Synthesis of anionic ionic liquids@TpBd-(SO3)2 for the selective adsorption of cationic dyes with superior capacity.

Meng Dang,Qi-Liang Deng,Hai-Peng Shi,Shuo Wang,Chang Liu,Yan-Yan Tian,Guo-Zhen Fang

doi:10.1039/c9ra10035k

Abstract

The discharge of industrial printing and dyeing wastewater is one of the main reasons for the increasing water shortage and deterioration. The treatment of dyestuff wastewater is an issue and needs to be urgently solved. In this work, anionic ionic liquid functional covalent organic materials (COMs) were firstly synthesized and used for the selective adsorption of cationic dyes. First, a series of sulfonic acid group (SO3H)-functionalized anionic TpPa-SO3, TpBd-(SO3)2, and TpCR-(SO3)2 were prepared, respectively, and then imidazole was grafted onto TpBd-(SO3)2 to obtain ImI@TpBd-(SO3)2. The full characterization using X-ray diffraction, FT-IR spectroscopy, 13C cross-polarization magic-angle spinning NMR spectroscopy, zeta-potentials, BET surface and pore analysis indicated that these COMs and ImI@TpBd-(SO3)2 exhibited different morphologies, porosities, and potentials. The effects of the type of dye, adsorption time, initial dye concentration, and pH on the adsorption of dyes on ImI@TpBd-(SO3)2 were systematically investigated, respectively. The results revealed that ImI@TpBd-(SO3)2 possessed good adsorption performance for nine different cationic dyes with adsorption capacities in the range from 2865.3 mg g−1 for methylene blue (MB) to 597.9 mg g−1 for basic orange 2 (BO), but little adsorption for anionic and neutral dyes, revealing charge selectivity. The adsorption ratio of ImI@TpBd-(SO3)2 for MB was as high as 74.0% at 10 min by using 1.0 mg material, owing to the post modification of TpBd-(SO3)2 with imidazole. The adsorption of MB on ImI@TpBd-(SO3)2 was pH dependent. The adsorption isotherm and kinetics fitted well with the Freundlich and pseudo second-order kinetic model, respectively. Finally, the very outstanding advantages of superior selective adsorption, desorption, convenient preparation, and low density of ImI@TpBd-(SO3)2 predicted its research and application potential in dye wastewater recovery.

Highlights

Wastewater caused by the large amount of dye consumption in textile and paper manufacturing industry poses serious threat to mankind and aquatic living organisms because dyes are highly toxic, resistant to degradation, and visible even in trace amounts.[1]
The full characterization using X-ray diffraction, Fourier transform-infrared spectra (FT-IR) spectroscopy, 13C cross-polarization magic-angle spinning NMR spectroscopy, zeta-potentials, BET surface and pore analysis indicated that these covalent organic materials (COMs) and ImI@TpBd-(SO3)[2] exhibited different morphologies, porosities, and potentials
The results revealed that ImI@TpBd-(SO3)[2] possessed good adsorption performance for nine different cationic dyes with adsorption capacities in the range from 2865.3 mg gÀ1 for methylene blue (MB) to 597.9 mg gÀ1 for basic orange 2 (BO), but little adsorption for anionic and neutral dyes, revealing charge selectivity

Summary

Introduction

Wastewater caused by the large amount of dye consumption in textile and paper manufacturing industry poses serious threat to mankind and aquatic living organisms because dyes are highly toxic, resistant to degradation, and visible even in trace amounts.[1]. Diffusion was hindered by the narrower pore size of TpPa-SO3.14 A er the modi cation of TpBd-(SO3)[2] with ILs, all ILs@TpBd-(SO3)[2] displayed outstanding adsorption performance for MB; especially, ImI@TpBd-(SO3)[2] showed the maximum adsorption capacity of 2841.5 mg gÀ1 at pH 9.0, which could compete with any of the other materials reported (Table S5†).

Results

Conclusion