Preparation of pyridine-modified cotton fibers for anionic dye treatment

Abstract

In order to prepare low-cost, biodegradable and processable adsorbent materials, and also provide a new solution for textile dyeing, novel modified cottons were obtained by introducing 4-aminopyridin into the surface of cotton fibers, and used for the removal of the anionic dyes from aqueous solution. The two modified cottons were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), which confirmed the amino groups and pyridine groups grafted onto the surface of modified cottons. The maximum adsorption capacities for congo red, methyl orange and orange II were 984.87 mg/g (pH = 12), 489.8 mg/g (pH = 8.5) and 599.66 mg/g (pH = 8), respectively. Kinetic and isotherm studies were carried out to investigate the adsorption behavior of the modified cottons on the anionic dyes. The results showed that the adsorption of the anionic dyes by modified cottons followed a pseudo-second-order kinetic model, the equilibrium data was well consistent with the Langmuir isotherm model, and chemisorption and monolayer adsorption were the main adsorption mechanisms. The reuse efficiency of modified cotton was over 80% after six cycles. In addition, the presence of cationic dyes has almost no effect on the adsorption of anionic dyes, and the modified cotton exhibited highly selective adsorption of methyl orange in mixed solutions of methyl orange and methylene blue. This paper also provided a new solution for textile dyeing.