Sequestration of As(III) pollutant from water using chemically activated pine cone biomass: evaluation of interaction and mechanism

Abstract

The growing occurrence of As(III) pollutant in surface and ground water has serious implications to human and plant life. Developing and understanding the interaction between priority pollutants and low-cost adsorbent materials is of importance in finding solution to the ever-growing threat of water pollution. In this study, pine cone biomass, an agricultural waste was chemically activated and applied as potential adsorbent for As(III) in water. Effect of sorption parameters such as pH and dose were investigated. Temperature effect on adsorption kinetics and equilibrium studies indicates ligand exchange as the main sorption mechanism with an activation energy of 26.24 kJ/mol. Ligand exchange mechanism was confirmed by FTIR, XPS and pHPZC analysis before and after adsorption and As(III)/NO3 exchange reaction. Effect of ionic strength and anion competition of several environmentally occurring anions on the uptake of As(III) by the adsorbent were also tested. The results showed that As(III) inhibition increased with pH and among the anions, $${\text{PO}}_{4}^{3 - }$$ anions inhibited As(III) ion adsorption strongly while As(III) uptake was slightly increased in the presence of $${\text{CO}}_{3}^{2 - }$$ , $${\text{SO}}_{4}^{2 - }$$ and Cl− anions.