Application of Langmuir and Freundlich Models in Phosphate Sorption Studies in Soil of Contrasting Parent Materials in South-Eastern Nigeria

Abstract

This study was conducted to determine phosphorus sorption characteristics of five soils from contrasting parent materials in south-eastern Nigeria. The soils were collected from Ikom (basalt), Akamkpa (basement complex), Bende (shale), Amaeke (sand stone) and Umudike (coastal plain sand). The standard P requirements for the soils were calibrated from the sorption curves, and the values were very low ranging from 11.1 mg·kg-1 in Bende to 60.2 mg·kg-1 in Ikom. The P maximum sorption capacity determined by the Freundlich and Langmuir models varied with the locations, and ranged from 65.7 mg·kg-1 in Akamkpa to 516 mg·kg-1 in Bende for the Freundlich model and from 231 mg·kg-1 in Akamkpa to 369 mg·kg-1 in Bende for the Langmuir model. Similarly the P maximum buffering capacity was determined by using the two models. The values varied from 993 mg·kg-1 in Amaeke to 1180 mg·kg-1 in Akamkpa with a mean of 1087 mg·kg-1. The highest bonding energy of P was in Akamkpa with a mean value of 6.05 ml/g and lowest was in Bende with a mean value of 0.76 ml/g. From this study, the P sorption data of the soils conformed better with the Freundlich model than the Langmuir model. Freundlich model is therefore recommended for the soils.