Adsorption removal of ammonium and phosphate from water by fertilizer controlled release agent prepared from wheat straw
2011
Ma, Zuohao | Li, Qian | Yue, Qinyan | Gao, Baoyu | Li, Wenhong | Xu, Xing | Zhong, Qianqian
This paper presents a study of the adsorption of ammonium and phosphate ions from aqueous solution using a new fertilizer controlled release agent (FCRA) which is produced through graft copolymerization with wheat straw, acrylic acid (AA), acrylic amide (AM) and dimethyl diallyl ammonium chloride (DMDAAC). A series of batch experiments were conducted to examine the effects of solution pH, adsorbent dosage, the initial concentration of adsorbate and contact time. The findings indicated that the new fertilizer controlled release agent had a significant effect on the adsorption of ammonium and phosphate ions. The adsorption could reach equilibrium through 4h reaction, and had the best adsorption amount at the pH values from 4 to 8. The adsorption amount increased with the increasing initial concentration of adsorbate. The adsorption amount of NH₄ ⁺ decreased with the increasing of adsorbent dosage while the adsorption of PO₄ ³⁻ showed the opposite trend. Kinetic analysis showed that the adsorption of ammonium and phosphate ions on the new fertilizer controlled release agent followed the pseudo-second-order model well. Equilibrium isotherm data of adsorption of NH₄ ⁺ were well fitted to the linear Langmuir and Freundlich models, while the data of adsorption of PO₄ ³⁻ were well fitted to the Freundlich model. The desorption experiments also showed that the desorption of NH₄ ⁺ and PO₄ ³⁻ on FCRA could reach saturation at the time of 5h and 4h, respectively. And the pH had a large effect on desorption.
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