Nitrate Adsorption on Clay Kaolin: Batch Tests

Morteza Mohsenipour,Shamsuddin Shahid,Kumars Ebrahimi

doi:10.1155/2015/397069

Morteza Mohsenipour, Shamsuddin Shahid + Show 1 more

Open Access

https://doi.org/10.1155/2015/397069

Copy DOI

Abstract

Soils possessing kaolin, gibbsite, goethite, and hematite particles have been found to have a natural capacity to attenuate pollution in aqueous phase. On the other hand, the hydroxyl group in soil increases anion exchange capacity under a low pH condition. The main objective of this paper was to evaluate effects of kaolin on nitrate reduction under acidic condition. In order to analyze the kaolin adsorption behaviour under various conditions, four different concentrations of nitrate, 45, 112.5, 225, and 450 mgNO3-/L, with a constant pH equal to 2, constant temperature equal to 25°C, and exposure period varying from 0 to 150 minutes were considered. The capacity of nitrate adsorption on kaolin has also been studied involving two well-known adsorption isotherm models, namely, Freundlich and Longmuir. The results revealed that approximately 25% of the nitrate present in the solution was adsorbed on clay kaolin. The laboratory experimental data revealed that Freundlich adsorption isotherm model was more accurate than Longmuir adsorption model in predicting of nitrate adsorption. Furthermore, the retardation factor of nitrate pollution in saturated zone has been found to be approximately 4 in presence of kaolin, which indicated that kaolin can be used for natural scavenger of pollution in the environment.

Highlights

Groundwater and soil can be polluted through various anthropogenic activities such as pesticide use and industrial processes [1]
The effect of initial nitrate concentration on equilibrium adsorption was investigated at different initial nitrate concentrations
The increasing rate of nitrate adsorption decelerated with further increase in nitrate concentration

Summary

Introduction

Groundwater and soil can be polluted through various anthropogenic activities such as pesticide use and industrial processes [1]. The breaking of the ecological equilibrium between human being and the nature is the main reason of environmental contamination issue [2]. Since 1970s nitrate leaching to subsoil has become an important environmental quality and human health issue, especially due to high use of nitrogen as nutrient in agriculture [3,4,5]. Inorganic nitrogen is used as an essential fertilizer in intensive agriculture to produce sufficient food for growing population and food security, a substantial part of which infiltrates into subsurface and contaminates soil and groundwater [6,7,8]. Various soil and solution parameters which have an effect on nitrate concentration in porous medium are categorized as follows: ionic strength [16], aluminum oxide concentrations [17], competition with other anions [18], pH of soil solutions [19], soil texture and clay mineralogy [20], and organic matter content [21]

Objectives

Methods

Results

Conclusion