Sulfonated polyvinyl chloride fibers for cation-exchange microextraction

Ionic transport properties improvement of a new cation-exchange membrane containing functionalized CNT as a clean technology for refining of saline-liquids

In the present research, a novel kind of homogeneous cation-exchange membranes were provided by solution casting technique via blending of sulfonated polyvinylchloride (SPVC) and sulfonated poly phenylene oxide (SPPO). The performance of the membranes was evaluated by membrane potential, areal resistance, transport number, ionic permeability, ion-exchange capacity, fixed ion concentration, energy consumption (EC), current efficiency, mechanical properties, membrane oxidative stability, water contact angle and water content tests. The microstructures of the membranes were investigated by scanning electron microscopy. Membrane with 70:30 (w/w) composition (SPPO: SPVC) exhibited suitable efficiency, mechanical strength and oxidative stability in comparison with other samples in this study. Also, amino groups have been successfully attached to the multi-walled carbon nanotubes (MWCNTs) structure and the modified MWCNTs were selected as filler additive. The results revealed that a series of membranes with improved transport properties, hydrophilicity and EC can be prepared with the polymeric matrix-containing aminated-MWCNTs.

Chemically Modified Polyvinyl Chloride for Removal of Thionine Dye (Lauth's Violet)

The chemical modification of hydrophobic polymer matrices is an alternative way to elchange their surface properties. The introduction of sulfonic groups in the polymer changes the surface properties such as adhesion, wettability, catalytic ability, and adsorption capacity. This work describes the production and application of chemically modified polyvinyl chloride (PVC) as adsorbent for dyes removal. Chemical modification of PVC was evaluated by infrared spectroscopy and elemental analysis, which indicated the presence of sulfonic groups on PVC. The chemically modified PVC (PVCDS) showed an ion exchange capacity of 1.03 mmol⁻¹, and efficiently removed the thionine dye (Lauth’s violet) from aqueous solutions, reaching equilibrium in 30 min. The adsorption kinetics was better adjusted for a pseudo second order model. This result indicates that the adsorption of thionine onto PVCDS occurs by chemisorption. Among the models for the state of equilibrium, SIPS and Langmuir exhibited the best fit to the experimental results and PVCDS showed high adsorption capacities (370 mg⁻¹). Thus, it is assumed that the system presents homogeneous characteristics to the distribution of active sites. The modification promoted the formation of surface characteristics favorable to the dye adsorption by the polymer.