment methods have been developed. One of the most promising methods of water treatment are adsorption methods. Of considerable interest is the use of natural clay minerals as sorption materials for wastewater treatment. The object of the study is model solutions of nitro and amino compounds, the adsorption of which was studied on different versions of modified bentonites. In this work, the adsorption capacity of modified bentonite with five different acid activation variants upon extraction of n-dinitrobenzene and o-phenylenediamine from solutions was studied. The adsorption parameters of the studied variants of bentonite, such as the adsorption value G, mg/g; interfacial distribution coefficient Kd, mg/dm3; degree of adsorption recovery S, %. The constructed adsorption isotherms made it possible to identify the most effective variants of modified bentonite with additional activation by acid to extract aromatic nitro and amino compounds from solutions. The best adsorption ability upon extraction of p-dinitrobenzene from a solution was shown by glycerin-modified bentonite, subjected to heat treatment at 550 °C, the average fraction of granules, after activation with 9 % HCl solution and 30 % CaCl2 solution. The best adsorption ability upon extraction of o-phenylenediamine from a solution was shown by glycerin-modified bentonite, subjected to heat treatment at 550 °C, the average fraction of granules, after activation with 18 % HCl solution and 38 % CaCl2 solution.