Comparison study of phosphorus adsorption on different waste solids: Fly ash, red mud and ferric–alum water treatment residues
Ying Wang
,
Yange Yu
,
Haiyan Li
,
Chanchan Shen
DOI:10.1016/j.jes.2016.04.025
Received December 21, 2015,Revised March 31, 2016, Accepted April 05, 2016, Available online July 06, 2016
Volume 28,2016,Pages 79-86
The adsorption of phosphorus (P) onto three industrial solid wastes (fly ash, red mud and ferric–alum water treatment residual (FAR)) and their modified materials was studied systematically via batch experiments. Compared with two natural adsorbents (zeolite and diatomite), three solid wastes possessed a higher adsorption capacity for P because of the higher Fe, Al and Ca contents. After modification (i.e., the fly ash and red mud modified by FeCl3 and FARs modified by HCl), the adsorption capacity increased, especially for the modified red mud, where more Fe bonded P was observed. The P adsorption kinetics can be satisfactorily fitted using the pseudo-second-order model. The Langmuir model can describe well the P adsorption on all of the samples in our study. pH and dissolved organic matter (DOM) are two important factors for P adsorption. Under neutral conditions, the maximum adsorption amount on the modified materials was observed. With the deviation from pH 7, the adsorption amount decreased, which resulted from the change of P species in water and surface charges of the adsorbents. The DOM in water can promote P adsorption, which may be due to the promotion effects of humic-Fe(Al) complexes and the pH buffer function exceeds the depression of competitive adsorption.
