Preparation And Properties Of Superabsorbnent Composites Based On Organo-zeolites

Superabsorbents,as a sort of functional polymers,can absorbent and retain a significant amount of water.Owing to its excellent characteristics,superabsorbents have been considerably utilized in many areas,such as agriculture,mechine,and sanitary goods.However,conventional superabsorbents based on synthetic polymers,e.g.poly(acrylic acid),have high production cost,poor saline resistance,and be hardly biodegraded in soil.Such drawbacks restrict its application,especially in the horticulture and agriculture.This study is focused on the current situation in the Tianjin Binhai area,such as shortness of water,high salinity in soil,and poor water holding capacity.Aim at reducing the production cost,improving the saline resistance and water holding capacity,zeolite 4A and mordenite were introduced into the polymerization to prepare starch-g-poly(acrylic aicd)/organo-zeolite 4A and starch-g-poly(acrylic acid)/organo-mordenite superpabsorbent composites.The study showed that cetyltrimethylammonium bromide(CTAB)as modifier would effectively make the particles of zeolites dispersed well.Aqueous solution graft polymerization was used to get starch-g-poly(acrylic acid)/organo-zeolite 4A.Under optimized condition,the water absorbency was 510 g/g,and the 0.9% saline absorbency was 45 g/g.Inverse suspension polymerization was employed to prepare starch-g-poly(acrylic acid)/organo-mordenite.Under optimized condition,the water absorbency was 655 g/g,and the 0.9% saline absorbency was 75 g/g.The analysis of XRD,FTIR,and SEM showed that the surface of starch-g-poly(acrylic acid)/organo-zeolite 4A was quite rough with many proes;starch-g-poly(acrylic acid)/organo-mordenite was spherical particle with many folds on its surface.What's more,zeolites can be dispersed homogeneously as crossliner during the polymerization.TG results were indicated that starch-g-poly(acrylic acid)/organo-4A zeolite superabsorbent composite had excellent thermal stability,but the thermal stability had a little decreasing according to starch-g-poly(acrylic acid)/organo-mordenite.The saline resistance,swelling-reswelling-swelling times,and water-holding capacity of the two superabsorbent compoites were improved by dopped the zeolites into composites.The two superabsorebent composites had repeatbale swelling-deswelling capacity in distilled water and 0.1 mol/L NaCl solutions,indicating that they can be treated as smart materials.The swelling kinetics in 0.1% NaCl solution were studied by conductivity method,showing that the two superabsorbent composites would not absorb sodium chloride until their welling ratio reached a certain value,and a hyteresis phenomenon took place during swelling process.In this paper,compared with agricultural superabsorbent,the two superabsorbent composites had higher water absorbency and 0.9% saline absorbency.In the end,the application of the two superabsorbent composites in the saline soil was discussed.The experimental results showed that the two superabsorbent composites can play a positive role on increasing the absorbability of soil,decreasing salinization,and adjustment pH value.