Fabrication of biopolymers encapsulated hybrid composites beads for nitrate and phosphate removal from water

Abstract

Nitrogen and phosphorus are the essential nutrients which have a significant contribution to biomass growth, energy transport and agricultural fields. However, the reduction of nitrate (NO3 - ) in potable water could lead to an blue baby syndrome (methemoglobinemia). Moreover, the excess NO3 - and phosphate (PO4 3- ) contents in water leads to eutrophication. Hence, NO3 - and PO4 3- remediation is needed for the safe drinking water. The developed toxic ions removal technologies such as reduction, precipitation, biological process, adsorption, membrane process and ion-exchange have been widely utilized for the removal of NO3 - and PO4 3- . Amongst adsorption seems to be most appropriate method. Upto date, the numerous inorganic materials such as metal oxides, clays, natural waste materials, etc., have been applied for the removal of both NO3 - and PO4 3- . Although they possess good adsorption property, the limitations such as swelling nature, pressure drops during filtration and stable colloid forms create aversion to separation from water. To succeed these troubles, by make use of biopolymers encapsulated composites/beads for NO3 - and PO4 3- removal have been focused by the environmental researchers. The biopolymers such as chitosan, alginate, etc., are utilized for the synthesis of new class of hybrid biocomposites/beads. The natural clay materials such as kaolin, bentonite, fly ash, etc., have been applied for toxic ions removal due to their abundance, low cost, eco-friendly and suitable properties for usage. The hybrid biocomposites possess many advantages like biodegradable, biocompatible and non-toxic. At the same time, the quick separation of adsorbent from aqueous solution is a challenging task. The metal ions can act as Lewis acid means that it will ready to bind with Lewis bases such as NO3 - and PO4 3- . The metal ions such as Zr(IV), La(III), Ce(III), etc., can easily co-ordinates with the functional groups of CS and Alg