POLYVINYL ALCOHOL/BENTONITE COMPOSITE HYDROGELS FOR DYES REMOVAL

LAURA M. SANCHEZ; ROMINA OLLIER; JIMENA S. GONZALEZ; VERA A. ALVAREZ

Granada

Conferencia; XVI Internatinal Clay Conference; 2017

Dye bearing effluents have become an important environmental hazard. In various industrial productions, such astextiles and leather, the dyeing processes are among the most polluting industrial processes because they produceenormous amounts of coloured wastewaters. It has been reported that that more than around 10,000 tons of syntheticdyes are produced every year worldwide. And the estimated amount of dyes discharged in the environmentare thought to be 1-2% loss during production, and 1-10% loss during uses [1]. Moreover, in addition to theircolour, some of these dyes may degrade to highly toxic and dangerous subproducts.Hydrogels are three-dimensional polymeric networks capable of imbibing large quantities of water in their structures.Polymer hydrogels have gained attention in many applications due to their unique water absorption alongwith its retention capacity. However, the use of hydrogels is restricted in some applications because of their poorstability and mechanical properties. Polymer/clay nanocomposite hydrogels have been developed to improve theseproperties. It is well-known that polymeric nanocomposites reinforced with clays show valuable improvements intheir mechanical properties, heat resistance and gas permeability, regarding conventional micro and macrocompounds.This is due to the large contact area between the matrix and the filler [2]. In addition, composite hydrogelsthat contain clays have shown being useful to do separations in a broader range of work conditions when comparedto those needed by the clays themselves [3]. Besides, bentonite is an abundant and low cost smectite-type clay inArgentina.The general objective of this work is to obtain composite hydrogels suitable to be used as absorbents for thedyes removal. Thus, composite hydrogels will be prepared employing polyvinyl alcohol (PVA) and bentonite asraw materials through a previously optimized physical crosslinking method (through freezing/thawing cycles, anon-toxic and relatively simple method), avoiding the use of potentially damaging components [4-5].The performance of the resulting nanocomposite hydrogels will be tested to remove methyleneblue, which is acationic dye. Removal efficiencies and adsorption kinetics will be compared with the respective polymeric matrixand bentonite by themselves.