Document Type : Research Paper


Assistant Professor, Department of Environment, Faculty of Natural Resources, Semnan University, Semnan, Iran


Phosphorus (P) is considered the main cause of eutrophication in natural waters and has received considerable attention recently from the scientific community. In this study, P removal from aqueous solutions was investigated using bentonite, kaolinite, calcite and zeolite mineral adsorbents modified with extract of walnut shell and wheat straw, chitosan, sodium carboxymethyl cellulose (CMC) and malic acid. Phosphorus sorption was evaluated using adsorption isotherms equations. The maximum sorption capacity of P was obtained by modified adsorbents with chitosan (Chitosan- adsorbents). The results showed that P sorption capacity by Chitosan-adsorbents (bentonite (0.35 mg/g), calcite (2.09 mg/g), kaolinite (0.41 mg/g) and zeolite (0.43 mg/g) was improved by ~ 129, 102, 128 and 119%, respectively compared to unmodified adsorbents (bentonite (0.27mg/g), calcite (2.04 mg/g), kaolinite (0.32 mg/g) and zeolite (0.36 mg/g). Langmuir and Freundlich models were used to simulate sorption of P on modified adsorbents. The double layer model (DLM) was able to predict P adsorption by modified adsorbents over a wide pH range and varying ionic strength. Thermodynamic parameters showed that the nature of P adsorption by these adsorbrnts was non-spontaneity nature.


Main Subjects