Dye adsorption properties of poly(p-phenylene terephthalamide)-embedded hollow fiber composite membranes

Abstract

Hollow fiber composite (HFC) membrane with improved dye adsorption properties was prepared by the embedding of poly(p-phenylene terephthalamide) (PPTA)/polysulphone (PSF) microparticles into the polyamide (PA) composite layer of PSF hollow fiber membrane. As the polymer raw material of Aramid-1414, high modulus and hydrophilic PPTA was polycondensated in situ in PSF system and PPTA/PSF microparticles were obtained by the cloud-point precipitation method. PSF hollow fiber membrane was fabricated by the dry-jet wet-spinning technique. The variations of membrane morphology, porosity, surface charge and hydrophilicity were evaluated by the scanning electron microscope (SEM) observation, dry-wet mass difference, Zeta potential and water contact angle (WCA) measurements. The adsorption thermodynamic and kinetic processes of different kinds of dyes including anionic dye (Congo red, CR) and cationic dye (methylene blue, MB) were thoroughly investigated by three typical typical sorption isotherm models and two classical kinetic models, respectively. Compared with the PSF hollow fiber membrane and the pristine HFC membrane, the surface roughness, hydrophilicity and electronegativity had an obvious enhancement. The PPTA-embedded HFC membrane presented an increased dye adsorption capacity. The adsorption isotherms for CR and MB of the PPTA-embedded HFC membrane could fit well with the Langmuir and Sips models. The adsorption kinetics for CR and MB are in good agreement with the pseudo-first-order model and pseudo-second-order model, respectively. The prepared PPTA-embedded hollow fiber composite membranes are expected to be a promising candidate for the treatment of textile dyeing wastewater.