Novel thin film composite membrane fabricated by mixed matrix nanoclay/chitosan on PVDF microfiltration support: Preparation, characterization and performance in dye removal

Abstract

Novel thin film composite (TFC) membrane was prepared by organoclay/chitosan nanocomposite coated on the commercial polyvinylidene fluoride (PVDF) microfiltration membrane. The procedure was set to prepare a PVDF/chitosan TFC membrane without applying a cross-linker agent. Various quantities of two different grades of organoclay (Cloisite 15A and 30B) were added into chitosan solution to find the optimum value and to compare the effect of organic modifier of clay nanoparticles on the prepared TFC characteristics. The membranes were examined with aqueous dye solution regarding to the performance qualification. The results showed that formation of coating layer decreased the water flux in all the prepared TFC membranes. Methylene blue dye removal increased with applying organoclay particles in chitosan coating. Cloisite 15A and 30B showed different properties in elimination of various dyes as well as alteration of feed acidity. The morphology of fabricated TFC membranes was compared to each other using scanning electron microscopy (SEM). The coating layer containing Cloisite 30B was denser rather than that of Cloisite 15A. X-ray diffraction pattern of prepared nanocomposites containing organoclay and chitosan indicated greater d-spacing for Cloisite 15A rather than 30B. The investigation of functional groups in clay/chitosan nanocomposite coating was performed by Fourier transform infrared spectroscopy (FTIR). The chemical structure (functional groups) of prepared TFC membranes offered adsorption as dominating dye removal mechanism.