Synthesis of novel Leonardite-PVA-Chitosan nanocomposite hydrogel for nitrate removal from drinking water

With the increasing contamination of groundwater from agriculture and wastewater, the nitrate pollution is being considered as a great threat to the safety of drinking water. Therefore, varieties of technologies, including physical, biological, and chemical removal processes were developed by researchers for nitrate removal from groundwater. The physical–chemical approaches such as reverse osmosis and ion exchange treatment can effectively remove nitrate from water, but potentially generate concentrated waste streams. Biological denitrification is the most commonly used method, but is difficult to maintain, and needs to polish the effluent through purification and disinfection in order to secure thewater quality for potablewater purpose.[1] Nitrate pollution in groundwater shows a great threat to the safety of drinking water.[2] In this study, The Leonardite-PVA-Chitosan nanocomposite hydrogel was prepared via cross linking method and Afterwards a periodic freezing-thawing process and the glutaraldehyde was used as cross linker. It has been found that this nanocomposite hydrogel processed dual functions: surface adsorption and chemical reaction. Nitrate removal rate was affected by the amount of naocomposite hydrogel, initial nitrate concentration, solution pH, reaction temperature, contact time and the presence of anions. Moreover, nitrate removal by Leonardite-PVA-Chitosan nanocomposite hydrogel followed the pseudo-second-order reaction kinetics. The removal rate of nitrate were about 80%, respectively, under the reaction condition of, pH value of 5, and initial nitrate concentration of 20mg/L.