Improved cationic dyeability of thermotropic liquid crystal polyarylate fabrics by ultraviolet irradiation-induced grafting of acrylic acid

As one of the most promising high-performance fibers, it is worthwhile to investigate the dyeing property of thermotropic liquid crystal polyarylate (TLCP) fibers. In this work, ultraviolet (UV) irradiation-induced grafting using the acrylic acid (AAc) method was employed to improve the cationic dyeability of the TLCP fabrics. The TLCP fabrics were firstly immersed in an AAc monomer solution for 24 h, followed with the UV radiation process for grafting polymerization. The results showed that the dyeing performance to C.I. Basic Red 46 of the modified TLCP fabrics was remarkably improved. Through several characterizations, it was found that the AAc-grafted TLCP fibers became more roughened with many pits on the fiber surface, while the crystalline structure of the TLCP fibers was hardly affected. More importantly, carboxyl groups have been successfully introduced onto the TLCP fiber surface, which is the main reason for the good dye uptake. Therefore, this paper provides a simple and efficient way for the improvement of the cationic dyeing property of TLCP fabrics.

Elimination of cationic azodye from aqueous media using doped polyaniline (PANI): adsorption optimization and modeling

An adsorbent doped polyaniline (PANI) has been explored for the elimination of a cationic azodye, basic red 46 (BR-46), from textile effluent. Essential factors from batch mode have been studied to investigate their effect on the removal of BR-46. The investigated data have been applied to two prevalent adsorption isothermal models (i.e., Langmuir and Freundlich). In addition to the coefficients of determination, six different statistical error functions have been used to identify the most appropriate model for the existing process. The Langmuir model has been shown to be the best adsorption isotherm with minimum error values and a high coefficient of determination value (R2 > 0.999). The maximum monolayer adsorption capacity observed was 1.83 × 10−4 mol g−1 at 50 °C. Thermodynamic parameters of Gibb’s free energy, enthalpy, and entropy were found to be –30.06 KJ mol−1, 374 J mol−1, and 97.25 J mol−1 K−1, respectively. The positive values of enthalpy and entropy indicate the process to be endothermic. The amount of the dye adsorbed increased from 1.02 to 5.42 × 10−5 g in moving from 30 to 50 °C. The measured energy of activation was 17.467 kJ mol−1. The maximum percent removal of BR-46 from wastewater has been 93% at pH 8.