Efficient phosphate removal from water for controlling eutrophication using novel composite adsorbent

Abstract

The excessive phosphate (P(V)) removal is a key factor to control the eutrophication. The ligand based composite adsorbent was fabricated from the stand point of ion-exchange adsorption, eletroselectivity and hydrogen bonding mechanism. The mesoporous silica and ligand embedded composite adsorbent were characterized to understand ordered porosity in the frameworks. The composite adsorbent was protonated before going to start the adsorption by using 2.0 M HCl. In this work, the competitive adsorption of the similar chemical properties and ionic radii of arsenic and phosphate was also evaluated. The adsorbent was exhibited rapid adsorption, significant selectivity and high adsorption capacity. Remarkably, this adsorbent demonstrated the adsorption in low pH area; however, the neutral pH 7.0 was selected to expel the competing ions. The adsorption process was fitted to the Langmuir model, confirming the monolayer coverage and the maximum adsorption capacity were also as high as 159.13 mg/g. The adsorbent clarified the specific selectivity towards the P(V) over the highly competed anions of Cl−, HCO3−, and SO42− according to the strong hydrogen bonding interactions between the divalent HPO42− and the protonated composite adsorbent of NH3+ groups at pH 7.0. Apart from the remarkable P(V) adsorption in terms of high adsorption and immense selectivity, the composite adsorbent was found to be environmental friendly based on the elution process. The adsorbent possessed high reusability in terms of several matrices treatments during the adsorption-elution-reuses cycles. The eluent was selected of the 2.0 M HCl from the consideration of regeneration to the protonated form rather than using NaOH. Therefore, the proposed composite adsorbent was found to be an ideal candidate for P(V) removal in the contaminated wastewater.