Chitosan-silver nanoparticles composite as point-of-use drinking water filtration system for household to remove pesticides in water

摘要

Adsorption techniques are widely used to remove certain classes of pollutants from water and wastewater. Biosorbents such as natural and waste materials from industries and agriculture can be used as alternatives adsorbents which are inexpensive and easily obtainable. The objective of this study was to prepare silver nanoparticles embedded in chitosan, which is a non-toxic and biodergadeable natural polymer, using microwave irradiation for the removal of pesticides from water. Cross-linked chitosan-silver nanoparticle composite bioadsorbent was prepared in order to investigate the adsorption and release behaviours of the pesticide, Atrazine. The concentration and time dependencies of the adsorbent for the pesticide were studied. The equilibrium time was found to be 65 min for 1, 5, 10, 20 and 25 ppm Atrazine concentration. A sharp increase in percent reduction of the pesticide content was observed in water as the adsorbent dose was increased from 0.5 to 2.0 g. At 2.0 g dosage of cross-linked chitosan-silver nanoparticle composite micro-beads, 98% removal was observed for 1 L of pesticide solution at 1 ppm concentration (1 mg L~(-1)). From the batch studies, the adsorbent capacity of the cross-linked chitosan-silver nanoparticle composite micro-beads toward Atrazine was 0.5 mg g-1 of the adsorbent in 65 min. An on-line filter was made using a column of cross-linked chitosan-silver nanoparticle composite micro-beads and the device was used for pesticide removal for extended periods. From the breakthrough curves, the results of breakthrough adsorption capacity and the total adsorption capacity were, respectively 115 and 360 μg mL-1 cross-linked chitosan-silver nanoparticles composite micro beads.